Pak J Biol Sci. 2020 Jan;23(12):1530-1538. doi: 10.3923/pjbs.2020.1530.1538.
Since the Dengue virus spreads rapidly and the vector becomes resistant to insecticides and larvicides, exploration of new compounds that overcome resistance problems, are easily degraded and do not lead to bioaccumulation, is needed. This study evaluated four extract types of Derris elliptica represented the polar, semi-polar and nonpolar extract against the 3rd-instar larvae of Ae. aegypti and determined the effective concentration among the extracts.
The crude extract was obtained from the maceration of root powder of the plant with methanol and subsequently evaporated. The crude extract was diluted in distilled water and partitioned sequentially with ethyl-acetate, n-hexane and water to obtain their fractions. All the fractions were evaporated to obtain their extract types. Initial bioassay test of the extracts with concentration ranges of 50, 100, 500 and 1,000 mg L-1 against Ae. aegypti larvae and resulted in 86-100% larval mortality rates at concentrations of 50 and 100 mg L-1, except for water extract. The lower concentration range of 3, 5, 10, 25, 50 and 100 mg L-1 of three extract types were tested.
Larval mortality rates of 18.4-100, 1.6-99.2 and 0.8-98.4% with LC50 of 4.088, 14.066 and 21.063 mg L-1, respectively for n-hexane, methanol and ethyl-acetate. FTIR analysis indicated nine lead compounds in which rotenone and ceramides were observed in all extract types.
The n-hexane extract showed the highest larvicidal toxicity and its specific compounds are necessarily isolated to obtain pure bioactive ingredients.
登革热病毒传播迅速，病媒对杀虫剂和杀幼虫剂产生抗药性，因此需要探索新的化合物来克服抗药性问题，这些化合物易于降解，不会导致生物累积。本研究评估了 4 种代表极性、半极性和非极性提取物的野牡丹根提取物对埃及伊蚊 3 龄幼虫的作用，并确定了提取物中的有效浓度。
从植物根粉的甲醇浸提物中提取粗提物，然后蒸发。粗提物用蒸馏水稀释，然后依次用乙酸乙酯、正己烷和水进行分配，以获得它们的馏分。所有馏分都蒸发以获得它们的提取物类型。用浓度范围为 50、100、500 和 1000mg/L 的提取物对埃及伊蚊幼虫进行初始生物测定试验，结果表明，除水提取物外，浓度为 50 和 100mg/L 的提取物对幼虫的死亡率为 86-100%。测试了 3 种提取物类型的浓度范围为 3、5、10、25、50 和 100mg/L 的较低浓度范围。
正己烷、甲醇和乙酸乙酯提取物的幼虫死亡率分别为 18.4-100%、1.6-99.2%和 0.8-98.4%，LC50 分别为 4.088、14.066 和 21.063mg/L。FTIR 分析表明，9 种主要化合物存在于所有提取物中，其中鱼藤酮和神经酰胺存在于所有提取物中。
正己烷提取物表现出最高的杀幼虫毒性，其特定化合物有必要进行分离，以获得纯的生物活性成分。
