Chirality and biosynthesis of lilac compounds in Actinidia arguta flowers

Abstract

Biosynthesis of lilac compounds in ‘Hortgem Tahi’ kiwifruit ( Actinidia arguta) flowers was investigated by treating inflorescences with d 5-linalool. The incorporation of the deuterium label into 8-hydroxylinalool, 8-oxolinalool, the lilac aldehydes, alcohols, and alcohol epoxides was followed by GC-MS and enantioselective GC-MS. Both ( R)- and ( S)-linalool were produced naturally by the flowers, but 8-hydroxylinalool, 8-oxolinalool, and the lilac aldehydes and alcohols occurred predominantly as the ( S) and 5′( S)-diastereoisomers, respectively. The enantioselective step in the biosynthesis of the lilac aldehydes and alcohols was concluded to be the oxidation of linalool to ( S)-8-hydroxylinalool. In contrast, the lilac alcohol epoxides had a 5′( R):( S) ratio, the same as for linalool, which suggests that either these compounds are not synthesised from the 5′( S)-configured lilac aldehydes and alcohols, or that if indeed they are, then it is by an enantioselective step that favours utilisation of the 5′( R)-configured compounds.