Chirality and biosynthesis of lilac compounds in Actinidia arguta flowers.

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.