杠柳新苷P和E对粘虫和小地老虎中肠3种解毒酶的影响
Effects of Periplocoside P and E from Periploca sepium on Activities of Three Detoxification Enzymes in Midgut of Mythimna separata and Agrotis ypsilon （Lepidoptera：Noctuidae）

为进一步探讨杠柳新苷类化合物在昆虫体内的代谢机制。比较研究高活性杠柳新苷P（Periploca sepium P，PSP）和杀虫活性的杠柳新苷E（Periploca sepium E，PSE）对6龄粘虫幼虫（Mythimna separata）与小地老虎幼虫（Agrotis ypsilon）中肠3种代谢酶［羧酸酯酶（CarE）、谷胱甘肽-S-转移酶（GST）、细胞色素P450-O-脱甲基酶］活性的影响。结果表明：药后8 h，PSP和PSE使粘虫幼虫GST活性增加，但PSP上升趋势比PSE更高。而2种化合物对试虫CarE活性均明显影响。药后12 h，PSP和PSE使粘虫中肠细胞色素P450-O-脱甲基酶酶比活力显著下降，而小地老虎中该酶活性明显变化。因此，可推测GST可能参与昆虫对杠柳毒素的解毒作用，[JP3]而细胞色素P450-O-脱甲基酶活性被杠柳毒素抑制可能是造成粘虫中毒的机制之一。[JP]
Periplocosides on detoxification enzymes in midgut of larvar has not been reported.In order to reveal the insecticidal activity and the effect of periplocosides on activities of detoxification enzymes in midgut of larvar.We investigated the effects of strong insecticidal periplocoside P (PSP) and periplocoside E (PSE) which had no insecticidal activity on the activities of three metabolism enzymes in midgut of 6th instar larvae of Mythimna separata and Agrotis ypsilon, including carboxylesterase (CarE), glutathione S-transferase (GST) and O-demethylase of cytochrome P450.GST activity could be increased by PSP and PSE when M.separata larvae were administrated orally with both compounds after 8 h, but PSP showed higher rise trend of GST than PSE.Both compounds showed no obvious effect on CarE activity of the tested insects.The activity of O-demethylase of cytochrome P450 on M.separata was significantly declined by PSP and PSE after 12 h, whereas had no obvious changes on A.ypsilon.The cytochrome P450 in the midgut may be relevant to the intoxication mechanism of PSP against M.separata, whereas GST may be involved in detoxification of periplocosides in insects.