Abstract: Four factors,namely ethanol concentration,solid-liquid ratio,extraction temperature and extraction duration were optimized for the extraction of total flavonoids from Lobelia chinensis through orthogonal design,The results showed that under the condition of ethanol concentration of 60 %,solid-liquid ratio of 1:40 (g/mL),extraction temperature of 60 ℃ and extraction duration of 2.5 h,the highest yield of total flavonoids was obtained (1.69%).The antimicrobial activities of flavonoids were studied by plate count and disk diffusion method.The results showed that flavonoids had certain antimicrobial activities,its inhibitory effect on gram negative bacteria was better than gram positive bacteria,and had little inhibitory effect on Penicillium and yeast with low concentration.

Key words: Lobelia chinensis, total flavonoids, extraction, antibacterial activity