Progesterone metabolism by the filamentous fungus Cochliobolus lunatus

Hydroxylation of Progesterone and Its Derivatives by the Entomopathogenic Strain Isaria farinosa KCh KW1.1

Progesterone biotransformation is worth studying because of the high industrial value of its derivatives. This study investigated the catalytic ability of the entomopathogenic filamentous fungus strain Isaria farinosa KCh KW1.1 to transform progesterone derivatives: 11α-hydroxyprogesterone, 17α-hydroxyprogesterone, 16α,17α-epoxyprogesterone and pregnenolone. In the culture of Isaria farinosa KCh KW1.1, 11α-hydroxyprogesterone was effectively transformed into only one product: 6β,11α-dihydroxyprogesterone. Transformation of 17α-hydroxyprogesterone gave three hydroxy derivatives: 6β,17α-dihydroxyprogesterone, 12β,17α-dihydroxyprogesterone and 6β,12β,17α-trihydroxyprogesterone. Two products: 6β-hydroxy-16α,17α-epoxyprogesterone and 6β,11α-dihydroxy-16α,17α-epoxyprogesterone, were obtained from the 16α,17α-epoxyprogesterone transformation. We isolated two compounds from the biotransformation medium with pregnenolone: 11α-hydroxy-7-oxopregnenolone and 5α,6α-epoxy-3β,11α-dihydroxypregnan-7,20-dione. In this study, we observed only mono- and dihydroxy derivatives of the tested substrates, and the number of obtained products for each biotransformation did not exceed three.

Engineering the Steroid Hydroxylating System from Cochliobolus lunatus in Mycolicibacterium smegmatis

14α-hydroxylated steroids are starting materials for the synthesis of contraceptive and anti-inflammatory compounds in the steroid industry. A synthetic bacterial operon containing the cytochrome P450 CYP103168 and the reductase CPR64795 of the fungus Cochlioboluslunatus able to hydroxylate steroids has been engineered into a shuttle plasmid named pMVFAN. This plasmid was used to transform two mutants of Mycolicibacterium smegmatis named MS6039-5941 and MS6039 that accumulate 4-androstene-3,17-dione (AD), and 1,4-androstadiene-3,17-dione (ADD), respectively. The recombinant mutants MS6039-5941 (pMVFAN) and MS6039 (pMVFAN) were able to efficiently express the hydroxylating CYP system of C.lunatus and produced in high yields 14αOH-AD and 14αOH-ADD, respectively, directly from cholesterol and phytosterols in a single fermentation step. These results open a new avenue for producing at industrial scale these and other hydroxylated steroidal synthons by transforming with this synthetic operon other Mycolicibacterium strains currently used for the commercial production of steroidal synthons from phytosterols as feedstock.

Biotransformation of progesterone and testosterone enanthate by Circinella muscae

In this study, the biotransformation of progesterone (1) and testosterone enanthate (5) using the whole cells of Circinella muscae was investigated for the first time. Microbial transformation of 1 with C. muscae afforded three known metabolites including 9α-hydroxyprogesterone (2), 14α-hydroxyprogesterone (3) and 6β,14α dihydroxyprogesterone (4) after 6 days of incubation at 26 °C. The biotransformation of 5 with C. muscae yielded a new metabolite; 8β,14α-dihydroxytestosterone (8), in addition to two known metabolites; 6β-hydroxytestosterone (6), and 9α-hydroxytestosterone (7). The structure of the metabolites were established on the basis of spectroscopic data.

Identification and expression of the 11β-steroid hydroxylase from Cochliobolus lunatus in Corynebacterium glutamicum

Hydroxylation of steroids has acquired special relevance for the pharmaceutical industries. Particularly, the 11β-hydroxylation of steroids is a reaction of biotechnological importance currently carried out at industrial scale by the fungus Cochliobolus lunatus. In this work, we have identified the genes encoding the cytochrome CYP103168 and the reductase CPR64795 of C. lunatus responsible for the 11β-hydroxylase activity in this fungus, which is the key step for the preparative synthesis of cortisol in industry. A recombinant Corynebacterium glutamicum strain harbouring a plasmid expressing both genes forming a synthetic bacterial operon was able to 11β-hydroxylate several steroids as substrates. This is a new example to show that the industrial strain C. glutamicum can be used as a suitable chassis to perform steroid biotransformation expressing eukaryotic cytochromes.

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.

Effect of different carbon sources on morphology and silver accumulation in Cochliobolus lunatus

The morphology of filamentous fungi plays very important role in uptake of metabolites and enzyme production. A filamentous fungus may be fibrous, hyphae, pellets, clumps, etc. Cochliobolus lunatus is a fungus which has previously been reported for silver accumulation and nanoparticles formation. The present study investigated the role of various carbon sources on morphology, biochemical profile, silver accumulation, and biosynthesis of silver nanoparticles by fungal strain C. lunatus. In this investigation, effect of different carbon sources was studied on morphology of C. lunatus and its silver accumulating ability. As a result of different carbon sources like carboxymethyl cellulose (CMC), pectin, starch, agar, sucrose, and mannitol, the organism showed three kinds of morphologies like homogenous smooth branched clumps, tough short fibrous filaments, and tough pellets, as well as silver accumulating ability. Atomic absorption spectroscopy (AAS) studies showed maximum uptake of Ag(+): 87.44 ± 0.23 and 82.57 ± 0.19 % in pectin- and CMC-grown biomass, respectively. The crystalline nature of silver nanoparticles (AgNPs) was confirmed by X-ray diffraction studies. Transmission electron microscopy (TEM) micrographs of silver nanoparticles confirmed size ranging from 5 to 38 nm.

Whole-Cell Mediated 11β-Hydroxylation on the Basic Limonoid Skeleton by Cunninghamella echinulata

Regio- and stereoselective 11β-hydroxylation was achieved on the basic limonoid skeleton through microbial transformation. Whole cells of Cunninghamella echinulata efficiently converted basic limonoids such as epoxyazadiradione, azadiradione, and gedunin to their 11β-hydroxy analogues as the sole metabolite. Fermentation conditions affecting the efficiency (96%) of biotransformation including substrate concentration, incubation period, pH, and temperature were optimized. The position and stereochemistry of hydroxyl functionality on the isolated metabolites were established through extensive spectroscopic and spectrometric studies (1D, 2D NMR, ESI-MS, and MS/MS).

Possible involvement of G-proteins and cAMP in the induction of progesterone hydroxylating enzyme system in the vascular wilt fungus Fusarium oxysporum

Fungi present the ability to hydroxylate steroids. In some filamentous fungi, progesterone induces an enzyme system which converts the compound into a less toxic hydroxylated product. We investigated the progesterone response in the vascular wilt pathogen Fusarium oxysporum, using mass spectrometry and high performance liquid chromatography (HPLC). Progesterone was mainly transformed into 15alpha-hydroxyprogesterone, which was found predominantly in the extracellular medium. The role of two conserved fungal signaling cascades in the induction of the progesterone-transforming enzyme system was studied, using knockout mutants lacking the mitogen-activated protein kinase Fmk1 or the heterotrimeric G-protein beta subunit Fgb1 functioning upstream of the cyclic adenosine monophosphate (cAMP) pathway. No steroid hydroxylation was induced in the Deltafgb1 strain, suggesting a role for the G-protein beta subunit in progesterone signaling. Exogenous cAMP restored the induction of progesterone-transforming activity in the Deltafgb1 strain, suggesting that steroid signaling in F. oxysporum is mediated by the cAMP-PKA pathway.

Aspects of the progesterone response in Hortaea werneckii: Steroid detoxification, protein induction and remodelling of the cell wall

Progesterone in sublethal concentrations temporarily inhibits growth of Hortaea werneckii. This study investigates some of the compensatory mechanisms which are activated in the presence of progesterone and are most probably contributing to escape from growth inhibition. These mechanisms lead on the one hand to progesterone biotransformation/detoxification but, on the other, are suggested to increase the resistance of H. werneckii to the steroid. Biotransformation can detoxify progesterone efficiently in the early logarithmic phase, with mostly inducible steroid transforming enzymes, while progesterone biotransformation/detoxification in the late logarithmic and stationary phases of growth is not very efficient. The relative contribution of constitutive steroid transforming enzymes to progesterone biotransformation is increased in these latter phases of growth. In the presence of progesterone, activation of the cell wall integrity pathway is suggested by the overexpression of Pck2 which was detected in the stationary as well as the logarithmic phase of growth of the yeast. Progesterone treated H. werneckii cells were found to be more resistant to cell lysis than mock treated cells, indicating for the first time changes in the yeast cell wall as a result of treatment with progesterone.

Guidelines for analytical method development and validation of biotechnological synthesis of drugs. Production of a hydroxyprogesterone as model

In connection with biotechnological synthesis of pharmaceutical drugs, validated methods for quantification of both product and substrate at different time intervals are essential for proper calculation of rate coefficients. In this field, there still exist no guidelines for analytical validation, unlike the situation in the bioanalytical field. Therefore, in this study the detailed guidelines by FDA for bioanalytical method validation were applied to a typical biotechnological process; the enzymatic synthesis of 9alpha-hydroxyprogesterone in E. coli using progesterone as substrate. The process liquid was extracted and analyzed using an HPLC-DAD system. The quality control (QC) samples of the product demonstrated excellent precision (C.V.<1.5%) and accuracy between 99.3 and 107%. The study showed that the recommendations and the validation terms for bioanalytical methods can be used also for biotechnological production, but with some important exceptions. The tolerances (C.V. values) of the validation terms should be much narrower; the internal standard (I.S.) must be present in the process liquid before the start of the process and must be much different in structure from the substrate (so as not to participate in the biotechnological process). In addition, the selectivity must be checked very frequently during the process due to the changes in the blank process liquid with time.

Microbial hydroxylation of progesterone with Acremonium strictum

Microbial hydroxylation of progesterone occurred in the culture of Acremonium strictum PTCC 5282 to produce two hydroxylated pregnene-like steroids. The metabolites were purified and characterized using spectroscopic methods and identified as 15alpha-hydroxyprogesterone and 15alpha-hydroxydeoxycorticosterone.

[Dehydroepiandrosterone metabolism by Epidermophyton floccosum]

Steroid hormones may be relevant for the fungus-host relation in dermatophytoses. In contrast to most other hosts of dermatophytes, humans are characterized by a high cutaneous concentration of the adrenal androgen dehydroepiandrosterone (DHEA) and its sulphate (DHEAS). To investigate whether the strictly anthropophilic dermatophyte Epidermophyton floccosum can metabolize this steroid hormone, cultures of E. floccosum were supplemented with DHEA. After 5 days of incubation the steroids in the culture supernatants were extracted and differentiated by gaschromatography and massspectrometry (GC-MS). The results show that a nearly complete metabolization of DHEA by E. floccosum leads to the formation of multiple new steroids/metabolites some of which have not been reported before. Therefore, this fungus could possibly mediate the hormone regulated cutaneous defense mechanisms of the host by an intraepidermal metabolization of DHEA.

Microbial models of drug metabolism: microbial transformations of Trimegestone (RU27987), a 3-keto-delta(4,9(10))-19-norsteroid drug

Screening microorganisms for the biotransformation of the 3-keto-delta(4,9(10))-19-norsteroid RU27987 (Trimegestone) resulted in the isolation of nine identified metabolites, some of them being selectively produced by different strains. Eight metabolites were found to be hydroxylated on various positions of the rings, and one was additionally epoxidized. These microbial metabolites could be used as chromatographic standards and two of them were found identical to the unknown major human metabolites. Moreover, most microbial metabolites were produced in sufficient amounts to be tested for their biological activities. All these features demonstrate the usefulness and versatility of microbial biotransformation systems as a tool for early identification and convenient production of potentially active mammalian and non-mammalian metabolites.

Biotransformation of steroids by the fission yeast Schizosaccharomyces pombe

The fungal biotransformation of steroids is of applied interest due to the economic importance of such stereo- and regiospecific reactions and also in the context of ergosterol pathway engineering to produce vitamin D and steroidal products. In Schizosaccharomyces pombe no steroid hydroxylation as is found in filamentous fungi was observed, but a cytosolic NAD(H)/NADP(H)-dependent hydroxysteroid dehydrogenase activity was identified. Progesterone was reduced at the delta 4 double bond (in vivo only) as well as at the C-3 and C-20 keto groups. Testosterone and 4-androstene-3,17-dione were interconverted and 5 alpha-pregnane-3,20-dione and 5 beta-pregnane-3,20-dione were reduced to 3-hydroxy products. The reactions were sometimes reversible and showed regio- and stereo specificity. In S. pombe more than one steroid dehydrogenase homologue is likely to occur, as has been observed in Saccharomyces cerevisiae. Our findings indicate that genes encoding soluble proteins should be examined as candidates for actual steroid dehydrogenase activity.

Induction of steroidal hydroxylase activity by plant defence compounds in the filamentous fungus Cochliobolus lunatus

We investigated the hypothesis that the endogenous role of the commercially important inducible steroid hydroxylase cytochrome P450s of fungi was in defense against plant toxophores/secondary metabolites. Two plant defense compounds, the aglycones tomatidine and solanidine, the steroidal glycoalkaloid alpha-tomatine and the triterpene saponin beta-escin were tested as inducers of 11beta/14alpha-steroid hydroxylase in the filamentous fungus Cochliobolus lunatus. The extracts of saponins from the roots of Primula veris and green oat leaves were also tested as inducers of 11beta/14alpha-hydroxylation activity in progesterone biotransformation with the same fungus. Induction of steroid hydroxylase and inhibition of activity in some cases support our hypothesis that their endogenous function is in biochemical defence against secondary metabolites. 4-Pregnene-3,11,20-trione was added as a substrate for biotransformation with C. lunatus. We isolated from culture broth 14alpha-hydroxy-4-pregnene-3,11,20-trione, and the hitherto unreported compounds, 7alpha,14alpha-dihydroxy-4-pregnene-3,11,20-trione and 7alpha-hydroxy-pregna-4,8(14)-diene-3,11,20-trione.

[Hormones, fungi and skin]

It is indicated by some epidemiological and clinical observations, that steroidal hormones may belong to those factors that are capable to influence the clinical courses of mycotic infections in man. Several fungal species, including pathogenic ones, are able to produce or metabolize steroidal hormones, or their growth can be affected by such hormones. Since, on the other hand, the steroid-responsive human skin is also capable to synthesize and convert steroidal hormones, the relationship between pathogenic fungi and host may be influenced by hormonal mediators in dermatomycoses.

11Beta-hydroxysteroid dehydrogenase activity in progesterone biotransformation by the filamentous fungus Cochliobolus lunatus

Progesterone biotransformation was examined in relation to hydroxylating and dehydrogenating enzymes of Cochliobolus lunatus. 11beta-hydroxysteroid dehydrogenase activity (11beta-HSD) was located in cytosolic fraction and was NADP-dependent, inducible by progesterone and apparently uni-directional. Several inhibitors of 11beta-hydroxysteroid dehydrogenase were tested; furosemide, glycyrrhizic-acid and carbenoxolone did not influence the dehydrogenation of 11beta-hydroxy-4-pregnene-3,20-dione to 4-pregnene-3,11,20-trione, although grapefruit juice significantly reduced the rate of progesterone hydroxylation.

Advances in microbial steroid biotransformation

Microbial biotransformations of various steroids are reviewed. Developmental studies on hydroxylation, carbon-carbon bond cleavage, enzymatic catalysis in nonaqueous solvents, use of cyclodextrin medium, cell immobilization, and new microbial reactions are highlighted. Various steroid substrates, their metabolites and the microorganisms used for the transformations are compiled covering the literature for the period 1992-1995.

Human androgenic steroids affect growth of dermatophytes in vitro

Hormonal effects on fungal growth are of particular interest to medical mycology. In the skin, androgenic steroids metabolized within pilosebaceous units may have direct effects on dermatophytes that invade hair follicles. In this study, 10(-1) to 10(2) mg 1(-1) testosterone, 5-alpha-dihydrotestosterone, dehydroepiandrosterone, androstenedione and androstanedione were used in agar dilution assays to test their effects on thallus diameters of Trichophyton rubrum, Epidermophyton floccosum, T. tonsurans, T. mentagrophytes and Microsporum canis. All dermatophytes responded in a dose-dependent manner with reduced diameters of thalli. Growth of T. rubrum and E. floccosum was completely or strongly suppressed by 10(2) mg 1(-1) androstenedione and androstanedione. A minor inhibition of all strains was obtained with 10(1) to 10(2) mg 1(-1) testosterone, dehydroepiandrosterone and 5-alpha-dihydrotestosterone, the last being least inhibitory for all species. Trichophyton mentagrophytes and M. canis were least responsive to most hormones. The high susceptibility of T. rubrum and E. floccosum to intrafollicular androstenedione and androstanedione could be one reason why these two species are unable to cause tinea capitis. Receptor-mediated effects and an unspecific interference with fungal sterol metabolism are discussed as mechanisms of fungal inhibition by steroidal hormones.