Microbial transformation of a series of androgens with Aspergillus tamarii

Flexibility of the endogenous progesterone lactonisation pathway in Aspergillus tamarii KITA: transformation of a series of cortical steroid analogues

“…Frequently [2] it has not been possible to isolate testosterone acetate (2); this has been explained by the presence of high levels of the esterase enzyme [2] resulting in rapid hydrolysis of the acetate. A minor hydroxylation pathway is also present in this organism, here testosterone is hydroxylated at the 11␤-position [1] with no further metabolism observed [9].…”

“…The 1 H NMR spectrum of the next metabolite isolated was devoid of the 21-methyl signal (δ H 2.28 ppm) present in the starting material suggesting loss of the cortical side chain. This was fully supported by loss of signals at δ C 211.6 and 27.8 ppm in the 13 C NMR spectrum of the starting material assigned to C-20 and C-21 and a downfield shift of the C-13 resonance signal of δ C 35.4 ppm consistent with insertion of oxygen adjacent to this position on ring D. This coupled with the upfield shift in the 18-methyl resonance signal of δ H 0.61 ppm and a new quaternary resonance signal at δ C 171.9 ppm were consistent with lactone formation [14] all other spectral data were consistent with the structure of testololactone (5) as was the melting point 208 • C following crystallisation from ethyl acetate in light petroleum as needles lit., 208 • C [1,9] (found: 302.187 C 19 H 26 O 3 requires 302.188). The final transformation product was identified as 17␣-oxa-d-homo-androst-1,4-diene-3,17-dione (12).…”

“…17␣-Hydroxyprogesterone (7), epoxyprogesterone (8) and deoxycorticosterone (9) were purchased form Aldrich (UK), cortexolone (10) was supplied by Acros Organics (UK). All compounds were used as supplied.…”

“…In order to test the flexibility of this pathway and determine its ability to generate novel steroidal metabolites we have challenged it with a series of progesterone analogues, namely 17␣-hydroxyprogesterone (7), 16␣,17␣-epoxyprogesterone (8), deoxycorticosterone (9) and cortexolone (10). To date there is a mass of information on the hydroxylation of steroids, however there is relatively little research into the area of steroidal lactonisation pathways with respect to the handling of a variety of cortical steroids.…”

Hydroxylation and Dihydroxylation

“…Interpretation of the relationship between substrate binding centers and the site of hydroxylation of steroids is complicated by the fact that binding can occur in several different orientations, a phenomenon first suggested for pragmatic reasons by BRANNON et al (1967) and later confirmed by site-directed mutagenesis studies (IWASAKI et al, 1995b).…”