USDA-ARS, Natural Products Utilization Research Unit, University, MS 38677, USA.
J Med Entomol. 2011 Jul;48(4):836-45. doi: 10.1603/me10244.
An investigation of the Indian folk remedy plant Jatropha curcas L., was performed to identify the constituents responsible for the mosquito biting deterrent activity of the oil. J. curcas seed oil is burned in oil lamps in India and parts of Africa to repel biting insects, primarily mosquitoes. The seed oil was thoroughly analyzed by 1H NMR, 13C NMR, high-performance liquid chromatography-refractive index, and gas chromatography-flame ionization detection to identify the constituents in the oil. Identified constituents, both free fatty acids and triglycerides, were evaluated for activity in Aedes aegypti (L.) (Diptera: Culicidae) biting deterrent assays. Furthermore, an oil condensation trap was used to demonstrate that free fatty acids or triglycerides are partially volatilized during the combustion process. These compounds were found to be responsible for the biting deterrency of the burned oil. Specifically, oleic, palmitic, linoleic, and stearic acids were all active at 25 nmol/cm2 above that of solvent control in Ae. aegypti biting deterrent assays. Oleic, palmitic, and linoleic acids were all more active than stearic acid in the same bioassay. Evaluation of the triglycerides containing each of these fatty acids revealed that tripalmitin, tristearin, trilinolein, and triolein all demonstrated significant activity above a solvent control at 10 microg/cm2, whereas tripalmitin was the most active. Due to literature reports suggesting larvicidal activity of the oil, J. curcas seed oil and its free fatty acid constituents also were evaluated against 1-d-old Ae. aegypti larvae up to 500 ppm. Oleic acid was the only fatty acid having larvicidal activity against 1-d-old Ae. aegypti larvae, with an LD50 of 47.9 ppm.
对印度民间药用植物麻疯树（Jatropha curcas L.）进行了研究，以确定其种子油中具有驱避蚊虫叮咬活性的成分。在印度和非洲部分地区，人们将麻疯树种子油燃烧在油灯中，以驱赶主要是蚊子等吸血昆虫。通过 1H NMR、13C NMR、高效液相色谱-折射指数和气相色谱-火焰离子化检测对 J. curcas 种子油进行了全面分析，以鉴定油中的成分。鉴定出的成分，包括游离脂肪酸和三酸甘油脂，都在埃及伊蚊（Diptera：Culicidae）驱避叮咬实验中进行了活性评估。此外，还使用油冷凝陷阱证明了游离脂肪酸或三酸甘油脂在燃烧过程中会部分挥发。这些化合物被认为是燃烧油驱避蚊虫叮咬的原因。具体来说，油酸、棕榈酸、亚油酸和硬脂酸在埃及伊蚊驱避叮咬实验中，在 25 nmol/cm2 以上的浓度下均比溶剂对照物具有活性。在相同的生物测定中，油酸、棕榈酸和亚油酸的活性均高于硬脂酸。对含有这些脂肪酸的三酸甘油脂进行评估发现，三棕榈酸酯、三硬脂酸酯、三油酸酯和三亚油酸酯在 10 microg/cm2 以上的浓度下均比溶剂对照物具有显著的活性，而三棕榈酸酯的活性最高。由于文献报道称该油具有杀幼虫活性，因此还评估了麻疯树种子油及其游离脂肪酸成分对 1 龄埃及伊蚊幼虫的活性，最高可达 500 ppm。油酸是唯一对 1 龄埃及伊蚊幼虫具有杀幼虫活性的脂肪酸，其 LD50为 47.9 ppm。
