AbstractBACKGROUND: 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 1 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. Copyright © 2008 Society of Chemical Industry