Transformation of 3β-hydroxy-5-en-steroids by Mucor racemosus

Metabolic fate of pregnene-based steroids in the lactonization pathway of multifunctional strain Penicillium lanosocoeruleum

Background

Metabolic activities of microorganisms to modify the chemical structures of organic compounds became an effective tool for the production of high-valued steroidal drugs or their precursors. Currently research efforts in production of steroids of pharmaceutical interest are focused on either optimization of existing processes or identification of novel potentially useful bioconversions. Previous studies demonstrated that P. lanosocoeruleum KCH 3012 metabolizes androstanes to the corresponding lactones with high yield. In order to explore more thoroughly the factors determining steroid metabolism by this organism, the current study was initiated to delineate the specificity of this fungus with respect to the cleavage of steroid side chain of progesterone and pregnenolone The effect of substituents at C-16 in 16-dehydropregnenolone, 16α,17α-epoxy-pregnenolone and 16α-methoxy-pregnenolone on the pattern of metabolic processing of these steroids was also investigated.

Results and discussion

All of the analogues tested (except the last of the listed) in multi-step transformations underwent the Baeyer–Villiger oxidation to their δ-d-lactones. The activity of 3β-HSD was a factor affecting the composition of the product mixtures. 16α,17α-epoxy-pregnenolone underwent a rare epoxide opening with retention stereochemistry to give four 16α-hydroxy-lactones. Apart from oxidative transformations, a reductive pathway was revealed with the unique hydrogenation of 5-ene double bond leading to the formation of 3β,16α-dihydroxy-17a-oxa-d-homo-5α-androstan-17-one. 16α-Methoxy-pregnenolone was transformed to the 20(R)-alcohol with no further conversion.

Conclusions

This work clearly demonstrated that P. lanosocoeruleum KCH 3012 has great multi-functional catalytic properties towards the pregnane-type steroids. Studies have highlighted that a slight modification of the d-ring of substrates may control metabolic fate either into the lactonization or reductive and oxidative pathways. Possibility of epoxide opening by enzymes from this microorganism affords a unique opportunity for generation of novel bioactive steroids.

Electronic supplementary material

The online version of this article (10.1186/s12934-018-0948-1) contains supplementary material, which is available to authorized users.

Biotransformation of Some Steroids by Mucor Hiemalis MRC 70325

In this work, incubations of testosterone, dehydroepiandrosterone and pregnenolone with Mucor hiemalis MRC 70325 have been reported. Incubation of testosterone afforded androst-4-en-3,17-dione (3%), 14α-hydroxyandrost-4-en-3,17-dione (9%), 6β-hydroxyandrost-4-en-3,17-dione (2%) and 14α,17β-dihydroxyandrost-4-en-3-one (62%). Incubation of dehy droepiandrosterone afforded 3β,17β-dihydroxyandrost-5-ene (6%) and 3β,7α-dihydroxyandrost-5-en-17-one (72%). Incubation of pregnenolone afforded 3β,14α-dihydroxypregn-5-en-7,20-dione (3%), 3β,7α-dihydroxy-pregn-5-en-20-one (64%) and 3β,7α,11α-trihydroxypregn-5-en-20-one (11%). 3β,14α-Dihydroxypregn-5-en-7,20-dione was identified as a new metabolite.

Microbial steroid transformations: current state and prospects

Studies of steroid modifications catalyzed by microbial whole cells represent a well-established research area in white biotechnology. Still, advances over the last decade in genetic and metabolic engineering, whole-cell biocatalysis in non-conventional media, and process monitoring raised research in this field to a new level. This review summarizes the data on microbial steroid conversion obtained since 2003. The key reactions of structural steroid functionalization by microorganisms are highlighted including sterol side-chain degradation, hydroxylation at various positions of the steroid core, and redox reactions. We also describe methods for enhancement of bioprocess productivity, selectivity of target reactions, and application of microbial transformations for production of valuable pharmaceutical ingredients and precursors. Challenges and prospects of whole-cell biocatalysis applications in steroid industry are discussed.

Interaction of bisphenol A with dissolved organic matter in extractive and adsorptive removal processes

The fate of endocrine disrupting chemicals (EDCs) in natural and engineered systems is complicated due to their interactions with various water constituents. This study investigated the interaction of bisphenol A (BPA) with dissolved organic matter (DOM) and colloids present in surface water and secondary effluent as well as its adsorptive removal by powdered activated carbons. The solid phase micro-extraction (SPME) method followed by thermal desorption and gas chromatography-mass spectrometry (GC-MS) was utilized for determining the distribution of BPA molecules in water. The BPA removal by SPME decreased with the increased DOM content, where the formation of BPA-DOM complexes in an aqueous matrix was responsible for the reduced extraction of BPA. Colloidal particles in water samples sorbed BPA leading to the marked reduction of liquid phase BPA. BPA-DOM complexes had a negative impact on the adsorptive removal of BPA by powered activated carbons. The complex formation was characterized based on Fourier transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy, along with the calculation of molecular interactions between BPA and functional groups in DOM. It was found that the hydrogen bonding between DOM and BPA would be preferred over aromatic interactions. A pseudo-equilibrium molecular coordination model for the complexation between a BPA molecule and a hydroxyl group of the DOM was developed, which enabled estimation of the maximum sorption site and complex formation constant as well as prediction of organic complexes at various DOM levels.

Microbial transformation of 3β-acetoxypregna-5,16-diene-20-one by Penicillium citrinum

The biotransformation of 3β-acetoxypregna-5,16-diene-20-one (1) by using a filamentous fungus Penicillium citrinum resulted in the production of four metabolites 2-5. The structures of these compounds were elucidated by different spectroscopic analysis (1D- and 2D-NMR) and HR-ESI-MS as 3β,7β-dihydroxy-pregn-5,16(17)-dien-20-one (2), 3β-hydroxy-7α-methoxy-pregn-5,16(17)-dien-20-one (3), 3β,7β,11α-trihydroxy-pregn-5,16(17)-dien-20-one (4), and a known 3β,7α-dihydroxy-pregn-5,16(17)-dien-20-one (5). The 7-O-methylation is a novel reaction in the field of microbial transformation of pregnane steroids.

Synthesis of 3beta, 7alpha, 11alpha-trihydroxy-pregn-21-benzylidene-5-en-20-one derivatives and their cytotoxic activities

A series of novel 3beta, 7alpha, 11alpha-trihydroxy-pregn-21-benzylidene-5-en-20-one derivatives were synthesized and characterized by NMR, HRMS. The pregnenolone (1) was first biotransformed by Mucor circinelloides var lusitanicus to 3beta, 7alpha, 11alpha-trihydroxy-pregn-5-en-20-one (3), then 3 was treated with various benzaldehydes to produce 3beta, 7alpha, 11alpha-trihydroxy-pregn-21-benzylidene-5-en-20-one derivatives. These derivatives showed remarkable activity against EC109 cells. The absolute configuration of 3 was also confirmed by signal-crystal X-ray analysis.