Mono and sesquiterpens and their aldehydes, alcohols, ketones, etc. are the dominant components of the purified products of volatile oils. Their physiological potencies (antibacterial, antihelminthic, fungicide, hyperemic, spasmolytic, carminative effects) are well known from the ancient aged of medicine, however the the very biological/molecular bases of these effects were not clarified untill the recent decades.

Our data showed that chemotaxis is one of the target reactions induced by volatile oils. Repellent effects of mono- and bicyclic monoterpene rich volatiles (Mentha piperita, Salvia officinalis), phenyl propane derivate (Cinnamomum  aromaticum) and acyclic monoterpene aldehyde (Eucalyptus citriodora)  are very characteristic as like as the chemoattractant ability of the linalool-acyclic monoterpene alcohol containing volatiles (Ocimum basilicum).     (Kőhidai et al. Acta Protozool. 34, 181-185, 1995)