Essential oils of green and red Perilla frutescens as potential sources of compounds for mosquito management

Abstract

Dengue fever is a mosquito-borne disease transmitted by Aedes aegypti producing high rates of human morbidity and mortality. In order to find new and effective compounds against A. aegypti with low mammalian and less environmental toxic products, green and red Perilla frutescens (L.) Britt. (perilla) essential oils were investigated for their deterrent and larvicidal activity. Green perilla oil showed more promising deterrent and larvicidal activity than red perilla oil. Therefore, we focused on the principle compounds in green perilla oil and, in addition, perilla alcohol and perillic acid were included for the activity relationship on the allylic methyl groups on carbon 7. Chemical composition of green and red perilla essential oils was compared using gas-chromatography–flame ionization detection (GC–FID) and gas chromatography–mass spectrometry (GC–MS). In biting deterrent bioassays, biting deterrence index (BDI) values for compounds methyl perillate (0.73), perillic acid (0.71), perilla alcohol (0.69), perilla aldehyde (0.62), caryophyllene oxide (0.60), and limonene (0.52) indicated good biting deterrent activity but the activity was significantly lower (proportion not biting (PNB) value 0.84) than the positive control N,N-diethyl-3-methylbenzamide (DEET) at 25nmol/cm2. In larval bioassays, methyl perillate was the most toxic compound with LC50 of 16.0ppm. Methyl perillate was the most active compound against A. aegypti larvae and this compound may offer a new biodegradable mosquito control agent.