Sepration And Pesticidal Activity Of Alkaloids From Cephalotaxus Sinensis

Botanical pesticides with safe to the environment, high-selective, easy-degradable, is one of the main development direction of new pesticides. Cephalotaxus sinensis is species category in China, which belongs to Cephalotaxus. A series of studies on Cephalotaxus sinensis had proved that extracts from the branch and leaf of Cephalotaxus sinensis have insecticidal, herbicidal and inactivation activity, alkaloids are the main compositions by Research & Development Center of Biorational Pesticide, Northwest A&F University. In order to evaluate the potential of Cephalotaxus sinensis in the development of new pesticides, it is necessary to clarify its main active alkaloids. Therefore, in this study, the agricultural activities of several alkaloids isolated from Cephalotaxus sinensis had been studied in order to verify the main pesticidal alkaloid which are the high-performance components by laboratory bioactivity method. The main results were given as follows:1. 9 compounds were isolated from the branch and leaf of Cephalotaxus sinensis, and the chemical structures of 8 compounds were identified by comparison of their MS and NMR data with those reported in the literature. Those chemicals include drupacine, 11-hydroxycephalotaxine, Cephalancetine A, isocephalotaxine, Cephalotaxine β-N-oxide, 4-hydroxycephalotaxine, wilsonine and cephalotaxine.2.Only four(drupacine, 11-hydroxycephalotaxine, Cephalotaxine β-N-oxide and cephalotaxine) of the compounds showed insecticidal activity. The antifeedant and mortality rate of cephalotaxine which is the strongest against 3rd instar larvae of Mythimna separatea are 41.00% and 60.00%(72 h) at the concentration of 1 mg/m L, respectively. The four compounds showed antifeedant activity to Plutella xylostella only, the Cephalotaxine β-N-oxide which is the strongest against 3rd instar larvae of Plutella xylostella is 77.41%(24 h) at the concentration of 1 mg/m L. There are not insecticidal activity to Culex pipiens, Musca domestica, Sitophilus zeamais, Tetranychina hani and Myzus persicae.3.The anti-TMV activity of 9 compounds was tested, and the results indicated that drupacine, 11-hydroxycephalotaxine and cephalotaxine showed a significant inhibitory activity against TMV on different host species. At a concentration of 1 mg/m L, those three compounds could strongly inactivate TMV in vitro, and the inhibition ratio could reach 50.76%, 52.48% and 51.24%.4.Only four(drupacine, 11-hydroxycephalotaxine, Cephalotaxine β-N-oxide and cephalotaxine) of the compounds showed herbicidal activity. The IC50 of drupacine, 11-hydroxycephalotaxine, Cephalotaxine β-N-oxide and cephalotaxine inhibit the root of Amaranthus retroflexus are 21.01, 48.08, 199.57, 90.74 mg/L, and the stem of Amaranthus retroflexus are 25.51、47.85、65.08 and 66.34 mg/L.These results suggest that alkaloids from Cephalotaxus sinensis have many kinds of pesticidal activities, lots of alkaloids have insecticidal, herbicidal and inactivation activity. But, alkaloids from Cephalotaxus sinensis may be not the main insecticidal activity compositions, which may be the herbicidal and inactivation activity compositions. Therefore, the insecticidal activity compositions should be isolated from Cephalotaxus sinensis, and the herbicidal and inactivation activity compositions should be verified by potting and field experiment.