Chirality and bioactivity

摘要

Contrary to the conventional wisdom that only pure enantiomers are bloactive, natural products with bioactivitles are not always enantiomerically pure. For example, fribolure (4,8-dimethyidecanal),theaggregationpheromoneofthered flour beetle, is a mixture of ail the four stereoisomers in a ratio of (4R,8R)/.(4R,8S)/ (4S,8R)/ (4S,8S)= 4:4:1:1. Sfereochemistry-bioactivity relationships among pheromones are not simple but complicated. In the case of tribolure, a mixture with the naturally occurring ratio of the stereoisomers is most active. Neither (R)- nor (S)-sulcatol (4-methyl-5-hepten-2-ol) is behaviourally bioactive as the aggregation pheromone of an ambrosia beetle, whereas their mixture is active. In the case of olean (1,7-dioxaspiro|S.5]undecane), the sex pheromone of the olive fruit fly, its (R)-isomer is active against the males, while its (S)-isomer is active against the females.