The search for new antimicrobials should take into account drug resistance phenomenon. Medicinal plants are known as sources of potent antimicrobial compounds including flavonoids. The objective of this investigation was to evaluate the antimicrobial activities of flavonoid glycosides from Graptophyllum grandulosum, as well as to determine their mechanism of antibacterial action using lysis, leakage and osmotic stress assays. The plant extracts were prepared by maceration in organic solvents. Column chromatography of the n-butanol extract followed by purification of different fractions led to the isolation of five flavonoid glycosides. The antimicrobial activities of extracts/compounds were evaluated using the broth microdilution method. The bacteriolytic activity was evaluated using the time-kill kinetic method. The effect of extracts on the red blood cells and bacterial cell membrane was determined by spectrophotometric methods. Chrysoeriol-7-O-β-D-xyloside (1), luteolin-7-O-β-D-apiofuranosyl-(1 → 2)-β-D-xylopyranoside (2), chrysoeriol-7-O-β-D-apiofuranosyl-(1 → 2)-β-D-xylopyranoside (3), chrysoeriol-7-O-α-L-rhamnopyranosyl-(1 → 6)-β-D-(4

Resistance of bacteria and fungi to antibiotics is one of the biggest problems that faces public health. The present work was designated to evaluate the antimicrobial activities of saponins from Melanthera elliptica and their synergistic effects with standard antibiotics against pathogenic phenotypes. The plant extract was prepared by maceration in methanol. The methanol extract was partitioned into ethyl acetate and n-butanol extracts. Column chromatography of the n-butanol extract followed by purification of different fractions led to the isolation of four saponins. Their structures were elucidated on the basis of spectra analysis, and by comparison with those from the literature. The antimicrobial activities of the extracts/compounds alone and their combinations with tetracycline and fluconazole were evaluated using the broth microdilution method through the determination of minimum inhibitory concentration (MIC) and minimum microbicidal concentration. Four compounds: 3-O-β-d-glucuronopyranosyl-oleanolic acid (1), 3-O-β-d-glucuronopyranosyloleanolic acid 28-O-β-d-glucopyranosyl ester (2), 3-O-β-d-glucopyranosyl(1 → 2)-β-d-glucuronopyranosyl oleanolic acid (3) and 3-O-β-d-glucopyranosyl(1 → 2)-β-d-glucuronopyranosyl oleanolic acid 28-O-β-d-glucopyranosyl ester (4) were isolated. Compounds 1, 2 and 3 showed the largest antibacterial activities (MIC = 8–128 μg/mL) whereas compound 4 displayed the highest antifungal activities (MIC = 8–16 μg/mL). The antibacterial activities of compounds 1 and 2 (MIC = 16–32 μg/mL) against multi-drug-resistant Escherichia coli S2 (1) and Shigella flexneri SDINT are equal to those of vancomycin (MIC = 16–32 μg/mL) used as reference antibiotic. The present study showed significant antimicrobial activity of compounds 1, 2, 3 and 4 against the tested microorganisms. The saponins act in synergy with the tested standard antibiotics. This synergy could lead to new options for the treatment of infectious diseases and emerging drug resistance.

From the ethyl acetate soluble fraction obtained by liquid-liquid partitioning of the hydro-ethanolic crude extract of Solanum aculeastrum fruits (Solanaceae), one new steroid (carpensterol, 1) and five other well known (2-6) were isolated. Their structures were elucidated by analysis spectroscopic and spectrometric data as well as comparison to data reported in the literature. The evaluation of their antimicrobial activities using the broth microdilution method revealed that, compound 4 (MIC = 4.8 µg/mL) exhibited the greatest activity against Escherichia coli, with an MIC value lower than that of the reference drug, ciprofloxacin (MIC = 256 µg/mL). Additionally, compounds 1 and 4 exhibited moderate activity against Staphylococcus aureus and Salmonella thyphi (MIC = 78.125 μg/mL). These results provide baseline information for the potential use of the isolated steroids.

Ethnopharmacological relevance: Bombax costatum Pellegr. & Vuillet (Malvaceae) is widely used in african traditional medicine for management of bacterial infections. The escalating antimicrobial resistance crisis drives the exploration of medicinal plants as alternative reservoirs for novel therapeutics and antibiotic adjuvants.Aim of the study: This study evaluates the in vitro antibacterial efficacy and modifying potential of extracts and isolated compounds from Bombax costatum (Malvaceae) in combination with ciprofloxacin (CIP).Materials and Methods: Ethanol extracts from various Bombax costatum organs (stem bark, fruits, leaves and roots) were screened against six pathogenic bacterial strains using the broth microdilution method. Chromatographic fractionation of the crude fruit extract (FBC) yielded eight compounds, with mangiferin (1) and quercetin-3-O-β-D-glucopyranoside (2) selected for further evaluation. Pharmacodynamic interactions between CIP, FBC, and the isolated compounds were quantitatively assessed via checkerboard microdilution assays to determine the Fractional Inhibitory Concentration Index (FICI).Results: Baseline testing against a panel of pathogens including Escherichia coli, Staphylococcus aureus, and Enterobacter revealed that the FBC extract was highly active against E. coli (MIC = 15.65 µg/mL), while compound 2 displayed notable inhibitory action against S. aureus (MIC = 15.65 µg/mL). The checkerboard pharmacodynamic analysis revealed highly favorable profiles completely devoid of antagonistic behavior. Notably, combining ciprofloxacin with Compound 1 induced a significant additive effect (FICI = 0.5) against S. aureus and Enterobacter, triggering a fourfold reduction in the antibiotic's MIC. Similarly, the crude fruit extract (FBC) acted additively when paired with ciprofloxacin (FICI = 0.5), effectively reducing the required inhibitory concentration of the conventional drug against E. coli and Enterobacter.Conclusion: These findings firmly validate the ethnopharmacological relevance of B. costatum and highlight the potential of its phytoconstituants to serve as effective resistance-modifying adjuvants in fluoroquinolone-based therapies.

Hypertension remains a major global health challenge, with oxidative stress playing a pivotal role in its pathogenesis and complications. In this study, six naturally-occurring xanthones isolated from Securidaca longepedunculata roots were evaluated for their dual-action potential against hypertension via molecular docking with Cu-Zn superoxide dismutase (SOD, PDB: 2C9V), angiotensin-converting enzyme (ACE, PDB: 5AMB) and the L-type calcium channel (Cav1.1, PDB: 6JP5). All xanthones exhibited strong binding affinities to SOD (docking scores: − 8.0 to − 7.3 kcal/mol), demonstrating potential for enzyme interaction, though with lower scores than the reference compound quercetin (− 9.0 kcal/mol) which is known to modulate SOD activity. 2D interaction analyses revealed that xanthones engage SOD through hydrogen bonds and π-alkyl/π-sulfur interactions with key residues, showing binding modes which are sharing some similarities with quercetin’s interaction pattern. All xanthones showed higher affinity to ACE with docking scores between − 8.3 and − 7.4 kcal/mol compared to captopril (− 5.7 kcal/mol). Several xanthones also demonstrated high binding to Cav1.1, comparable to or exceeding nifedipine. ADMET profiling predicted favorable oral bioavailability and low toxicity for all compounds. These computational results provide a molecular rationale for the traditional antihypertensive use of S. longepedunculata and highlight its xanthones as promising dual-action scaffolds for further experimental drug development. Graphical abstract