Study on the Antibacterial Activity of Ultrasonic Wave Extracts from Leaves of Three Species of Michelia L.

摘要

The extracts from leaves of Michelia maudiae Dunn, M. chapensis Dandy and M. platypetala Hand.-Mazz. were studied for their antibacterial activities by agar diffusion method and plate dilution method with Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella sp. Antibacterial zone diameters and values of the minimal inhibitory concentrations were determined. The results indicated that the extracts showed better inhibition to the experimented bacteria. The extract of M. maudiae had the strongest antibacterial activity on E. coli; the extract of M. chapensis had the strongest antibacterial activity on 5. aureus and the extract of M platypetala had the strongest antibacterial activity on E. coli. Their antibacterial zone diameters are 12.2±0.27 mm, 15.8±0.16 mm and 19.0±0.36 mm respectively. And their values of MIC are 0.313%, 0.156% and 0.156% respectively. The extract of M. maudiae has stronger antibacterial activity than common antiseptic sodium benzoate and potassium sorbate, while the extracts of M. chapensis and M. platypetala have weaker antibacterial activity than those antiseptics.