Abdul Rahuman A, Gopalakrishnan Geetha, Venkatesan P, Geetha Kannappan
Unit of Bioactive Natural Products, Department of Zoology, C.Abdul Hakeem College, Melvisharam 632 509, India.
Parasitol Res. 2008 Apr;102(5):981-8. doi: 10.1007/s00436-007-0864-5. Epub 2008 Jan 3.
Larvicidal activity of crude hexane, ethyl acetate, petroleum ether, acetone and methanol extracts of five medicinal plants, Abutilon indicum, Aegle marmelos, Euphorbia thymifolia, Jatropha gossypifolia and Solanum torvum were assayed for their toxicity against the early fourth-instar larvae of Culex quinquefasciatus. The larval mortality was observed after 24 h exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in petroleum ether extract of A. indicum. In the present study, bioassay-guided fractionation of A. indicum led to the separation and identification of a beta-sitosterol as a potential new mosquito larvicidal compound with LC50 value of 11.49, 3.58 and 26.67 ppm against Aedes aegypti L, Anopheles stephensi Liston and C. quinquefasciatus Say (Diptera: Culicidae), respectively. 1H NMR, 13C NMR and mass spectral data confirmed the identification of the active compound. beta-sitosterol has been recognized as the active ingredient of many medicinal plant extracts. All the crude extracts when screened for their larvicidal activities indicated toxicity against the larvae of C. quinquefasciatus. This article reports the isolation and identification of the beta-sitosterol as well as bioassay data for the crude extracts. There are no reports of beta-sitosterol in the genus A. indicum, and their larvicidal activities are being evaluated for the first time. Results of this study show that the petroleum ether extract of A. indicum may be considered as a potent source and beta-sitosterol as a new natural mosquito larvicidal agent.
对苘麻、木苹果、地锦草、棉叶麻风树和刺茄这五种药用植物的粗己烷、乙酸乙酯、石油醚、丙酮和甲醇提取物进行杀幼虫活性测定，以检测其对致倦库蚊四龄初期幼虫的毒性。暴露24小时后观察幼虫死亡率。所有提取物均显示出中等程度的杀幼虫效果；然而，苘麻的石油醚提取物中幼虫死亡率最高。在本研究中，对苘麻进行生物测定导向的分离，得到并鉴定出β-谷甾醇为一种潜在的新型杀蚊幼虫化合物，其对埃及伊蚊、斯氏按蚊和致倦库蚊（双翅目：蚊科）的LC50值分别为11.49、3.58和26.67 ppm。1H NMR、13C NMR和质谱数据证实了该活性化合物的鉴定。β-谷甾醇已被认为是许多药用植物提取物的活性成分。所有粗提物在进行杀幼虫活性筛选时均显示出对致倦库蚊幼虫的毒性。本文报道了β-谷甾醇的分离鉴定以及粗提物的生物测定数据。苘麻属中尚无β-谷甾醇的相关报道，其杀幼虫活性首次得到评估。本研究结果表明，苘麻的石油醚提取物可被视为一种有效的来源，β-谷甾醇可作为一种新型天然杀蚊幼虫剂。
