Bioassay-guided isolation and identification of Aedes aegypti larvicidal and biting deterrent compounds from Veratrum lobelianum

Abstract

AbstractAn ethanol extract fromVeratrum lobelianumBernh. rhizomes showed larvicidal activity with LC50values of 11.79 ppm and 89.9 ppm against 1stand 4thinstar larvae, respectively, at 24 h post-treatment. The extract also showed proportion not biting (PNB) value of 0.76 at 100 μg/cm2against females ofAe.aegypti. Systematic bioassay-guided fractionation ofV.lobelianumextract resulted in the isolation of five compounds that were identified as ethyl palmitate (1), ethyl linoleate (2), β-sitosterol (3), resveratrol (4) and oxyresveratrol (5) by GC-MS,1H-NMR, and13C-NMR techniques, comparison with literature data, and confirmation with authentic compounds. Compound2exhibited larvicidal activity with an LC50value of 24.1 (22.0-26.2) ppm whereas1was inactive. β-Sitosterol (3) displayed the highest larvicidal activity with LC50= 1.7 (1.3-12.3) ppm and LC90= 5.1 (3.4-13.8) ppm. Compounds4and5had larvicidal activity with LC50values of 18.5 (15.3-23.3) and 22.6 (19.0-26.8) ppm, respectively, and had an equivalent PNB values of 0.75 at 25 nmol/cm2. In addition,4and5were explored for their human-based repellency againstAe.aegypti, attractiveness against male medfliesCeratitis capitata, and also evaluated against series of human carcinoma cells (A549, HEK293, HeLa, SH-SY5Y); however, no significant activity was found.