Larvicidal Activity of Geranylacetone Derivatives against Culex quinquefasciatus Larvae and Investigation of Environmental Toxicity and Non-Target Aquatic Species

Abstract

A grindstone method based on Mannich condensation was used to synthesize gerany-lacetone derivatives (1a–1f). The method showed a high yield under milder reaction conditions. Analyses of the synthesized compounds were carried out by FTIR,1H,13C NMR, mass spec-trometry, and elemental analysis. We synthesized and evaluated the larvicidal and ichthyotoxic activities of six compounds (1a–1f) in this study. Compound 1f (5,9-dimethyl-1-phenyl-3-(2-(3-phenylallylidene)hydrazinyl)deca-4,8-dien-1-one) was more active (LD50: 14.1 µg/mL) against the second instar larvae of Culex quinquefasciatus than geranylacetone (67.2 µg/mL), whereas the former caused 13.9% mortality at 100 µg/mL. Geranylacetone, in an antifeedant screening test, showed 53.1% against Oreochromis mossambicus within 24 h. The compound 1f showed high larvicidal activity against C. quinquefasciatus and was non-toxic to non-target aquatic species.