Antimicrobial screening of different extracts of South Indian medicinal plants of meliaceae

Members of Meliaceae are widely used by different tribal communities in South India for the treatment of many bacterial and fungal diseases. In this context, antimicrobial potential of aqueous and alcoholic soxhlet extracts of leaf, stem/bark and root of Azadirachta indica,Naregamia alata and Swietenia mahagoni against five bacterial strains was studied to validate the ethno therapeutic claims of these plants against different bacterial diseases. The alcoholic and aqueous extracts of the plants showed significant antibacterial activity against all the organisms: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa Proteus vulgaris and Bacillus subtilis. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) (mg/ml) of the alcoholic and aqueous extracts were also determined. The antibacterial potential of the plants were then compared with Benzyl Penicillin and Amphicillin, two common antibiotics employed in allopathic treatment of bacterial diseases. The alcoholic extracts of plants proved to be more effective than the aqueous extracts due to broad spectrum antibiotic compounds. The good antibacterial potency of the plants indicates the presence of some active principle in the phytoextracts, which can be purified and employed in the treatment of bacterial diseases as an alternative to the costly antibiotics.   Key words: Antibacterial activity, antibiotics, minimum inhibitory concentration, minimum bactericidal concentration, soxhlet extracts.