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. RESULTS: Compound I was converted to (-)-(10S,11S)-10,13,14-trihydroxyaromadendrane (4). Compound 2 was converted to (+)-(1S,11S)-1,13-dihydroxyaromadendrene (5) and (-)-5,11-epoxycadin-1(10)-en-14-ol (6). Compound 3 was converted to compound 6, (+)-(10R,11S)-10,13-dihydroxyaromadendr-1-ene (7) and (+)(10S,11S)-10,13-dihydroxyaromadendr-1-ene (8). The structure of the metabolic products has been elucidated on the basis of their spectral data. CONCLUSION: Compound 1 gave only one product that was hydroxylated at C-10, C-13 and C-14. By contrast, compounds 2 and 3 gave a number of products, one of which was common. The differences in oxidation of 1-3 are due to the configuration of the C-1 position. Compounds 4-8 were new compounds. (C) 2008 Society of Chemical Industry.