Very-long-chain hydroxyaldehydes from the cuticular wax of Taxus baccata needles

In the cuticular wax of Taxus baccata needles, homologous series of very-long-chain 1,5-alkanediols and 5-hydroxyaldehydes were identified by various chemical transformations with product assignment using GC-MS. The 1,5-alkanediols had chain lengths ranging from C-28 to C-38, with strong predominance of even carbon numbers and a maximum at C-32 (29%). The series of 5-hydroxyaldehydes comprised chain lengths C-24 and C-26-C-36, and showed a pronounced prevalence of even-numbered homologues. 5-Hydroxyoctacosanal was the most abundant compound of the series (42%). The 5-hydroxyaldehydes together amounted to 0.4 mu g/cm(2), corresponding to 1.2% of total wax of the needles. A polyketide-like biosynthetic pathway is proposed based on the (similar) chain length distributions and functional group patterns for both compound classes. (C) 2007 Elsevier Ltd. All rights reserved.