Background: Biotransformation by using microbial and plant cell cultures has been applied effectively for the production of fine chemicals on large scale. Inspired by the wealth of literature available on the biotransformation of steroids, we decided to investigate the biotransformation of ethynodiol diacetate (1) by using plant and microbial cultures.
Results: The biotransformation of ethynodiol diacetate (1) with Cunninghamella elegans and plant cell suspension cultures of Ocimum basilicum and Azadirachta indica is being reported here for the first time. Biotransformation of 1 with Cunninghamella elegans yielded three new hydroxylated compounds, characterized as 17α-ethynylestr-4-en-3β,17β-diacetoxy-6α-ol (2), 17α-ethynylestr-4-en-3β,17β-diacetoxy-6β-ol (3), and 17α-ethynylestr-4-en-3β,17β-diacetoxy-10β-ol (4) and a known metabolite, 17α-ethynyl-17β-acetoxyestr-4-en-3-one (5). The biotransformation of 1 with Ocimum basilicum included hydrolysis of the ester group, oxidation of alcohol into ketone, and rearrangement of the hydroxyl group. Thus four major known metabolites were characterized as 17α-ethynyl-17β-acetoxyestr-4-en-3-one (5), 17α-ethynyl-17β-hydroxyestr-4-en-3-one (6), 17α-ethynyl-3 β-hydroxy-17β-acetoxyestr-4-ene (7) and 17α-ethynyl-5α,17β-dihydroxyestr-3-ene (8). Biotransformation of 1 with Azadirachta indica culture yielded compounds 5 and 6. Spectroscopic data of compound 8 is being reported for the first time. Structure of compound 6 was unambiguously deduced through single-crystal x-ray diffraction studies.
Conclusion: Biotransformation of an oral contraceptive, ethynodiol diacetate (1), by using microbial and plant cell cultures provides an efficient route to the synthesis of a library of new steroids with potential contraceptive properties. These methods can be employed in the production of such compounds with high stereoselectivity.