Competitive binding assay using a receptor for the active metabolite 5, which is the best method currently in use, lacks specificity, so it is troublesome and needs special techniques and its precision is poor. The detection limit of the method is ca. 10 fmol.

BACKGROUND: The biotransformation of sesquiterpenoids, which are a large class of naturally occurring compounds, using microorganisms as a biocatalyst to produce useful novel organic compounds was investigated. The biotransformation of sesquiterpenoids, (+)-aromadendrene (1), (−)-alloaromadendrene (2) and (+)-ledene (3) has been investigated using Aspergillus wentii as a biocatalyst.