Antifeedant Activity and Active Ingredients Against Plutella xylostella from Momordica charantia Leaves

With the bioguided fractionation of the ethanol extracts from the leaves of Momordica charantia, we obtained two most active compounds against the feeding of the diamondback moth, Plutella xylostella larvae. The antifeedant activity of momordicine Ⅰ and momordicine Ⅱ against the second and the third instar larvae of Plutella xylostella were tested using leaf discs of cabbage in the laboratory. The results showed that momordicin Ⅰ and momordicin Ⅱ had significant antifeedant activity on the larvae of P. xylostella, and momordicin Ⅱ was more active than momordicin Ⅰ. The concentrations for 50% antifeedant effects （AFC50） of momordicin Ⅱ against the second and the third instar larvae of P. xylostella were 76.69 and 116.24μg mL^-1, whereas that of momordicin I was 144.08 and 168.42μg mL^-1, respectively. In addition, momordicin Ⅰ and momordicin Ⅱ had significant inhibitive effect on the rate of weight gain and survival of P. xylostella larvae.

苦瓜叶提取物对小菜蛾的拒食活性及有效成分研究

【目的】从苦瓜叶乙醇提取物中分离鉴定活性成分苦瓜素Ⅰ和苦瓜素Ⅱ,测定其对小菜蛾幼虫的拒食和抑制生长发育活性。【方法】用石油醚、乙酸乙酯、正丁醇和水依次对苦瓜叶片乙醇提取物进行萃取,结果发现乙酸乙酯萃取物的拒食活性最强。活性组分经柱层析和高效液相色谱等方法分离纯化,并通过核磁共振谱(NMR)和质谱(MS)鉴定出化合物的分子结构。【结果】苦瓜素Ⅰ和苦瓜素Ⅱ对小菜蛾2、3龄幼虫的取食有明显的抑制作用。其中,苦瓜素Ⅱ的活性最高,对小菜蛾2、3龄幼虫的拒食中浓度(AFC50)分别为76.69μg·ml-1和116.24μg·ml-1。苦瓜素Ⅰ的活性次之,对小菜蛾2、3龄幼虫的AFC50分别为144.08μg·ml-1和168.42μg·ml-1。同时,苦瓜素I和苦瓜素Ⅱ对小菜蛾幼虫体重增长和存活也有抑制作用。【结论】苦瓜素Ⅱ和苦瓜素Ⅰ对小菜蛾幼虫有很强的拒食作用和抑制生长发育的作用,这些化合物的阐明对理解植物与昆虫的相互关系及其对小菜蛾的控制潜力有重要意义。