Mosquitocidal efficacy of embelin and its derivatives against Aedes aegypti L. and Culex quinquefasciatus Say. (Diptera: Culicidae) and computational analysis of acetylcholinesterase 1 (AChE1) inhibition. (July 2022) - Stalin, Antony
Abstract: Embelin was isolated from the chloroform extract of Embelia ribes (Burm.f.) fruits; its derivative compounds 6-bromoembelin and vilangin were prepared, and they were evaluated for mosquitocidal activities against the third instar larvae and pupae of Aedes aegypti L. and Culex quinquefasciatus Say. (Diptera: Culicidae). The concentrations used were 0.5, 1.0, 1.5, and 2.0 ppm. Embelin recorded LC50 values of 5.79 and 5.54 ppm against the larvae of Ae. aegypti and Cx. quinquefasciatus, respectively. Similarly, the LC50 values of embelin were 10.23 and 6.93 ppm against the pupae of Ae. aegypti and Cx. quinquefasciatus, respectively. Of the two derivatives tested, vilangin showed the highest larvicidal activity with LC50 values of 1.38 and 1.28 ppm against the larvae of Ae. aegypti and Cx. quinquefasciatus, respectively. Similarly, the LC50 values of vilangin were 1.60 and 1.43 ppm against the pupae of Ae. aegypti and Cx. quinquefasciatus, respectively. The LC50 values of 6-bromoembelin were 3.30 and 2.83 ppm against the larvae and 4.40 and 4.30 ppm against the pupae of Ae. aegypti and Cx. quinquefasciatus, respectively. The histopathological results displayed significant damage on cuboidal cells of the midgut (CU) in vilangin treated larvae of Ae. aegypti and Cx. quinquefasciatus at a concentration of 2.0 ppm. Similarly, peritrophic membrane (PM) was completely impaired in vilangin-treated larvae of Cx. quinquefasciatus and midgut content (MC) was very low in vilangin-treated larvae of Cx. quinquefasciatus . In addition, molecular docking and molecular dynamics studies demonstrated the efficacy of vilangin on the inhibition of acetylcholinesterase (AChE1) in Ae. aegypti and Cx. quinquefasciatus . The present results suggest that vilangin could be used to develop a natural active product against mosquito larvae. Highlights: Embelin and its derivatives viz., 6-bromoembelin and vilangin have been studied for their mosquitocidal efficacy. Vilangin significantly acted on the midgut cells of treated larvae and showed higher mosquitocidal activity. Vilangin showed strong binding to the catalytic binding sites of AChE1 of Ae. aegypti and Cx. quinquefasciatus . MD analysis also showed the significant inhibitory effect of vilangin through the strong interaction with AChE1.