Synthesis and evaluation of mosquito larvicidal activity of pongamol and lanceolatin B

Abstract

Pongamol and lanceolatin B are two well known active components present in different parts of karanj (Pongamia glabra) tree. However, the level of their content is very low and structural similarity with karanjin (major furanoflavonoid) makes their isolation in pure form difficult. This has compelled chemist to synthesize pongamol and lanceolatin B from simpler raw materials. The present research work is one such attempt to synthesize pongamol and lanceolatin B from 4-hydroxy-2-methoxybenzaldehyde in an alternate and efficient pathway. Structural confirmation of synthesized pongamol and lanceolatin B are based on NMR (1H and 13C) and mass and purity by HPLC. X-ray crystallographic study of synthesized lanceolatin B is also carried for the first time to confirm its structure. Both these compounds are evaluated for mosquito larvicidal activity against early 4th instar larvae of Culex quinquefasciatus strain for 24 h. Both these compounds exhibited very good mosquito larvicidal activity. Activity of pongamol (LC50 = 327.4 ± 108 ppm) is found to be better than lanceolatin B (LC50 = 897.6 ± 140 ppm).