PhD Degree Program in Environmental Science, Environmental Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand.
Department of Chemistry, School of Science, University of Phayao, Phayao, 56000, Thailand.
Ecotoxicol Environ Saf. 2019 Oct 30;182:109448. doi: 10.1016/j.ecoenv.2019.109448. Epub 2019 Jul 26.
The electrocoagulation (EC) technique is an alternative method of isolating natural products with the advantage of minimizing the amounts of organic solvents required for this process, which are often harmful to the environment. In this research, the EC and the conventional solvent extraction methods were used in the isolation of Stemona alkaloids from the aerial parts of Stemona aphylla. A comparison was made between the amounts of the isolated alkaloids and the solvents used. The isolated alkaloids were evaluated for their larvicidal, ovicidal and oviposition-deterrent activities against the dengue vector, Aedes aegypti. The morphology and histopatology of the alkaloid treated larvae were also investigated. Two Stemona alkaloids, (2'S)-hydroxystemofoline and stemofoline, were isolated from both the EC and the conventional method. The amounts of (2'S)-hydroxystemofoline from the EC method was about the same as that obtained from the conventional method. However, the amounts of stemofoline obtained from the EC method were about two times larger than those obtained from the conventional method. Importantly, the EC method required six times less total organic solvents. The larvicidal activity assays of (2'S)-hydroxystemofoline and stemofoline showed that these were highly effective against Aedes aegypti larvae with LC values of 3.91 μg/ml and 4.35 μg/ml, respectively. Whereas, the crude EC extract (LC = 11.86 μg/ml) showed greater larvicidal activity than the crude extract obtained from the conventional extraction method (LC = 53.40 μg/ml). The morphological observations of the (2'S)-hydroxystemofoline and the stemofoline treated larvae revealed that the anal gills were the sites of aberrations. A histopathological study showed that larvae treated with these alkaloids had cytopathological alterations to the epithelial cells of the midgut. At a concentration 40 μg/ml (2'S)-hydroxystemofoline showed 100% ovicidal activity on 24 h old eggs while stemofoline showed 97.2%. Furthermore, the oviposition-deterrent effects of (2'S)-hydroxystemofoline and stemofoline, at a concentration of 80 μg/ml were 99.5% and 97.2%, respectively.
电凝聚 (EC) 技术是一种分离天然产物的替代方法，其优点是最大限度地减少了该过程所需的有机溶剂的用量，而这些有机溶剂通常对环境有害。在这项研究中，EC 和常规溶剂萃取法被用于从直立百部地上部分中分离百部生物碱。比较了两种方法分离得到的生物碱和使用的溶剂的量。还评估了分离得到的生物碱对登革热传播媒介埃及伊蚊的幼虫的杀幼虫、杀卵和产卵驱避活性。还研究了生物碱处理幼虫的形态和组织病理学。从 EC 法和常规法都分离得到了两种百部生物碱，(2'S)-羟基斯替诺宁和百部宁。从 EC 法得到的(2'S)-羟基斯替诺宁的量与从常规法得到的量大致相同。然而，从 EC 法得到的百部宁的量大约是从常规法得到的两倍。重要的是，EC 法所需的有机溶剂总量减少了六倍。(2'S)-羟基斯替诺宁和百部宁的杀幼虫活性测定表明，它们对埃及伊蚊幼虫具有很高的有效性，LC 值分别为 3.91μg/ml 和 4.35μg/ml。而粗 EC 提取物（LC=11.86μg/ml）的杀幼虫活性大于从常规提取法获得的粗提取物（LC=53.40μg/ml）。对(2'S)-羟基斯替诺宁和百部宁处理幼虫的形态观察表明，异常发生在肛门鳃上。组织病理学研究表明，用这些生物碱处理的幼虫中，中肠上皮细胞发生了细胞病理改变。在 40μg/ml 的浓度下，(2'S)-羟基斯替诺宁对 24 小时龄的卵表现出 100%的杀卵活性，而百部宁表现出 97.2%的杀卵活性。此外，在 80μg/ml 的浓度下，(2'S)-羟基斯替诺宁和百部宁的产卵驱避效果分别为 99.5%和 97.2%。
