Antibacterial activity of selected species of Lamiaceae against human pathogens

Eight selected plant species belonging to the family Lamiaceae were collected from different localities of Tirunelveli district of Tamil Nadu, dried and extracted by crude methanol extraction method. The antimicrobial activity and Minimum Inhibitory Concentration (MIC) of the extracts were evaluated against ten human pathogens. Antimicrobial activities of the extracts were determined by the agar disc diffusion method. MIC was determined in the plant extracts that showed some efficacy against pathogens. Ciprofloxacin (5 mcg/disc) was used as positive control for comparison of the inhibition zones. The microbial activity of the methanolic extract of Coleus aromaticus Benth. was found efficient against all the tested pathogens. In Lamiaceae, C. aromaticus, Mentha arvensis Linn. and Leucas aspera Willd. had lower MIC values of 12.5 mg/ml with inhibition zones of 10, 10 and 8 mm, respectively.