J. M. Evans

Microbiological hydroxylation of steroids. Part VIII. The pattern of monohydroxylation of diketones and keto-alcohols derived from 5α-androstane with cultures of the fungus, Rhizopus nigricans

Diketones and keto-alcohols derived from 5α-androstane are readily converted into monohydroxy-derivatives by Rhizopus nigricans. Varying the positions and oxidation levels of the oxygen functions leads to hydroxylation at different positions. Substrates with one oxygen substituent in each of the terminal rings are attacked at position 11 or 7; those with one group in rings B or C are hydroxylated at position 16 if the second group is in ring A, and at position 3 if the second group is in ring D.The results are rationalised by assuming the presence of three dual-purpose sites on the enzyme surface capable of binding to the steroidal oxygen groups and of hydroxylating those positions of the steroid nucleus which come into their vicinity.

Microbiological hydroxylation. Part XVI. Incubation of derivatives (mainly acetals) of 5α-androstane ketones with the fungi Calonectria decora, Aspergillus ochraceus, and Rhizopus nigricans

Acetals and enol ethers derived from oxoandrostanes are less reactive than the parent ketones towards the title fungi. None of the derivatives is hydroxylated by Rhizopus nigricans, and only one by Aspergillus ochraceus. With Calonectria decora the acetals generally give patterns of hydroxylation similar to, but less specific than, those of the corresponding ketones. 16,16-Ethylenedioxy-5α-androstane is exceptional in that its hydroxylation with Calonectria decora to a 6α,12β-dihydroxy-product is more efficient than the 6α,11α-dihydroxylation of 5α-androstan-16-one.

Microbiological hydroxylation of steroids. Part III. A convenient, microbiological route to 15-oxygenated 5α-androstanes.

By utilising the specific hydroxylating capabilities of the fungi Aspergillus ochraceus Wilhelm and Penicillium urticae Bain in combination with standard chemical reactions, 5α-androstan-15α-ol has been obtained from 3α-hydroxy-5α-androstan-17-one in an overall yield of 16%.