Extraction methods and bioautography for evaluation of medicinal plant antimicrobial activity

A comparative study on the antimicrobial properties of extracts from medici nal plants obtained by two different methods was carried out. The screening of the antimicrobial activity of extracts from six plants was conducted by a disc diffusion test against Gram-positive, -negative and fungal organism s. The most active extracts (inhibition diameter greater than or equal to 1 2 mm) were assayed for the minimum inhibitory concentration and submitted t o phytochemical screening by thin-layer chromatography and bioautography. T he results obtained indicate that the diethyl ether extracts were the most efficient antimicrobial compounds. The activity was more pronounced against Gram-positive and fungal organisms than against Gram-negative bacteria. Bi oautography showed that the antimicrobial activity was probably due to flav onoids and terpenes.