Repellent activity of monoterpenoid esters with neurotransmitter amino acids against yellow fever mosquito, Aedes aegypti

Abstract

AbstractRepellent activity of monoterpenoid esters (1-6) with neurotransmitter amino acids (GABA and glycine) was investigated against Aedes aegypti by using a “cloth-patch” assay and compared to reference standard N,N-diethyl-3-methylbenzamide (DEET). Monoterpenoid esters showed repellent activity with minimum effective dosages (MED) in the range of 0.031-0.469 mg/cm2. The carvacrol ester of GABA (2, MED of 0.031 ± 0.008 mg/cm2) exhibited the highest repellency of six monoterpenoid esters tested in comparison to the standard repellent DEET (MED of 0.009 ± 0.002 mg/cm2); however, the repellent activity of carvacrol-glycine ester (5) decreased 4-fold compared to the carvacrol-GABA derivative (2). The repellent activities of menthol GABA (1, MED= 0.375 ± 0.000 mg/cm2) and glycine ester (4, MED=0.312 ± 0.063 mg/cm2) were similar The guaiacol-glycine ester (6) was 3.75-fold more efficacious than the guaiacol ester of GABA (3). In the present study, we report repellent efficacy of prolonged exposure to GABA and glycine esters of menthol, carvacrol, guaiacol (1-6) as compared to the repellent activities of their monoterpene moieties alone.