The investigation began with a pragmatic problem. Earlier work had shown that the chloroform fraction of G. thalictroides roots was strongly cytotoxic against cancer cell lines, and four active compounds had already been isolated, including two beta-carboline alkaloids and two cyclopeptides. But several minor metabolites visible in chromatographic profiles could not be captured in sufficient quantity for full structural elucidation. To close these gaps, the researchers re-extracted four kilograms of dried roots with ethanol, partitioned the resulting extract into hexane, chloroform, and ethyl acetate fractions, and prepared a traditional water decoction in parallel, mirroring exactly how local practitioners steep half a teaspoon of dried root in boiling water and drink it twice a day.

Before any purification began, the team mapped the plant’s entire metabolome using ultra-high-performance liquid chromatography coupled with high-resolution tandem mass spectrometry. The resulting data were assembled into a molecular network, a computational map in which each node represents a detected compound and edges connect molecules with similar fragmentation patterns. The network contained 2,066 nodes linked by 3,075 edges, and through in silico database searching combined with a taxonomically informed scoring filter, the team tentatively annotated 284 compounds, refining thirteen of them to metabolites previously reported in the Rubiaceae family. Distinct clusters emerged corresponding to indole alkaloids characteristic of the plant family and to the cyclopeptides already known from this species.

Armed with this map, the researchers then chased the actual molecules. Medium-pressure liquid chromatography with ultraviolet detection generated eighty-two fractions, many of which were further purified by semi-preparative HPLC, ultimately yielding twenty-six fully characterized compounds. The haul included phenolic glycosides, iridoids, coumarins, lignans, anthraquinones, and two important families of nitrogen-containing metabolites: Rubiaceae-type cyclopeptides of the bouvardin series and beta-carboline alkaloids. Three of the isolated compounds proved to be previously unknown natural products, and one anthraquinone, 1-methoxy-2,7-dihydroxyanthraquinone, was reported as a natural-source isolate for the first time.

The new cyclopeptides were the first major prize. Compound 18, named 5-beta-hydroxy-RA-XII, turned out to be a bouvardin-type cyclic hexapeptide bearing an appended glucose unit attached to the tyrosine-6 residue, a feature confirmed by nuclear magnetic resonance correlations from the sugar’s anomeric proton to the aromatic carbon of the tyrosine ring and by high-resolution mass spectrometry. Compound 19, dubbed 5-beta-hydroxy-RA-I, carries an additional oxygen relative to bouvardin: careful inspection of its spectra revealed that a methyl doublet belonging to the alanine-2 residue had vanished, replaced by an oxymethylene signal, indicating that an alanine had been converted to a serine. Both nomenclatures follow the RA-series convention established decades ago for related antitumor hexapeptides from Rubia species.

The most consequential chemical revision involved the beta-carboline alkaloids 24 and 25, which had been described in earlier studies of the same species. The original assignments posited two independent tertiary alcohols in the aliphatic side chain and treated key mass spectrometric ions as water-loss adducts. The new analysis flipped that interpretation. Instead, the team proposed that the two tertiary alcohols cyclize to form an internal ether, creating an extra five-membered ring, so that the observed ions correspond directly to protonated molecules. Carbon-13 chemical shift comparisons with structurally related ether-bridged compounds in the literature supported this reading, and the consistency of the proposed structures with all one- and two-dimensional NMR data was verified using the CT web application, which performs complete quantum mechanical spectral analysis, iteratively optimizing chemical shifts and coupling constants against calculated proton spectra.

Establishing the three-dimensional architecture demanded additional computational muscle. Relative configurations were locked down through nuclear Overhauser effect correlations, while absolute configurations were assigned by comparing experimental electronic circular dichroism spectra with spectra calculated for both candidate stereoisomers using time-dependent density functional theory. For the revised alkaloid 24, the experimental trace matched the 14R,15R,18S isomer. For the genuinely new alkaloid 23, which features an intramolecular ether bridge and a hydroxylated methine in a compact tetracyclic framework, the calculations pointed unambiguously to the 14S,15S,18R,19R configuration. Every structural claim in the paper therefore rests on converging lines of spectroscopic and computational evidence rather than a single technique.

With pure compounds in hand, the biological evaluation delivered striking results. Testing against BT-20 triple-negative breast cancer cells, an aggressive subtype lacking the three most common therapeutic targets, the bouvardin family dominated the potency rankings. Bouvardin itself and 6-O-methylbouvardin inhibited cell survival with IC50 values of roughly 0.25 micromolar, while 5-beta-hydroxy-RA-III followed at 2.7 micromolar. Structure-activity patterns emerged clearly: adding a hydroxyl group at the alanine-2 position reduced potency several-fold, and the bulky, highly polar glucose of compound 18 attenuated activity tenfold, plausibly by limiting cellular uptake. Anthraquinones showed moderate activity between 23 and 110 micromolar, and the beta-carbolines ranged from 65 to 193 micromolar, weaker but still biologically meaningful. Mechanistically, bouvardins are known inhibitors of protein biosynthesis, while anthraquinones can generate reactive oxygen species and form the scaffold of several approved anticancer drugs.

The beta-carbolines told a more intriguing mechanistic story. Because this scaffold had previously been shown to suppress Wnt signaling, a central oncogenic pathway implicated in tumor progression, therapy resistance, cancer stem cell maintenance, and epithelial-mesenchymal transition, the researchers ran a TopFlash reporter assay measuring Wnt3a-driven transcription in the same BT-20 cells. Compound 24 emerged as a selective Wnt pathway inhibitor with an IC50 near 40 micromolar, while its close analog 25, lacking the C-19 hydroxyl group, showed no specific Wnt inhibition at all. Compound 23 was entirely inactive, likely because its indole nitrogen is sequestered in an intramolecular cyclization and cannot engage biological targets. Both active and inactive derivatives were ten to twenty times less potent than the best Wnt-targeting beta-carbolines reported previously, so the authors are candid that these particular molecules are not optimal scaffolds, but the sharp activity difference between 24 and 25 provides a valuable structural clue about which molecular features matter for pathway inhibition.

Perhaps the most provocative conclusion concerns the plant as a whole. The cytotoxic bouvardins and the Wnt-selective beta-carboline coexist in the same chloroform fraction, and the authors argue that this combination may function as a multi-component anticancer system, with Wnt inhibition potentially sensitizing cancer cells to cytotoxic stress and simultaneous effects on tumor progression, recurrence, and apoptosis. Notably, the molecular network revealed that the cyclopeptides and beta-carbolines appear absent or only trace in the traditional water decoction, raising questions about which constituents actually reach patients drinking the remedy. The authors frame their findings as a foundation for pharmacological investigation, in vivo studies, and ultimately drug development, and the discovery of three new molecules, the correction of two flawed structures, and the demonstration of pathway-specific activity together make G. thalictroides one of the more compelling underexplored sources of anticancer natural products to emerge from Brazilian ethnobotany in recent years.

Subject of Research: Phytochemistry and anticancer bioactivity of Galianthe thalictroides metabolites

Article Title: Comprehensive phytochemical study of Galianthe thalictroides: isolation of three new compounds, structural revision of β-carbolines, and evaluation of cytotoxic and anti-wnt activities

Article References: Figueiredo, P. D. O., Kirchhoffer, O. A., Marcourt, L., Quiros-Guerrero, L., Koval, A., Kato Junior, W. H., Yoshida, N. C., Garcez, F. R., Garcez, W. S., Katanaev, V. L., Wolfender, J.-L., & Queiroz, E. F. (2026). Comprehensive phytochemical study of Galianthe thalictroides: isolation of three new compounds, structural revision of β-carbolines, and evaluation of cytotoxic and anti-wnt activities. Frontiers in Natural Products, 5, Article 1840056. https://doi.org/10.3389/fntpr.2026.1840056

Image Credits: AI Generated

DOI: 10.3389/fntpr.2026.1840056

Keywords: Galianthe thalictroides, natural products, cyclopeptides, beta-carboline alkaloids, Wnt signaling, cytotoxicity, triple-negative breast cancer, molecular networking, NMR, electronic circular dichroism, bouvardin, ethnopharmacology

Biosurfactants are amphiphilic molecules, meaning they possess both water-loving and water-fearing regions, and this dual nature allows them to dramatically reduce surface and interfacial tension between immiscible liquids such as oil and water. Unlike their petroleum-derived synthetic counterparts, biosurfactants are biodegradable, exhibit low toxicity, and maintain high surface activity across a range of industrial conditions. These properties make them attractive for applications spanning environmental remediation of oil spills, enhanced petroleum recovery, food preservation, pharmaceutical formulations, and cosmetic products. The most extensively studied and commercialized classes are lipopeptides like surfactin, produced by Bacillus species, and glycolipids like rhamnolipids, produced by Pseudomonas species. However, the search for novel biosurfactant producers has increasingly turned toward lactic acid bacteria, a group generally recognized as safe (GRAS) and widely employed in food fermentation.

Lactobacillus species are particularly compelling candidates because they are already embedded in human food systems, carry a long history of safe use, and produce bioactive metabolites with both antimicrobial and surface-active properties. Prior research has shown that biosurfactants from Lactobacillus can inhibit pathogens, preserve foods, and support probiotic preparations. The biosynthetic machinery behind these molecules typically involves non-ribosomal peptide synthetases, which are large multidomain enzymes that assemble peptide structures without the ribosomal translation machinery. These NRPS systems contain conserved catalytic domains, including adenylation (A), condensation (C), and peptidyl carrier protein (PCP) domains, each responsible for specific steps in substrate recognition, activation, and peptide elongation. What makes the current study distinctive is its focus on whether the adenylation domain alone, without the full NRPS assembly line, could still contribute meaningfully to biosurfactant production.

To answer this question, the research team first turned to comparative bioinformatics. They retrieved the NRPS protein sequence from Bacillus velezensis FZB42, a well-characterized commercial biosurfactant producer with extensively studied NRPS domains, and used it as a query against the NCBI non-redundant protein database. The most significant hit was a non-ribosomal peptide synthetase from Lactococcus lactis subsp. lactis KF147, with 99% query coverage, a BLAST score of 1,052, and an E-value of 0.0, indicating a highly significant alignment despite only moderate sequence identity of approximately 26%. This combination of high coverage and low E-value strongly suggested functional relatedness between the NRPS systems of these taxonomically distant bacteria. Further BLASTp analysis using the Lactococcus sequence as query revealed homologous proteins across multiple Lactobacillus species, including hybrid NRPS-polyketide synthase proteins and adenylate-forming enzymes.

Domain architecture analysis using InterProScan confirmed the presence of conserved functional modules across the analyzed sequences. The team identified the NRPS domain (IPR010060), the PCP domain (IPR009081), and the PKS domain (IPR020806), confirming the hybrid modular nature of these proteins. The condensation domain (IPR001242), responsible for peptide bond formation between activated amino acid substrates, appeared at multiple positions. Critically, the adenylation AMP-binding domain (IPR000873) and the amino acid adenylation domain (IPR010071) were highly conserved across all analyzed strains, underscoring their central role in substrate recognition and activation. The AMP-binding C-terminal domain (IPR025110) was also detected, providing structural stability to the adenylation modules. Notably, the number and organization of these domains varied considerably between strains. Lactobacillus helveticus MTCC 5463 and L. helveticus DPC 4571 each carried two conserved domains, representing a relatively streamlined biosynthetic organization. In contrast, Lactococcus lactis subsp. lactis KF147 harbored seven conserved domains, suggesting a more complex biosynthetic architecture and potentially greater catalytic capacity.

With the bioinformatic foundation in place, the researchers moved to the laboratory. They extracted genomic DNA from L. helveticus MTCC 5463 and used gene-specific primers to amplify the AMP-binding domain by polymerase chain reaction. The resulting fragment, approximately 353 base pairs in length, was directionally cloned into the pET-28a expression vector using XhoI and EcoRI restriction enzymes. Successful cloning was verified through restriction digestion analysis, which released an insert fragment of the expected size in positive clones. The recombinant plasmid was then transformed into Escherichia coli BL21(DE3) for heterologous protein expression. Induction with isopropyl 2-D-1-thiogalactopyranoside (IPTG) at concentrations ranging from 0.2 to 1.0 mM, followed by time-course analysis from 1 to 7 hours, revealed a clear recombinant protein band at approximately 14 kilodaltons on SDS-polyacrylamide gel electrophoresis. Expression intensity increased progressively with both inducer concentration and induction time, reaching maximum accumulation between 5 and 7 hours post-induction.

The recombinant biosurfactant was then extracted from the E. coli culture using chloroform:methanol solvent systems. The researchers tested two ratios, 1:1 and 2:1, and found that the 2:1 ratio produced significantly more visible precipitation, with the greatest accumulation observed at the 5-hour extraction time point. This enhanced recovery is attributed to the higher chloroform content, which improves solubilization of lipid-rich amphiphilic molecules. To rule out the possibility that the observed activity originated from endogenous E. coli membrane lipids, the team conducted a critical empty-vector control experiment. An E. coli BL21(DE3) strain carrying the empty pET-28a vector was processed under identical conditions, and the resulting extract showed no measurable emulsification activity against any of the tested oils and no detectable bands on thin-layer chromatography. This control definitively linked the biosurfactant phenotype to the recombinant AMP-binding domain construct rather than host-derived lipids.

Functional evaluation of the extracted biosurfactant revealed impressive emulsification performance across multiple substrates. Using the emulsification index (E24) assay, which measures the percentage of emulsified layer height relative to total liquid column height after 24 hours, the recombinant product achieved approximately 75% to 82% emulsification against petrol and diesel oil, maintaining stability for a full week with minimal variation. Against mustard oil, the performance was even more striking, reaching 88% to 95%, far exceeding the 10% to 12% achieved by rhamnolipid and the 30% to 38% achieved by surfactin under the same conditions. For refined oil, the recombinant biosurfactant delivered 65% to 75% emulsification at 24 hours, sustaining approximately 65% to 70% even after one week, while rhamnolipid showed only 4% to 6% and surfactin showed moderate activity of 46% to 50%. These results demonstrate that the recombinant glycolipopeptide consistently outperformed both benchmark biosurfactants across hydrocarbon and vegetable oil substrates.

Analytical characterization provided detailed structural insights into the recombinant molecule. Thin-layer chromatography using iodine vapor revealed a yellow-brown spot with an Rf value of 0.80, indicating a relatively non-polar lipid-rich compound, while anisaldehyde staining produced a spot at Rf 0.75, consistent with glycolipid or lipopeptide chemistry. Fourier-transform infrared spectroscopy identified key functional groups: a broad band at 3,325 cm⁻¹ corresponding to hydrogen-bonded O-H and N-H stretching from carbohydrate and protein moieties, aliphatic C-H stretching at 2,916 cm⁻¹ confirming long hydrocarbon chains, a band at 1,649 cm⁻¹ assigned to amide I (C=O stretching) indicating peptide bonds, and C-O stretching at 1,021 cm⁻¹ pointing to carbohydrate or ester linkages. Together, these spectral features are characteristic of a glycolipopeptide structure containing lipid, peptide, and carbohydrate components.

Gas chromatography-mass spectrometry profiling further confirmed the hydrophobic lipid architecture of the biosurfactant. The most abundant compound identified was 9-octadecenamide, accounting for 20.50% of the total relative area, followed by significant amounts of C16 and C18 long-chain fatty acid derivatives and amides. These hydrophobic moieties form the structural basis for surface tension reduction, emulsification, and micelle formation. Nuclear magnetic resonance spectroscopy, conducted on a Bruker Avance NEO spectrometer at 400 MHz, provided complementary evidence. Proton NMR revealed strong signals at δ 1.23 to 1.58 ppm from methylene protons of long-chain fatty acyl groups, glyceryl and carbohydrate-associated signals at δ 3.72 ppm, and a broad singlet at δ 7.3 ppm assigned to exchangeable amide N-H protons, confirming peptide-associated functionalities. Carbon-13 NMR showed resonances at δ 18 ppm for terminal methyl carbons of branched-chain fatty acids, δ 66 and 76 ppm for O-CH₂ and CH-O carbons of glycerol or carbohydrate moieties, δ 56 and 58 ppm for alpha-methine carbons of amino acid residues, and carbonyl carbons at δ 173 to 175 ppm for amide or ester linkages. Collectively, the spectroscopic data confirm a multicomponent amphiphilic glycolipopeptide structure. The authors note that while the isolated adenylation domain alone is unlikely to catalyze complete glycolipopeptide biosynthesis, it may influence production indirectly through interactions with endogenous metabolic pathways in the E. coli host, and they plan future transcriptomic, proteomic, and metabolomic investigations to elucidate the precise molecular mechanism underlying this observation.

Subject of Research: Biosurfactant production mediated by the NRPS adenylation domain of Lactobacillus helveticus MTCC 5463

Article Title: In silico and experimental characterization of NRPS adenylation domain-mediated biosurfactant production in Lactobacillus helveticus MTCC 5463

Article References: Kumari, M., Pandey, K., Mehtab, S., & Singhal, B. (2026). In silico and experimental characterization of NRPS adenylation domain-mediated biosurfactant production in Lactobacillus helveticus MTCC 5463. Frontiers in Bacteriology, 5, Article 1895576. https://doi.org/10.3389/fbrio.2026.1895576

Image Credits: AI Generated

DOI: 10.3389/fbrio.2026.1895576

Keywords: biosurfactant, Lactobacillus helveticus, NRPS, adenylation domain, glycolipopeptide, emulsification, probiotics, non-ribosomal peptide synthetase, heterologous expression, FTIR, GC-MS, NMR

The significance of the target material lies in its status as an agricultural by-product. Musa balbisiana is a wild progenitor of many cultivated banana varieties, and its corm, the underground bulb-like stem from which the pseudostem grows, has long featured in folk medicine across Vietnam, Laos, and Thailand, where preparations have been used against stomach ulcers, kidney stones, metabolic disorders, and diabetes. Earlier laboratory studies have supported some of these traditional claims: corm extracts have shown antioxidant activity, hypoglycemic effects in vitro and in vivo, and inhibition of metabolic enzymes such as tyrosinase, xanthine oxidase, and lipase, which are implicated in skin disorders, gout, and obesity respectively. Yet despite this pharmacological promise, corms are routinely discarded after harvest, representing a wasted stream of raw material. Turning that waste into standardized, bioactive extracts would fit squarely within the growing circular-economy push in food and pharmaceutical research, where by-products are reimagined as feedstocks for nutraceuticals, cosmetics, and functional foods.

The extraction technology at the heart of the study, microwave-assisted extraction, works on a principle quite different from conventional soaking or Soxhlet methods. Microwaves heat the solvent and the plant matrix from within, generating localized thermal gradients that rupture cell walls and drive dissolved compounds rapidly into the surrounding liquid. The result is dramatically shorter processing times and lower solvent consumption, both important credentials for a technique marketed as green. But microwave extraction is not a one-size-fits-all affair. The optimal combination of solvent composition, power, irradiation pattern, and duration depends heavily on the specific plant tissue and the chemistry of the target molecules, which is why the Vietnamese team insisted that conditions must be tailored to each new matrix. Previous studies had applied the technique to banana peels and other Musa waste streams, recovering phenolics with water or glycerol-ethanol mixtures, but no published protocol existed for extracting both polyphenols and saponins from M. balbisiana corm.

The researchers began with a systematic one-factor-at-a-time exploration of the key variables. Fresh corms collected in Dong Thap province were cleaned, sliced, dried at 60 degrees Celsius, ground into a fine powder, and extracted with aqueous methanol at ratios of one gram of material to thirty milliliters of solvent. Polyphenol recovery climbed steadily as methanol concentration rose from 40 to 60 percent, reaching a plateau above that level, while saponin content followed the same trajectory, peaking near 70 percent methanol. The explanation is a tug-of-war between polarity and microwave physics: moderately polar phenolic aglycones and glycosylated triterpenoid saponins dissolve better in less polar mixtures, but above roughly 60 to 70 percent methanol the solvent’s dielectric properties deteriorate, so it can no longer convert microwave energy into heat efficiently. Power told a similar story of diminishing returns, with 360 watts delivering the best yields but no statistically significant gain over 270 watts, and higher settings risking thermal degradation of heat-sensitive compounds.

Irradiation cycling and extraction time completed the picture. Pulsing the microwaves for four seconds per minute outperformed both shorter and longer duty cycles, an effect the authors attribute to the need for rest intervals that allow active compounds to diffuse from the plant matrix into the solvent between heating pulses. Extending the total extraction time from 20 to 40 minutes significantly boosted yields, with polyphenols reaching 71.63 milligrams per gram and saponins 60.45 milligrams per gram, but longer exposures caused yields to slip, consistent with cumulative microwave-induced degradation. Screening experiments using a two-level factorial design then confirmed which variables truly mattered. Microwave irradiation cycle, power, and solvent concentration emerged as the three dominant factors at the 5 percent significance level, while extraction time proved the least influential and was fixed at 40 minutes for all subsequent modeling.

With the influential variables identified, the team turned to response surface methodology using a Box-Behnken design, a statistical framework that fits a quadratic model to experimental data and locates the optimum without testing every possible combination. Fifteen experimental runs spanning three levels of methanol concentration, power, and irradiation cycle produced regression equations for both target responses. The models performed well, explaining 94 percent of the variance in polyphenol yield and 95 percent in saponin yield, with non-significant lack-of-fit tests indicating that the fitted surfaces faithfully represented the underlying chemistry. Strikingly, the response surfaces for the two compound classes were nearly congruent, both showing dome-shaped profiles with maxima near the center of the experimental domain. This overlap means a single set of operating conditions serves both chemically distinct metabolite families, a practical advantage for any future industrial process aiming at a dual-action extract.

The predicted optimum called for 70 percent methanol, 270 watts of microwave power, and a 4-second-per-minute irradiation cycle. Validation experiments under these conditions delivered 71.35 plus or minus 0.51 milligrams of polyphenols and 60.68 plus or minus 1.23 milligrams of saponins per gram of dry matter, deviations below 5 percent from the model predictions and statistically indistinguishable from them. The extract was then concentrated and fractionated through liquid-liquid partitioning with n-butanol and water, followed by silica gel chromatography eluted with chloroform-methanol gradients. Thin-layer chromatography, visualized with ferric chloride for phenolics and anisaldehyde-sulfuric acid for saponins, guided the collection of enriched fractions for structural analysis.

The spectroscopic characterization formed the analytical centerpiece of the work. Raman spectra displayed intense bands for conjugated aromatic carbon-carbon stretching between 1600 and 1620 wavenumbers, along with ring deformation modes and sugar-region signals near 843, 974, and 1100 wavenumbers, features compatible with glycosylated flavonoids and carbohydrate-bearing constituents. The authors were careful to note, however, that these Raman features are supportive rather than confirmatory for saponins, since no band uniquely identifies a triterpenoid or steroidal saponin skeleton. Fourier-transform infrared spectroscopy told a complementary story, revealing a broad hydroxyl stretch near 3400 wavenumbers, a conjugated carbonyl at 1666 wavenumbers characteristic of the gamma-pyrone ring of flavonoids, and multiple aromatic ring stretches between 1450 and 1611 wavenumbers, together with carbon-oxygen bands in the fingerprint region consistent with glycosidic moieties.

Nuclear magnetic resonance provided the most specific identification. The purified fraction, designated compound CC, showed five aromatic proton signals in its proton NMR spectrum, including the meta-coupled pair at 6.18 and 6.40 parts per million diagnostic of the A-ring of a flavonol, and the three-proton pattern of a catechol-type B-ring. A strongly deshielded singlet at 12.49 parts per million confirmed the 5-hydroxyl group hydrogen-bonded to the C-4 carbonyl, while carbon NMR displayed fifteen signals including a carbonyl at 176.3 parts per million. Every chemical shift matched published quercetin values within 0.3 parts per million for carbon and 0.15 for hydrogen. The authors nonetheless label the identification tentative: without high-resolution mass spectrometry or two-dimensional NMR experiments, the molecular formula could not be verified experimentally, and follow-up analyses are planned. No individual saponin was isolated at all, with evidence for that class resting on colorimetric assays, TLC staining, and vibrational bands. Those caveats aside, the study makes a persuasive case that a discarded banana corm, zapped with carefully tuned microwaves, can deliver pharmaceutical-grade chemistry from the compost heap.

Subject of Research: Microwave-assisted extraction and spectroscopic characterization of polyphenol- and saponin-rich extracts from Musa balbisiana corm

Article Title: Extraction and spectroscopic characterization of polyphenol- and saponin-rich extracts from musa balbisiana corm with tentative identification of quercetin

Article References: Nhon, H. T. N., Trang, N. T. H., & Anh, L. T. H. (2026). Extraction and spectroscopic characterization of polyphenol- and saponin-rich extracts from musa balbisiana corm with tentative identification of quercetin. Food Chemistry: X, Article 104578. https://doi.org/10.1016/j.fochx.2026.104578

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104578

Keywords: Musa balbisiana, banana corm, microwave-assisted extraction, polyphenols, saponins, quercetin, response surface methodology, Box-Behnken design, FT-IR spectroscopy, Raman spectroscopy, NMR, agricultural by-products

The study, published in the journal Magnetic Resonance, focused on the flagship meetings of the magnetic resonance community: EUROMAR, the Experimental Nuclear Magnetic Resonance Conference (ENC) and the International Conference on Magnetic Resonance in Biological Systems (ICMRBS). These events draw between roughly 470 and 1,100 participants and last four to six days. The team gathered participant lists from conference organizers, apps and abstract books, then used automated text extraction and manual curation to link each attendee’s institutional affiliation to a city of origin. From there, they computed the presumed travel trajectory of every participant and converted those distances into emissions.

The conversion was deliberately rigorous. For journeys shorter than 400 kilometres one way, the researchers assumed train travel, using actual rail distances calculated through the Carbontracer service rather than straight-line estimates. Longer trips were assumed to be flown. Crucially, the team refused to rely on the optimistic figures often quoted by railway companies. They added an infrastructure surcharge of about 25 grams of CO2 equivalent per passenger kilometre to account for the construction and maintenance of rail lines and the heating and cooling of stations — costs that most carbon calculators quietly ignore. Drawing on data from the Austrian Federal Railways and a study of the Austrian rail network, they estimated that indirect emissions roughly multiply the direct emissions of a train journey by a factor of about 2.5.

For aviation, the accounting was similarly unforgiving. The researchers applied a radiative forcing index, which captures the fact that greenhouse gases emitted at altitude warm the planet more powerfully than the same gases released at ground level, with values ranging from 1.3 to 3 depending on altitude. They also corrected the great-circle distance between cities by an uplift factor of 8 percent to reflect real-world flight paths, holding patterns and takeoff inefficiencies, and added an estimated 15 percent for airport infrastructure. Even so, they acknowledge their flight figures are likely underestimates by about 20 percent, because connecting flights — which can add up to 100 kilograms of CO2 per additional takeoff — were not modelled.

The headline numbers are striking. Total travel emissions for a typical EUROMAR conference came to 700 to 900 tonnes, or about 1.2 to 1.3 tonnes of CO2 per participant when flights are assumed beyond 400 kilometres, dropping to roughly one tonne if attendees take trains up to 800 kilometres. For conferences held outside Europe, per-person emissions were two to three times higher, with intercontinental round trips reaching four to five tonnes. The geography of attendance matters enormously: more than 80 percent of EUROMAR participants typically come from Europe, and the most frequent one-way journey is between 800 and 1,200 kilometres. At the 2024 ICMRBS meeting in Seoul, 200 of about 580 participants were from the Republic of Korea, yet the per-person average excluding those local attendees exceeded 3.1 tonnes.

Perhaps the most provocative finding is how conference travel stacks up against the rest of a scientist’s carbon ledger. The team compared it with the emissions of actually doing magnetic resonance research: building and running NMR spectrometers with their supercooled magnets, powering cryogenics, computing, laboratory consumables, buildings and commuting. For a model facility with three spectrometers at 600, 700 and 800 megahertz shared by 20 researchers, the annual operating footprint ranged from 0.8 to 5 tonnes per person, depending on how fossil-heavy the national electricity grid is. In other words, attending a five-day EUROMAR conference can emit more carbon than running NMR experiments for an entire year in a country like France, where the grid is largely low-carbon. Traveling from Europe to the ENC meeting in California, the authors note, emits more CO2 than half a year of making samples, performing NMR and computing combined.

Accommodation, catering and the venue itself, by contrast, barely register. A three-star European hotel generates roughly 10 to 20 kilograms of CO2 equivalent per person per night, meals add perhaps 14 to 28 kilograms over a five-day meeting, and the venue contributes around 10 kilograms per attendee. All told, everything except travel amounts to a few tens of kilograms — meaning transportation accounts for the overwhelming majority of a conference’s footprint. The comparison with the global carbon budget is stark: the IPCC’s SR15 report estimated a remaining budget of about 420 gigatonnes of CO2 equivalent for a two-thirds chance of limiting warming to 1.5 degrees Celsius, which distributes to roughly 4.5 tonnes per person per year in 2025 — a figure that must fall to zero by 2050. A single transatlantic conference trip can consume an entire annual allowance.

The study does not stop at diagnosis; it models remedies. Choosing more geographically central venues emerges as a powerful lever. The team used the EUROMAR 2024 attendee list to predict emissions if the meeting had been held in Frankfurt, Lyon or Vienna instead of more remote locations, and found that central sites could cut per-attendee emissions by more than a factor of two — a saving of roughly 500 to 800 tonnes for a conference the size of EUROMAR. A similar calculation for the ENC meeting suggested that moving it from California to the US East Coast would save about 25 percent, or 400 to 500 tonnes, thanks to shorter distances for European attendees and the density of NMR groups on the East Coast. The authors caution, however, that systematically favoring central locations disadvantages colleagues in more distant regions, a trade-off that must be weighed.

Decentralized conferences offer another path. The researchers modelled a two-site EUROMAR in which participants travel to whichever hub is closer to their home institution, with plenary talks shared by video link. Savings of around 25 percent appeared realistic — consistent with earlier case studies that projected one-third reductions for three-hub conferences and up to 80 percent savings for split meetings. Fully online formats are in a different league altogether: videoconferencing generates an estimated 0.15 to 0.25 kilograms of CO2 equivalent per participant-hour, or about 1.6 kilograms per person for an eight-hour day, two to three orders of magnitude below in-person meetings. A large astronomy conference that went online reduced its footprint by a factor of 3,000. Online formats also broaden access, lifting barriers for junior scientists, caregivers and researchers at underfunded institutions — attendance at the largest European geoscience meeting rose by more than 60 percent when it moved online during the pandemic.

At the individual level, the choice between train and plane matters enormously. Across model journeys from cities such as Frankfurt, Vienna and Paris to prospective EUROMAR venues in Oulu, Gothenburg and Lyon, train travel saved between 75 and 95 percent of emissions compared with flying — a fourfold to twentyfold reduction — even after the team’s deliberately conservative accounting of rail infrastructure. Even in worst-case scenarios with low radiative forcing assumptions and night trains with reduced capacity, trains still saved at least 40 percent. The authors also point to behavioral evidence that trimming travel need not cost careers: a survey of German scientists found respondents attended about three conferences per year on average, and while 8 percent of postdocs reported receiving a job offer through conference travel, a separate study of air travel and scholarly metrics found no significant relationship between the volume of flying and research output measured by indicators such as the h-index. The team hopes their open data and scripts will help conference organizers and individual scientists make informed, quantitatively grounded choices — and spark a community-wide conversation about how the scientific meeting, one of academia’s most cherished traditions, can survive the transition to a net-zero world.

Subject of Research: Carbon emissions from conference travel in the magnetic resonance research community and strategies to reduce them

Article Title: Quantifying the carbon footprint of conference travel: the case of NMR meetings

Article References: Kapoor, L. N., Ružičková, N., Živadinović, P., Leitner, V., Sisak, M. A., Mweka, C., Dobbelaere, J., Katsaros, G., & Schanda, P. (2025). Quantifying the carbon footprint of conference travel: the case of NMR meetings. Magnetic Resonance, 6(2), 243-256. https://doi.org/10.5194/mr-6-243-2025

Image Credits: AI Generated

DOI: 10.5194/mr-6-243-2025

Keywords: carbon footprint, conference travel, magnetic resonance, NMR, greenhouse gas emissions, EUROMAR, train versus plane, academic mobility, climate mitigation, sustainable science, virtual conferences, aviation emissions

The starting point for the study, published in The Journal of Antibiotics, is waldiomycin, an antibiotic originally isolated from a Streptomyces actinomycete. Waldiomycin is a striking molecule: a set of angucyclic rings bearing a naphthoquinone scaffold, connected through a tetraene linker to a dioxolan ring. Earlier nuclear magnetic resonance work had suggested that the angucyclic portion of the compound wedges itself into the H-box, a short stretch of amino acids conserved across bacterial histidine kinases, and thereby suppresses the autophosphorylation reaction that the catalytic ATP-binding domain depends on. Crucially, the H-box sequence is specific to histidine kinases and does not appear in the serine/threonine or tyrosine kinases of human cells, which makes it a potentially selective point of attack against dangerous pathogens, including the ESKAPE organisms that dominate hospital-acquired infections.

Previous attempts to drug this region have produced a long list of chemotypes, including trityles, benzoxazines, salicylanilides, triazoles, benzimidazoles, benzoxazoles, thiazolidiones, thiophenes, and adenine derivatives. None has advanced to clinical testing. The problem, in part, is that most medicinal chemistry campaigns against histidine kinases have started from structures that resemble the natural ligand, limiting the chemical space explored. The new work, led by Teruhiko Ishikawa, Yoko Eguchi, Toshihide Okajima, Masayuki Igarashi, and Ryutaro Utsumi, set out to break that pattern by using a screening method that deliberately ignores the three-dimensional structure of the protein-ligand complex altogether.

The method, called amino acid mapping, was proposed by Kyosuke Tsumura and colleagues. Instead of modeling how a compound sits inside a binding pocket, amino acid mapping asks a simpler question: which amino acid residues tend to cluster around the compound in aqueous solution? The answer is encoded as a spatial probability distribution of individual amino acid residues surrounding the molecule, calculated from molecular dynamics simulations and independent of any explicit protein structure. Two compounds with similar descriptors are likely to be recognized by similar binding environments, even if their chemical scaffolds look nothing alike. This makes the approach a form of scaffold hopping: it can carry the biological activity of a known ligand across to chemically distant molecules without requiring a crystal structure of the target.

To apply the method, the team first computed a high-precision reference descriptor for the naphthoquinone moiety of waldiomycin, the fragment that directly contacts the H-box. One hundred low-precision conformations were generated with Open Babel and then refined using density functional theory calculations with the B3LYP functional, a 6-31G* basis set, and a polarizable continuum solvation model in Gaussian16, yielding the most stable conformation. The researchers then compared this reference against a commercially available library of 11,973,825 compounds, using cosine similarity between descriptors as the measure of resemblance. Because a full comparison of millions of compounds is computationally punishing, the team applied a stepwise filter: compounds were first screened against a phenylalanine-only descriptor, then against descriptors for charged residue types, and only survivors of both stages underwent the complete 27-residue calculation. A similarity threshold of 0.75, chosen on the basis of earlier screening campaigns in which roughly one in ten compounds above that value showed activity comparable to the reference ligand, narrowed the field to 714 candidate molecules.

From those 714 hits, the team extracted rigid substructures, defined as condensed ring systems together with adjacent atoms connected through double or higher-order bonds, using an RDKit-based Python workflow. The analysis yielded 227 distinct scaffolds. After excluding frameworks smaller than a two-ring system, the eleven most frequent scaffolds were shortlisted, and the team settled on 9-hydroxy-4H-pyrido[1,2-a]pyrimidin-4-one, a scaffold ranked ninth by frequency but chosen for its novelty as an H-box inhibitor and its synthetic accessibility. Fifteen derivatives were synthesized through condensation reactions in polyphosphoric acid, nitration and reduction sequences, and a newly developed magnesium(II) triflate-mediated coupling, producing compounds designated FF-053 through FF-081.

The biological results were encouraging. When the fifteen compounds were tested at 100 micrograms per milliliter against the cytoplasmic regions of three histidine kinases, Bacillus subtilis WalK, Streptococcus mutans VicK, and Escherichia coli EnvZ, several showed more than 30 percent inhibition of autophosphorylation and were advanced to full dose-response analysis. Three derivatives, FF-054, FF-055, and FF-060, emerged as the standouts, with IC50 values ranging from 4.39 to 259 micromolar. Against WalK, none of the new compounds surpassed waldiomycin itself, which inhibits at 13.1 micromolar. But against VicK, the story reversed dramatically: FF-055 inhibited at 6.92 micromolar and FF-060 at 4.39 micromolar, both considerably more potent than waldiomycin’s 25.8 micromolar. The authors suggest that structural differences between the dimeric forms of WalK and VicK, which remain incompletely characterized, may explain the enhanced affinity of the new compounds for VicK.

The mechanistic evidence is where the study becomes particularly compelling. When the conserved H-box serine at position 242 of EnvZ, adjacent to the autophosphorylation site H243, was mutated to alanine, the potency of all three lead compounds dropped three- to six-fold, while a T247A mutation had no such effect. This pattern contrasts with waldiomycin, which loses potency against both mutants, and suggests that the new compounds bind on the S242 side of the phosphorylated histidine rather than the T247 side favored by the natural product. Nuclear magnetic resonance experiments with the isolated DHp domain of EnvZ, residues 223 to 289, confirmed direct physical interaction: addition of FF-054 perturbed the chemical shifts of V241, D244, and R246 within the H-box, while FF-060 produced dose-dependent perturbations at S242, R246, and T247. Affinity selection mass spectrometry added a further twist. At 100 micromolar, FF-060 increased the amount of waldiomycin bound to VicK from roughly 50 to 120 nanomolar, mirroring the behavior of previously described Type B H-box inhibitors, which bind a distinct site and allosterically enhance waldiomycin binding to both H-boxes of the dimeric kinase.

Perhaps the most elegant demonstration came from converting the descriptors themselves into a map. The team computed a ten-by-ten similarity matrix among the naphthoquinone reference, the three new pyridopyrimidinones, and six previously synthesized naphthoquinone-derived inhibitors, then applied classical multidimensional scaling to visualize the relationships in two dimensions. The compounds separated cleanly into two clusters that corresponded exactly to their experimentally determined modes of action: Type A inhibitors, which compete with waldiomycin for the same site, grouped with the natural product, while Type B inhibitors, including all three new FF compounds, grouped on the opposite side of the map. In other words, the amino acid mapping descriptor, computed without any knowledge of the protein, predicted which compounds share a binding site.

The implications extend beyond this single target class. The study represents the first successful application of amino acid mapping-based screening to identify histidine kinase inhibitors targeting the H-box, and it demonstrates that a descriptor derived from a natural product can be used to mine a library of nearly twelve million compounds for chemically unrelated hits with genuine biochemical activity. Because the method requires no structure of the protein-ligand complex, it could open doors against targets that have resisted traditional structure-based design, a category that includes many membrane-associated and dimeric signaling proteins. The authors caution that future work will be needed to determine whether the descriptor framework can be used prospectively to rationally select inhibitors with specific functional properties. But for a field in which no histidine kinase inhibitor has yet reached clinical trials, the arrival of three potent, structurally novel lead compounds, together with a computational tool that maps their binding modes, is a meaningful step toward antibiotics that disarm bacterial signaling rather than simply poisoning the cell.

Subject of Research: Amino acid mapping-based virtual screening for novel histidine kinase inhibitors targeting the bacterial H-box region

Article Title: Amino acid mapping–guided scaffold selection and hit identification of histidine kinase inhibitors from a virtual library of over 12 million compounds

Article References: Ishikawa, T., Eguchi, Y., Okajima, T., Igarashi, M., Ohira, S., Tsumura, K., Sakurai, K., Ishizaki, Y., Hayashi, C., Akter, S., Nakayama, J., Kohayakawa, C., Tani, A., Sawa, N., Katsumoto, T., Matsumoto, F., Haruta, J.-I., & Utsumi, R. (2026). Amino acid mapping–guided scaffold selection and hit identification of histidine kinase inhibitors from a virtual library of over 12 million compounds. The Journal of Antibiotics. https://doi.org/10.1038/s41429-026-00953-9

Image Credits: AI Generated

DOI: 10.1038/s41429-026-00953-9

Keywords: histidine kinase, amino acid mapping, virtual screening, waldiomycin, two-component system, antibiotic resistance, H-box, scaffold hopping, molecular dynamics, NMR, pyridopyrimidinone, drug discovery

The threat itself operates through two intertwined mechanisms. The first is physical: sulfate solutions penetrate the porous network of cement through capillary action and osmosis, and as temperature and humidity fluctuate, dissolved sulfates reach supersaturation and crystallize inside capillary pores, voids, and micro-cracks. Growing crystals press relentlessly against pore walls, and once that pressure exceeds the internal cohesion of the matrix, pores expand and coalesce, the framework loosens, and surfaces begin to crack, peel, and powder. This damage opens fresh pathways for more sulfate ingress, creating a self-reinforcing cycle of erosion, deterioration, and accelerated erosion. The second mechanism is chemical and far more destructive. Sulfate ions react with calcium hydroxide to form gypsum and with calcium aluminates to generate ettringite—two expansive products that swell to roughly twice and one-and-a-half times their original volume, respectively. In the cramped interior of hardened cement, this expansion generates internal stresses that break chemical bonds between hydration products, raise porosity, propagate cracks, and ultimately strip away compressive strength, rupture strength, and interfacial bonding capacity.

Earlier work had already hinted that nanomaterials could help. Studies cited by the team showed that 1.5% nano-SiO₂ boosted the rupture strength of fly ash-cement mortar by 90%, while 0.5% raised compressive strength by 67.1% to 118.2%, and that 1% nano-CaCO₃ refined concrete’s microstructure enough to mitigate late-stage expansion damage. But nanomaterials carry a notorious drawback: their ultrafine particle size and enormous specific surface area make them prone to agglomeration during mixing, which raises water demand, degrades workability, and can undermine the very strength they are meant to enhance. The new research set out to resolve this tension by systematically comparing both nanoparticles across multiple dosages, combining macroscopic measurements of mass, compressive strength, and rupture strength with microscopic characterization by scanning electron microscopy (SEM), X-ray diffraction (XRD), and nuclear magnetic resonance (NMR).

The experimental design was rigorous and methodical. Seven mortar groups were prepared with a water-to-cement ratio of 0.55: an unmodified control, three groups with nano-SiO₂ at 1%, 3%, and 5% by mass of cement, and three groups with nano-CaCO₃ at the same dosage levels. The nano-SiO₂ particles measured about 20 nanometers with a specific surface area of 80 square meters per gram, while the nano-CaCO₃ particles were roughly 40 nanometers with 30 square meters per gram. After 28 days of standard curing and drying at 80 degrees Celsius, the 40 by 40 by 160 millimeter prisms were fully immersed in a 5% sodium sulfate solution at 20 degrees Celsius, with the solution renewed every 30 days to maintain stable concentration and pH. Specimens were retrieved at 30, 60, 90, 120, 150, and 180 days for testing, with three parallel specimens averaged for each measurement.

The mass evolution told a striking story. All groups first gained weight as invading sulfate reacted with hydration products to form pore-filling ettringite and gypsum, then lost weight as excessive expansion triggered micro-cracking, surface spalling, and detachment of erosion products. The nano-SiO₂ group at 3% dosage peaked at a 4.39% mass gain at 90 days and still retained a 3.70% mass change at 180 days, losing only 0.69% after its peak. By contrast, the 5% nano-CaCO₃ group reached a slightly higher peak of 4.55% but then shed a full 3.55% of its mass in the same window, ending at roughly 1%. After 180 days, the optimal nano-SiO₂ group’s mass change was 122.9% higher than that of the optimal nano-CaCO₃ group—a quantitative demonstration that the mass gained by nano-SiO₂ modification reflects a dense, penetration-resistant matrix, whereas the mass gained by heavily dosed nano-CaCO₃ stems from expansive ettringite that later causes severe spalling.

Compressive and rupture strength followed a three-stage trajectory of initial rise, mid-term plateau, and final decline, with peaks generally appearing between 30 and 90 days as ongoing hydration gave way to expansion damage. The 5% nano-SiO₂ group posted the highest peak compressive strength of 55.59 megapascals at just 30 days, while the 3% nano-SiO₂ group peaked at 51.47 megapascals. Crucially, strength retention revealed the deeper advantage of nano-SiO₂: at both the 1% and 3% dosage levels, nano-SiO₂-modified specimens retained more of their peak strength than their nano-CaCO₃ counterparts, with the 1% nano-SiO₂ group preserving 75% of its peak compressive strength after 180 days compared with 65.4% for the equivalent nano-CaCO₃ group. In rupture strength, the 3% nano-SiO₂ group held a retention rate of 44.4% versus 34.2% for 3% nano-CaCO₃, and its residual strength of 1.82 megapascals clearly exceeded the control group’s 1.65 megapascals. The team attributes this resilience to nano-SiO₂’s dual action: its pozzolanic reaction chemically consumes calcium hydroxide—the very ingredient sulfate ions need to form gypsum—while its micro-aggregate filling effect physically blocks ion transport channels.

The microscopic evidence sealed the argument. X-ray diffraction showed that in the unmodified control, ettringite and gypsum peaks surged between 90 and 120 days, reached maximum intensity by 150 to 180 days, and were joined by thaumasite, a notoriously destructive sulfate-bearing phase, marking the onset of accelerated deterioration. The 1% nano-SiO₂ group, by contrast, showed the lowest ettringite and gypsum peak intensities of all groups throughout the 90-to-180-day window and no obvious thaumasite signal at all, because the pozzolanic reaction had stripped the system of the calcium hydroxide needed to fuel attack reactions. Scanning electron microscopy at 10,000-fold magnification made the damage hierarchy visible: after 180 days, the control mortar displayed interconnected crack networks, spalling, and a failed hydration skeleton, while the 3% nano-SiO₂ specimen maintained a complete, continuous gel skeleton with only trace surface attack products. The overall degradation ranking ran from worst to best as control, 5% nano-CaCO₃, 3% nano-CaCO₃, 1% nano-CaCO₃, 1% nano-SiO₂, 5% nano-SiO₂, and 3% nano-SiO₂.

Nuclear magnetic resonance added a non-destructive, quantitative dimension by tracking pore size distribution through the relaxation behavior of hydrogen nuclei in pore water. At the outset, all nano-modified samples already showed lower initial porosity than the control’s 11.41%, thanks to nanoparticle filling. Porosity then fell during the first 90 days as expansive products temporarily plugged capillary channels—the 5% nano-SiO₂ group plummeting from 10.16% to a remarkable 3.97%—before rebounding after 120 days as expansion stress cracked the matrix. By 180 days, the control’s porosity had climbed back to 11.12%, nearly erasing its early densification, while the nano-modified specimens showed far smaller rebounds. Classifying pores by the widely used Wu Zhongwei system, the researchers found that the fractions of harmful pores (50 to 200 nanometers) and severely harmful pores (above 200 nanometers) grew most dramatically in the control group and most slowly in the 5% nano-SiO₂ group, whose T₂ spectra shifted least and whose harmless pore fraction remained the highest throughout.

The study’s practical verdict is nuanced: the optimal dosage depends on which performance indicator matters most. For nano-SiO₂, 3% proved best for mass stability while 5% excelled in compressive strength, rupture strength, and porosity, leading the team to recommend a 3% to 5% window. For nano-CaCO₃, 1% was optimal for mass and mechanical properties, and although 5% minimized porosity, SEM images showed clustered ettringite enrichment at that dose, with expansion stress initiating micro-cracks that no amount of physical filling could offset—so 1% stands as the overall recommendation. The fundamental difference lies in mechanism: nano-SiO₂ fights sulfate attack on two fronts, chemically through pozzolanic conversion of calcium hydroxide into dense calcium-silicate-hydrate gel and physically through pore refinement, while nano-CaCO₃ works mainly through nucleation and filling. For engineers designing structures destined for sulfate-laden coastlines, saline soils, or aggressive industrial environments, the message is clear: a few well-chosen nanometers of silica, added at just the right fraction, can mean the difference between a structure that crumbles within decades and one that endures for generations.

Subject of Research: Sulfate resistance of cement-based materials modified with nano-SiO₂ and nano-CaCO₃ nanoparticles

Article Title: Optimum dosage and long-term sulfate resistance of cement-based materials modified by nano-SiO₂ and nano-CaCO₃

Article References: Hao, E., Yuhang, L., Zhang, D., Wang, J., Ya, G., Wang, X., & Cao, Y. (2026). Optimum dosage and long-term sulfate resistance of cement-based materials modified by nano-SiO₂ and nano-CaCO₃. Case Studies in Construction Materials, 25, Article e06585. https://doi.org/10.1016/j.cscm.2026.e06585

Image Credits: AI Generated

DOI: 10.1016/j.cscm.2026.e06585

Keywords: sulfate attack, nano-SiO2, nano-CaCO3, cement-based materials, concrete durability, ettringite, gypsum, pozzolanic reaction, pore structure, NMR, XRD, SEM