Alayo M A, Femi-Oyewo M N, Bakre L G, Fashina A O
Southeast Asian J Trop Med Public Health. 2015 Jul;46(4):596-601.
This study aims to investigate larvicidal activities of extracts of Cassia mimosoides leaves and pods as a potential agent in vector control of malaria and to evaluate repellent effect against Anopheles gambiae mosquito of the extract formulated in an aqueous cream base. Petroleum spirit, ethanol, water and dichloromethane extracts were tested against third and fourth instar Anopheles gambiae larvae. The petroleum extract was formulated in an aqueous cream base and repellency determined using N-N-diethyl-m-toluamide (DEET) as control. Phytochemical analysis showed the presence of saponins, tannins, anthraquinones, steroids, and flavonoids but absence of cardiac glycosides and alkaloids in powdered C. mimosoides. A dose related response was observed in the mortality rate of the extracts, with 2 mg/ml petroleum ether and dichloromethane extracts achieving 100 % mortality. Larvicidal activity of extracts based on LC50 values was petroleum ether > dichloromethane > ethanol > water. The formulated petroleum ether extract cream had a characteristic odor, hard and smooth texture, skin feeling of smoothness, ease of application by rubbing, easy removal using soap and water, non-irritating effect on skin and an acceptable pH value. The cream containing 2%-6% (w/w) extract and control achieved 100% repellency against mosquitoes after an exposure time of 5 minutes. There was a linear relationship between percent concentration of plant extract in the cream samples and repellent activity. These results suggest that crude extracts of C. mimosoides can be developed as eco-friendly larvicide and mosquito repellent and encourage further effort to investigate the bioactive compounds in the extracts.
本研究旨在调查含羞草决明叶子和豆荚提取物作为疟疾病媒控制潜在药剂的杀幼虫活性，并评估以水乳膏基质配制的该提取物对冈比亚按蚊的驱避效果。用石油醚、乙醇、水和二氯甲烷提取物对冈比亚按蚊的三龄和四龄幼虫进行测试。将石油提取物配制成水乳膏基质，并以N - N - 二乙基 - m - 甲苯胺（避蚊胺）作为对照测定其驱避性。植物化学分析表明，含羞草决明粉末中存在皂苷、单宁、蒽醌、甾体和黄酮类化合物，但不存在强心苷和生物碱。观察到提取物的死亡率与剂量相关，2mg/ml的石油醚和二氯甲烷提取物死亡率达到100%。基于半数致死浓度（LC50）值，提取物的杀幼虫活性为石油醚＞二氯甲烷＞乙醇＞水。配制的石油醚提取物乳膏具有特征性气味，质地硬且光滑，涂抹时皮肤感觉顺滑，易于揉搓涂抹，用肥皂和水易于清洗，对皮肤无刺激作用且pH值可接受。含2% - 6%（w/w）提取物的乳膏和对照在暴露5分钟后对蚊子的驱避率达到100%。乳膏样品中植物提取物的浓度百分比与驱避活性之间存在线性关系。这些结果表明，含羞草决明粗提取物可开发成为生态友好型杀幼虫剂和驱蚊剂，并鼓励进一步努力研究提取物中的生物活性化合物。
