Studies on Bacillus stearothermophilus. Part 1. Transformation of progesterone to a new metabolite 9,10-seco-4-pregnene-3,9,20-trione

Discovery of potential components characteristic by conjugated enone from the branches and leaves of Croton lauioides with anti-neuroinflammatory activity via regulating the NF-κB pathway

In this study, the chemical composition and pharmacological activity of Croton lauioides were investigated for the first time. The bioactive and HPLC-UV guided isolation led to the discovery of twenty-three conjugated enone-type components (1-23), including nine previously unknown sesquiterpenoid derivatives (1-4, 9-10, 12-14). Notably, compounds 1 and 12 are epoxides containing an endoperoxide bridge (1) or a unique dioxaspiro core (12), respectively. Compounds 2-7 are non-benzenoid aromatics featuring a tropone function, while 9-11 possess a rare rearranged scaffold with tropone shift into benzene. Extensive characterization was performed using NMR spectra, HRESIMS data, and electronic circular dichroism (ECD) calculations. Furthermore, we evaluated the bioactivities of all isolated compounds against neuroinflammation in LPS-stimulated BV-2 microglial cells. Remarkably, most sesquiterpenoid derivatives exhibited significant NO inhibit activities, and compound 5 showed the most potent effect with an IC50 value of 0.14 ± 0.04 μM. Structure-activity relationship (SAR) analysis revealed that sesquiterpenoids modified with endocyclic enone conjugation may serve as a key pharmacophore for NO inhibition, particularly involving aromatic tropone moiety. The qPCR and Western blot results demonstrated that 5 exerted an inhibitory effect on the mRNA levels of iNOS, TNF-α and COX-2 in a time-dependent manner, as well as suppressed the protein expression of iNOS, TNF-α, COX-2. In mechanism, 5 could prevented activation of NF-κB pathway by suppressing phosphorylation of p65 and IκB-α. These findings revealed C. lauioides might be a promising resource for drug candidate development targeting neuroinflammation.

Biological transformations of steroidal compounds: a review

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.

Tryptophan oxidative metabolism catalyzed by geobacillus stearothermophilus: a thermophile isolated from kuwait soil contaminated with petroleum hydrocarbons

Tryptophan metabolism has been extensively studied in humans as well as in soil. Its metabolism takes place mainly through kynurenine pathway yielding hydroxylated, deaminated and many other products of physiological significance. However, tryptophan metabolism has not been studied in an isolated thermophilic bacterium. Geobacillus stearothermophilus is a local thermophile isolated from Kuwait desert soil contaminated with petroleum hydrocarbons. The bacterium grows well at 65 °C in 0.05 M phosphate buffer (pH 7), when supplied with organic compounds as a carbon source and has a good potential for transformation of steroids and related molecules. In the present study, we used tryptophan ethyl ester as a carbon source for the bacterium to study the catabolism of the amino acid at pH 5 and pH 7. In this endeavor, we have resolved twenty one transformation products of tryptophan by GC/LC and have identified them through their mass spectral fragmentation.

Modification of progesterone and testosterone by a food-borne thermophile Geobacillus kaustophilus

The present work was carried out to study structural modification of steroids by Geobacillus kaustophilus, a bacterial thermophile present in milk and the environment. Incubation of progesterone and testosterone with G. kaustophilus at 65 degrees C resulted in oxygenated steroid nuclei. The oxygenation of the steroid molecule was stereo specific. Seven metabolites of progesterone horizontal line 6beta/6alpha-hydroxytestosterone, 20-hydroxyprogesterone, 6beta-/6alpha-20-dihydroxyprogesterone, 5alpha-pregnane-3,6,20-trione, and 3beta-hydroxy-5alpha-pregnane-6,20-dione horizontal line were identified. Four compounds horizontal line namely, 66-/6--hydroxytestosterone and 6beta/6alpha-hydroxyandrostenedione horizontal line and androst-4-en-3,17-dione were identified as testosterone metabolites. This shows that G. kaustophilus is capable of modifying steroid nuclei at elevated temperatures. G. kaustophilus is a stable thermophile first isolated from milk. Our results show that endogenous steroids present in milk can be modified by G. kaustophilus, causing detrimental effect on human health.

Antioxidant activity of biotransformed sex hormones facilitated by Bacillus stearothermophilus

Bacillus stearothermophilus, a thermophilic bacterium isolated from Kuwaiti desert, when incubated with exogenous progesterone for 10 days at 65 degrees C produced two monohydroxylated, two dihydroxy isomers of progesterone and a B-Seco compound. These metabolites were purified by TLC and HPLC followed by their identification through (1)H, (13)C NMR and other spectroscopic data. Microbial hydroxylation of 17beta-estradiol resulted in the production of estrone. The effect of some inducers resulted in the production of two metabolites from 17beta-estradiol one of which was identified as 3,6beta,17beta-trihydroxyestra-1,3,5,14(10)-tetrene and the other metabolite remained unidentified. The transformation products were identified through their spectral data and comparison with reference to compounds. Antioxidant activities of progesterone transformed mixture and purified metabolites of 17beta-estradiol were studied by linoleic acid/beta-carotene assay. An enhanced antioxidant activity for progesterone transformation products was observed, when compared to progesterone. A comparison of antioxidant activity of progesterone and 17beta-estradiol transformation products is reported.

Antioxidant activity of biotransformed sex hormones facilitated by Bacillus stearothermophilus

Bacillus stearothermophilus, a thermophilic bacterium isolated from Kuwaiti desert, when incubated with exogenous progesterone for 10 days at 65 degrees C produced two monohydroxylated, two dihydroxy isomers of progesterone and a B-Seco compound. These metabolites were purified by TLC and HPLC followed by their identification through (1)H, (13)C NMR and other spectroscopic data. Microbial hydroxylation of 17beta-estradiol resulted in the production of estrone. The effect of some inducers resulted in the production of two metabolites from 17beta-estradiol, one of which was identified as 3,6beta,17beta-trihydroxyestra-1,3,5,14(10)-tetrene and the other metabolite remains unidentified. The transformation products were identified through their spectral data and comparison with reference compounds. Antioxidant activities of progesterone transformed mixture and purified metabolites of 17beta-estradiol were studied by linoleic acid/beta-carotene assay. An enhanced antioxidant activity for progesterone transformation products was observed when compared to progesterone. A comparison of antioxidant activity of progesterone and 17beta-estradiol transformation products is reported.

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.

Enhancement of androstadienedione production from progesterone by biotransformation using the hydroxypropyl-beta-cyclodextrin complexation technique

The enhanced production of androstadienedione (ADD) from progesterone (P) using the hydroxypropyl-beta-cyclodextrin (HPbetaCD) complexation technique by biotransformation was demonstrated. The microorganisms used were Bacillus sphaericus ATCC 245, B. sphaericus ATCC 7063, B. sphaericus ATCC 13805, Arthrobacter simplex ATCC 6946, B. sphaericus TISTR 670 and those screened from soils in Chiang Mai Province, Thailand which were B. sphaericus SRP I, B. sphaericus SRP II and B. sphaericus SRP III. The complexed (P-complex) and the uncomplexed P at 0.3-1.2mg/ml were investigated. Samples were withdrawn from the bioconversion mixture at various time intervals for 168 h. The ADD and P contents were determined by HPLC. All organisms showed ADD production from either P or P-complex by one-step biotransformation (including side chain cleavage and dehydrogenation). At 0.3mg/ml of P in the systems of B. sphaericus ATCC 13805, A. simplex ATCC 6946 and B. sphaericus ATCC 245, the uncomplexed form showed the highest ADD yield of 2.82, 1.63 and 64.67% at 168, 168 and 144 h, whereas P-complex gave 98.44, 19.58 and 97.10% at 144, 24 and 168 h, respectively. This indicated an increase of ADD production from the P-complex in comparison to P of 35, 12 and 1.5 times, respectively. This study has shown that the complexation of P with HPbetaCD enhanced the ADD production in a novel one-step bioconversion.

Studies on Bacillus stearothermophilus. Part IV. Influence of enhancers on biotransformation of testosterone

The impact of chemical enhancers on the biotransformation of testosterone has been exploited. Application of crude cell concentrates to produce Bacillus stearothermophilus-mediated bioconversion of testosterone at 65 degrees C for 72 h has been examined. After incubation, the xenobiotic substrate was added to the concentrated whole cell suspensions. The enhancer molecules were included in the whole cell suspension. The resultant products, after extraction into an organic solvent, were purified by thin layer chromatography and identification was carried out through spectroscopic data. Five steroid metabolites 9,10-seco-4-androstene-3,9,17-trione, 5alpha-androstan-3,6,17-trione, 17beta-hydroxy-5alpha-androstan-3,6-dione, 3beta,17beta-dihydroxyandrost-4-ene-6-one and 17beta-hydroxyandrost-4,6-diene-3-one were identified as biotransformation products of testosterone. A possible biosynthetic route for these bioconversion products is postulated.

Structure-function relationships of rat liver CYP3A9 to its human liver orthologs: site-directed active site mutagenesis to a progesterone dihydroxylase

CYP3A9 is an estrogen-inducible ortholog of human liver CYP3A4 with 76.5% sequence identity to CYP3A4. Unlike CYP3A4, it is a very poor testosterone 6beta- and 2beta-hydroxylase, but a relatively better catalyst of progesterone monohydroxylation largely at 6beta, 16alpha, and 21 positions with negligible 6beta, 21-dihydroxylation. We reasoned that such differences in substrate catalyses must be due to differences in the active site architecture of each CYP3A enzyme. Indeed, alignment of CYP3A4 substrate recognition sites (SRSs) with the corresponding regions of CYP3A9 sequence revealed that of the 22 fully divergent residues, 4 reside in SRS regions [P107N (SRS-1), M371G (SRS-5), and L479K and G480Q (SRS-6)]. Accordingly, we substituted these and other divergent CYP3A9 SRS residues with the corresponding residues of CYP3A4 and/or CYP3A5. Our findings of the influence of these site-directed mutations of the CYP3A9 active site on its catalysis of testosterone and three other established but structurally different CYP3A substrates (progesterone, imipramine, and carbamazepine) are described. These findings revealed that some mutations (N107P, N107S, V207T, G371M, and Q480G) not only improved the ability of CYP3A9 to hydroxylate testosterone at the 6beta and 2beta positions, but also converted it into a robust progesterone 6beta, 21-dihydroxylase. The latter in the case of CYP3A9N107P was accompanied by a shift from sigmoidal to hyperbolic enzyme-substrate kinetics. In contrast, the catalytic potential of CYP3A9 mutants K206N, K206S, M240V, and K479L/Q480G was either relatively unchanged or negligible to nonexistent. Together these findings attest to the unique substrate-active site fit of each CYP3A enzyme.

Studies on Bacillus stearothermophilus. Part II. Transformation of progesterone

Bacillus stearothermophilus, a thermophilic bacterium isolated from Kuwaiti desert, when incubated with exogenous progesterone for 10 days at 65 degrees C produced two new dihydroxy isomers of progesterone, and two known compounds, 5 alpha-pregnane-3,6,20-trione and 6-dehydroprogesterone, along with the earlier reported monohydroxylated metabolites and a B-Seco compound. The two new dihydroxy compounds were identified as 6 alpha,20 alpha-dihydroxyprogesterone and 6 beta,20 alpha-dihydroxyprogesterone. These metabolites were purified by TLC and HPLC followed by their identification through 1H, 13C NMR and other spectroscopic data.