Wandscheer Carolina B, Duque Jonny E, da Silva Mario A N, Fukuyama Yoshiyasu, Wohlke Jonathan L, Adelmann Juliana, Fontana José D
Biomass Chemo/Biotechnology Laboratory (LQBB), Department of Pharmacy, Federal University of Parana (UFPR), 80210-170 Curitiba, PR, Brazil.
Toxicon. 2004 Dec 15;44(8):829-35. doi: 10.1016/j.toxicon.2004.07.009.
Ethanolic extracts from the kernels of ripe fruits from the Indian Lilac Melia azedarach and from the well-known Neem tree, Azadirachta indica were assayed against larvae of Aedes aegypti, the mosquito vector of dengue fever. The lethality bioassays were carried out according to the recommendations of the World Health Organization. Extracts were tested at doses ranging from 0.0033 to 0.05 g% in an aqueous medium for 24 and 48 h, at 25 or 30 degrees C, with or without feeding of the larvae. LC50, LC95 and LC99 were determined. Both seed extracts proved lethal for third to fourth instar larvae. Non-fed A. aegypti larvae were more susceptible to Azadirachta extracts at both temperatures. Under a more realistic environmental situation, namely with fed larvae at 25 degrees C, the death rates caused by the Melia extract were higher, although at 30 degrees C the extract of Azadirachta had an even higher lethality. Inter allia, the LC50 values for the crude extracts of these two members of the Meliaceae ranged from 0.017 to 0.034 g% while the LC99 values ranged from 0.133 to 0.189 g%. Since no downstream processing was undertaken to purify the active agents in the extracts, our findings seem very promising, suggesting that it may be possible to increase the larvicidal activity further by improving the extraction and the fractionation of the crude limonoids, for instance removing the co-extracted natural fats.
对印度丁香（楝树）和著名的印楝树成熟果实的果仁乙醇提取物进行了抗埃及伊蚊幼虫的试验，埃及伊蚊是登革热的传播媒介。按照世界卫生组织的建议进行了致死性生物测定。提取物在水介质中以0.0033至0.05 g%的剂量进行测试，在25或30摄氏度下处理24小时和48小时，幼虫喂食或不喂食。测定了LC50、LC95和LC99。两种种子提取物对三龄至四龄幼虫均有致死作用。在这两个温度下，未喂食的埃及伊蚊幼虫对印楝提取物更敏感。在更实际的环境条件下，即在25摄氏度下喂食幼虫时，楝树提取物导致的死亡率更高，尽管在30摄氏度时印楝提取物的致死率更高。尤其值得一提的是，楝科这两个成员的粗提物的LC50值在0.017至0.034 g%之间，而LC99值在0.133至0.189 g%之间。由于没有进行下游加工来纯化提取物中的活性剂，我们的研究结果似乎很有前景，这表明通过改进粗柠檬苦素的提取和分级，例如去除共提取的天然脂肪，有可能进一步提高杀幼虫活性。
