STUDIES ON IDENTIFICATION OF TROPICAL PLANT CHEMICALS AND THEIR APPLICATION AS A NEW PEST CONTROL AGENTS

以热带山药薯蓣根茎的MeOH提取物为原料，分离出生物碱和非生物碱两部分，并根据其对小菜蛾的阻食活性对其有效成分进行了纯化。从提取液的生物碱部分分离出薯蓣皂苷（分子量：221）和薯蓣皂苷n -氧化物（分子量：237）作为饵料抑制剂。在100 ~ 25mug/ml浓度范围内，薯蓣皂苷比氧化薯蓣皂苷活性更强。两种生物碱均能显著延缓幼虫发育，并表现出较高的幼虫和蛹死亡率。非生物碱部分也能抑制幼虫的摄食，目前正在对其活性成分进行化学分析。众所周知，鸢尾是一种对哺乳动物有毒的植物。本研究以对致倦库蚊的杀虫活性为基础，从茜草种子中提取有毒化合物，并通过膜片钳实验在离子通道水平上阐明其作用模式。种子MeOH粗提物对蚊子幼虫有毒性，LC_<50>值估计为63.0mug/ml。将粗提物分水后，毒性向AcOEt部位转移，AcOEt活性部位LC_<50>增大至43.7mug/ml。AcOEt组分对gaga诱导的1 μ g/ml Cl电流有抑制作用。

MeOH extracts of rhizome of a tropical yam, Dioscorea hispida was separated into alkaloid and nonalkaloid fractions, and their active components were purified based on the feeding deterrent activity against Plutella xylostella. From alkaloid fraction of the extract, dioscorin (mw : 221) and dioscorin N-oxcide (mw : 237) were isolated as feeding deterrents. Dioscorin was more active than dioscorinN-oxcide at 100to 25mug/ml. Both alkaloids significantly retarded larval development, and showed high mortality at larvae and pupae. Non-alkaloid fraction also inhibited larval feeding, and chemical analysis of active compounds in the fraction is under way. Sikimi, Illicium anisatium is known to be a toxic plant to mammals. We ectracted the toxic compounds based on the insecticidal activity against the Culex quinquefasatus from the seed of Sikimi and performed the patch clamp experiments to clarify the mode af action at ion channel level. Crude MeOH extract of the seed was toxic to mosquito larvae, its LC_<50> value was estimated to be 63.0mug/ml. The toxicity moved to AcOEt fraction when the crude extract was partitioned into water and AcOEt, LC_<50> of the active fraction increased to 43.7mug/ml. The AcOEt fraction exerted a suppresive effect on GAGA-induced Cl current at 1 mug/ml.