Antibacterial steroids from roots of Bersama abyssinica

Abstract

Bersama abyssinica is one of the medicinal plants used traditionally to treat various diseases such as leprosy, wound, diarrhea, fever, eye disease, rabies and tumor/cancer. Phytochemical screening test of dichloromethane/methanol (1:1) and methanol extracts revealed the presence of glycosides, alkaloids, tannins, flavanoids, saponins, terpenoids, steroids and phytosterols. Silica gel column chromatography separation of dichloromethane/methanol (1:1) root extracts afforded β-sitosterol (1), 7-hydroxysitosterol (2) and 2-methylamino-butyric acid (3) of which the latter is isolated for the first time from natural source. The crude extracts and isolated compounds were screened for in vitro antibacterial activity against strains of Salmonella thphimurium, Escherichia coli, Bacillus subtilis and Staphylococcus aureus. Dichloromethane/methanol (1:1) extract, methanol extract and β-sitosterol (1) showed moderate activity against E. coli and S. aureus (zone of inhibition 13±0, 13±2 and 12.6±0.48, respectively) and (zone of inhibition 13.6±0.55, 12±2, and 12.5±0.5 mm, respectively) compared to ciprofloxacin (28.6±1.25 and 26±5.1 mm) at 0.5 mg/mL. The structures of compounds were determined by spectroscopic techniques (IR and NMR) and comparison with literature report.