Studies onGeobacillus stearothermophilus– Part V: Transformation of 11α-hydroxyprogesterone

Biotransformation of progesterone by Aspergillus nidulans VKPM F-1069 (wild type)

Biotechnological transformation of steroids using enzyme systems of microorganisms is often the only possible method to modify the molecule in the industrial production of steroid drugs. Filamentous fungus Aspergillus nidulans has been little studied as a steroid-transforming microorganism. We studied the ability of the A. nidulans VKPM F-1069 strain to transform progesterone (PG) for the first time. This strain converts PG into 3 main products: 11α-hydroxy-PG, 11α-acetoxy-PG and 6β,11α-dihydroxy-PG. It has been established that in the first stage, the hydroxylation of PG occurs into C11α position, then the formed 11α-hydroxy-PG is modified into 11α-acetoxy-PG and 6β,11α-dihydroxy-PG. It was found that changes in the composition of the growth medium, aeration and the duration of the mycelium cultivation do not affect the qualitative composition of PG transformation products, but their ratios have changed. Under conditions of limited aeration, the direction of secondary modification of 11α-hydroxy-PG is shifted towards the formation of 11α-acetoxy-PG.

Biocatalyst mediated production of 6β,11α-dihydroxy derivatives of 4-ene-3-one steroids

Biotransformation of steroids with 4-ene-3-one functionality such as progesterone (I), testosterone (II), 17α-methyltestosterone (III), 4-androstene-3,17-dione (IV) and 19-nortestosterone (V) were studied by using a fungal system belonging to the genera of Mucor (M881). The fungal system efficiently and quantitatively converted these steroids in regio- and stereo-selective manner into corresponding 6β,11α-dihydroxy compounds. Time course experiments suggested that the transformation was initiated by hydroxylation at 6β- or 11α-(10β-hydroxy in case of V) to form monohydroxy derivatives which upon prolonged incubation were converted into corresponding 6β,11α-dihydroxy derivatives. The fermentation studies carried out using 5L table-top fermentor with substrates (I and II) clearly indicates that 6β,11α-dihydroxy derivatives of steroids with 4-ene-3-one functionality can be produced in large scale by using M881.

Biotransformation of progesterone by Absidia griseolla var. igachii and Rhizomucor pusillus

Biotransformation of progesterone using Absidia griseolla var. igachii and Rhizomucor pusillus strains as biocatalysts were investigated. Microbial hydroxylation of progesterone by A. griseolla produced two hydroxylated pregnane-like steroids. The metabolites identified as 6β,14α-dihydroxyprogesterone and 7α,14α-dihydroxyprogesterone. R. pusillus produced 6β,11α-dihydroxyprogesterone with excellent yield (65.5%) and 7α,14α-dihydroxyprogesterone. These metabolites were purified by TLC followed by their identification through (1)H, (13)C NMR and other spectroscopic data.

Predominant allylic hydroxylation at carbons 6 and 7 of 4 and 5-ene functionalized steroids by the thermophilic fungus Rhizomucor tauricus IMI23312

This paper demonstrates for the first time transformation of a series of steroids (progesterone, androst-4-en-3,17-dione, testosterone, pregnenolone and dehydroepiandrosterone) by the thermophilic fungus Rhizomucor tauricus. All transformations were found to be oxidative (monohydroxylation and dihydroxylation) with allylic hydroxylation the predominant route of attack functionalizing the steroidal skeleta. Timed experiments demonstrated that dihydroxylation of progesterone, androst-4-en-3,17-dione and pregnenolone all initiated with hydroxylation on ring-B followed by attack on ring-C. Similar patterns of steroidal transformation to those observed with R. tauricus have been observed with some species of thermophilic Bacilli and mesophilic fungi. All metabolites were isolated by column chromatography and were identified by (1)H, (13)C NMR, DEPT analysis and other spectroscopic data. The application of thermophilic fungi to steroid transformation may represent a potentially rich source for the generation of new steroidal compounds as well as for uncovering inter and intraspecies similarities and differences in steroid metabolism.