Abstract: Response surface methodology was applied to optimize the extraction condition for total alkaloids from the leaves of Camptotheca acuminate,and investigating their antibacterial and antioxidant activities.Preliminary single factor experiments show that solid-liquid ratio,ultrasonic power and methanol concentration notably altered the extraction efficiency,thus a Box-Behnken second-order polynomial model involving three factors at three levels was developed to investigate the favourable alkaloids extraction condition,while ultrasonic time was fixed as 40 min.The optimal conditions were determined as followings:methanol concentration (methanol ∶formic acid ∶water = 17.5 ∶1 ∶1.5),solid-liquid ratio(1 ∶22 g/mL),ultrasonic power (240 W).Under these conditions,the extraction yield of total alkaloids is 1.67±0.08 mg/g.Leaf alkaloid extract (LAE) displays antibacterial activity against S.aureus, E.coli and P.aeruginosa, with MIC value 4.38,8.75,8.75 μg/mL,respectively.LAE displays significant antioxidant activity in ferric reducing antioxidant power (FRAP) and the IC₅₀ value for ABTS and DPPH scavenging tests is 4 μg/mL and 3 μg/mL.These results proved that the optimized extraction technology was reliable and provides a reference for further development and utilization of the metabolite resources of Camptotheca acuminata Decne.

Key words: Camptotheca acuminata, alkaloids, response surface methodology, antibacterial activity, antioxidant activity