<i>In vitro</i> antimicrobial and antiulcer activities of hymeglusin and septicine constituents of Barteria nigritiana stem bark

Purpose: To identify the phytochemical contents of the bioactive fractions of Barteria nigritiana (Passifloraceae) extract using the HPLC-DAD/MS techniques and evaluate its antimicrobial and anti-ulcer activities using in vitro models. Method: The phytoconstituents of the methanol extract were identified using standard methods. The extract was fractionated by solvent-solvent partitioning, vacuum liquid and column chromatographic techniques following a bioactivity-guided approach. The constituents of the most active sub-fraction were identified using HPLC-DAD/MS techniques. The antimicrobial (Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhi and Candida albicans) and anti-Helicobacter pylori activities assay adopted agar well diffusion methods to determine inhibition zone diameters (IZDs) and minimum inhibitory concentrations (MICs) using gentamicin/nystatin and clarithromycin (1 μg/mL) as standards. Result: Repeated bioactivity-guided chromatographic purification yielded a hymeglusin/septicine-enriched sub-fraction identified from the HPLC-DAD/MS analysis. The sub-fraction (20 μg/mL) exhibited significantly (p < 0.05) higher IZDs of > 20 mm against four of the six Helicobacter pylori strains tested, with MICs of 0.3906 - 1.5625 μg/mL compared with other tested samples. Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Candida albicans recorded significantly (p < 0.05) high susceptibility patterns to the sub-fraction compared with the control, with IZDs of 15.3 ± 2.1, 18.2 ± 0.2, 15.8 ± 1.1 and 16.9 ± 0.3 mm, but lower than that of gentamicin/nystatin which showed MICs of 3.125, 1.5625, 6.25 and 3.125 μg/mL respectively. Conclusion: The hymeglusin/septicine-enriched sub-fraction shows significant inhibition of H. pylori, C. albicans, E. coli, P. aeruginosa and S. typhi and hence, is are potential lead compound for the development of potent therapeutic agents for the management of peptic ulcer and other infectious diseases.