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Fungal mediated biotransformation of melengestrol acetate, and T-cell proliferation inhibitory activity of biotransformed compounds
Abstract
Glomerella fusaroide, and Rhizopus stolonifer were effectively able to transform the steroidal hormone melengestrol acetate (MGA) (1) into four (4) new metabolites, 17α-acetoxy-11α-hydroxy-6-methyl-16-methylenepregna-4,6-diene-3,20-dione (2), 17α-acetoxy-11α-hydroxy-6-methyl-16-methylenepregna-1,4,6-triene-3,20-dione (3), 17α-acetoxy-6,7α-epoxy-6β-methyl-16-methylenepregna-4,6-diene-3,20-dione (4), and 17α-acetoxy-11β,15β-dihydroxy-6-methyl-16-methylenepregna-4,6-diene-3,20-dione (5). All these compounds were structurally characterized by different spectroscopic techniques. The objective of the current study was to assess the anti-inflammatory potential of melengestrol acetate (1), and its metabolites 2–5. The metabolites and the substrate were assessed for their inhibitory effects on proliferation of T-cells in vitro. The substrate (IC50 = 2.77 ± 0.08 µM) and its metabolites 2 (IC50 = 2.78 ± 0.07 µM), 4 (IC50 = 2.74 ± 0.1 µM), and 5 (IC50 = < 2 µM) exhibited potent T- cell proliferation inhibitory activities, while compound 3 (IC50 = 29.9 ± 0.09 µM) showed a moderate activity in comparison to the standard prednisolone (IC50 = 9.73 ± 0.08 µM). All the metabolites were found to be non-toxic against 3T3 normal cell line. This study thus identifies some potent compounds active against T-cell proliferation. Their anti-inflammatory potential, therefore, deserves to be further investigated.
... The incubation period for IL-1β and TNF-α is 4 h, for IL-6 it is 24 h and for GM-CSF it is 72 h. After the incubation period, the cell supernatant was collected in sterile labeled Eppendorf's tubes and proceeded further for ELISA according to manufacturer instruction using human ELISA kits for TNF-α, IL-6, GM-CSF and IL-1β (R and D sys, Minneapolis, United States) [26]. ...
Ribavirin (1) esters 4–36 have been synthesized and tested for their anti-inflammatory and anti-viral properties against SARS-CoV-2. The impaired host immune response known as cytokine release syndrome is one of the major causes of COVID-19 infection-related death. The current study aimed to assess compounds 4–36 against viral infection in Vero cells (viral titration, cytopathic effects, anti-viral efficacy, and results of treatment points) and anti-inflammatory activity against cytokines (IL-2, GM-CSF, IL-6, TNF-α, IFN-γ and IL-1β) were quantified at the protein level by using ELISA, oxidative burst assay, nitric oxide inhibition assay, anti-proliferative activity. Cytotoxicity of compounds was also determined. Compound 13 showed promising results against anti-inflammatory activity (100.80%, IC50 = 0.40 ± 0.01 µM) and SARS-CoV-2 infection inhibition up to 80% (IC50 = 1.42 ± 0.28). Nonetheless, further investigation is necessary to enhance and synthesize long-acting Ribavirin esters-based anti-inflammatory and SARS-CoV-2 medications based on the identified patterns.
... Five new transformed products, 2α-methyl-3α,14α,17β-trihydroxy-5α-androstane (335) (0.8%), 2methylandrosta-11α-hydroxy-1, 4-diene-3,17-dione (336) (0.9%), 2-methylandrosta-14α-hydroxy-1, 4diene-3, 17-dione (337) (1.2%), 2α-methyl-7α-hydroxy-5α-androstan-3, 17-dione (340) (1.1%), and 2methyl-5α-androsta-7α-hydroxy-1-ene-3, 17-dione (341) (0.75%), along with three known metabolites, 2αmethyl-3α, 17β-dihydroxy-5α-androstane (338) (3.5%), 2-methylandrosta-1, 4-diene-3, 17-dione (339) In addition, nine more derivatives, 2α-methyl-7α, 11β, 17β-trihydroxy-5α-androstan-3-one (343), 2α-methyl-7β, 15α, 17β-trihydroxy-5α-androstan-3-one (344), 2α-hydroxymethyl-11β, 17β-dihydroxy-5α-androstan-3one (345), 2α-methyl-7α, 11α, 17β-trihydroxy-5α-androstan-3-one (346), 2α-methyl-11α, 15β, 17βtrihydroxy-5α-androstan-3-one (347), 2α-methyl-3β, 5α, 17β-trihydroxy-5α-androstane (348), 2α-methyl-3β, 14α, 17β-trihydroxy-5α-androstane (349), 2α-methyl-17β-hydroxy-5α-androstan-3-one (350), and 2αmethyl-3β, 17β-dihydroxy-5α-androstane (351) were also synthesized through the biotransformation of anticancer drug 334 with Beauveria bassiana, and Macrophomina phaseolina [82] [ Figure 62]. ...
Biotransformation of natural, synthetic, and semi-synthetic compounds has emerged as a frontier branch of chemical sciences that is progressively being applied in numerous fields. In the present review, we have summarized our biotransformation studies on bioactive compounds from 1997 to 2022. Various microbial and plant cell cultures were used for biocatalytic structural transformations. We present here an overview of biotransformation of 53 compounds belonging to various classes of natural, synthetic, and semi-synthetic compounds, published in several leading journals. The structures of the resulting metabolites have been elucidated by detailed spectroscopic studies. Oxidation, reduction, dehydrogenation, chlorination, aromatization, methylation, demethylation, rearrangements, etc. were the main reactions that occurred during the biotransformation processes. Many of the biotransformed products exhibited interesting biological activities. Structural transformations in some cases have also led to improved pharmacokinetic profiles. This review is aimed to provide a focused account of extensive work carried out in our laboratories in this field, as well as the immense potential of biocatalytic transformations in organic chemistry.
Non-catalytic sites are commonly present in many enzymes, but how to classify and modulate such sites for activity improvement is not well-explored. Herein a non-catalytic cavity in the 3-ketosteroid-Δ¹-dehydrogenase (Δ¹-KstD) from Mycobacterium smegmatis (MsKstD1), which could competitively bind to substrate to form non-catalytic complex, was predicted next to substrate tunnel by the CAVER/molecular dynamics. Based on that, a rational design was performed by Focused Site-directed Iterative Saturation Mutagenesis (FSISM) for blocking the non-catalytic cavity to enhance substrate enter active site to improve the Δ¹-dehydrogenation activity of MsKstD1. We obtained the best quadruple mutant (H132M\L113F\V419W\M51L) with 10-fold higher specific activity toward hydrocortisone than that of wild type enzyme. The Δ¹-dehydrogenation space time yield toward hydrocortisone reached 36.0 g/L/h to produce prednisolone. This work displays how to combine focused mutagenesis with computational analysis to effectively identify and modify non-catalytic cavity to enhance enzyme activity for efficient production of Δ¹-3-ketosteroid.
Glomerella fusarioides-mediated structural modifications of steroidal anabolic drug, oxandrolone (1), yielded a new product 17β,11α-dihydroxy-17α-methylandrosta-2-oxa-4-ene-3-one (2). Similarly, Cunninghamella elegans-catalyzed transformation of a steroidal anti-epileptic drug ganaxolone (3) afforded a new metabolite 14α-hydroxy-5α-pregnan-1-ene-3,20-dione (4). Structures of new metabolites 2 and 4 were deduced via 1D-, and 2D-NMR, HREI-, HRFAB-MS, and IR spectroscopic techniques. New derivative 2 showed a remarkable anti-aromatase activity with an IC50 = 0.6 ± 0.005 μM, when compared to substrate 1 (IC50 = 0.808 ± 0.07 μM), and standard anti-cancer drug exemestane (IC50 = 0.232 ± 0.031 μM). Ganaxolone (3) (IC50 = 13.76 ± 2.00 μM) also showed a good activity against human aromatase enzyme, while its derivative 4 was found to be inactive. Inhibition of aromatase enzyme is a key approach in the treatment of estrogen positive breast cancers. Compounds 1-4 were non-cytotoxic to 3T3 cell line (mouse fibroblast).
Seven metabolites were obtained from the microbial transformation of anabolic-androgenic steroid mibolerone (1) with Cunninghamella blakesleeana, C. echinulata, and Macrophomina phaseolina. Their structures were determined as 10β,17β-dihydroxy-7α,17α-dimethylestr-4-en-3-one (2), 6β,17β-dihydroxy-7α,17α-dimethylestr-4-en-3-one (3), 6β,10β,17β-trihydroxy-7α,17α-dimethylestr-4-en-3-one (4), 11β,17β-dihydroxy-(20-hydroxymethyl)-7α,17α-dimethylestr-4-en-3-one (5), 1α,17β-dihydroxy-7α,17α-dimethylestr-4-en-3-one (6), 1α,11β,17β-trihydroxy-7α,17α-dimethylestr-4-en-3-one (7), and 11β,17β-dihydroxy-7α,17α-dimethylestr-4-en-3-one (8), on the basis of spectroscopic studies. All metabolites, except 8, were identified as new compounds. This study indicates that C. blakesleeana, and C. echinulata are able to catalyze hydroxylation at allylic positions, while M. phaseolina can catalyze hydroxylation of CH2 and CH3 groups of substrate 1. Mibolerone (1) was found to be a moderate inhibitor of β-glucuronidase enzyme (IC50 = 42.98 ± 1.24 μM) during random biological screening, while its metabolites 2–4, and 8 were found to be inactive. Mibolerone (1) was also found to be significantly active against Leishmania major promastigotes (IC50 = 29.64 ± 0.88 μM). Its transformed products 3 (IC50 = 79.09 ± 0.06 μM), and 8 (IC50 = 70.09 ± 0.05 μM) showed a weak leishmanicidal activity, while 2 and 4 were found to be inactive. In addition, substrate 1 (IC50 = 35.7 ± 4.46 μM), and its metabolite 8 (IC50 = 34.16 ± 5.3 μM) exhibited potent cytotoxicity against HeLa cancer cell line (human cervical carcinoma). Metabolite 2 (IC50 = 46.5 ± 5.4 μM) also showed a significant cytotoxicity, while 3 (IC50 = 107.8 ± 4.0 μM) and 4 (IC50 = 152.5 ± 2.15 μM) showed weak cytotoxicity against HeLa cancer cell line. Compound 1 (IC50 = 46.3 ± 11.7 μM), and its transformed products 2 (IC50 = 43.3 ± 7.7 μM), 3 (IC50 = 65.6 ± 2.5 μM), and 4 (IC50 = 89.4 ± 2.7 μM) were also found to be moderately toxic to 3T3 cell line (mouse fibroblast). Interestingly, metabolite 8 showed no cytotoxicity against 3T3 cell line. Compounds 1–4, and 8 were also evaluated for inhibition of tyrosinase, carbonic anhydrase, and α-glucosidase enzymes, and all were found to be inactive.
Microbial transformation of the anti-inflammatory steroid medrysone (1) was carried out for the first time with the filamentous fungi Cunninghamella blakesleeana (ATCC 8688a), Neurospora crassa (ATCC 18419), and Rhizopus stolonifer (TSY 0471). The objective was to evaluate the anti-inflammatory potential of the substrate (1) and its metabolites. This yielded seven new metabolites, 14α-hydroxy-6α-methylpregn-4-ene-3,11,20-trione (2), 6β-hydroxy-6α-methylpregn-4-ene-3,11,20-trione (3), 15β-hydroxy-6α-methylpregn-4-ene-3,11,20-trione (4), 6β,17α-dihydroxy-6α-methylpregn-4-ene-3,11,20-trione (5), 6β,20S-dihydroxy-6α-methylpregn-4-ene-3,11-dione (6), 11β,16β-dihydroxy-6α-methylpregn-4-ene-3,11-dione (7), and 15β,20R-dihydroxy-6α-methylpregn-4-ene-3,11-dione (8). Single-crystal X-ray diffraction technique unambiguously established the structures of the metabolites 2, 4, 6, and 8. Fungal transformation of 1 yielded oxidation at the C-6β, -11β, -14α, -15β, -16β positions. Various cellular anti-inflammatory assays, including inhibition of phagocyte oxidative burst, T-cell proliferation, and cytokine were performed. Among all the tested compounds, metabolite 6 (IC50 = 30.3 μg/mL) moderately inhibited the reactive oxygen species (ROS) produced from zymosan-induced human whole blood cells. Compounds 1, 4, 5, 7, and 8 strongly inhibited the proliferation of T-cells with IC50 values between <0.2-10.4 μg/mL. Compound 7 was found to be the most potent inhibitor (IC50 < 0.2 μg/mL), whereas compounds 2, 3, and 6 showed moderate levels of inhibition (IC50 = 14.6-20.0 μg/mL). Compounds 1, and 7 also inhibited the production of pro-inflammatory cytokine TNF-α. All these compounds were found to be non-toxic to 3T3 cells (mouse fibroblast), and also showed no activity when tested against HeLa (human epithelial carcinoma), or against PC3 (prostate cancer) cancer cell lines.
Antifungal drugs belong to few chemical groups and such low diversity limits the therapeutic choices. The urgent need of innovative options has pushed researchers to search new bioactive molecules. Literature regarding the last 15 years reveals that different research groups have used different approaches to achieve such goal. However, the discovery of molecules with different mechanisms of action still demands considerable time and efforts. This review was conceived to present how Pharmaceutical Biotechnology might contribute to the discovery of molecules with antifungal properties by microbial biotransformation procedures. Authors present some aspects of (1) microbial biotransformation of herbal medicines and food; (2) possibility of major and minor molecular amendments in existing molecules by biocatalysis; (3) methodological improvements in processes involving whole cells and immobilized enzymes; (4) potential of endophytic fungi to produce antimicrobials by bioconversions; and (5) in silico research driving to the improvement of molecules. All these issues belong to a new conception of transformation procedures, so-called “green chemistry,” which aims the highest possible efficiency with reduced production of waste and the smallest environmental impact.
Fermentation of mesterolone (1) with Cunninghamella blakesleeana yielded four new metabolites, 1α-methyl-1β,11β,17β-trihydroxy-5α-androstan-3-one (2), 1α-methyl-7α,11β,17β-trihydroxy-5α-androstan-3-one (3), 1α-methyl-1β,6α,17β-trihydroxy-5α-androstan-3-one (4) and 1α-methyl-1β,11α,17β-trihydroxy-5α-androstan-3-one (5), along with three known metabolites, 1α-methyl-11α,17β-dihydroxy-5α-androstan-3-one (6), 1α-methyl-6α,17β-dihydroxy-5α-androstan-3-one (7) and 1α-methyl-7α,17β-dihydroxy-5α-androstan-3-one (8). Biotransformation of 1 with Macrophomina phaseolina also yielded a new metabolite, 1α-methyl, 17β-hydroxy-5α-androstan-3,6-dione (9). The isolated metabolites were subjected to various in vitro biological assays, such as anti-cancer, inhibition of α-glucosidase, phosphodiesterase-5 and oxidative brust. However, no significant results were observed. This is the first report of biotransformation of 1 with Cunninghamella blakesleeana and Macrophomina phaseolina.
Background
Microbial transformation of steroids has been extensively used for the synthesis of steroidal drugs, that often yield novel analogues, not easy to obtain by chemical synthesis. We report here fungal transformation of a synthetic steroidal drug, exemestane, used for the treatment of breast cancer and function through inhibition of aromatase enzyme.
Results
Microbial transformation of anti-cancer steroid, exemestane (1), was investigated by using two filamentous fungi. Incubation of 1 with fungi Macrophomina phaseolina, and Fusarium lini afforded three new, 11α-hydroxy-6-methylene-androsta-1, 4-diene-3,17-dione (2), 16β, 17β-dihydroxy-6-methylene-androsta-1, 4-diene-3-one (3), and 17β-hydroxy-6-methylene-androsta-1, 4-diene-3, 16-dione (4), and one known metabolites, 17β-hydroxy-6-methylene-androsta-1, 4-diene-3-one (5). Their structures were deduced spectroscopically. Compared to 1 (steroidal aromatase inactivator), the transformed metabolites were also evaluated for cytotoxic activity by using a cell viability assay against cancer cell lines (HeLa and PC3). Metabolite 2 was found to be moderately active against both the cell lines.
Conclusions
Biotransformation of exemestane (1) provides an efficient method for the synthesis of new analogues of 1. The metabolites were obtained as a result of reduction of double bond and hydroxylation. The transformed product 2 exhibited a moderate activity against cancer cell lines (HeLa and PC3). These transformed products can be studied for their potential as drug candidates.
Expanded use of artificial insemination in the beef cattle industry depends on successful application of treatments designed to synchronize estrus. Regulation of estrous cycles is associated with control of the corpus luteum (CL), whose life span and secretory activity are subject to trophic and lytic mechanisms. The advantages of melengestrol acetate (MGA) in estrous synchronization incorporate ease of administration, lower cost relative to other estrous synchronization products, and potential for use to induce estrus in prepubertal heifers. Treatments first designed to synchronize estrous cycles of normally cycling heifers by feeding MGA were imposed daily for 14 to 18 d at levels of .5 to 1 mg. The minimal daily effective dose required to inhibit ovulation was .42 mg. Longer feeding periods of MGA were associated with low fertility at the first synchronized estrus, but at the second estrus, conception was normal. Low fertility at the synchronized estrus resulted in development of alternative treatment practices, which combined feeding of MGA with injections or implants of estradiol-17 beta, estradiol cypionate, luteinizing hormone, human chorionic gonadotropin, pregnant mare serum gonadotropin, or oxytocin. Estrus was synchronized after MGA and estradiol-17 beta or estradiol cypionate treatments, but fertility was low. Short-term feeding of MGA (5 to 7 d) combined with prostaglandin F2 alpha or its analogs (PGF) on the last day of MGA reduced fertility at the synchronized estrus. The reduced conception at first service occurred in animals that began treatment after d 12 of the estrous cycle. However, feeding MGA for 14 d and then injecting PGF 17 d later avoided problems with reduced conception. Fertility of animals after this treatment was similar to that of contemporaries synchronized with Syncro-Mate-B. However, the length of the treatment period creates a need for increased management and may extend management beyond practical limits. Further research is warranted to address problems associated with reduced fertility after short-term treatment with MGA.
A one-step non-radioactive assay to determine the proliferation of murine lymphocytes, lymphoid tumor cells and hybridoma cells is described. This assay requires the addition of Alamar Blue dye to cell cultures and the degree of change in its color, which is reflective of the extent of cellular proliferation, can be determined by an ELISA plate reader. Alamar Blue must be added during the initial phase of cell culture. The pattern of concanavalin A (ConA) or anti-CD3 antibody-induced proliferative response of murine lymphocytes as assessed by Alamar Blue was similar to that of a [3H]thymidine assay. Similarly, the spontaneous proliferation curve of anti-CD3 antibody secreting cell line (YCD3-1), monocytic macrophage cell lines (PU5-1.8, P388D1, J774.1) and myeloma cells (Sp2/0) as determined by Alamar Blue closely resembled that of the [3H]thymidine assay. The minimum detectable number of proliferating cells was comparable in Alamar Blue and [3H]thymidine assays. Since cell lysis/extraction and washing procedures are not involved in the Alamar Blue assay, this approach has several distinct advantages over currently available assays (eg. [3H]thymidine). First, it allows daily monitoring of proliferation without compromising the sterility of cultures. An indication of proliferation can be evaluated (spectrophotometrically or visually) as early as 24 h after ConA stimulation. Second, unlike previously reported assays, Alamar Blue permits further analysis of proliferating cells by other methods. Analysis of cells in culture with Alamar Blue for various surface antigens (CD44, CD45RB, CD4, heat stable antigen) by flow cytometry revealed that the fluorescent profile and relative percentage of cells in cultures with the Alamar Blue were comparable to those without this reagent. The salient advantages of Alamar Blue assay over the [3H]thymidine assay include: (i) non-radioactivity; (ii) simplicity; (iii) less costly; (iv) non-labor intensive; (v) rapidity of assessment of proliferation of large number of samples; (vi) non-toxicity; (vii) usefulness in determining the kinetics of cell growth of hybridomas; and (viii) non-interference of secretion of antibodies by a hybridoma cell line.
Staphylococcus aureus is one of the most infectious agents among staphylococcal bacteria. Currently many strains of S. aureus have developed resistance against available antibiotics. Therefore, the treatment of infections caused by them is a major challenge. During current study, desogestrel (1), a contraceptive drug, was found to be a potent growth inhibitor of drug resistant strains of S. aureus. Therefore, in search of new and effective agents against multi-drug resistant S. aureus strains, whole-cell bio-catalytic conversion of desogestrel (1) by Cunninghamella blakesleeana ATCC 8688A at pH 7.0 and 25 °C was carried out, yielding three new metabolites, 13-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-6β,15β,17β-triol (2), 13-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-3β,6β,17β-triol (3), and 13-ethyl-11-methylene-18,19-dinor-17α-pregn-20-yn-3α,5α,6β,17β-tetraol (4), along with a known metabolite, 13-ethyl-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-6β,17β-dihydroxy-3-one (5). Among them, compounds 1-2 showed a potent activity against S. aureus EMRSA-17, S. aureus NCTC 13277 (MRSA-252), and S. aureus NCTC 13143, and clinically isolated Pakistani strain of S. aureus in an in vitro Microplate Alamar Blue Assay (MABA). Vancomycin was used as the standard drug in this assay. In addition, compound 1 also showed a significant activity against vancomycin-resistant S. aureus (VRSA) ATCC 700699. Compounds 1-5 were also evaluated against 3T3 normal cell line (mouse fibroblast) where they all were identified as non-cytotoxic. The present study thus provides new leads for the development of anti-bacterial drugs against MDR S. aureus.
Biotransformation of an orally active contraceptive drug, drospirenone (1), by Cunninghamella elegans ATCC36114 yielded four new metabolites, 6β,7β,15β,16β-dimethylene-3-oxo-14α-hydroxy-17α-pregn-4-ene-21,17-carbolactone (2), 6β,7β,15β,16β-dimethylene-3,11-dioxo-17α-pregn-4-ene-21,17-carbolactone (3), 6β,7β,15β,16β-dimethylene-3,12-dioxo-17α-pregn-4-ene-21,17-carbolactone (4), and 6β,7β,15β,16β-dimethylene-3-oxo-11β,14α-dihydroxy-17α-pregn-4-ene-21,17-carbolactone (5), along with a known metabolite, 6β,7β,15β,16β-dimethylene-3-oxo-11α-dihydroxy-17α-pregn-4-ene-21,17-carbolactone (6). This study provides not only new analogues of orally active contraceptive drug, drospirenone, but also help in understanding the metabolism of this important drug.
Microbial transformation of methasterone (1) was investigated with Macrophomina phaseolina, Cunninghamella blakesleeana, and Fusarium lini. Biotransformation of 1 with M. phaseolina yielded metabolite 2, while metabolites 3-7 were obtained from the incubation of 1 with C. blakesleeana. Metabolites 8-13 were obtained through biotransformation with F. lini. All metabolites, except 13, were found to be new. Methasterone (1) and its metabolites 2-6, 9, 10, and 13 were then evaluated for their immunomodulatory effects against TNF-α, NO , and ROS production. Among all tested compounds, metabolite 6 showed a potent inhibition of proinflammatory cytokine TNF-α (IC50 = 8.1 ± 0.9 µg/mL), as compared to pentoxifylline used as a standard (IC50 = 94.8± 2.1 µg/mL). All metabolites were also evaluated for the inhibition of NO production at concentration of 25 µg/mL. Metabolites 6 (86.7 ± 2.3%) and 13 (62.5 ± 1.5%) were found to be the most potent inhibitors of NO as compared to the standard NG-monomethyl-L-arginine acetate (65.6 ± 1.1%). All metabolites were found to be non-toxic against PC3, HeLa, and 3T3 cell lines. Observed inhibitory potential of metabolites 6 and 13 against pro-inflammatory cytokine TNF-α, as well as NO production makes them interesting leads for further studies.
Microbial transformation of the steroidal sapogenin diosgenin (1) by resting cells of the filamentous fungus, Cunninghamella echinulata CGMCC 3.2716 was studied. Four metabolites were isolated and unambiguously characterized as (25R)-spirost-5-ene-3β,7β-diol-11-one (2), (25R)-spirost-5-ene-3β,7β-diol (3), (25R)-spirost-5-ene-3β,7β,11α-triol (4), and (25R)-spirost-5-ene-3β,7β,12β-triol (5), by various spectroscopic methods (1H, 13C NMR, DEPT, 1H–1H COSY, HMBC, HSQC and NOESY). Compound 2 is a new metabolite. The NMR data and full assignment for the known metabolites (25R)-spirost-5-ene-3β,7β-diol (3) and (25R)-spirost-5-ene-3β,7β,11α-triol (4) are described here for the first time. The biotransformation characteristics observed included were C-7β, C-11α and C-12β hydroxylations. Compounds 1–5 exhibited no significant cytotoxic activity to human glioma cell line U87.
Microbial transformation is an important tool for structural modification of organic compounds, especially natural products with complex structures like steroids. It can be used to synthesize chemical structures that are difficult to obtain by ordinary methods and as a model of mammalian metabolism due to similarity between mammalian and microbial enzyme systems. During recent years research has been focused on the structural modifications of bioactive steroids by using various microorganisms, in order to obtain biologically potent compounds with diverse structures. Steroidal compounds are responsible for important biological functions in the cells and manifest a variety of activities. This article covers the microbial transformation of sterols, steroidal hormones and some new types of steroids known as bufadienolides. Emphasis has placed on reporting metabolites that may be of general interest and on the practical aspects of work in the field of microbial transformations. The review covers the literature from 1994 to 2011.
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.
Structural transformation of the steroidal lactone, oxandrolone (1), by suspended-cell cultures of the plant pathogen fungus Rhizopus stolonifer, resulted in the production of three new metabolites. These metabolites were identified as 11alpha-hydroxyoxandrolone (2), 6alpha-hydroxyoxandrolone (3) and 9alpha-hydroxyoxandrolone (4), by different spectroscopic methods and single-crystal X-ray diffraction analysis for metabolite 2. Compounds 1 and 3 showed a significant beta-glucuronidase inhibitory activity.
The fate of trenbolone acetate and melengestrol acetate after application as growth promoters in cattle: environmental studies
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