Aroma constituents in plants and their repellent activities against mosquitoes.

Abstract

New repellents, p -menthane-3,8-diols ( cis and trans), were isolated from the leaves of Eucalyptus citriodora. In particular, the pentanoyl (C 5) and caproyl (C 6) esters of the diols exhibited much higher activity than did N,N -diethyl- m -toluamide (DEET, a commercially available mosquito repellent) in terms of repellency and repellent durability the against mosquitoes, Aedes albopictus and Culex pipiens. In addition, (+)-eucamalol, (1 R,6 R)-(+)-3-formyl-6-isopropyl-2-cyclohexene-1-ol, which is a new mosquito repellent, was isolated from E. camaldulensis leaves. The absolute configuration was determined by synthesizing from ( S)-(-)-perillaldehyde. Isolation of repellents from leaves of V. rotundifolia, which was traditionally used for repelling mosquitoes in the southern part of Japan, yielded a cyclopentene dialdehyde, named rotundial.