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

Trace metals are a deceptively complicated class of contaminants. Unlike organic pollutants that eventually degrade, elements such as lead and cadmium persist indefinitely in the environment, cycling between water, sediment, and living tissue. At vanishingly small concentrations some of them, like zinc and copper, are actually essential micronutrients for marine organisms, while all four become toxic above certain thresholds. The challenge for monitoring programs is that dissolved metal concentrations in seawater are extraordinarily low, often fractions of a microgram per liter, and they fluctuate with tides, currents, and seasonal runoff. That is why many researchers prefer to read the chemical history of a coastline through its organisms. Brown algae in particular are famous bioaccumulators: their cell walls are rich in polysaccharides such as alginates and fucoidans that bind dissolved metal ions with remarkable efficiency, effectively concentrating metals from thousands of liters of water into a few grams of tissue. Seagrasses, rooted in sediment and bathed in the same water, provide a complementary signal that integrates both dissolved and sedimentary metal pools.

The Cuban team’s sampling design exploited this biology. At four beaches within the park, they collected specimens of Padina pavonica, Turbinaria tricostata, Dictyota dichotoma, Sargassum buxifolium, and the free-floating pelagic Sargassum natans, along with the two dominant Caribbean seagrasses, Thalassia testudinum, commonly known as turtle grass, and Syringodium filiforme, or manatee grass. Water samples were handled according to international ISO standards for preservation and handling, a detail that matters enormously in trace metal work, where contamination from sampling gear or storage containers can swamp the signal being measured. Dissolved metals in the seawater were quantified using square-wave anodic stripping voltammetry, an electrochemical technique prized for its sensitivity at the microgram-per-liter level. The technique works by plating dissolved metal ions onto an electrode under an applied potential and then stripping them off again, measuring the current generated as each metal is released, which produces a characteristic fingerprint of concentration for each element.

The plant and algal samples followed a different analytical route. After digestion, metal contents were determined by inductively coupled plasma optical emission spectrometry, or ICP-OES, a workhorse technique in which a plasma torch heated to roughly 10,000 Kelvin atomizes the sample and excites its constituent elements, causing them to emit light at wavelengths specific to each metal. The intensity of that emitted light translates directly into concentration. From these paired measurements of water and tissue, the researchers calculated bioaccumulation factors, or BAFs, which express how many times more concentrated a metal is inside an organism than in the surrounding water. A high BAF signals either efficient uptake by the organism or high bioavailability of the metal in its dissolved form, and comparing BAFs across species and sites is one of the standard ways ecotoxicologists gauge environmental quality without needing to deploy costly continuous chemical sensors.

The seawater results themselves tell a story of a relatively pristine environment. Zinc ranged from 12.7 to 40.1 micrograms per liter, cadmium from 0.39 to 1.3, lead from 0.69 to 3.6, and copper from 1.3 to 5.5. One site, Los Cayuelos, registered the highest concentrations of all four metals, a spatial pattern the authors flag as noteworthy even though the absolute values remain low by the standards of industrialized coastlines. For context, regulatory frameworks such as the United States Environmental Protection Agency’s national recommended water quality criteria set thresholds designed to protect aquatic life, and the values measured across Guanahacabibes sit comfortably within ranges associated with minimal risk. In a region where the Yucatan Current and the Cuban Countercurrent sweep through the basin, exchanging water between the Caribbean and the Gulf, low dissolved metal levels also suggest that the park is not receiving significant inputs from shipping lanes or from distant continental sources, at least not at the time of sampling.

Inside the organisms, the picture was more textured. Metal concentrations in the macrophytes followed a consistent hierarchy of zinc greater than copper greater than cadmium greater than lead, mirroring the relative abundance and biological demand for these elements in seawater. The maximum tissue values were 52.5 milligrams per kilogram of zinc in Dictyota dichotoma and 5.97 milligrams per kilogram of copper in Padina pavonica. Brown algae consistently showed higher bioaccumulation factors than the seagrasses, which fits with their known physiology: macroalgae absorb dissolved metals directly across their entire thallus surface, while seagrasses regulate uptake through both roots and leaves and possess internal detoxification mechanisms that can sequester metals in vacuoles and cell walls. Crucially, the BAFs varied not just between the two groups but among individual species and among the four beaches, confirming that a single sentinel species cannot capture the full picture of metal bioavailability across a heterogeneous coastal landscape.

To untangle these overlapping patterns, the team turned to principal component analysis, a statistical technique that compresses many correlated measurements into a few underlying axes of variation. The first components explained 83.4 percent of the total variance in the dataset, a remarkably high proportion that indicates the metal chemistry at these sites is governed by a small number of dominant processes. The analysis cleanly separated two contrasting regimes: a zinc-associated pattern characterizing the beach at El Perjuicio and a copper-associated pattern at La Barca. Such distinctions matter because different metals enter coastal waters through different pathways, whether natural geological weathering of the limestone substrate, atmospheric deposition, or localized human activity, and identifying which metal dominates at which site provides clues about the underlying source, even in the absence of an obvious polluter.

Perhaps the most intriguing finding, and the one with the widest implications for how biomonitoring is done, was the relationship between dissolved metal concentrations and the bioaccumulation factors themselves. Using log-log regressions, the researchers found significant inverse relationships between dissolved metal levels and BAFs for all four metals, with statistical significance at p below 0.05. In other words, where the water carried more metal, the organisms’ concentration factors were lower. This counterintuitive pattern is a recognized feature of accumulation biology: organisms have a finite capacity to take up and regulate metals, so as dissolved concentrations rise, the ratio of tissue concentration to water concentration tends to fall, partly because of active down-regulation of transport and partly because of saturation of binding sites. The practical lesson is sobering for monitoring programs. A falling BAF does not necessarily mean a cleaner environment; it can mean the opposite. Interpreting bioaccumulation data without the corresponding dissolved measurements risks drawing exactly the wrong conclusion, which is why the integrated approach adopted here, pairing water chemistry with tissue analysis, is so valuable.

For Guanahacabibes National Park itself, the study delivers a clean bill of health and a durable reference point. The park is one of Cuba’s most important protected areas, home to coral reefs, nesting sea turtles that depend on those seagrass meadows, and a coastline that has so far escaped the intensive development seen elsewhere in the Caribbean. Establishing that its waters and macrophytes carry low metal burdens today creates the baseline that any future assessment will need. If shipping traffic increases, if upstream development expands, or if climate-driven changes in ocean chemistry alter metal mobility, as recent research on trace element biogeochemistry in warming coastal ecosystems suggests is possible, the 2026 dataset will make those shifts detectable. The work also adds to a growing global literature showing that brown algae have declined in metal content over recent decades in many regions, and it demonstrates that even a modest suite of seven macrophyte species, sampled at a handful of beaches and analyzed with careful electrochemical and spectroscopic methods, can yield a scientifically rigorous portrait of environmental quality. For tropical marine protected areas around the world, many of which lack the resources for continuous instrumental monitoring, that is a template worth copying.

Subject of Research: Trace metal distribution and bioaccumulation in seawater, brown algae, and seagrasses of a Cuban marine protected area

Article Title: Trace metal distribution in seawater, brown algae, and seagrasses from Guanahacabibes National Park, Cuba

Article References: Piña-Leyte-Vidal, J. J., Vilasó-Cadre, J. E., Reyes-Domínguez, I. A., Márquez-Llauger, L., de Jesús Barraza-García, F., Díaz-Castañón, S., Rodríguez, R., & Ricardo, J. A. (2026). Trace metal distribution in seawater, brown algae, and seagrasses from Guanahacabibes National Park, Cuba. Environmental Monitoring and Assessment, 198(10), Article 1103. https://doi.org/10.1007/s10661-026-15961-3

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15961-3

Keywords: trace metals, brown algae, seagrasses, bioaccumulation, Guanahacabibes National Park, Cuba, seawater chemistry, biomonitoring, marine pollution, Caribbean, anodic stripping voltammetry, ICP-OES

The central question the researchers posed was deceptively simple: does the solvent used to extract a seaweed’s chemistry matter? The answer, emphatically, is yes. The team prepared five distinct extracts of H. scoparia using solvents of increasing polarity, n-hexane, dichloromethane, ethanol, methanol and water, and then quantified the total polyphenol, flavonoid and tannin content of each using standardized colorimetric assays. This gradient approach is grounded in a well-established principle of natural products chemistry: polar solvents tend to pull phenolic acids, flavonoid glycosides and tannins out of plant and algal tissue, while nonpolar solvents preferentially dissolve lipids, pigments and terpenoid compounds. By comparing the same biomass extracted five ways, the researchers could effectively partition the alga’s chemical inventory into discrete fractions, each with its own biological signature.

The results confirmed the polarity principle with striking clarity. The aqueous extract, the most polar of the five, registered the highest total polyphenol and tannin contents, and it translated that chemical richness into biological performance, topping the ferric reducing antioxidant power (FRAP) assay, the ABTS radical scavenging assay and the metal-chelating assay. These three tests probe complementary antioxidant mechanisms: FRAP measures the capacity to reduce ferric ions, a proxy for electron-donating ability; ABTS tracks the neutralization of a stable synthetic radical cation; and metal chelation assesses the ability to bind transition metals such as iron and copper that catalyze the formation of destructive hydroxyl radicals through Fenton chemistry. Tannins, with their dense arrays of hydroxyl groups, are particularly effective metal chelators, which helps explain why the tannin-rich aqueous fraction dominated that particular assay.

The methanolic extract told a different but equally instructive story. It achieved the strongest performance in the DPPH assay, which measures scavenging of a lipophilic synthetic radical, and in the CUPRAC assay, which evaluates the reduction of cupric ions. Meanwhile, the dichloromethane extract, the least polar fraction apart from hexane, showed the greatest activity in the phosphomolybdenum assay, a measure of total antioxidant capacity based on the reduction of molybdenum(VI) to molybdenum(V). The fact that no single extract won every contest is not a contradiction but a feature of antioxidant chemistry: different assays respond to different mechanisms, solubilities and reaction kinetics, and a compound that excels at quenching one radical may be mediocre at reducing a metal ion. For bioprospectors, this means the choice of extraction solvent is effectively a choice of which biological activity to prioritize.

Antioxidant capacity was only half of the pharmacological picture. The team also evaluated the extracts’ ability to inhibit two digestive enzymes, alpha-amylase and alpha-glucosidase, that sit at the heart of post-meal glucose spikes. Alpha-amylase cleaves long starch molecules into shorter oligosaccharides in the mouth and small intestine, and alpha-glucosidase then trims those fragments down to absorbable glucose at the intestinal brush border. Drugs that blunt both enzymes, such as acarbose, are standard adjuncts in the management of type 2 diabetes, but they come with gastrointestinal side effects, which has fueled a sustained hunt for gentler plant- and algae-derived inhibitors. Here the ethanolic and dichloromethane extracts stood out, exhibiting dual inhibitory activity against both enzymatic targets, a result the authors highlight as evidence that H. scoparia’s antidiabetic potential is distributed across chemically distinct fractions rather than confined to a single polar class of compounds.

To move beyond crude extracts, the researchers turned to high-performance liquid chromatography (HPLC), which allowed them to tentatively identify individual bioactive compounds within the extracts. Among the molecules flagged by this profiling were sophocarpine, a quinolizidine alkaloid tentatively identified here as an isomer of monocrotaline, and a structurally elaborate phenanthrene carboxylic acid, formally named 1,4a-dimethyl-9-oxo-7-propan-2-yl-3,4,10,10a-tetrahydro-2H-phenanthrene-1-carboxylic acid. The word tentatively matters: HPLC-based identification without full isolation and nuclear magnetic resonance confirmation remains provisional, and the authors are careful to frame their assignments accordingly. Even so, the presence of sophocarpine is particularly noteworthy, because this alkaloid has previously attracted attention in the diabetes literature for its effects on PPAR-gamma-regulated gene expression, a key transcriptional axis in glucose and lipid metabolism.

The study’s most technically ambitious phase was computational. Using molecular docking, the team positioned the tentatively identified compounds inside the three-dimensional active sites of alpha-amylase and alpha-glucosidase, calculating binding affinities and mapping the specific amino acid residues that anchor each ligand. Docking, however, offers only a static snapshot, so the researchers followed up with molecular dynamics simulations, which allow the protein-ligand complexes to flex and breathe in a simulated aqueous environment over time. A ligand that looks perfect in a static dock can fall apart once the enzyme’s loops and side chains begin to move; sustained stability across a dynamics trajectory is therefore a much stronger signal of genuine binding potential. By this combined criterion, sophocarpine and the phenanthrene carboxylic acid emerged as the most promising compounds toward both enzymatic targets, suggesting that the alga’s antidiabetic activity may ultimately trace back to these specific molecules rather than to a diffuse collective effect.

The findings land in a research landscape that has been warming to marine macroalgae as pharmaceutical feedstocks. Previous work on H. scoparia has documented apoptosis-inducing activity in cancer cell lines, antimicrobial effects, antiprotozoal potential and a rich inventory of sulfated polysaccharides, fucoxanthins and mycosporine-like amino acids. A 2024 in vivo study in alloxan-induced diabetic mice had already hinted at the alga’s antihyperglycemic promise. What the new study adds is a rigorous, solvent-resolved map of which chemical fractions carry which activities, plus a computational shortlist of candidate molecules that can now be prioritized for isolation, synthesis and wet-lab validation. It also situates H. scoparia alongside related brown algae, such as Halopithys incurva and Cladostephus spongiosus, that the same Moroccan-Turkish collaboration has recently profiled, building a comparative framework for the region’s phlorotannin-rich seaweed flora.

Significant caveats remain before any of this reaches a pharmacy shelf. In vitro enzyme inhibition does not guarantee clinical efficacy, since intestinal absorption, metabolism and off-target toxicity all intervene between a docking score and a therapeutic effect. The tentative compound identifications require confirmation by isolation and structural elucidation, and the most active extracts will need to be tested in animal models of diabetes and subjected to standard safety pharmacology. Nonetheless, the study makes a persuasive case that a seaweed most people walk past on the beach is a chemically layered resource whose polar fractions deliver antioxidant firepower while its mid-polarity fractions carry dual enzyme-inhibitory activity. As the global burden of type 2 diabetes continues to climb and the search for safer, food-derived enzyme inhibitors intensifies, Halopteris scoparia has earned a place on the shortlist of marine organisms worth watching, and the pipeline from Moroccan tide pools to computational drug design has rarely looked more productive.

Subject of Research: Phytochemical characterization and antioxidant and antidiabetic evaluation of Halopteris scoparia brown alga extracts

Article Title: Exploration of Halopteris scoparia extracts and their bioactive compounds: from phytochemical characterization to in silico investigations

Article References: Aalilou, Y., Zengin, G., Karim, E. M., Hassoun, M., El karfi, W., Moussa, H., Mortada, S., Ak, G., Chtita, S., Ullah, R., Alotaibi, A., Meddah, B., Bouyahya, A., & Faouzi, M. E. A. (2026). Exploration of Halopteris scoparia extracts and their bioactive compounds: from phytochemical characterization to in silico investigations. Plant Biosystems, 160(4), Article 234. https://doi.org/10.1007/s44473-026-00237-y

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00237-y

Keywords: Halopteris scoparia, brown algae, antioxidant, antidiabetic, alpha-amylase, alpha-glucosidase, polyphenols, tannins, sophocarpine, molecular docking, molecular dynamics, marine natural products

In a study published in the journal Plant Biosystems, Youssra Aalilou of Mohammed V University in Rabat and her colleagues report the first comprehensive laboratory and computational evaluation of the antidiabetic potential of C. spongiosus, a branching brown seaweed of the family Cladostephaceae. The work combined classic enzyme inhibition assays with a battery of modern computational tools, including molecular docking, binding interaction analysis, molecular dynamics simulations and ADMET predictions, to ask a deceptively simple question: can this marine organism, and the nine small molecules previously identified in its extracts, meaningfully block the two key enzymes that drive post-meal glucose spikes?

The experimental design followed a logic that medicinal chemists have refined over decades. The researchers prepared five extracts of the alga using solvents of increasing polarity, a technique that separates the plant’s chemical inventory into fractions rich in different classes of compounds, from nonpolar lipids to highly polar phenolics and sugars. Each extract was then tested for its ability to inhibit alpha-glucosidase and alpha-amylase, the two carbohydrate-hydrolyzing enzymes of the human digestive tract whose blockade is the pharmacological basis of widely prescribed antidiabetic drugs such as acarbose. Inhibiting these enzymes delays the conversion of complex carbohydrates into absorbable glucose, flattening the blood sugar curve that follows a meal and easing the chronic metabolic stress that damages blood vessels, nerves and organs in diabetic patients.

The results were striking. Among all five extracts, the ethanol extract emerged as the clear standout, delivering the strongest dual inhibition of both enzymes. In quantitative terms, the ethanol extract inhibited alpha-glucosidase at 4.28 mmol acarbose equivalents per gram of extract, a standard measure expressing potency relative to the clinical drug acarbose. Against alpha-amylase, it recorded 0.54 mmol acarbose equivalents per gram in the iodine assay and, in the more sensitive DNSA colorimetric assay, an IC50 value of just 9.73 micrograms per millilitre, meaning that a very small concentration of the extract was enough to halve the enzyme’s activity. Values in this range, particularly for a crude, unfractionated natural extract, suggest a rich reservoir of inhibitory molecules working in concert.

But crude extracts are chemical black boxes, and the Moroccan-led team wanted to open it. Drawing on nine compounds that their earlier phytochemical work had already identified in C. spongiosus extracts, the researchers ran a full computational workup on each molecule to see which of them could plausibly account for the enzyme inhibition measured in the test tube. Molecular docking was used to computationally fit each compound into the active sites of alpha-glucosidase and alpha-amylase and to estimate binding energies, while binding interaction analysis mapped the specific hydrogen bonds, hydrophobic contacts and other forces holding each ligand in place at the atomic scale.

Docking alone can be misleading, however, because enzymes are not rigid sculptures. To test whether the predicted complexes would survive in a more realistic, dynamic environment, the team turned to molecular dynamics simulations, in which the protein-ligand complexes are allowed to move and flex in a simulated watery solution over time. Compounds whose binding falls apart in such simulations are usually artifacts of static docking; those that remain stably wedged in the active site are far more credible drug leads. In this study, several molecules displayed favorable interactions and stable binding profiles throughout the analyses, with four compounds standing out from the crowd: loliolide, isololiolide, herniarin and a monocrotaline isomer.

These four molecules make an intriguing chemical cast. Loliolide and isololiolide are structurally related carotenoid degradation products, small oxygenated lactones that have attracted growing attention in marine and plant natural products research for antioxidant and pharmacological properties. Herniarin is a simple methoxylated coumarin, a compound class with a long medicinal pedigree, and coumarin derivatives have previously been reported to show antidiabetic activity in other marine and coastal plants. The monocrotaline isomer represents a pyrrolizidine alkaloid scaffold, though the authors note that the toxicology of this class warrants careful attention, which is precisely why the study did not stop at binding predictions.

That attention came in the form of ADMET prediction, a computational screening step that estimates how a candidate molecule would behave in the human body across absorption, distribution, metabolism, excretion and toxicity. Using graph-based pharmacokinetic prediction tools, the researchers assessed whether their top-scoring enzyme inhibitors possessed drug-like properties or carried red flags that would disqualify them from further development. The integration of this pharmacokinetic layer with docking and dynamics data reflects a broader shift in natural products research, where the question is no longer simply whether a compound binds a target, but whether it could ever become a usable medicine.

The broader context makes the findings timely. Marine ecosystems remain dramatically underexplored compared with terrestrial biodiversity, yet seaweeds are already known to produce an extraordinary diversity of bioactive molecules, from phlorotannins and sulfated polysaccharides to carotenoids and terpenes, with reported activities spanning antioxidant, antimicrobial, anti-inflammatory and antihyperglycemic effects. Brown macroalgae in particular have accumulated a growing body of evidence supporting functional food and pharmaceutical applications. C. spongiosus itself has been the subject of seasonal volatile and antioxidant profiling in earlier studies, and the current work builds directly on the same team’s prior phytochemical characterization of the species, completing a pipeline that runs from specimen collection in the marine ecosystem to validated biological application.

For now, the results remain at the preclinical, exploratory stage: enzyme assays in vitro and simulations in silico, not human trials. The authors are careful to frame the work as identifying C. spongiosus as a promising marine source of bioactive compounds with potential applications in antidiabetic drug discovery, rather than as a ready-made therapy. Yet the convergence of strong dual enzyme inhibition in the ethanol extract, a shortlist of compounds with stable predicted binding to both therapeutic targets, and preliminary drug-likeness profiling gives the field exactly what early-stage natural product discovery needs: a prioritized set of molecules and a mechanistic hypothesis worth testing in the wet lab. If follow-up studies confirm that loliolide, isololiolide, herniarin or their algal companions inhibit carbohydrate digestion as potently in living systems as the computations suggest, the modest tufted seaweed clinging to Atlantic and Mediterranean rocks may yet contribute to the global fight against diabetes.

Subject of Research: Antidiabetic activity of the brown alga Cladostephus spongiosus evaluated through in vitro enzyme inhibition and computational molecular analysis

Article Title: First comprehensive in vitro and in silico investigations of the antidiabetic activity of Cladostephus spongiosus (Cladostephaceae): from marine ecosystem to biological application

Article References: Aalilou, Y., Qostal, M., Karfi, W. E., Rossafi, B., Mortada, S., Hassoun, M., Moussa, H., Zengin, G., Ak, G., Ullah, R., Alotaibi, A., Chtita, S., Bouyahya, A., Meddah, B., & Faouzi, M. E. A. (2026). First comprehensive in vitro and in silico investigations of the antidiabetic activity of Cladostephus spongiosus (Cladostephaceae): from marine ecosystem to biological application. Plant Biosystems, 160(5), Article 253. https://doi.org/10.1007/s44473-026-00264-9

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00264-9

Keywords: Cladostephus spongiosus, brown algae, antidiabetic, alpha-glucosidase, alpha-amylase, molecular docking, molecular dynamics, ADMET, loliolide, herniarin, marine natural products, type 2 diabetes