Therapeutic evaluation of certain Indian drug plants a screening study

ABSTRACT

Present study compares the sensitivity of some human pathogenic bacteria to various plant extracts and commonly employed chemotherapeutic substances. Aqueous and ethanolic extracts from various parts of seven Indian medicinal plants were screened for therapeutic potential as antibacterial agents against three Gram-positive and five Gram-negative bacterial species. Of the twenty-four extracts assayed by agar well diffusion method, nine extracts - three aqueous extracts [Azadiruchta indica-bark, Ficus religiosa - bark and Ephedra foliata - aerial parts] and six ethanolic extracts [A. indica - leaf and bark, F. religiosa-bark, Adhatoda vasica - shoots, Ephedra foliata - aerial parts and Calotropis procera - shoots] showed varying degrees of antibacterial activity. Ethanolic extract from the shoots of A. vasica was the most active, exhibiting greatest inhibitory activity against multi-drug resistant Escherichia coli. The bark extracts of F. religiosa and A. indica were effective against all the tested organisms. The screened plant extracts displayed maximum bioactivity at 100% concentration i.e., when used undiluted and a linear decrease or complete loss of activity was observed with dilution. Bacterial test organisms were also subjected to antibiotic sensitivity test against eight antibiotics and majority of the organisms demonstrated resistance to one or more antibiotics. Some bacteria such as E. coli and Shigella dysenterieae showing resistance to certain antibiotics, were found sensitive to the plant extracts. The antibacterial activity of A. vasica - shoots, A. indica - bark and F. religiosa - bark against some test bacteria was found to be much higher than that of certain potential antibiotics. The results suggest that these plant extracts might have a great potential to be used as antimicrobial agents