Antibacterial Activity of Eight Tibetan Medicinal Plants in Vitro

OBJECTIVE In order to obtain the active extracts of antibacterial effects of Tibetan medicine. Tibetan medicinal plants: Dracocephalum heterophyllu, Aconitum tanguticum, Swertia mussotii, Gentiana urnula, Meconopsis quintuplinervia, Aconitum flavum, Tribulus terrester, Lagotis brevituba were collected and their antibacterial activity were studied in vitro. METHODS The agar disc diffusion method and a broth microdilution method were employed for the determination of antimicrobial activity. The inhibition zone and the minimal inhibitory concentration (MIC) values were used to estimate index of antibacterial activity. RESULTS The eight extracts of D. heterophyllum, A. tanguticum, S. mussotii, G. urnula, M. quintuplinervia, A. flavum, T. terrester and L. brevituba posses moderate antibacterial activity against tested bacterial stains. The inhibition zones and MIC values were in the range of 8–22 mm, and 1.56-50.00 mg·mL^-1, respectively. D. heterophyllum and A. tanguticum showed strong antibacterial effect, while M. quintuplinervia had no effect. CONCLUSION The antibacterial activity of water extracts is D. heterophyllum>A. tanguticum>S. mussotii>A. flavum>L. brevituba>T. terrester>G.urnula>M. quintuplinervia; while that of ethanol extracts is D. heterophyllum> A. tanguticum>S. mussotii>A. flavum>L. brevituba>T. terrester>G. urnula>M. quintuplinervia.