Biotransformation of dehydroepiandrosterone (DHEA) with Penicillium griseopurpureum Smith and Penicillium glabrum (Wehmer) Westling

Bio-oxidation of progesterone by Penicillium oxalicum CBMAI 1185 and evaluation of the cytotoxic activity

We report the biotransformation of progesterone 1 by whole cells of Brazilian marine-derived fungi. A preliminary screening with 12 fungi revealed that the strains Penicillium oxalicum CBMAI 1996, Mucor racemous CBMAI 847, Cladosporium sp. CBMAI 1237, Penicillium oxalicum CBMAI 1185 and Aspergillus sydowii CBMAI 935 were efficient in the biotransformation of progesterone 1 in the first days of the reaction, with conversion values ranging from 75 % to 99 %. The fungus P. oxalicum CBMAI 1185 was employed in the reactions in quintuplicate to purify and characterize the main biotransformation products of progesterone 1. The compounds testololactone 1a, 12β-hydroxyandrostenedione 1b and 1β-hydroxyandrostenedione 1c were isolated and characterized by NMR, MS, [α]D and MP. In addition, the chromatographic yield of compound 1a was determined by HPLC-PDA in the screening experiments. In this study, we show a biotransformation pathway of progesterone 1, suggesting the presence of several enzymes such as Baeyer-Villiger monooxygenases, dehydrogenases and cytochrome P450 monooxygenases in the fungus P. oxalicum CBMAI 1185. In summary, the results obtained in this study contribute to the synthetic area and have environmental importance, since the marine-derived fungi can be employed in the biodegradation of steroids present in wastewater and the environment. The cytotoxic results demonstrate that the biodegradation products were inactive against the cell lines, in contrast to progesterone.

Biotransformation of α-terpineol by Alternaria alternata

α-Terpineol (1), the main volatile constituent in some traditional Chinese medicines, has been reported to be metabolized to 4R-oleuropeic acid by the larvae of common cutworms. The present study verified that α-terpineol could be converted to 4R-oleuropeic acid (2) and (1S,2R,4R)-p-menthane-1,2,8-triol (3) by Alternaria alternata fermentation. Using shortened fermentation times, 7-hydroxy-α-terpineol (2a) was identified as an oxidative intermediate, which was consistent with the hypothesis put forward by previous studies. Cytochrome P450 enzymes were also confirmed to catalyze this biotransformation. This is the first study on the biotransformation of α-terpineol by microbial fermentation.

The 11α-hydroxylation of medroxyprogesterone acetate by Absidia griseolla var. igachii and Acremonium chrysogenum

Medroxyprogesterone acetate (MPA) (1) has been transformed by two filamentous fungi, including Absidia griseolla var. igachii and Acremonium chrysogenum, into 11α-hydroxy-medroxyprogesterone acetate (2) as the major metabolite. The structure of the product was identified by different spectroscopic methods (1D- and 2D-NMR, EI-MS, and elemental analysis). Moreover, a time course study determined by HPLC showed 63% and 48% yields for the metabolite by using the two mentioned fungi, respectively. Finally, the effect of the temperature and concentration of the substrate were investigated, which the optimal fermentation conditions were found to be 25 °C with a substrate concentration of 0.1% (w/v). This study reports for the first time the production of 11α-hydroxy-medroxyprogesterone acetate as a fungal biotransformation product.

Distinct Regioselectivity of Fungal P450 Enzymes for Steroidal Hydroxylation

In this study, we identified two P450 enzymes (CYP5150AP3 and CYP5150AN1) from Thanatephorus cucumeris NBRC 6298 by combination of transcriptome sequencing and heterologous expression in Pichia pastoris The biotransformation of 11-deoxycortisol and testosterone by Pichia pastoris whole cells coexpressing the cyp5150ap3 and por genes demonstrated that the CYP5150AP3 enzyme possessed steroidal 7β-hydroxylase activities toward these substrates, and the regioselectivity was dependent on the structures of steroidal compounds. CYP5150AN1 catalyzed the 2β-hydroxylation of 11-deoxycortisol. It is interesting that they display different regioselectivity of hydroxylation from that of their isoenzyme, CYP5150AP2, which possesses 19- and 11β-hydroxylase activities.IMPORTANCE The steroidal hydroxylases CYP5150AP3 and CYP5150AN1 together with the previously characterized CYP5150AP2 belong to the CYP5150A family of P450 enzymes with high amino acid sequence identity, but they showed completely different regioselectivities toward 11-deoxycortisol, suggesting the regioselectivity diversity of steroidal hydroxylases of CYP5150 family. They are also distinct from the known bacterial and fungal steroidal hydroxylases in substrate specificity and regioselectivity. Biocatalytic hydroxylation is one of the important transformations for the functionalization of steroid nucleus rings but remains a very challenging task in organic synthesis. These hydroxylases are useful additions to the toolbox of hydroxylase enzymes for the functionalization of steroids at various positions.

An efficient biotransformation of progesterone into 11α-hydroxyprogesterone by Rhizopus microsporus var. oligosporus

Rhizopus microsporus var. oligosporus is a fungus that belongs to the Mucoraceae family that is used for the preparation of some soy-fermented foods. Microbial biotransformation of progesterone by R. microsporus var. oligosporus afforded some monohydroxylated and dihydroxylated metabolites. The main product was purified using chromatographic methods and identified as 11α-hydroxyprogesterone on the basis of its spectroscopic features. Time course studies by high-performance thin-layer chromatography demonstrated that this fungi efficiently hydroxylated progesterone at the 11α-position for 3 days with a yield of 76.48%, but beyond this time, the microorganism transformed 11α-hydroxyprogesterone into dihydroxylated metabolites. 11α-Hydroxyprogesterone is widely used as a precursor in the synthesis of hydrocortisone and other steroidal anti-inflammatory agents.

Baeyer-Villiger oxidation of progesterone by Aspergillus sojae PTCC 5196

Microbial transformations are capable of producing steroid substances difficult to synthesize by chemical methods. Strains belonging to the genus Aspergillus are effective facilitators of microbial biotransformations due to their enzymatic diversity. In this study, the biotransformation of progesterone by the fungus Aspergillus sojae (A. sojae) PTCC 5196 was examined. Analysis of the bioconversion process revealed that progesterone was converted to testololactone through a three-step pathway (17β-acetyl side chain cleavage, 17β-hydroxyl oxidation, and oxygenative lactonization of 17-ketone), indicating the presence of Baeyer-Villiger monooxygenase (BVMO) activity in the fungal strain. GC analysis confirmed the production of testololactone with a yield of 99% in 24 h. Faster testololactone production was induced in the presence of both C-21 (progesterone) and C-19 (androstenedione, testosterone, and dehydroepiandrosterone [DHEA]) steroid substances. Due to the high biotransformation rate observed in the present study, A. sojae may be a novel and promising candidate in the production of testololactone.

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 dehydroepiandrosterone (DHEA) by environmental strains of filamentous fungi

Study on the ability of selected filamentous fungus species to transform dehydroepiandrosterone was performed (DHEA) and interesting DHEA derivatives were obtained with high yield.

Biotransformation of dehydro-epi-androsterone by Aspergillus parasiticus: Metabolic evidences of BVMO activity

The research on the synthesis of steroids and its derivatives is of high interest due to their clinical applications. A particular focus is given to molecules bearing a D-ring lactone like testolactone because of its bioactivity. The Aspergillus genus has been used to perform steroid biotransformations since it offers a toolbox of redox enzymes. In this work, the use of growing cells of Aspergillus parasiticus to study the bioconversion of dehydro-epi-androsterone (DHEA) is described, emphasizing the metabolic steps leading to D-ring lactonization products. It was observed that A. parasiticus is not only capable of transforming bicyclo[3.2.0]hept-2-en-6-one, the standard Baeyer-Villiger monooxygenase (BVMO) substrate, but also yielded testololactone and the homo-lactone 3β-hydroxy-17a-oxa-D-homoandrost-5-en-17-one from DHEA. Moreover, the biocatalyst degraded the lateral chain of cortisone by an oxidative route suggesting the action of a BVMO, thus providing enough metabolic evidences denoting the presence of BVMO activity in A. parasiticus. Furthermore, since excellent biotransformation rates were observed, A. parasiticus is a promising candidate for the production of bioactive lactone-based compounds of steroidal origin in larger scales.

Metabolic fate of 3α,5-cycloandrostanes in the endogenous lactonization pathway of Aspergillus tamarii KITA

A series of 3α,5-cycloandrostane analogues with a range of functionality (6α and 6β alcohols and ketone) at carbon 6 were tested in the endogenous lactonization pathway in Aspergillus tamarii KITA. This metabolic route converts progesterone to testololactone in high yield through a four step enzymatic pathway. To date, no studies have looked at the effect of steroids devoid of polar functionality at carbon 3 and their subsequent metabolic fate by fungi which contain Baeyer-Villiger monooxygenases. Incubation of all of the cycloandrostane analogues resulted in lactonization of ring-D irrespective of C-6 stereochemistry or absence of C-3 functionality. Presence of 6β-hydroxy group and the C-17 ketone was required in order for these analogues to undergo hydroxylation at C-15β position. All metabolites were isolated by column chromatography and were identified by (1)H, (13)C NMR, DEPT analysis and other spectroscopic data.

Enhanced biotransformation of dehydroepiandrosterone to 3β,7α,15α-trihydroxy-5-androsten-17-one with Gibberella intermedia CA3-1 by natural oils addition

Dihydroxylation of dehydroepiandrosterone (DHEA) is an essential step in the synthesis of many important pharmaceutical intermediates. However, the solution to the problem of low biohydroxylation conversion in the biotransformation of DHEA has yet to be found. The effects of natural oils on the course of dihydroxylation of DHEA to 3β,7α,15α-trihydroxy-5-androsten-17-one (7α,15α-diOH-DHEA) were studied. With rapeseed oil (2 %, v/v) addition, the bioconversion efficiency was improved, and the 7α,15α-diOH-DHEA yield was increased by 40.8 % compared with that of the control at DHEA concentration of 8.0 g/L. Meantime, the ratio of 7α,15α-diOH-DHEA to 7α-OH-DHEA was also increased by 4.5 times in the rapeseed oil-containing system. To explain the mechanism underlying the increase of 7α,15α-diOH-DHEA yield, the effects of rapeseed oil on the pH of the bioconversion system, the cell growth and integrity of Gibberella intermedia CA3-1, as well as the membrane composition were systematically studied. The addition of rapeseed oil enhanced the substrate dispersion and maintained the pH of the system during bioconversion. Cells grew better with favorable integrity. The fatty acid profile of G. intermedia cells revealed that rapeseed oil changed the cell membrane composition and improved cell membrane permeability for lipophilic substrates.

Research on Biochemical Materials with Hydroxylation of Androst-4-en-3,17-dione by Colletotrichum lini AS3. 4486

Microbial transformation of androst-4-en-3,17-dione (AD; 1) usingColletotrichum liniAS3. 4486 resulted in the production of two metabolites 2 and 3. The structures of these compounds were elucidated by spectroscopic analysis (LC-MS, FTIR and NMR) as 15α-hydroxyandrost-4-en-3,17-dione (15α-OH-AD; 2) and 11α,15α-dihydroxyandrost-4-en-3,17-dione (11α,15α-diOH-AD; 3). AD underwent regioselective hydroxylation at 15α position, subsequently hydroxylated at 11α position and converted to compound 3. 11α,15α-diOH-AD as an important metabolic product was pharmaceutical intermediate and the yield was up to 97.58% when the concentration of substrate was 4 g L-1.

Microbial Baeyer-Villiger oxidation of 5α-steroids using Beauveria bassiana. A stereochemical requirement for the 11α-hydroxylation and the lactonization pathway

Beauveria bassiana KCH 1065, as was recently demonstrated, is unusual amongst fungal biocatalysts in that it converts C19 3-oxo-4-ene and 3β-hydroxy-5-ene as well as 3β-hydroxy-5α-saturated steroids to 11α-hydroxy ring-D lactones. The Baeyer-Villiger monooxygenase (BVMO) of this strain is distinguished from other enzymes catalyzing BVO of steroidal ketones by the fact that it oxidizes solely substrates with 11α-hydroxyl group. The current study using a series of 5α-saturated steroids (androsterone, 3α-androstanediol and androstanedione) has highlighted that a small change of the steroid structure can result in significant differences of the metabolic fate. It was found that the 3α-stereochemistry of hydroxyl group restricted "normal" binding orientation of the substrate within 11α-hydroxylase and, as a result, androsterone and 3α-androstanediol were converted into a mixture of 7β-, 11α- and 7α-hydroxy derivatives. Hydroxylation of androstanedione occurred only at the 11α-position, indicating that the 3-oxo group limits the alternative binding orientation of the substrate within the hydroxylase. Only androstanedione and 3α-androstanediol were metabolized to hydroxylactones. The study uniquely demonstrated preference for oxidation of equatorial (11α-, 7β-) hydroxyketones by BVMO from B. bassiana. The time course experiments suggested that the activity of 17β-HSD is a factor determining the amount of produced ring-D lactones. The obtained 11α-hydroxylactones underwent further transformations (oxy-red reactions) at C-3. During conversion of androstanedione, a minor dehydrogenation pathway was observed with generation of 11α,17β-dihydroxy-5α-androst-1-en-3-one. The introduction of C1C2 double bond has been recorded in B. bassiana for the first time.

Design and synthesis of novel D-ring fused steroidal heterocycles

Using dehydroepiandrosterone as the starting material, we have synthesized a series of steroid analogs possessing a D-ring fused with heterocycles which are pyridine, imidazo [2,1-b]thiazoles or substituted thiazole imines. All the final structures are first reported and identified by NMR and MS spectroscopys, the yields of these products are moderate to good and the reaction conditions are mild. The cytotoxicity of the synthesized compounds against EC-109(human esophageal carcinoma), EC-9706(human esophageal carcinoma), MGC-803(human gastric carcinoma) were investigated.

Biotechnological transformation of hydrocortisone to 16α-hydroxy hydrocortisone by Streptomyces roseochromogenes

Streptomyces roseochromogenes is able to hydroxylate steroid compounds in different positions of their cycloalkane rings thanks to a cytochrome P-450 multi-enzyme complex. In this paper, the hydroxylation of the hydrocortisone in the 16α position, performed by bacterial whole cells, was investigated in both shake flask and fermentation conditions; the best settings for both cellular growth and transformation reaction were studied by investigating the optimal medium composition, the kinetic of conversion, the most suitable substrate concentration and the preferred addition timing. Using newly formulated malt extract- and yeast extract-based media, a 16α-hydrohydrocortisone concentration of 0.2 ± 0.01 g L(-1) was reached in shake flasks. Batch experiments in a 2-L fermentor established the reproducibility and robustness of the biotransformation, while a pulsed batch fermentation strategy allowed the production to increase up to 0.508 ± 0.01 g L(-1). By-product formation was investigated, and two new derivates of the hydrocortisone obtained during the bacterial transformation reaction and unknown so far, a C-20 hydroxy derivate and a C-21 N-acetamide one, were determined by NMR analyses.

Baeyer-Villiger oxidation of some C(19) steroids by Penicillium lanosocoeruleum

The biotransformation of androsterone (1), epiandrosterone (2), androstanedione (3) and DHEA (dehydroepiandrosterone) (4) by Penicillium lanosocoeruleum-a fungal species not used in biotransformations so far-were described. All the substrates were converted in high yield (70%-99%) into D ring δ-lactones. The oxidation of 1 produced 3α-hydroxy-17a-oxa-D-homo-5α-androstan-17-one (5). The oxidation of 2 led to 3β-hydroxy-17a-oxa-D-homo-5α-androstan-17-one (6). The biotransformation of 3 resulted in the formation of 3α-hydroxy-17a-oxa-D-homo-5α-androstan-17-one (5) and 17a-oxa-D-homo-5α-androstan-3,17-dione (7). An analysis of the transformation progress of the studied substrates as a function of time indicates that the Baeyer-Villiger monooxygenase of this fungus does not accept the 3β-hydroxy-5-ene functionality of steroids. In this microorganism steroidal 3β-hydroxy-dehydrogenase (3β-HSD) was active, and as a result DHEA (4) was transformed exclusively to testololactone (8). Apart from the observed oxidative transformations, a reductive pathway was revealed with the C-3 ketone being reduced to a C-3α-alcohol. It is demonstrated for the first time that the reduction of the 3-keto group of the steroid nucleus can occur in the presence of a ring-D lactone functionality.

Facile synthesis of novel D-ring modified steroidal dienamides via rearrangement of 2H-pyrans

A simple and practical method for synthesis of the D-ring modified steroidal dienamides (4a-k) from the steroidal α,α-dicyanoalkene 3 and aldehydes via vinylogous aldol reaction was first reported. By using NaOAc as a base, the desired products were obtained in moderate to good yields in ethanol under mild conditions. All the synthesized steroidal dienamides are new and are currently being evaluated for their biological activities.

Follow-up of natural products isolation

Follow-up of natural products isolation refers to re-isolation of compound(s) of interest in larger amounts for further pharmacological testing, conclusive structure elucidation, structure modifications to synthesize analogs for structure-activity relationships (SAR) studies, preformulation and formulation studies or clinical trials. In addition to conventional synthetic chemistry approaches, several other methodologies can be applied for following-up natural products isolation. This chapter outlines, with specific examples, various strategies and methods involved in follow-up of natural products isolation.

Progesterone Hydroxylation with Colletotrichum Lini AS3. 4486

The biotransformation of progesterone by Colletotrichum lini AS3. 4486 was studied. The formation of the product was monitored by HPLC. Product was purified from broth culture supernatants by silica gel column chromatography and identified as 7β,12β-dihydoxylprogesterone with MS, 1H NMR, 13C NMR and NOE.