Design and action of steroidal aromatase inhibitors

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.

Preselection of A- and B- modified d-homo lactone and d-seco androstane derivatives as potent compounds with antiproliferative activity against breast and prostate cancer cells - QSAR approach and molecular docking analysis

The problem with trial-and-error approach in organic synthesis of targeted anticancer compounds can be successfully avoided by computational modeling of molecules, docking studies and chemometric tools. It has been proven that A- and B- modified d-homo lactone and d-seco androstane derivatives are compounds with significant antiproliferative activity against estrogen-independent breast adenocarcinoma (ER-, MDA-MB-231) and androgen-independent prostate cancer cells (AR-, PC-3). This paper presents the quantitative structure-activity relationship (QSAR) models based on artificial neural networks (ANNs) which are able to predict whether d-homo lactone and/or d-seco androstane-based compounds will express antiproliferative activity against breast cancer cells (MDA-MB-231) or not. Also, the present paper describes the molecular docking study of 3β-acetoxy-5α,6α-epoxy- (3) and 6α,7α-epoxy-1,4-dien-3-one (24) d-homo lactone androstane derivatives, as well as 4-en-3-one (15) d-seco androstane derivative, which are compounds with strong or moderate antiproliferative activity against prostate cancer cells (PC-3), and compares them with commercially available medicament for prostate cancer - abiraterone. The obtained promising results can be used as guidelines in further syntheses of novel d-homo lactone and d-seco androstane derivatives with antiproliferative activity against breast and prostate cancer cells.

Steroidal carbonitriles as potential aromatase inhibitors

Estrogens, responsible for the growth of hormone-dependant breast cancer are biosynthesized from androgens involving aromatase enzyme in the last rate limiting step. Inhibition of aromatase is an efficient approach for the prevention and treatment of breast cancer. Novel 4-phenylthia derivatives (2, 3 and 7) have been synthesized as aromatase inhibitors. The synthesized compounds (2, 3 and 7) exhibited noticeable enzyme inhibiting activity. Kinetics study of these compounds (2, 3, and 7) showed negligible inhibition of the enzyme under conditions conducive for irreversible inhibition of the enzyme. Introduction of unsaturation at C-4, C-1 & 4 or C-4 & 6 (compounds 5, 9 and 11) was observed to not be an effective strategy for entrancing aromatase inhibiting activity in 17-oxo-16β-carbonitrile derivatives. The D-seco derivatives (13-15 and 17) having unsaturation at C-4, C-1 & 4 or C-4 & 6 along with carbonitrile function in ring-D showed complete loss of aromatase inhibiting activity.

Baeyer–Villiger oxidation of some steroids by Aspergillus tamarii MRC 72400

Biotransformations of epiandrosterone (1), dehydroepiandrosterone (2), testosterone (3), progesterone (4) and pregnenolone (5) byAspergillus tamariiMRC 72400 for 5 days have been reported and the results of these incubations have been compared with previously published data obtained withAspergillus tamariiQM 1223.A. tamariiMRC 72400 showed higher Bayer–Villiger monooxygenase activities thanA. tamariiQM 1223 did. Apart from pregnenolone (5),A. tamariiMRC 72400 metabolized these steroids in different ways. Incubation of epiandrosterone (1) afforded 3β,11β-dihydroxy-5α-androstan-17-one (6) (3%) and 3β-hydroxy-17a-oxa-D-homo-5α-androstan-17-one (7) (9.5%). Incubation of dehydroepiandrosterone (2) afforded 3β-hydroxy-17a-oxa-D-homoandrost-5-en-17-one (8) (28%), testolactone (9) (6%), 3β,7β-dihydroxyandrost-5-en-17-one (10) (13%) and 3β,7α-dihydroxy- androst-5-en-17-one (11) (24%). Incubation of testosterone (3) afforded testolactone (9) (58%). Incubation of progesterone (4) also afforded testolactone (9), however in higher yield (86%). Incubation of pregnenolone (5) afforded 3β-hydroxy-17a-oxa-D-homoandrost-5-en-17-one (8) (25%) and testolactone (9) (27%).

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

Microbial transformation of dehydroepiandrosterone (DHEA, 1) using Penicillium griseopurpureum Smith and Penicillium glabrum (Wehmer) Westling has been investigated. Neither fungi had been examined previously for steroid biotransformation. One novel metabolic product of DHEA (1) transformed with P. griseopurpureum Smith, 15α-hydroxy-17a-oxa-d-homo-androst-4-ene-3,17-dione (5), was reported for the first time. The steroid products were assigned by interpretation of their spectral data such as (1)H NMR, (13)C NMR, IR, and HR-MS spectroscopy. P. griseopurpureum Smith was proven to be remarkably efficient in oxidation of the DHEA (1) into androst-4-en-3,17-dione (2). The strain was also observed to yield different monooxygenases to introduce hydroxyl groups at C-7α, -14α, and -15α positions of steroids. Preference for Baeyer-Villiger oxidation to lactonize D ring and oxidation of the 3β-alcohol to the 3-ketone were observed in both incubations. The strain of P. glabrum (Wehmer) Westling catalyzed the steroid 1 to generate both testololactone 3, and d-lactone product with 3β-hydroxy-5-en moiety 8. In addition, the strain promoted hydrogenation of the C-5 and C-6 positions, leading to the formation of 3β-hydroxy-17a-oxa-d-homo-5α-androstan-3,17-dione (9). The biotransformation pathways of DHEA (1) with P. glabrum (Wehmer) Westling and P. griseopurpureum Smith have been investigated, respectively. Possible metabolic pathways of DHEA (1) were proposed.

3β,11α-Dihy-droxy-17a-oxa-d-homoandrost-5-en-17-one

The title compound, C₁₉H₂₈O₄, was prepared from DHEA (dehydro­epiandrosterone) by its biotransformation using whole cells of the filamentous fungus Beauveria bassiana. The asymmetric unit contains two mol­ecules. The lactone ring is trans-positioned to the neighboring six-membered ring. In the crystal structure, O—H⋯O hydrogen bonds form layers, which are linked to each other by O—H⋯O and C—H⋯O hydrogen bonds.

Biotransformation of some steroids by Aspergillus terreus MRC 200365

The biotransformations of testosterone, epiandrosterone, progesterone and pregnenolone byAspergillus terreusMRC 200365 for five days were described. The biotransformation of testosterone afforded testolactone. The biotransformation of epiandrosterone afforded 3β-hydroxy-17a-oxa-D-homo-5α-androstan-17-one. The biotransformation of progesterone afforded androst-4-ene-3,17-dione and testolactone. The biotransformation of pregnenolone afforded 3β-hydroxy-17a-oxa-D-homoandrost-5-en-17-one and testolactone.

Synthesis of steroidal lactone by penicillium citreo-viride

The biotransformations of a series of steroids by the fungus penicillium citreo-viride A.C.C.C. 0402 have been investigated, and the conversion to the same product testolactone (1) was observed from progesterone (2), dehydroepiandrosterone (3), 4-androstene-3, 17-dione (4), 5-androstene-3, 17-diol (5) with the exception of pregnenolone (6) and 3beta-hydroxy-5, 16-pregnadien-20-one (7). The possible metabolic pathways of the biotransformations were also discussed in the paper and the fungus penicillium citreo-viride A.C.C.C. 0402 was isolated during screening stains from samples collected from Zhengzhou, Henan province of China.

Synthesis and Biological Activity of Some 17a-Substituted Homolactones of Androst-5-ene Derivatives

Some new 17a-homolactones were prepared from 3β-hydroxy-16-(hydroxyimino)androst-5-en-17-one (1) as a starting compound, which was transformed first to the corresponding 17α-phenyl and 17α-benzyl derivatives 2 and 3. The structure of compound 3 was confirmed by X-ray structure analysis. Beckmann fragmentation of compounds 2 and 3 yielded 16,17-seco-cyano ketones 4-7, whose reduction with NaBH4 gave 16,17-seco-cyano alcohols 8-11, whereby the structure of compound 7 was established by X-ray structural analysis. Compounds 8-11 served as the starting compounds for obtaining lactones 12 and 13 in a reaction with potassium hydroxide in ethylene glycol. One-pot procedures were also developed for preparing 17a-homolactones 12, 13 and 16 from the hydroxyimino alcohols 2, 3 and 14. Compounds 12 and 13 showed an inhibitory activity against the enzyme aromatase (63 and 59%, respectively).

Synthesis and anti-aromatase activity of some new steroidal D-lactones

Starting from D-seco derivatives of 5-androstene 1-3, the D-homo lactones, 4 and 5, were synthesized. By the Oppenauer oxidation and/or by dehydration of 4 and 5 with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil), the corresponding D-lactones 6-12 were obtained. The structures of 6 and 10 were unambiguously proved by the appropriate X-ray structural analysis. Anti-aromatase assay showed that tested compounds possess inhibition potency, however, two to four times smaller (IC50 from 0.2 to 0.7 microM, respectively) in comparison to aminoglutethimide (AG).

New D-modified androstane derivatives as aromatase inhibitors

Starting from a 16-oximino derivative of 5-androstene the newly-synthesized 16-oximino-17-hydroxy-17-substituted derivatives 2-4 gave by the Beckmann fragmentation reaction the corresponding D-seco derivatives 6-9. Besides, in the case of the 17-hydroxy-17-methyl-16-oximino derivative 2, as a result of the rearrangement, the hydrolysis product 5 of the 16-oximino group with the opposite configuration at the C-17 was obtained. By the Oppenauer oxidation and/or by dehydration of 7 with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ), the corresponding derivatives 12, 13, and 14 were obtained. The structures of 6 and 12 were unambiguously proved by the appropriate X-ray structural analysis. Kinetic analysis for anti-aromatase activity showed that compound 12 expressed the highest inhibition in the denucleated rat ovarian fraction in comparison to other androstene derivatives (IC(50) was 0.42 microM). In comparison to aminoglutethimide (AG) activity, it was 3.5 times lower. The inhibition was competitive, with K(i) of 0.27 microM. Introduction of additional units of unsaturation (compounds 13 and 14) in D-seco derivatives did not increase anti-aromatase activity.

Design and synthesis of new steroidal inhibitors of estrogen synthase (aromatase)

The estrogen synthase (aromatase) enzyme system is responsible for the biosynthesis of estrogen hormones in human females. Estrogens are vital for normal growth and development, but will promote the growth of certain breast cancers. Approximately 30-50% of breast cancers are considered to be hormone-dependent. Consequently regulation of estrogen biosynthesis has advanced as a potential therapeutic strategy. This has led to the development of active-site inhibitors, which may have potential for the control of breast cancer. We have recently prepared a number of new steroidal inhibitors that have been evaluated as aromatase inhibitors. These include steroidal A/B-ring isoxazoles and a series of A/B-ring pyrazoles with alkyl- and aryl-substituted nitrogen. In addition, we have developed new chemical procedures for the synthesis of 6beta-hydroxy steroids, which could be key intermediates in the preparation of C-19 inhibitors of aromatase activity.

Synthesis of new steroidal isoxazoles: inhibitors of estrogen synthase

A novel class of steroidal A/B ring isoxazoles have been prepared by two independent reaction schemes using 3 beta,17 beta-diacetoxyandrost-5-ene (1) and 3 beta,17 beta-diacetoxyandrost-4-en-6-one (4) as synthetic precursors. The key common intermediate in these syntheses, 3 beta,17 beta-diacetoxyandrost-4-eno[6,5,4-c,d] isoxazole (3), was prepared by synthetic methods described in both schemes. Further chemical modification of 3 yielded 3 beta,17 beta-dihydroxyandrost-4-eno[6,5,4-c,d] isoxazole (6), androst-3,17-dione-4-eno[6,5,4-c,d] isoxazole (7), and 17 beta-hydroxyandrost-3-one-4-eno[6,5,4-c,d] isoxazole (9). Human placental estrogen synthase (aromatase) bioassays were conducted to obtain the following IC50 values resulting from a 50% reduction of enzymatic activity: 6, 120.5 microM; 7, 1.889 microM. 9, 18.57 microM.