Pharmacologyonline 2: 170-178 (2010) K. Nagarajan 170 IN-VITRO ASSESSMENT OF ANTIMICROBIAL ACTIVITY OF ALCOHLIC STEM EXTRACTS OF WRIGHTIA TOMENTOSA *Dr. K. NAGARAJAN ASSOCIATE PROFESSOR & DEPUTY DIRECTOR, DIVISION OF BIO-MEDICINAL CHEMISTRY R&D LABORATORY, DEPARTMENT OF PHARMACY, IIMT COLLEGE OF MEDICAL SCIENCES, 'O' POCKET, GANGA NAGAR, MAWANA ROAD, MEERUT-250001 E-Mail: nagarajan_mph@yahoo.co.in ___________________________________________________________________________ Summary The ethanol extract of the stem of Wrightia tomentosa was evaluated for antimicrobial activity against Gram positive (S. aureus, S. fecalis and B. subtilis) and gram negative (E. coli and P. aeruginosa) organisms and the fungi Candida albicans by disc diffusion method. The extracts (200 µl) does not show any significant degree of activity against all pathogenic microbes. The results obtained were compared with standard drugs ciprofloxacin (10µg/disc) and clotrimazole (10µg/disc). Among the various microbial strains tested, the extract has shown complete resistance against S. aureus, B. subtilis, P. aaeruginosa, C. albicans and partial resistance against S. fecalis (2 mm) and E.coli (1mm) respectively. The probable mechanism of void antimicrobial activity of Wrightia tomentosa stem extract was mainly due to the effect of mutations at specific binding sites of bacterial DNA gyrase, which ultimately decreases the effectiveness of stem extract. Hence the stem extract of Wrightia tomentsa may also be accompanied with some other herbal drug species as combination therapy to avoid the problem of drug resistance in near future. Key words: Extracts, Wrightia tomentosa, stem, disc method, antimicrobial activity. Shortened Title: Anti-microbial activity of stem extract of Wrightia tomentosa Introduction The importance of plants as a source of novel compounds is probably related in large measure to the fact that they are not mobile, and hence must defend themselves by deterring or killing predators, whether insects, micro organisms, animals, or even other plants (1). Traditional uses of plants have led to investigating their bioactive compounds through screening programmes, which have resulted in the detection of a significant number of therapeutic properties (2). The increasing prevalence of multi-drug resistant strains of bacteria and the recent appearance of strains with reduced susceptibility to antibiotics raises the specter of untreatable bacterial infections and adds urgency to the search for new infection combating strategies and new effective therapeutic agents (3). Numerous studies have been conducted with the extracts of various plants, screening antimicrobial activity as well as for the discovery of new, antimicrobial compounds (4). Plants are used medicinally in different countries and are a source of many potent and powerful drugs (5). Therefore, the development of alternative antimicrobial drugs from medicinal plants for the treatment of infectious diseases has become necessary.