Microbial transformation of testosterone by Rhizopus stolonifer and Fusarium lini

Abstract

The microbial transformation of testosterone by the fungi Rhizopus stolonifer and Fusarium lini has been investigated for the first time. The bioconversion reactions observed from R. stolonifer included oxidation of a 17β-hydroxyl group, a hydroxylation at equatorial 11α position, reduction of the double bond at C-4 with oxidation of the methylene at C-6 to the corresponding keto group, and lactonisation of ring D; the latter is the first report of this reaction by a Rhizopus species. Fusarium lini promoted 1-dehydrogenation of the steroid, which has been rarely observed in fungi cultures. The other routes of biotransformations included oxidation of the 17β-hydroxyl group and the hydroxylation at 11α position. These reactions are not common for Fusarium species.

Keywords:

• testosterone
• microbial transformation
• Rhizopus stolonifer
• Fusarium lini
• lactonisation
• 1-dehydrogenation
• 11α-hydroxylation

Acknowledgements

The authors would like to thank the Deanship of Scientific Research at the University of Jordan for financial support, Dr Jalal Zahra (University of Jordan, Amman, Jordan), Sarfarazullah (HEJ, Karachi University) and Yaqoob John (HEJ, Karachi University) for recording the NMR and MS spectra.