The researchers examined antioxidant activity using DPPH, hydrogen peroxide, superoxide dismutase and ABTS assays. The essential oil produced pronounced scavenging activity across all four tests, according to the study summary. Because the available report does not provide assay-specific numerical results, it does not allow direct comparison of the magnitude of activity among the four methods or calculation of an overall effect size.

The summary also does not report the detailed chemical composition of the tested oil, limiting attribution of the measured effects to particular constituents. The cancer-cell experiment used KB, a human oral carcinoma cell line. MTT testing covered concentrations ranging from 6.25 to 100 µg/mL, a 16-fold span between the lowest and highest doses.

The reported IC50 was 22.8 µg/mL, while viability declined as the oil concentration increased. The investigators described this pattern as significant, concentration-dependent cytotoxicity and considerable antiproliferative activity. Their separate membrane-damage assessment also indicated an effect on KB cells, although the supplied summary does not identify the procedure or provide quantitative membrane results.

The authors proposed that the oil’s many bioactive components, including functional groups associated with free-radical scavenging and inhibition of cancer cells, may account for the observed activity. The results therefore support further investigation of Piper betle leaf essential oil as a material with laboratory-measured antioxidant and cytotoxic activity, not a conclusion that it acts as a therapeutic anticancer agent. This was a laboratory study conducted in vitro, with testing in chemical assay systems and one cultured human cancer cell line.

It did not evaluate treatment of cancer in animals or humans, and the supplied evidence does not establish effects on normal cells, selectivity between cancer and non-cancerous cells, absorption, dosing, safety, efficacy or clinical benefit. No basis is provided for recommending ingestion, inhalation or topical use of the essential oil. Taken together, the findings offer a preliminary experimental signal across four free-radical-scavenging assays and KB-cell viability and membrane assessments, while questions about composition, mechanism, selectivity and translation to living organisms remain unresolved.

Subject of Research: In vitro antioxidant and cytotoxic testing of Piper betle leaf essential oil

Article Title: In vitro assessment of the free radical scavenging and cytotoxic activities of Piper betle leaf essential oil

Article References: Janani, P., Anju, A., Anjana, A., Babu, R. D., & Meiyalagan, V. (2026). In vitro assessment of the free radical scavenging and cytotoxic activities of Piper betle leaf essential oil. Medical Oncology, 43(11), Article 336. https://doi.org/10.1007/s12032-026-03462-9

Image Credits: AI Generated

DOI: 10.1007/s12032-026-03462-9

Keywords: Piper betle, leaf essential oil, free-radical scavenging, antioxidant assays, oral carcinoma, KB cells, cell viability, cytotoxicity, MTT assay, in vitro research, vitro, assessment

The rationale behind the study lies in a fundamental biological balancing act. Cells constantly produce reactive oxygen species, or ROS, as byproducts of normal metabolism, particularly in the mitochondria where electron leakage from the respiratory chain generates superoxide radicals. When antioxidant defenses fail to keep pace, these reactive species accumulate and attack lipids, proteins, and DNA, a state known as oxidative stress. Chronic oxidative stress has been implicated in an astonishingly broad range of conditions, from Alzheimer’s and Parkinson’s disease to cancer, depression, obesity, and cataracts, which is why chemists around the world are racing to develop more powerful and selective antioxidant molecules.

The research team focused on a class of compounds called hydrazide-hydrazones, which are built around an azomethine linkage formed by condensing aldehydes with primary amines. Schiff bases of this kind are prized in medicinal chemistry because the imine bond promotes extended pi-conjugation and electron delocalization, allowing radicals to be stabilized and quenched efficiently. When phenolic hydroxyl groups sit close to this linkage, they enable hydrogen atom transfer and single electron transfer mechanisms, the two dominant pathways by which small molecules neutralize free radicals. These scaffolds can also chelate pro-oxidant transition metals such as iron and copper, blocking the Fenton reactions that generate the notoriously destructive hydroxyl radical.

What makes the new study distinctive is its modular design. The researchers attached hydroxyl-substituted aromatic aldehydes to a pyrrole core bearing five different amino acid scaffolds: glycine, beta-alanine, isoleucine, phenylalanine, and tryptophan. Each amino acid was chosen for a specific purpose. Glycine and beta-alanine add flexible polar groups that improve water solubility, isoleucine contributes hydrophobic branching that may help the molecules cross cell membranes, phenylalanine enables pi-stacking interactions with radical species, and tryptophan brings an indole ring that is itself a formidable peroxyl radical scavenger. The pyrrole ring serves as the main radical-trapping unit, while the hydrazone nitrogen-hydrogen group loses a proton to form a stable, resonance-delocalized radical across the molecule.

The synthesis itself was strikingly efficient. By refluxing equimolar amino acid hydrazides with the aldehyde derivatives in glacial acetic acid for just one hour, the team obtained all twenty target compounds as crystalline solids in yields ranging from 83 to 95 percent. Every compound was rigorously characterized by infrared spectroscopy and both proton and carbon-13 nuclear magnetic resonance, with diagnostic signals confirming the imine linkage, the phenolic hydroxyl groups, and the intact pyrrole core. Sharp melting points between 168 and 251 degrees Celsius indicated pure, stable crystalline forms suitable for biological testing.

Antioxidant performance was assessed using two complementary assays. The DPPH test measures the ability of a compound to donate a proton to a stable violet-colored free radical, while the ABTS test probes electron transfer by monitoring the decolorization of a blue-green radical cation. The results revealed a clear structure-activity relationship. Tryptophan-derived compounds dominated the rankings, with beta-alanine derivatives close behind, while glycine analogs lacking a side chain performed worst, with inhibitory concentrations often exceeding 200 micromolar. The aldehyde component mattered just as much: derivatives bearing catechol-like arrangements of adjacent hydroxyl groups, specifically the 2,3,4- and 2,4,5-trihydroxy patterns, dramatically outperformed compounds whose hydroxyl groups were arranged differently, because adjacent hydroxyls facilitate resonance stabilization of the resulting phenoxyl radical and more efficient hydrogen atom donation.

TrpOH-3, which pairs the tryptophan scaffold with a 2,4,5-trihydroxybenzaldehyde fragment, emerged as the undisputed champion of the series. Three other compounds, TrpOH-4, BAlaOH-3, and PheOH-2, also matched or beat Trolox in both assays, confirming that the design principles were sound rather than a lucky outlier. The indole ring of tryptophan appears to be the key differentiator, providing an additional electron-rich system that stabilizes radical intermediates and supports both proton and electron transfer simultaneously.

To explore whether the lead compound could do more than simply mop up radicals, the team turned to molecular docking against the Keap1 Kelch domain, a protein that acts as a cellular brake on the Nrf2 pathway, the master regulator of the body’s own antioxidant defenses. Disrupting the Keap1-Nrf2 interaction releases Nrf2 to activate genes for protective enzymes such as those that produce glutathione. TrpOH-3 docked into the Keap1 binding pocket with a competitive score of minus 6.25 kilocalories per mole, forming direct hydrogen bonds with Ser602 and Tyr525, a water-mediated bond with Ser363, and an unusual directional halogen bond between its bromine substituent and Tyr334. This multifaceted interaction profile suggests the molecule mimics key contacts at the natural Keap1-Nrf2 interface, positioning it as a promising non-covalent inhibitor scaffold.

Computational pharmacokinetic predictions using the QikProp module painted a nuanced picture of the lead compound’s drug-likeness. TrpOH-3 violates Lipinski’s rule of five in only one parameter, molecular weight, which at 645.5 daltons exceeds the conventional 500-dalton threshold. That heft, combined with three free polar hydroxyl groups, limits passage through biological membranes, yielding a predicted human oral absorption of just 56 percent and poor penetration of the blood-brain barrier, a potential drawback for central nervous system applications. The octanol-water partition coefficient of 4.65 and other descriptors fall within acceptable pharmaceutical ranges, so the main optimization challenge is clear: trim the molecular weight without sacrificing the radical-scavenging machinery.

The study demonstrates how modern drug discovery can weave together synthesis, biological assays, structure-activity analysis, docking, and ADME prediction into a single rational workflow. By identifying tryptophan scaffolds and catechol-type hydroxyl patterns as the winning combination, and by validating a plausible mechanism of action at the Keap1-Nrf2 interface, the researchers have delivered a versatile lead compound for developing next-generation antioxidants aimed at neurodegeneration and inflammation. The team’s next steps include preparing structural analogs with improved permeability, running enzyme inhibition assays, and validating the most promising candidates in living systems, a pipeline that could eventually translate these laboratory champions into real therapies for oxidative stress-related disorders.

Subject of Research: Design and antioxidant evaluation of novel pyrrole-based hydrazide-hydrazone compounds

Article Title: Design, synthesis, antioxidant activity, SAR, molecular docking, and ADME studies of novel hydroxyl-derived compounds

Article References: Mateev, E., Tzankova, D., Karatchobanov, V., Irfan, A., Pepeldzhiyska, E.-M., Kostov, S., & Zlatkov, A. (2026). Design, synthesis, antioxidant activity, SAR, molecular docking, and ADME studies of novel hydroxyl-derived compounds. Pharmacia, 73, Article e194529. https://doi.org/10.3897/pharmacia.73.e194529

Image Credits: AI Generated

DOI: 10.3897/pharmacia.73.e194529

Keywords: antioxidants, hydrazide-hydrazones, pyrrole, tryptophan, free radicals, DPPH assay, ABTS assay, molecular docking, Keap1-Nrf2, oxidative stress, structure-activity relationship, ADME

The team, publishing in the journal Pharmacia, collected fresh Sargassum polycystum from the east coast of Pangandaran at coordinates 7°42’22.5″S, 108°39’50.3″E, and had the material authenticated as Sargassaceae by the Herbarium Jatinangor at Universitas Padjadjaran. Forty kilograms of fresh algae were cleaned, dried at 40 °C for 24 hours, ground, and sieved, yielding just 2.6 kilograms of dried powder, a dry-material recovery of 6.50 percent. Crucially, a single common batch of this powder fed both extraction experiments, ensuring that any differences between the two methods reflected processing rather than raw-material variability.

Sargassum polycystum is a chemically rich target. Like other brown algae, it contains phlorotannins and other phenolic compounds capable of donating electrons or hydrogen atoms to neutralize free radicals, along with flavonoids, pigments, polysaccharides, and sterol-related metabolites. Brown algal cell walls, however, are formidable barriers: alginates, sulfated polysaccharides, cellulose, and proteins restrict solvent penetration and can slow the release of intracellular constituents. This structural complexity means that a high extraction yield, which simply measures total soluble mass, may largely reflect dissolved polysaccharides, salts, and pigments rather than the phenolic and flavonoid constituents that drive antioxidant quality.

To disentangle these effects, the researchers ran two independent three-factor, three-level Box–Behnken designs, each with 15 extraction runs including three independently prepared center points to estimate pure experimental error. Reflux extraction was tested across temperatures of 50 to 70 °C, durations of 1 to 3 hours, and solid-to-solvent ratios of 1:5 to 1:15, with particle size fixed at 60 mesh and 96 percent ethanol as the solvent. Maceration, the gentle room-temperature alternative, was tested across 24 to 72 hours, particle sizes of 40 to 80 mesh, and the same ratio range at 25 ± 2 °C. Four responses were tracked for every run: extraction yield, total phenolic content (TPC), total flavonoid content (TFC), and radical-scavenging potency expressed as the DPPH IC50, the concentration needed to quench half of the DPPH radicals in the assay.

The observed ranges told the first part of the story. Reflux produced yields of 5.46 to 15.38 percent, with the maximum at 60 °C, 2 hours, and a 1:10 ratio, while maceration spanned 2.01 to 15.30 percent, peaking after 72 hours at 60 mesh and 1:15. But the quality responses inverted the picture. Maceration achieved the highest phenolic content of the entire study, 62.98 mg gallic acid equivalents per gram of extract, and by far the strongest DPPH activity, with an IC50 of just 36.19 µg/mL, both at 24 hours, 80 mesh, and 1:10. Reflux peaked at 53.05 mg GAE/g and an IC50 of 98.66 µg/mL, notably at its mildest condition of 50 °C and 1 hour. In both designs, the recipe for maximum yield was a different recipe from the recipe for maximum antioxidant quality.

The statistical models behind these observations were robust. All eight response models, four per method, were significant, with p-values ranging from 0.001 to 0.006, and lack-of-fit tests were non-significant throughout, indicating the second-order models adequately represented the design space. R² values ranged from 81.78 to 99.16 percent. The dominant factors were revealing: extraction temperature carried the largest F-values among the reflux factors, while extraction time dominated every maceration response. The researchers also flagged an important caveat, noting that predicted R² values for the bioactive responses were substantially lower than adjusted R² values, particularly for reflux, signaling limited out-of-sample precision for TPC, TFC, and IC50 even when the models fit the observed data well.

Desirability-based multi-response optimization then translated the models into recommended operating points. For reflux, the optimum landed at 50.404 °C, 1.0404 hours, and a ratio of approximately 1:9.55, with a composite desirability of 0.663. Validation runs using three independently prepared extractions delivered a 10.32 percent yield, 39.68 mg GAE/g TPC, 33.24 mg QE/g TFC, and an IC50 of 109.25 µg/mL, all within the corresponding 95 percent confidence and prediction intervals. For maceration, the optimum was 24 hours, 80 mesh, and roughly 1:5.30, with a higher composite desirability of 0.704. Validation produced a 5.54 percent yield, 59.39 mg GAE/g TPC, 38.03 mg QE/g TFC, and an IC50 of 55.66 µg/mL, again within intervals, though the maceration IC50 prediction interval was wide, reflecting genuine uncertainty in that estimate.

The most consequential insight emerged when the team normalized results to the starting biomass rather than to the extract itself. Because the optimized maceration extract was more concentrated but obtained at lower yield, reflux actually recovered more total antioxidant-related material per unit of seaweed: an estimated 409.50 mg of gallic acid equivalents and 343.04 mg of quercetin equivalents per 100 grams of dry algae, versus 329.02 and 210.69 mg respectively for maceration. In other words, the choice between methods is not a simple ranking but a decision about the goal. If the priority is a concentrated, potent extract per gram, maceration wins. If the priority is stripping the maximum phenolic and flavonoid payload from a given harvest of biomass, reflux wins, provided temperature and duration are kept mild to protect thermolabile constituents.

The mechanistic explanation fits the physics of each process. Reflux accelerates mass transfer through controlled heating and continuous solvent condensation, but heat is a double-edged sword, since elevated temperatures and prolonged exposure can degrade phenolic and flavonoid structures. That is why reflux quality peaked at its gentlest setting. Maceration relies on passive diffusion, and grinding the seaweed to 80-mesh powder shortened diffusion pathways and increased contact area, allowing phenolics to be recovered within 24 hours. Extending maceration to 72 hours pulled more total soluble material into solution, inflating yield, but the additional mass was evidently not proportional phenolic content, and prolonged contact risks oxidation or degradation of compounds already released.

The authors are careful about the limits of their claims. Qualitative phytochemical screening of representative extracts confirmed reagent-reactive phenolics, flavonoids, tannins, saponins, and steroidal or triterpenoid constituents, with alkaloid reactions depending on the reagent used, but these colorimetric and precipitation tests are group-level indicators, not compound identifications. The Folin–Ciocalteu and aluminum chloride assays quantify equivalent classes rather than specific phlorotannins, and DPPH measures chemical radical scavenging under defined solvent conditions, not activity in living cells. The team recommends chromatographic profiling by HPLC-DAD or LC-MS to link process conditions to individual constituents, additional assays such as ABTS, FRAP, or ORAC to broaden the antioxidant picture, and quantification of residual solvent in future standardization work.

Even with those caveats, the study offers a practical blueprint for a growing industry. Indonesia’s extensive tropical coastline holds substantial Sargassum resources, and brown algae are increasingly pursued for antioxidant, anti-inflammatory, antidiabetic, and neuroprotective applications. The finding that reflux and maceration should be treated as complementary rather than interchangeable options, each with its own validated optimum, gives process developers a defensible starting point. The researchers suggest that future work should explore assisted extraction technologies and green-process metrics, including solvent consumption and energy demand, to push these conventional methods toward more sustainable production. For now, the message from Pangandaran is clear: in seaweed chemistry, what you extract and how much you extract are two different questions, and answering only one of them can leave the real prize in the pot.

Subject of Research: Multi-response optimization of reflux and maceration extraction of bioactive compounds from the brown alga Sargassum polycystum

Article Title: Parallel multi-response optimization of reflux and maceration extraction of Sargassum polycystum from the east coast of Pangandaran using Box–Behnken design

Article References: Susanti, S., Fisabilah, A., Kamil, I., Adlina, S., Rizkuloh, L. R., Mardianingrum, R., & Singgih, M. (2026). Parallel multi-response optimization of reflux and maceration extraction of Sargassum polycystum from the east coast of Pangandaran using Box–Behnken design. Pharmacia, 73, Article e209685. https://doi.org/10.3897/pharmacia.73.e209685

Image Credits: AI Generated

DOI: 10.3897/pharmacia.73.e209685

Keywords: Sargassum polycystum, brown algae, extraction optimization, response surface methodology, Box–Behnken design, antioxidant activity, total phenolic content, total flavonoid content, DPPH assay, reflux extraction, maceration, Pangandaran

The team, led by Hadia Kellil of Abbes Laghrour University of Khenchela together with colleagues from Ferhat Abbas University of Setif 1 and partner institutions, used a classic fractionation strategy that exploits the differing solubilities of plant molecules. A crude methanolic extract served as the starting point, from which a chloroform fraction, an ethyl acetate fraction, and a residual aqueous phase were separated. A fifth preparation, a decoction extract, mimicked the traditional practice of boiling nettle in water, the way herbalists and home cooks have prepared the plant for generations. By comparing these five preparations side by side, the researchers could ask a deceptively simple question with major practical implications: which way of extracting nettle delivers the most useful medicine?

The phytochemical profiling told a clear story about where the plant’s power resides. The ethyl acetate fraction and the chloroform fraction were the richest in total phenolics, containing 44.27 and 42.26 milligrams of gallic acid equivalents per gram of extract respectively, and also led on flavonoids, with 3.83 and 2.46 milligrams of quercetin equivalents per gram. The methanolic extract, by contrast, carried the greatest load of tannins, at 26.34 milligrams of tannic acid equivalents per gram. These numbers matter because phenolic compounds and flavonoids are the molecules most often credited with the antioxidant behavior of medicinal plants, donating electrons or hydrogen atoms to neutralize reactive species before they can damage lipids, proteins, and DNA in living tissue.

Antioxidant capacity was then assessed using a battery of four complementary assays, a deliberate design choice that reflects a growing consensus in the field. No single test can capture the full complexity of antioxidant action, since each probe responds to a different mechanism and a different class of radical or oxidant. The researchers employed the DPPH radical scavenging assay, which tracks the ability of extracts to quench a stable synthetic free radical; the ferric reducing power assay, which measures the capacity to donate electrons; the beta-carotene bleaching inhibition assay, which models the protection of lipids against oxidative attack; and a ferrous ion chelation assay, which tests whether compounds can bind transition metals that would otherwise catalyze the formation of the most destructive radicals in biological systems.

The results of this four-pronged analysis were strikingly solvent-dependent. In the DPPH assay, the chloroform fraction emerged as the standout performer, with an IC50 value of 93.88 micrograms per milliliter, followed by the aqueous phase at 150.89 micrograms per milliliter. Those same two preparations also showed notable inhibition of beta-carotene bleaching, reaching about 37 percent, indicating a genuine capacity to shield fatty molecules from peroxidation. Reducing power was highest in the ethyl acetate fraction and the aqueous phase, while the decoction extract and the methanolic extract proved the most effective at chelating ferrous ions. Taken together, the data show that no single extract wins across the board; instead, different preparations excel at different lines of antioxidant defense, from direct radical scavenging to metal sequestration.

The anti-inflammatory findings were arguably the most dramatic. In vitro, the methanolic extract inhibited heat-induced protein denaturation by 90 percent, a laboratory model widely used as a first screen because protein denaturation is thought to contribute to inflammatory diseases ranging from rheumatoid arthritis to diabetes. More importantly, the team took the work into a living system, using the PMA-induced ear edema model in mice, in which a chemical irritant applied to the ear triggers acute inflammatory swelling. The methanolic extract reduced that swelling by up to 89.06 percent, an effect size that places it among the more impressive performances reported for plant extracts in this type of assay. The researchers note that the methanolic extract’s high tannin content may underpin this activity, since tannins are known to interact with proteins and modulate inflammatory cascades.

The in vivo experiments were conducted under ethical oversight consistent with the guidelines of the Algerian Association of Sciences in Animal Experimentation, and the mice used in the study were sourced from the Pasteur Institute of Algeria. The authors also align their work with the modern emphasis on the responsible use of animals in research, keeping the animal component focused on the single edema model that could validate the in vitro signals. That careful staging—chemistry first, test-tube biology second, animal validation last—is exactly the pathway that regulatory agencies and pharmacologists expect when a traditional remedy is being evaluated for modern drug development potential.

Why does geography matter here? The nettle in this study grew in a semi-arid climate, an environment characterized by water stress, intense sunlight, and temperature extremes. Plants under such conditions typically ramp up production of phenolic secondary metabolites as part of their own photoprotective and defensive machinery, since these molecules absorb ultraviolet radiation and quench the reactive oxygen species generated by drought and heat stress. That ecological logic appears to pay off for the Algerian nettle, whose phenolic yields compare favorably with figures reported for the species in more temperate settings. The finding adds to a growing body of evidence that the climate and habitat of a medicinal plant can materially shape its pharmacological value, a consideration that could inform future cultivation programs aimed at standardizing herbal raw materials.

The broader context is a plant with an already impressive dossier. Stinging nettle has been documented in prior research as an antioxidant, an antihistamine in allergic rhinitis trials, a modulator of blood pressure and oxidative stress in hypertensive rats, and a source of antimutagenic protein fractions. The European Medicines Agency’s herbal committee maintains a monograph covering the herb, reflecting its long and accepted role in European herbal medicine. What the new Algerian study adds is a systematic, head-to-head comparison of extraction strategies, giving formulators and researchers a practical map of which solvent system to choose depending on whether the target application calls for radical scavenging, lipid protection, metal chelation, or anti-inflammatory action. For a plant that many gardeners curse as a weed, the accumulating science paints a very different picture: a chemical arsenal fine-tuned by harsh environments and waiting to be harnessed.

The authors are careful not to overclaim. Their conclusions emphasize that Urtica dioica extracts are rich in phenolic compounds and possess significant antioxidant and anti-inflammatory properties, without asserting clinical efficacy in humans. The road from a mouse ear edema model to a validated therapeutic is long, and future work will need to identify the individual active molecules, establish safe and effective doses, and test the findings in well-designed human studies. Still, the study offers a compelling proof of concept and a methodological template for evaluating other traditional plants growing in marginal climates. In an era when inflammatory and oxidative stress-related diseases dominate global health burdens, and when the search for new bioactive scaffolds increasingly turns back to the plant kingdom, the sting in the nettle’s tail may turn out to be its greatest asset after all.

Subject of Research: Antioxidant and anti-inflammatory bioactivity of solvent extracts of Urtica dioica from a semi-arid climate

Article Title: Bioactive potential of various extracts of Urtica dioica (Urticaceae) in a semi-arid climate: phytochemical analysis and evaluation of antioxidant and anti-inflammatory properties

Article References: Kellil, H., Kada, S., Hamdellou, A., Addad, D., Mohguen, K., Charef, N., Baghiani, A., & Arrar, L. (2026). Bioactive potential of various extracts of Urtica dioica (Urticaceae) in a semi-arid climate: phytochemical analysis and evaluation of antioxidant and anti-inflammatory properties. Plant Biosystems, 160(5), Article 292. https://doi.org/10.1007/s44473-026-00315-1

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00315-1

Keywords: Urtica dioica, stinging nettle, polyphenols, flavonoids, tannins, antioxidant activity, anti-inflammatory activity, phytochemistry, DPPH assay, protein denaturation, ear edema model, semi-arid climate

The central finding is striking: the parts of the parsnip that most people throw away are precisely the parts richest in bioactive compounds. Among the edible tissues, the skin of the ‘Warrior’ cultivar recorded the highest flavonoid content, at 15.27 milligrams of catechin equivalents per 100 grams of fresh weight. Among the inedible tissues, ‘Warrior’ leaves topped the chart for phenolic content, reaching 525.17 milligrams of gallic acid equivalents per 100 grams of fresh weight. These numbers matter because phenolic compounds and flavonoids are among the most studied classes of plant secondary metabolites, valued for their capacity to neutralize reactive oxygen species and modulate inflammatory signaling pathways in human cells.

Antioxidant activity in the study was assessed using two widely accepted colorimetric assays, DPPH and ABTS, each of which measures the ability of plant extracts to scavenge synthetic free radicals in solution. The DPPH assay relies on the reduction of a stable nitrogen-centered radical, which changes color from deep purple to pale yellow as antioxidants donate electrons or hydrogen atoms. The ABTS assay works on a similar principle, generating a green-blue radical cation that is decolorized by antioxidant molecules. When the researchers ran these assays on extracts from different parsnip tissues, the results tracked closely with the distribution of phenolic compounds, reinforcing a long-standing observation in food chemistry that total phenolic content is often a reliable predictor of radical-scavenging capacity.

Cultivar differences emerged as a consistent theme throughout the data. The ‘Warrior’ cultivar generally exhibited higher total flavonoid content, higher total phenolic content, and stronger antioxidant activities than ‘Albion’ across the tissues examined. This kind of genotype-dependent variation is well documented in other vegetables; comparable studies of onions, blueberries, and aronia berries have all shown that polyphenol profiles can differ substantially between cultivars grown under identical conditions. For breeders and food scientists, the implication is that cultivar selection is not merely a matter of yield, texture, or flavor, but also a lever for enhancing the nutritional and functional value of a crop.

The anti-inflammatory experiments took the investigation a step further, moving from chemical assays into living cells. The team used RAW 264.7 macrophages, a mouse cell line that has become a standard model for studying inflammatory responses in vitro. These immune cells were stimulated with lipopolysaccharide, or LPS, a molecule derived from the outer membrane of Gram-negative bacteria that triggers a potent inflammatory response, including the production of nitric oxide and a burst of intracellular reactive oxygen species. Nitric oxide, while serving important signaling functions at low concentrations, contributes to tissue damage and inflammatory pathology when overproduced by activated macrophages, making its inhibition a key benchmark for anti-inflammatory activity.

Against this backdrop, ‘Warrior’ parsnip skin extract delivered the study’s most compelling result. The skin extract showed the strongest anti-inflammatory activity of all the tissues tested, suppressing both nitric oxide production and the generation of intracellular reactive oxygen species in the LPS-stimulated macrophages. This dual action is significant because oxidative stress and inflammation are tightly intertwined processes; reactive oxygen species can activate inflammatory signaling cascades, and inflammatory enzymes in turn generate more free radicals. Compounds that interrupt this feedback loop at both points are of particular interest to researchers exploring dietary approaches to chronic inflammatory conditions, which underlie diseases ranging from atherosclerosis to arthritis.

The concentration of bioactive compounds in outer tissues is not unique to parsnip, but the study adds a valuable quantitative dimension to a pattern seen across the plant kingdom. In apples, grapes, and onions, the peel routinely outperforms the flesh in phenolic content, a consequence of the plant’s own defensive strategy. The outer layers of a root or fruit are the first line of contact with the environment, exposed to ultraviolet radiation, pathogens, and physical damage, and plants respond by accumulating protective secondary metabolites precisely where they are needed most. Leaves, similarly, face intense oxidative pressure from photosynthesis and sunlight, which helps explain why ‘Warrior’ parsnip leaves, normally discarded as agricultural waste, turned out to be the single richest source of phenolics in the entire analysis.

That last point carries real economic and environmental weight. Parsnip is grown primarily for its taproot, and the foliage is typically left in the field or composted after harvest. If the leaves contain more than 500 milligrams of phenolic compounds per 100 grams of fresh weight, they represent a largely untapped reservoir of functional ingredients that could be recovered for use in nutraceuticals, functional foods, or natural preservatives. The same logic applies to peeling waste from food processing operations, where parsnip skins are removed on an industrial scale. Converting these by-products into value-added extracts would align with a broader movement in food science toward circular economy approaches, in which agricultural residues are reimagined as raw materials rather than refuse.

The study also situates parsnip within a growing body of literature on root vegetables as sources of health-promoting compounds. Previous work by the same research group had already characterized the physicochemical properties, organic acids, and sugar profiles of parsnip cultivars harvested in Korea, and other teams have documented the antioxidant activity of essential oils from wild parsnip subspecies. Historical texts and traditional medicine systems have long attributed therapeutic properties to Pastinaca sativa, and modern pharmacological reviews have catalogued its chemical constituents. What the new research adds is a systematic, tissue-by-tissue, cultivar-by-cultivar comparison that connects specific chemical measurements to measurable biological effects in cell-based models, bridging the gap between compositional analysis and functional validation.

For consumers, the practical takeaways are straightforward, if somewhat counterintuitive. Keeping the skin on parsnips when cooking preserves the tissue shown to have the highest flavonoid content and the strongest anti-inflammatory activity in laboratory tests, and choosing cultivars such as ‘Warrior’ may offer a modest nutritional edge over alternatives. The researchers caution, as all in vitro studies must, that cellular assays do not directly translate into clinical outcomes; compounds must survive digestion, reach target tissues, and act in the complex environment of the human body before any health benefit can be claimed. Nevertheless, the work provides a clear roadmap for future research, from identifying the individual polyphenols responsible for the observed effects to testing bioavailability and efficacy in more advanced models. In the meantime, it offers a fresh reason to reconsider one of the supermarket’s most overlooked vegetables, and a reminder that in the chemistry of plants, the parts we discard often hold the greatest treasures.

Subject of Research: Antioxidant and anti-inflammatory bioactive compound distribution in parsnip cultivars and plant parts

Article Title: Distribution of antioxidant compounds, antioxidant activities, and anti-inflammatory properties in different cultivars and plant parts of parsnip (Pastinaca sativa)

Article References: Shim, H., Jung, S. K., & Shin, Y. (2026). Distribution of antioxidant compounds, antioxidant activities, and anti-inflammatory properties in different cultivars and plant parts of parsnip (Pastinaca sativa). Food Science and Biotechnology. https://doi.org/10.1007/s10068-026-02344-0

Image Credits: AI Generated

DOI: 10.1007/s10068-026-02344-0

Keywords: parsnip, Pastinaca sativa, antioxidant, anti-inflammatory, polyphenols, flavonoids, phenolic compounds, cultivar, RAW 264.7 macrophages, nitric oxide, DPPH assay, food by-products

The appeal of green synthesis lies in what it avoids. Conventional physical and chemical routes to nanoparticles typically demand high temperatures, large energy inputs, organic solvents, and strong reducing or stabilizing agents, all of which raise costs and leave behind undesirable chemical residues. Plant extracts offer an alternative that is inexpensive, widely available, and environmentally benign. The chemistry works because phytochemicals such as phenolics, flavonoids, alkaloids, tannins, and terpenoids carry hydroxyl, carbonyl, carboxyl, and amine functional groups that can donate electrons to metal ions, driving nucleation, and then adsorb onto the growing particle surfaces, capping them and preventing runaway aggregation. In effect, the plant performs the roles of reducing agent, stabilizer, and shape-directing template simultaneously.

Soursop was a deliberate choice. The evergreen tree, a member of the Annonaceae family found across tropical and subtropical regions, has a long ethnopharmacological record, with leaves, bark, roots, fruit, and seeds used in decoctions and poultices against fever, pain, inflammation, hypertension, diabetes, malaria, and infections. The researchers quantified the bioactive content of their leaf powder and found flavonoids dominated the profile at 173.5 milligrams per 100 grams, followed by total phenolics at 52.97 milligrams per 100 grams, with tannins, triterpenes, starch, coumarins, and reducing sugars present at lower levels. That abundance of flavonoids and phenolics, compounds renowned for electron and hydrogen donation, made the extract a promising candidate for mediating nanoparticle formation.

The synthesis itself was straightforward. For the calcium oxide nanoparticles, five grams of dried leaf powder were extracted in 100 milliliters of distilled water at 60 degrees Celsius, and 20 milliliters of that extract were combined with 100 milliliters of a 1 millimolar calcium nitrate solution for one hour. For the zinc nanoparticles, 50 milliliters of a more concentrated extract were added to 200 milliliters of 0.02 molar zinc chloride and allowed to react for two hours. In both cases, formation was tracked by ultraviolet-visible spectroscopy, and the colloids were centrifuged, washed repeatedly, and dried. Yields were modest, at 3.3 percent for the zinc nanoparticles and 2.8 percent for the calcium oxide particles, but the characterization data revealed strikingly small, well-defined materials.

Transmission electron microscopy showed zinc nanoparticles with an irregular shape and an average diameter of just 3.68 nanometers, among the smallest reported for soursop-mediated zinc structures, while the calcium oxide particles were oval with an average size of 4.09 nanometers. Ultraviolet-visible spectra displayed absorption maxima at 304 nanometers for the zinc particles and 294 nanometers for the calcium oxide particles, consistent with successful nanostructure formation. Fourier transform infrared spectroscopy told the mechanistic story: broad bands near 3448 and 3387 inverse centimeters pointed to hydroxyl groups from phenolics and flavonoids, bands near 2928 and 2850 inverse centimeters matched methyl and methylene stretches, and metal-oxygen vibrations appeared at 567 inverse centimeters for zinc-oxygen and around 1438 and 702 inverse centimeters for calcium-oxygen species. Energy-dispersive X-ray analysis confirmed zinc as the dominant metallic component at 44.89 weight percent, while calcium was detected at 5.44 weight percent, with abundant carbon and nitrogen signals reflecting the phytochemical capping layer.

X-ray diffraction added an interesting contrast between the two systems. The zinc nanoparticles showed a broad, poorly resolved diffraction profile between roughly 10 and 30 degrees two-theta, indicating low crystallinity and a substantial amorphous contribution, likely a consequence of the phytochemical capping and mild synthesis conditions. The calcium oxide particles, by contrast, were highly crystalline, with sharp reflections matching a reference calcium oxide phase and an average crystallite size of 23 nanometers, along with preferential orientation along one crystallographic plane. Scanning electron microscopy showed both materials forming larger, densely agglomerated clusters, around 78.5 nanometers for the zinc structures and 54.5 nanometers for the calcium oxide aggregates, a common artifact of drying during sample preparation rather than a true measure of the primary particles.

The heart of the study was the comparative antioxidant evaluation, conducted across four complementary assays: DPPH and ABTS radical scavenging, ferric reducing antioxidant power, and the phosphomolybdate total antioxidant capacity test. All samples showed concentration-dependent activity between 0.2 and 1.0 milligrams per milliliter, but the zinc nanoparticles were the standout performers. In the DPPH assay they achieved 93.90 percent inhibition at the highest concentration, with an IC50 of 0.17 milligrams per milliliter, essentially matching ascorbic acid at 0.18 and trailing only gallic acid. In the ABTS assay their IC50 of 0.233 milligrams per milliliter placed them well ahead of both the calcium oxide particles and the crude extract, and their Trolox equivalent antioxidant capacity followed the same ordering.

The calcium oxide particles did claim one victory. In the ferric reducing antioxidant power assay, which measures the ability to convert ferric to ferrous iron under acidic conditions, the calcium oxide nanoparticles scored 16.99 milligrams of gallic acid equivalent per gram, roughly double the 8.13 achieved by the zinc nanoparticles and the crude extract. The researchers attribute this divergence to the mechanism-specific nature of antioxidant chemistry: each assay probes a different mode of action, and the surface-associated phytochemicals on the calcium particles appear particularly effective at electron transfer to the ferric complex. In the phosphomolybdate assay, however, the zinc nanoparticles again dominated, with a total antioxidant capacity of 59.14 milligrams of ascorbic acid equivalent per gram versus 26.13 for the calcium oxide particles, indicating a broader reducing power that extends beyond simple radical scavenging.

Perhaps the most consequential finding is that both nanoparticle formulations outperformed the crude soursop leaf extract from which they were made. The authors suggest that converting the phytochemicals into a nanoparticle-bound form enhances the accessibility and effectiveness of the surface-associated bioactive compounds, and that synergistic interactions between the metallic core and its organic shell amplify radical neutralization. Zinc’s own biological credentials, spanning immune regulation, enzyme function, and antioxidant defense, may add to the effect, while calcium’s physiological familiarity makes the oxide particles attractive from a biocompatibility standpoint. Both elements are essential nutrients, offering a potentially safer alternative to noble metal nanomaterials such as silver and gold for antioxidant applications.

The authors are careful to note the limits of the work. All antioxidant data come from in vitro chemical assays, which do not capture how these particles behave in living systems, and the study did not include zeta potential analysis, long-term stability testing, detailed identification of surface-bound phytochemicals, or cytotoxicity assessments. Future work, they argue, should address those gaps with advanced surface characterization, mechanistic studies, and in vivo dose-response investigations before any therapeutic claims can be made. Even so, the study delivers a clear proof of concept: a single, sustainable plant extract can produce two distinct essential-element nanoparticles with markedly different structures and assay-dependent antioxidant strengths, and the zinc version, in particular, rivals conventional antioxidant standards. For a tree whose leaves have been steeped in folk remedies for centuries, that is a remarkably modern endorsement.

Subject of Research: Green synthesis and comparative antioxidant characterization of calcium oxide and zinc nanoparticles mediated by Annona muricata leaf extract

Article Title: Characterization and comparative antioxidant study of calcium oxide and zinc nanoparticles mediated by Annona muricata leaves

Article References: Opatokun-Saliu, R. O., Azeez, L. A., Anifowose, J. A., Awojide, H. S., Busari, H. K., Saheed, A., Oladejo, A. A., & Ajibola, K. O. (2026). Characterization and comparative antioxidant study of calcium oxide and zinc nanoparticles mediated by Annona muricata leaves. Discover Chemistry, 3(1), Article 459. https://doi.org/10.1007/s44371-026-00915-y

Image Credits: AI Generated

DOI: 10.1007/s44371-026-00915-y

Keywords: green synthesis, nanoparticles, Annona muricata, soursop, antioxidant activity, zinc nanoparticles, calcium oxide nanoparticles, DPPH assay, ABTS assay, FRAP, phytochemicals, nanomedicine

The significance of embelin lies in its unusual molecular architecture. Chemically identified as 2,5-dihydroxy-3-undecyl-2,5-cyclohexadiene-1,4-benzoquinone, the molecule combines a quinone ring with a long hydrophobic carbon chain. That structure underpins a striking range of reported biological activities. Embelin has been described as a cell-permeable, non-peptide anticancer agent that selectively targets the BIR3 domain of XIAP, a key regulator of apoptosis, and it has been investigated in the context of neurodegenerative disorders and even antiviral research against SARS-CoV-2. Yet despite this pharmacological promise, the researchers note a persistent gap: the extraction process has never been properly optimized, which has limited the compound’s wider application, particularly in cosmetic formulations aimed at protecting skin from oxidative damage.

To close that gap, the team prepared six different extracts from the fruits of E. ribes, systematically varying both the solvent and the extraction temperature. Finely pulverized berries were extracted with methanol, 50 percent aqueous-methanol, and water, each in triplicate, under two contrasting conditions: a gentle cold extraction using 30 minutes of sonication at room temperature, and a hot extraction lasting four hours at 100 degrees Celsius in a Soxhlet apparatus. The extracts were filtered, pooled, and evaporated under vacuum, then stored chilled for analysis. This comparative design allowed the researchers to see exactly how solvent polarity and heat shape both the quantity and the quality of what comes out of the plant.

The results revealed a clear winner for overall extraction. Cold methanol sonication produced the highest yield at 12.5 percent by weight, while hot water extraction performed worst at 5.6 percent. The cold methanol extract also carried the richest load of total polyphenols, measured by the Folin-Ciocalteu method at 4.92 percent, expressed as gallic acid equivalents. The explanation, the researchers argue, is twofold. Heat appears to denature sensitive phenolic compounds, including embelin itself, while the hydrophobic character of the benzoquinone molecule means it simply does not dissolve well in water-rich systems. Semi-polar organic solvents like methanol are therefore ideally suited to leaching benzoquinone-type compounds from plant material.

Antioxidant performance told a slightly different story. Using the DPPH radical scavenging assay, a standard technique that measures how effectively a sample donates hydrogen atoms to neutralize free radicals, the strongest activity came from the cold aqueous-methanol extract, with an IC50 value of 1.19 micrograms expressed as ascorbic acid equivalents, followed closely by the cold methanol extract at 1.49 micrograms. The hot aqueous-methanol extract was the weakest performer, once again implicating heat as the enemy of antioxidant-active compounds. Importantly, the antioxidant potency of the extracts broadly tracked their polyphenol content, reinforcing a strong correlation between phenolic composition and free radical scavenging ability. The authors point out that the strong DPPH activity of the cold extracts is largely attributable to the overall polyphenol content rather than to embelin’s benzoquinone moiety alone.

With the optimal extract identified, the team turned to purification. Fifteen grams of the cold methanolic extract, absorbed onto silica gel, were loaded into a flash chromatography system, a pressure-assisted technique that dramatically accelerates separation compared with conventional gravity-flow columns. A gradient running from pure n-hexane to pure ethyl acetate, at a flow rate of 30 milliliters per minute and a pressure of 3 to 8 psi, separated the mixture into 95 fractions collected in 15-milliliter test tubes, monitored by ultraviolet detection at 285 nanometers. Fractions containing embelin were pooled and crystallized in hexane, yielding 560 milligrams of an orange amorphous powder, a 0.448 percent yield by weight of the crude extract. The compound’s identity was confirmed by its melting point of 141 degrees Celsius, matching the reported range for authentic embelin, and by mass spectrometry showing characteristic ions consistent with the molecular formula C17H26O4.

The analytical centerpiece of the study is a validated high-performance liquid chromatography method for quantifying embelin. The method uses a gradient of phosphate buffer and acetonitrile on a standard C18 column, detecting embelin at 288 nanometers, and produces a single, well-resolved peak at a retention time of 8.835 minutes. Validation followed the International Council for Harmonization Q2(R2) guidelines, the global benchmark for analytical method quality. Linearity was excellent across the working range of 200 to 1000 nanograms, with a correlation coefficient of 0.999. The limits of detection and quantification were 96.43 and 292.22 nanograms respectively, satisfying the ICH criterion that the quantification limit must be at least three times the detection limit.

The remaining validation parameters were equally convincing. Precision studies, covering system precision, intra-day variation across six independent sample preparations, and inter-day variation across three consecutive days, all produced relative standard deviations well below the 2 percent acceptance threshold. Accuracy was assessed through spike recovery experiments at 80, 100, and 120 percent addition levels, yielding a mean recovery of 95.3 percent, within the acceptable range. Ruggedness was demonstrated by having two different analysts run samples on two different HPLC systems with different column lots, and robustness was confirmed by deliberately perturbing the flow rate by 10 percent and the detection wavelength by 5 nanometers, with results remaining stable throughout. The theoretical plate count of 26,779 and a tailing factor of 1.338 further indicated good column efficiency and peak symmetry.

When the validated method was applied across all six extracts, an intriguing nuance emerged. The hot methanol extract actually contained the highest embelin content, at 22.33 percent, compared with 11.94 percent in the cold methanol extract, likely because higher temperatures improve the solubility and diffusion of the lipophilic embelin molecule even as they degrade thermo-labile polyphenols. The cold aqueous-methanol extract contained only a trace at 0.247 percent, and no embelin was detectable in any of the purely aqueous extracts, conclusively confirming the compound’s hydrophobic nature. This creates a practical decision point: cold methanol extraction is the better choice when the goal is to preserve antioxidant-active polyphenols and potential anti-photoaging activity, while hot methanol extraction may be preferred when maximizing pure embelin yield is the priority. Photoaging, the premature skin aging caused by ultraviolet radiation, is driven by oxidative stress that degrades collagen and elastin, and naturally derived phenolic antioxidants are considered promising candidates to counteract it.

The authors conclude that their optimized cold methanol extraction, combined with flash chromatography and the validated HPLC assay, constitutes a cost-effective and time-saving standard procedure that can be employed for quality control and quality assurance of E. ribes. Because the berries were collected following national guidelines and authenticated by a taxonomist with a deposited voucher specimen, the work also provides a traceable reference material chain. For an industry increasingly hungry for plant-derived actives that can be standardized, quantified, and reproduced batch after batch, the study demonstrates that an ancient Ayurvedic fruit can meet modern analytical expectations, and it opens the door to embelin-enriched extracts being investigated further as reliable sources of antioxidant agents for cosmetic and pharmaceutical development.

Subject of Research: Optimized extraction, flash chromatographic isolation, validated HPLC quantification, and antioxidant evaluation of embelin from Embelia ribes fruits

Article Title: Fast isolation of embelin from Embelia ribes Burm. f. by comparative evaluation of extract, HPLC method validation and evaluation of its antioxidant activity

Article References: Ash, A., Chatterjee, A., Ganguly, S., Mohapatra, S., & Singh, R. (2026). Fast isolation of embelin from Embelia ribes Burm. f. by comparative evaluation of extract, HPLC method validation and evaluation of its antioxidant activity. Discover Chemistry, 3(1), Article 575. https://doi.org/10.1007/s44371-026-01006-8

Image Credits: AI Generated

DOI: 10.1007/s44371-026-01006-8

Keywords: embelin, Embelia ribes, Ayurvedic medicine, antioxidant activity, HPLC validation, flash chromatography, polyphenols, DPPH assay, natural products, cosmetic ingredients, benzoquinone, extraction optimization

The choice of plant was no accident. Millettia ferruginea is a member of the legume family found across Ethiopia, Kenya, and Tanzania, where its seeds serve as a natural purgative and deworming agent, its leaves are used against inflammation and malaria, and its bark and roots feature in remedies for fever and infections. The tree is also an ecological workhorse: fast-growing and hardy, it anchors reforestation and agroforestry programs, combats soil erosion, improves soil fertility, and provides shade and habitat for wildlife. Its durable timber supports furniture-making and construction, and its seeds yield oil used in medicine and cosmetics. Crucially for the chemists, its leaves are rich in phenolic and flavonoid compounds, molecules whose hydroxyl, carbonyl, and carboxyl groups can grab onto metal ions and coat growing crystal surfaces.

That chemistry is exactly what green nanomaterial synthesis requires. The team used a hydrothermal method, in which reactions run in water inside a sealed, Teflon-lined stainless-steel autoclave at elevated temperature and pressure. Dissolved zinc nitrate was mixed with filtered leaf extract and treated bentonite clay, the pH was adjusted to 6.5, and the mixture was heated for three hours at 125 to 138 degrees Celsius under autogenous pressure of about 9.87 atmospheres. After cooling, filtration, centrifugation, washing, and drying at 325 degrees Celsius, the result was a powder in which zinc oxide had formed in the presence of the clay and the plant’s phytochemicals.

An important subtlety lies in what the plant extract actually does. Unlike silver or gold nanoparticles, where plant chemicals reduce metal ions to metal atoms, zinc ions are not reduced by phytochemicals; the standard reduction potential of the zinc couple is far too negative. Instead, zinc oxide forms through hydrolysis of zinc ions to zinc hydroxide followed by dehydration into ZnO. The researchers therefore assign the extract a different role: its phenolics, flavonoids, tannins, coumarins, and alkaloid nitrogen atoms chelate zinc ions and act as capping and stabilizing agents, shaping nucleation and growth rather than supplying electrons. The team even worked out why pH 6.5 works: at the zinc concentration used, the solubility equilibrium of zinc hydroxide predicts precipitation beginning near that pH, and the hydrothermal treatment then drives further hydrolysis, dehydration, and crystallization.

Characterization confirmed the product. X-ray diffraction showed the characteristic reflections of hexagonal wurtzite zinc oxide, matching the standard reference card for that structure, alongside peaks from montmorillonite, the main mineral in bentonite. Applying the Scherrer equation to the strongest zinc oxide reflection gave a crystallite size of about 14.6 nanometers, a measure of coherently diffracting domains rather than whole particles. Infrared spectroscopy of the composite retained the clay’s silicate bands, with a small shift of the silicon-oxygen band from 1030 to 1025 wavenumbers hinting at weak surface interactions, though the authors caution that this alone cannot prove covalent bonding between the oxide and the clay. Scanning electron microscopy revealed irregular agglomerates several micrometers across, each likely containing many nanoscale crystallites, and energy-dispersive X-ray analysis detected zinc, oxygen, silicon, aluminum, and sodium, consistent with zinc oxide on an aluminosilicate support.

Before making the composite, the team profiled the leaf extract itself. Standard colorimetric screening detected alkaloids, flavonoids, tannins, phenolics, terpenoids, coumarins, glycosides, and saponins, a broad pharmacological toolkit that provides a scientific rationale for the tree’s traditional uses. Quantification by the Folin-Ciocalteu method, calibrated against gallic acid, yielded a total phenolic content corresponding to about 105 milligrams of gallic acid equivalents per liter in the assay solution, while the aluminum chloride assay gave a flavonoid level of roughly 32 milligrams of catechin equivalents per liter, and a gelatin precipitation method put tannins at about 28 milligrams of tannic acid equivalents per liter. In a DPPH radical scavenging test, the extract neutralized 56.92 percent of the stable purple radical at a single tested concentration of 21.3 parts per million, a performance comparable to ascorbic acid standards in the 30 to 40 parts per million range, whose own half-maximal inhibitory concentration was 33.8 parts per million.

The antibacterial results were the most striking. Using the agar well diffusion method against four bacterial strains, two Gram-positive and two Gram-negative, the researchers applied a fixed 20 micrograms of each material per well. Bentonite alone showed essentially no inhibition, with zones smaller than 5 millimeters. Plain zinc oxide produced zones of 12 to 17 millimeters. The composite, however, generated zones of 20.2 to 21.0 millimeters against Escherichia coli and Klebsiella pneumoniae, and, remarkably, 28.0 to 28.6 millimeters against Staphylococcus aureus and Streptococcus pyogenes. Against the Gram-positive strains, the composite even outperformed the gentamicin antibiotic control, which produced a 23.7-millimeter zone, and exceeded tetracycline, which showed no measurable inhibition under the test conditions.

Why would anchoring zinc oxide on clay boost its antibacterial punch? The authors propose that the composite’s activity stems from the intrinsic antibacterial properties of zinc oxide, potentially amplified by the clay’s large surface area and adsorption capacity, which may concentrate material at the bacterial surface. Zinc oxide nanoparticles are thought to kill bacteria partly through the generation of reactive oxygen species and physical damage to cell membranes, although the team notes these mechanisms were not directly probed in this study. The strong showing against Gram-positive bacteria is notable, since those organisms lack the outer membrane that partially shields Gram-negative species from many antimicrobial agents.

The researchers are candid about the limits of their data. The extract’s antioxidant result is preliminary, based on a single concentration, so no dose-response curve or IC50 value could be derived for the extract or the composite. The antibacterial assay used only one applied amount, so minimum inhibitory and bactericidal concentrations remain undetermined. Electron microscopy and elemental mapping could not show whether the zinc oxide sits on the clay surface, within the particles, or as a separate phase, and the available spectra cannot establish the detailed interface between the two components. Notably, some follow-up measurements, including additional X-ray diffraction, diffuse reflectance spectroscopy, BET surface area analysis, transmission electron microscopy, and X-ray photoelectron spectroscopy, could not be performed because the relevant laboratory facilities were damaged during the civil war in Ethiopia, a sobering reminder that scientific infrastructure is often among conflict’s quiet casualties.

Even with those caveats, the study stakes out a genuinely novel claim: this is, to the authors’ knowledge, the first report of a Millettia ferruginea-mediated zinc oxide/bentonite composite. Previous green syntheses used neem or tea extracts to make bare zinc oxide nanoparticles, and earlier zinc oxide-clay composites relied on conventional chemical routes without plant assistance. By combining a locally abundant bioresource with a widely used clay and a low-energy aqueous process, the work points toward antimicrobial materials that could eventually serve in environmental remediation, catalysis, or biomedical applications. The authors recommend that future studies include control syntheses without the plant extract, full dose-response and MIC/MBC testing, cytotoxicity and biocompatibility evaluation, detailed interfacial characterization, and scalability trials. For now, the humble Birbira leaf has demonstrated that traditional knowledge and modern nanotechnology can crystallize together, quite literally, into something more potent than either alone.

Subject of Research: Green synthesis of a ZnO/bentonite nanocomposite using Millettia ferruginea leaf extract and evaluation of its antioxidant and antibacterial activity

Article Title: Green synthesis and characterization of ZnO/bentonite composites using Millettia ferruginea leaf extract, determination of antioxidant and antibacterial activity

Article References: Gebrye, A. B., Gebrie, T. B., Alem, F. W., & Metto, M. (2026). Green synthesis and characterization of ZnO/bentonite composites using Millettia ferruginea leaf extract, determination of antioxidant and antibacterial activity. Current Research in Biotechnology, 12, Article 100425. https://doi.org/10.1016/j.crbiot.2026.100425

Image Credits: AI Generated

DOI: 10.1016/j.crbiot.2026.100425

Keywords: green synthesis, zinc oxide nanoparticles, bentonite, Millettia ferruginea, hydrothermal synthesis, antibacterial activity, antioxidant, phytochemistry, nanocomposite, DPPH assay, Ethiopia, wurtzite ZnO

Indian borage, known scientifically as Coleus amboinicus and sometimes called Mexican mint or country borage, is a fleshy-leaved herb in the mint family whose aroma comes from a dense payload of volatile compounds. Neem, Azadirachta indica, is a tree revered across South Asia for centuries of medicinal use, and its leaves contain a complex mixture of limonoids, flavonoids and other defensive chemicals. Both plants have long folk histories, but the research team set out to address a more modern problem: the limited availability of sustainable and efficient extraction methods that reliably deliver bioactive compounds from these leaves. Their approach was to characterise the extracts not just for the headline activities, but for the physicochemical fingerprints that explain them, including colour, chlorophyll content, functional groups and volatile profiles.

The experimental design hinged on a single variable with outsized consequences: solvent polarity. The researchers prepared ethanolic extracts of both leaves using two concentrations, 50 percent and 95 percent ethanol, the remainder being water. This seemingly small difference in the water-alcohol ratio changes which molecules the solvent can dissolve. Water-rich mixtures favour hydrophilic compounds such as phenolic acids and polar flavonoids, while nearly pure ethanol preferentially pulls out hydrophobic constituents such as terpenoids and lipophilic phenolics. By running both conditions side by side for both plants, the team could directly attribute differences in biological activity to the chemistry that each solvent mobilised, rather than to the plant species alone.

To measure antioxidant power, the team used the DPPH assay, a widely adopted test in which a stable purple free radical is decolourised when an antioxidant donates a hydrogen atom or electron. The results were striking for the 50 percent ethanol extracts, which achieved DPPH radical scavenging activity between 87 and 89 percent. That level of radical quenching indicates that the half-strength ethanol was highly effective at extracting hydrophilic antioxidants, the water-soluble phenolic compounds that plants deploy against oxidative stress. For food formulators, such extracts could serve as natural alternatives to synthetic antioxidants, which have faced increasing consumer scrutiny, in products where preventing lipid oxidation and colour degradation is the priority.

The antimicrobial story inverted that picture. When the 95 percent ethanol extracts were tested against common foodborne pathogens, they produced inhibition zones ranging from 1.06 to 1.52 centimetres, a measure of how far the antibacterial effect spread from a test well or disk in an agar plate assay. The team attributed this stronger antimicrobial performance to the extraction of hydrophobic bioactive compounds, which can integrate into and disrupt bacterial cell membranes. Pathogens of this kind include organisms responsible for food spoilage and foodborne illness, so an extract that suppresses their growth could extend shelf life or improve safety. The practical implication is that a manufacturer seeking an antimicrobial ingredient should reach for the stronger ethanol, while one seeking an antioxidant should choose the weaker one.

Beyond activity assays, the study built a detailed physicochemical portrait of each extract. Colour was quantified with a Chromameter CR-400, an instrument that converts visual appearance into objective numerical values, an important step for any ingredient destined for food or cosmetics where appearance drives consumer acceptance. Chlorophyll-a, chlorophyll-b and total chlorophyll were measured spectrophotometrically, exploiting the characteristic wavelengths at which these pigments absorb light. Chlorophyll is not merely a marker of plant material; its degradation products and associated compounds such as phytol have drawn scientific interest in their own right, and pigment content influences both the colour stability and the potential bioactivity of a leaf extract during storage and processing.

Functional group analysis was carried out with Fourier-transform infrared spectroscopy, or FT-IR, a technique that shines broadband infrared light through a sample and records which frequencies are absorbed. Each absorption band corresponds to a specific molecular bond, such as the stretches of hydroxyl groups in phenolics, carbonyl groups in acids and esters, or carbon-hydrogen bonds in lipids and terpenes. By comparing the spectra of the 50 percent and 95 percent ethanol extracts, the researchers could confirm at the molecular level that the two solvents had indeed pulled out chemically distinct suites of compounds, providing a mechanistic underpinning for the divergent antioxidant and antimicrobial results.

The most granular layer of characterisation came from gas chromatography-mass spectrometry, or GC-MS, which separates volatile compounds in a heated column and then identifies each one by the characteristic fragmentation pattern it produces when bombarded with electrons. This technique is ideally suited to plants like Indian borage, whose aromatic identity is defined by volatile terpenes, and to neem, whose leaf chemistry includes an array of volatile and semi-volatile constituents. The volatile profiles documented in the study help explain both the traditional sensory appeal of these plants and the biological activities observed, since many terpenoids are known to contribute to both antioxidant defences and membrane-disrupting antimicrobial action.

The broader significance of the work lies in its framing of solvent polarity and processing methods as design levers rather than fixed choices. Instead of asking simply whether a plant extract is active, the study demonstrates that the same leaf can yield two functionally different ingredients depending on a single processing parameter that is cheap and easy to control industrially. That flexibility is valuable for the growing market for clean-label preservatives and bioactive ingredients, where producers want predictable performance. It also supports sustainability goals: leaves of widely cultivated, fast-growing plants can be valorised as sources of high-value compounds, reducing reliance on synthetic antioxidants and antimicrobials derived from petrochemical feedstocks.

The authors, whose collaboration spanned the Faculty of Applied Sciences and Faculty of Health Sciences at Universiti Teknologi MARA, Auckland University of Technology in New Zealand, and Universitas Brawijaya in Indonesia, emphasise the potential of Coleus amboinicus and Azadirachta indica as sustainable sources of antioxidants and antimicrobials for applications spanning food, pharmaceuticals and cosmetic products. As with any laboratory study, the path from inhibition zones and spectrophotometer readings to commercial products will require further work on safety, dosage, stability and sensory impact in real formulations. But the core message is already clear and actionable: when it comes to extracting useful chemistry from these two familiar leaves, the solvent is not just a medium, it is the recipe.

Subject of Research: Solvent-dependent antioxidant and antimicrobial activities of ethanolic leaf extracts from Indian borage and neem

Article Title: Antioxidant and antimicrobial activities of Indian borage leaves (Coleus amboinicus, Lamiaceae) and neem leaves (Azadirachta indica, Meliaceae) ethanolic extracts

Article References: Khairunnisa-Yusra, A. R., Wan-Razarinah, W. A. R., Aida, F. M. N. A., Dasiman, R., Hamid, N., Huda, N., Murtini, E. S., & Raseetha, S. (2026). Antioxidant and antimicrobial activities of Indian borage leaves (Coleus amboinicus, Lamiaceae) and neem leaves (Azadirachta indica, Meliaceae) ethanolic extracts. Plant Biosystems, 160(5), Article 277. https://doi.org/10.1007/s44473-026-00272-9

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00272-9

Keywords: Indian borage, neem, Coleus amboinicus, Azadirachta indica, ethanolic extraction, antioxidant activity, antimicrobial activity, DPPH assay, GC-MS, FT-IR, chlorophyll, natural preservatives

The molecules at the heart of the study belong to a class known as [1]benzopyrano[b]dioxolo[g]quinolines, a mouthful of a name that describes a structure fusing three biologically privileged frameworks: a benzopyran (also called a chromene), a dioxole ring, and a quinoline. Benzopyrans are among the most ubiquitous scaffolds in medicinal chemistry. They appear in compounds with antibacterial, antiviral, antitumor and antiproliferative activities, and they show up in natural products such as Callistenone A, an antibacterial agent, and Urolithin M5, an antioxidant from the leaves of Canarium album. Because these frameworks keep proving their worth in drug discovery, chemists are constantly searching for faster and cleaner ways to build new derivatives.

The team’s strategy was a three-component condensation. They combined 4-hydroxycoumarin, a range of aromatic aldehydes, and 3,4-(methylenedioxy)aniline in water, then bombarded the mixture with ultrasonic irradiation at 80 watts while a trace amount of a Cu/ZnO@GO nanocomposite did the catalytic heavy lifting. The result: eight novel compounds, designated 4a through 4h, isolated in yields ranging from 93 to 97 percent. For comparison, running the same reaction in water without any catalyst, even under reflux for a grueling 300 minutes, produced only a 20 percent yield. Ultrasound alone, without the catalyst, managed just 48 percent in fifteen minutes. The synergy between the sound waves and the nanomaterial proved essential.

Ultrasound accelerates chemical reactions through a phenomenon called acoustic cavitation. As sound waves pass through a liquid, they generate microscopic bubbles that rapidly grow and collapse, producing intense local heating, high pressures and powerful shock waves. These transient hot spots dramatically enhance mass transfer and can create reactive surfaces on solid catalysts, all while the bulk solution remains at room temperature. In this study, the reaction proceeded at a comfortable 25 degrees Celsius, meaning the energy input is localized at the nanoscale rather than wasted heating an entire flask. That combination of ambient conditions and dramatically shortened reaction times is precisely what green chemistry advocates have been demanding for decades.

The catalyst itself is as much a story as the reaction it drives. Cu/ZnO@GO is a composite in which copper-doped zinc oxide nanoparticles are anchored to sheets of graphene oxide. Graphene-based supports are prized in catalysis for their enormous surface area, chemical and thermal stability, and low cost, providing an ideal platform on which to disperse catalytically active metal particles. The researchers prepared the Cu/ZnO nanoparticles using an aqueous extract of Petasites hybridus, commonly known as butterbur, whose rhizome was dried, powdered and steeped in boiling deionized water. The plant extract acted as both a reducing and a stabilizing agent, steering the formation of the nanoparticles without any synthetic capping chemicals. Zinc acetate and copper chloride were added to the extract, heated to 200 degrees Celsius, and the resulting nanoparticles were then dispersed with graphene oxide in a second round of plant-extract-assisted growth.

Characterization confirmed the composite was exactly what the team intended. Fourier-transform infrared spectroscopy revealed the characteristic Zn–O and Cu–O stretching vibrations, while X-ray diffraction showed the hexagonal wurtzite phase of ZnO alongside the expected copper reflections, with copper incorporation visibly damping the intensity of the primary ZnO planes. Scanning and transmission electron microscopy showed spherical nanoparticles effectively anchored to the graphene oxide support, and energy-dispersive X-ray analysis verified the elemental composition. It is a textbook example of a well-built heterogeneous catalyst: robust, well-defined, and ready to work in water.

Optimization experiments, centered on a model reaction producing the 4-bromophenyl derivative 4b, systematically varied the catalyst loading, solvent and energy source. Just 0.05 grams of Cu/ZnO@GO in 3 milliliters of water, under 80-watt sonication for fifteen minutes, delivered the maximum 97 percent yield. Conventional solvents such as ethanol, dichloromethane, acetonitrile and dimethylformamide all underperformed relative to water. Other conventional catalysts were tested and consistently fell short of the nanocomposite. Equally important, the catalyst proved durable: after each reaction it was recovered by centrifugation, washed with ethanol, dried, and reused, retaining its activity for at least four consecutive cycles without significant loss of performance. That recyclability directly reduces waste and cost, two of the biggest obstacles to sustainable industrial chemistry.

The proposed mechanism follows a well-established cascade. The acidic sites on the nanocatalyst activate the carbonyl group of the aromatic aldehyde, which then undergoes a Knoevenagel condensation with the methylenedioxyaniline to form an alkene intermediate. 4-Hydroxycoumarin adds to this alkene in a Michael-type addition, and the resulting intermediate cyclizes, dehydrates and aromatizes to deliver the fused quinoline product. The method worked smoothly across aldehydes bearing both electron-donating groups, such as methoxy, hydroxy and methyl substituents, and electron-withdrawing groups, including bromo, chloro, cyano and nitro variants. One limitation emerged: aliphatic aldehydes gave poor yields, apparently because their low boiling points cause them to vaporize under sonication.

What elevates the study beyond synthetic methodology is the biological evaluation. The team subjected four of the new compounds to the DPPH free radical scavenging assay, a standard test in which a compound’s ability to neutralize a stable purple radical is measured spectrophotometrically at 517 nanometers, with the industrial antioxidants butylated hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ) as benchmarks. The activity ranking was TBHQ, followed by BHT roughly tied with compound 4e, then 4a, 4c and 4h. Compound 4e, which carries a hydroxyl group on its aryl ring, emerged as the standout performer, approaching the activity of the commercial standards at a concentration of 1000 parts per million. The finding matters because oxidative stress is implicated in diseases ranging from diabetes and cancer to atherosclerosis and Alzheimer’s, fueling the search for new antioxidant scaffolds.

The broader significance of the work lies in its demonstration that sustainable chemistry need not sacrifice speed or efficiency. Water replaces toxic organic solvents. Ultrasound replaces hours of energy-intensive reflux. A plant extract replaces synthetic reagents in catalyst preparation. A recyclable nanocomposite replaces stoichiometric activators. And the products themselves are not merely laboratory curiosities but candidates for antioxidant drug development. As the authors note, the approach represents a meaningful advance for green chemistry, and it offers a template that other laboratories can adapt: pair a well-designed nanocatalyst with acoustic energy and an aqueous medium, and even multi-component reactions that once demanded harsh conditions can be coaxed to completion in minutes, at room temperature, with yields that would have seemed implausible a generation ago.

Subject of Research: Ultrasound-assisted green synthesis of benzopyranoquinoline derivatives with antioxidant activity using a Cu/ZnO@GO nanocatalyst

Article Title: Ultrasound assisted aqua-mediated synthesis of novel [1]benzopyrano[b]dioxolo[g]quinolines with promising antioxidant activities using Cu/ZnO@GO nanocatalyst

Article References: Abdolmohammadi, S., Azadi, S., Imanov, H., Al Omari, R. H., Pal, A., & Vessally, E. (2026). Ultrasound assisted aqua-mediated synthesis of novel [1]benzopyrano[b]dioxolo[g]quinolines with promising antioxidant activities using Cu/ZnO@GO nanocatalyst. Journal of Saudi Chemical Society, 30(2), Article 16. https://doi.org/10.1007/s44442-026-00061-1

Image Credits: AI Generated

DOI: 10.1007/s44442-026-00061-1

Keywords: green chemistry, ultrasound synthesis, nanocatalyst, Cu/ZnO@GO, graphene oxide, quinolines, benzopyran, antioxidant, DPPH assay, aqueous media, Petasites hybridus, heterogeneous catalysis