苦瓜素Ⅰ对亚洲玉米螟幼虫酚氧化酶活性的抑制作用

Inhibition effects of momordicin Ⅰ on phenoloxidase of Asian corn borer,Ostrinia furnacalis (Guenée) (Lepidoptera: Pyralidae)

为了探讨苦瓜素类化合物抑制昆虫生长发育的作用机制,测定了苦瓜叶乙酸乙酯萃取物和苦瓜素Ⅰ对亚洲玉米螟Ostrinia furnacalis幼虫体内酚氧化酶活性的抑制作用以及苦瓜素Ⅰ、苦瓜素Ⅱ和苦瓜皂苷元L对亚洲玉米螟幼虫离体酚氧化酶活性的抑制作用。结果表明,苦瓜叶乙酸乙酯萃取物和苦瓜素Ⅰ均能明显抑制亚洲玉米螟幼虫酚氧化酶的活性。用含有不同浓度苦瓜叶乙酸乙酯萃取物和苦瓜素I的人工饲料饲喂亚洲玉米螟3龄幼虫48 h后,苦瓜叶乙酸乙酯萃取物和苦瓜素Ⅰ对亚洲玉米螟幼虫体内酚氧化酶活性的抑制中浓度IC_(50)分别为0.17%和0.34%。苦瓜素Ⅰ和苦瓜素Ⅱ对亚洲玉米螟离体酚氧化酶的活力也表现出明显的抑制作用,抑制中浓度IC_(50)分别为169.28μg/mL和1182.08μg/mL。苦瓜素I的抑制作用明显强于苦瓜素Ⅱ。苦瓜叶提取物及其活性成分苦瓜素Ⅰ对亚洲玉米螟幼虫酚氧化酶活性的抑制作用可能是其抑制昆虫生长发育的主要机制之一。

In order to explore the insecticidal mechanism of momordicins on pest, here, ethyl acetate extracts of Momordica charantia leaves and momordicin I were selected to evaluate inhibitory effects to phenoloxidase activity of Ostrinia furnacalis larvae in vivo, and momordicin I, momordicin II and the aglycone of momordicoside L were also treated for phenoloxidase activity in vitro. The results showed that ethyl acetate extracts of M. charantia leaves and momordicin I exerted significant inhibitory effects on phenoloxidase activity of O. furnacalis larvea. The results showed that ethyl acetate extracts of M. charantia leaves and momordicin I exerted significant inhibitory effects on phenoloxidase activity of O. furnacalis larvae. Moreover, momordicin I and momordicin II could inhibit the activity of phenoloxidase in vitro, the IC50 values were 169. 28 μg/mL and 1182. 08 μg/mL, respectively. The inhibitory effects of momordicin I were more potent than momordicin II on phenoloxidase activity. In conclusion, the major mechanism of action of growth inbibition can be attributed to activity of O. furnacalis larvae phenoloxidase inhibited by ethyl acetate extracts of M. charantia leaves and momordicin I.