Larvicidal studies of chalcones and their derivatives

Abstract

Chalcone (1,3-diphenyl-2-propen-1-one) is considered as the lead compound among all the chalcone type compounds used for the larvicidal studies, as it has the highest toxicity against the larvae of Culex quinquefasciatus. 4-Phenylbut-3-en-2-one, where a methyl group replaces the phenyl group of chalcone, is less active than chalcone; but still has higher activity than other derived compounds except the oxime of the same compound, while 1,5-diphenylpenta-1,4-dien-3-one (in which the lengthening of the acyclic conjugated portion occurs) has almost no activity at 100 ppm at an interval of 24 h. ANOVA and CD values of the compounds show that larvicidal activity of 4-phenylbut-3-en-2-one and its oxime is greater than its phenylhydrazone, which has, however, higher activity than that of semicarbazone of 4-phenylbut-3-en-2- one. On the other hand the activities of 1,5-diphenylpenta-1,4-dien-3-one itself and 2,4-dinitrophenylhydrazone of chalcone and chalcone type compounds are almost nil at 100 ppm concentration at an interval of 24 h at 30 ± 2°C. The probable explanation of the fall of larvicidal activities of these compounds has been presented.