Antimicrobial testing of Vanda tessellata leaf extracts.

摘要

Vanda tessellate (Roxb.) Hook, ex G. Don (Orchidaceae) is an important medicinal epiphyte of Southern Rajasthan generally found growing on the trunk of Madhuca indica tree. In the present study an attempt has been made to bio-prospect the antimicrobial activity of chloroform, petroleum ether, ethyl acetate, acetone and methanolic extracts of V. tessellata leaves against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Proteus mirabilis and Bacillus subtilis. The ethyl acetate extracts of the leaves at 10 mg/ml concentration exhibited the most pronounced antibacterial action against E. coli, S. aureus and K. pneumonia with 14.66, 13.66 and 12.00 mm zone of inhibition and 0.78, 0.156 and 1.25 mg/ml MIC values respectively. The corresponding MBC values of ethyl acetate extracts against these bacteria varied from 0.625-0.312 mg/ml. The ethyl extracts of V. tessellate leaf at 5.0 and 10.0 mg/ml concentrations was also found inhibitory to Candida albicans with 10.0-11.0 mm zone of inhibition, respectively. Such anticandidal activity was also evident in case of chloroform and methanolic extracts of leaves, but to a lesser extent than ethyl acetate fraction. None of the extract, however, was found effective against Aspergillus niger. Possible isolation of potential anti-microbial candidates from V. tessellate for further exploitation in medical microbiology is discussed.