POTENTIAL OF THAI HERBAL WEEDS FOR ANTIMICROBIAL ACTIVITY USING AGAR DISC DIFFUSION METHOD

Up to now, use of medicinal plants has been widespread because it is believed that it is less toxic than modern medicine. In general, weeds are useless plants, but some species contain active compounds which may affect against microorganism. The present research aimed at evaluating the potential in antifungal and antibacterial activities of aqueous, acetone hexane and methanolic extracts from 4 weed species against Candida albicans, Malassezia furfur, M. globosa, Escherichia coli, Staphylococcus aureus and Bacillus subtilis using agar disc diffusion method. The extracts with water, acetone and hexane of all plants had nearly no effect to fungi and E. coli. Moreover, all extracts from Polygonum tomentosum Willd. could not inhibit all tested microorganisms. However, the methanolic extracts from Eclipta prostrata L., Heliotropium indicum L. and Cleome viscosa L. showed the good inhibition for S. aureus and B. subtilis. The zones of inhibition for S. aureas were 10.0±0.5, 9.0±0.5 and 13.0±0.5 mm, respectively and for B. subtilis were 9.0±0.5, 9.0±0.5 and 13.0±0.5 mm, respectively. Maximum antibacterial activity was exhibited by C. viscosa against S. aureas (MIC = 0.781 mg/ml, MBC = 1.562 mg/ml) followed by E. prostrate and H. indicum (MIC = 6.25 mg/ml, MBC = 12.5 mg/ml), whereas C. viscosa against B. subtilis (MIC = 0.781 mg/ml, MBC = 1.562 mg/ml) followed by E. prostrate (MIC = 3.125 mg/ml, MBC = 6.25 mg/ml) and H. indicum (MIC = 6.25 mg/ml, MBC = 12.5 mg/ml). The consequences of this study suggest that the methanolic extract of C. viscosa can be used to discover antibacterial agent for developing new pharmaceuticals.