Department of Applied Chemistry and Biochemistry, University for Development Studies, Navrongo Campus, Navrongo, Ghana.
Department of Pharmacognosy, Faculty of Pharmacy and Pharmaceutical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
Parasit Vectors. 2017 Nov 10;10(1):562. doi: 10.1186/s13071-017-2512-y.
The edible and medicinal leguminous plant Cassia tora L. (Fabaceae) is known to possess insecticidal properties against a wide range of plant-feeding insects. However, the bioactivity of extracts of this plant and their constituents against vectors of medical importance has been largely unexplored. We investigated the mosquito larvicidal activity of the seed extract and its major anthraquinones against larvae of the African malaria vector Anopheles gambiae (s.s.).
Third-fourth instar larval mortality was observed after 24, 48, 72 and 96 h of exposure to varying doses of the extracts, and two anthraquinones isolates identified using liquid chromatography- quadrupole time of flight mass spectrometry (LC-QtoF-MS). The mosquito larval mortality was evaluated relative to the natural insecticide azadirachtin.
Fractionation of the crude extract decreased mosquito larvicidal activity, however, larvicidal activity increased with increasing dose of the treatment and exposure time. The known anthraquinones aurantio-obtusin and obtusin were identified as key larvicidal compounds. Aurantio-obtusin and obtusin, exhibited similar toxicity to larvae of A. gambiae (s.s.) with LD values of 10 and 10.2 ppm, respectively. However, the two anthraquinones were four- and ~ six-fold less potent than that of the crude seed extract and azadirachtin, which had comparable LD values of 2.5 and 1.7 ppm, respectively.
Both aurantio-obtusin and obtusin showed mosquito larvicidal activity which were comparable to their respective fractions although they were less potent relative to the crude extract and azadirachtin. Further studies need to be conducted on C. tora for its exploitation as a potential eco-friendly tool in mosquito larval source reduction.
食用药用豆科植物决明子（豆科）已知对广泛的植物取食昆虫具有杀虫特性。然而，这种植物的提取物及其成分对具有医学重要性的病媒的生物活性在很大程度上尚未得到探索。我们研究了种子提取物及其主要蒽醌类化合物对非洲疟疾媒介按蚊（s.s.）幼虫的杀蚊幼虫活性。
在暴露于不同剂量提取物 24、48、72 和 96 小时后，观察到第三-第四龄幼虫死亡率，并使用液相色谱-四极杆飞行时间质谱法（LC-QtoF-MS）鉴定两种蒽醌类分离物。用天然杀虫剂印苦素评价蚊幼虫死亡率。
粗提物的分级分离降低了杀蚊幼虫活性，但随着处理剂量和暴露时间的增加，杀蚊幼虫活性增加。鉴定出两种已知蒽醌类化合物金橙素和钝叶决明素为关键的杀幼虫化合物。金橙素和钝叶决明素对 A. gambiae（s.s.）幼虫的毒性相似，LD 值分别为 10 和 10.2 ppm。然而，两种蒽醌类化合物的毒性比粗种子提取物和印苦素分别低四到六倍，粗种子提取物和印苦素的 LD 值分别为 2.5 和 1.7 ppm。
尽管金橙素和钝叶决明素的效力相对粗提取物和印苦素较低，但两者均表现出杀蚊幼虫活性，与各自的馏分相当。需要对决明子进行进一步的研究，以将其作为减少蚊虫幼虫源的潜在环保工具进行开发。
