Objective:By studying the alkaloids of Sophora flavescens and Sophora tonkinensis in vitro antibacterial activity

the relationship between the antibacterial activity and structure was examined. Method: Using Oxford cup method

strains had been cultured for 24 hours at a constant temperature of 37 ℃

the antimicrobial effect of alkaloids in S. flavescens and S. tonkinensis was studied in vitro against seven strains(Staphylococcus aureus

Pseudomonas aeruginosa

P. alcaligenes

P. putida

Streptococcus pneumoniae

α-hemolytic streptococcus

β-hemolytic streptococcus). Result: The experimental results indicated the alkaloids in S. flavescens and S. tonkinensis showed the good inhibiting effect for seven strains

antibacterial activities of oxymatrine and oxysophocarpine were weak in vitro antibacterial activities of sophoridine showed remarkable effect for α-hemolytic streptococcus and β-hemolytic streptococcus

the inhibition zones by sophoridine were (2.60±0.10)

(2.53±0.15) cm to α-hemolytic streptococcus and β-hemolytic streptococcus respectively. The inhibition zones by total matrine and total alkaloids in Tonkin sophora root were(2.43±0.21)

(1.77±0.05)cm to β-hemolytic streptococcus respectively. Conclusion: It is concluded that there is some relationship between antibacterial activity and structure of alkaloids in S. flavescens and S. tonkinensis. Alkaloids as a natural antimicrobial components can be developed and utilized.