Dose-dependent therapeutic antiinfectives from ethnomedicines of bay islands

Background: The methanol extract of Ophirrhiza nicobarica, Alstonia macrophylla and Mallotus peltatus, ethnomedicines of Little Andaman, were investigated for antiinfective, antiinflammatory and antioxidant activities. Methods: Toxicity was determined in cells and in an animal model. Antiviral, antibacterial and antifungal activity was determined by plaque reduction, disc diffusion and agar dilution methods. The antiinflammatory and antioxidant activities were also studied. Results: O.nicobarica at 300 mu g ml(-1) showed anti-HSV activity while M. peltatus and A. macrophylla showed antibacterial activity at 64-1,000 mu g ml(-1). Both extracts showed significant dose-dependent antiinflammatory and antioxidant activity at nontoxic concentrations. Conclusion: The alkaloid, flavonoid and beta-sitosterol isolated from bioactive parts had a dose-dependent therapeutic efficacy, justifying their use. Further study is required to know the mechanism of action.