Antibacterial activity of Harungana madagascariensis leaf extracts

Aqueous extracts of the leaf of Harungana madagascariensis were analysed phytochemically and evaluated for antimicrobial activity against strains of Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhi and Pseudomonas aeruginosa. Glycosides, tannins, saponins, flavonoids and alkaloids were detected in the plant material. B. subtilis, E. coli and S. typhi, but not Ps. aeruginosa, showed susceptibility at MICs of 2.0 and 15.6 mg/mL; and MBCs of 2.0–3.9 mg/mL and 15.6–31.3 mg/mL, respectively, for the cold and hot extracts. Staph. aureus showed susceptibility only to the hot extract. Concentrations of 2.5–10.0 mg/mL of the cold extract killed over 7 log₁₀ of the test bacterial population within 30–60 min of exposure. The hot extract needed higher concentrations and longer treatment to achieve similar levels of bacterial cell killing. The results provide a rationalization for the traditional use of H. madagascariensis leaf extracts for the treatment of gastrointestinal disorders. Copyright © 2002 John Wiley & Sons, Ltd.