Synthesis of Atamestane (SH 489): An Aromatase Inhibitor

Biotransformation of metenolone acetate and epiandrosterone by fungi and evaluation of resulting metabolites for aromatase inhibition

The present study describes the microbial transformation of anabolic drugs, metenolone acetate (1), and epiandrosterone (6). Three new metabolites, 6β,17β-dihydroxy-1-methyl-3-oxo-5α-androst-1-en (2), 5α,15α-dihydroxy-1-methyl-3-oxo-1-en-17-yl acetate (3), 15β-hydroxy-1-methyl-3-oxo-5α-androst-1,4-dien-17-yl acetate (4), and a known metabolite, 17β-hydroxy-1-methyl-4-androstadiene-3-one (5) were obtained by biotransformation of metenolone acetate (1) via Trametes hirsuta mushroom. Metabolites 7, and 8 were obtained from the incubation of epiandrosterone (6) with Cunninghamella blakesleeana. While bioconversion of compound 6 with Aspergillus alliaceus yielded seven known metabolites 9-15. Modern spectroscopic techniques were employed for the structure elucidation of biotransformed products. All compounds were evaluated for their aromatase inhibitory activity. Among them, new metabolite 3 exhibited a significant human placental aromatase activity with an IC50 = 19.602 ± 0.47 µM, as compared to standard anti-cancer drug exemestane (IC50 = 0.232 ± 0.031 µM), whereas, metabolite 5 (IC50 = 0.0049 ± 0.0032 µM) exhibited a very potent activity. While substrate 6, and metabolites 2, 7, and 9 were found inactive. Aromatase plays a key role in the biosynthesis of estrogen hormone, responsible for cancer cell proliferation. Its inhibition is therefore targeted for the treatment of ER + breast cancer. Further structural modifications (lead optimization) of compound 3 can lead to more potent aromatase inhibition for possible treatment of ER + breast cancer.

Whole-cell fungal-mediated structural transformation of anabolic drug metenolone acetate into potent anti-inflammatory metabolites

Seven new derivatives, 6α-hydroxy-1-methyl-3-oxo-5α-androst-1-en-17-yl acetate (2), 6α,17β-dihydroxy-1-methyl-3-oxo-5α-androst-1-en (3), 7β-hydroxy-1-methyl-3-oxo-5α-androst-1-en-17-yl acetate (4), 15β,20-dihydroxy-1-methyl-3-oxo-5α-androst-1-en-17-yl acetate (5), 15β-hydroxy-1-methyl-3-oxo-5α-androst-1-en-17-yl acetate (6), 12β,17β-dihydroxy-1-methyl-3-oxoandrosta-1,4-dien (11), and 7β,15β,17β-trihydroxy-1-methyl-3-oxo-5α-androst-1-en (14), along with six known metabolites, 17β-hydroxy-1-methyl-3-oxoandrosta-1,4-dien (7), 17β-hydroxy-1-methyl-3-oxo-5α-androst-1-en (8), 17β-hydroxy-1-methyl-3-oxo-5β-androst-1-en (9), 1-methyl-5β-androst-1-en-3,17-dione (10), 1-methyl-3-oxoandrosta-1,4-dien-3,17-dione (12), and 17β-hydroxy-1α-methyl-5α-androstan-3-one (13) of metenolone acetate (1), were synthesized through whole-cell biocatalysis with Rhizopus stolonifer, Aspergillus alliaceous, Fusarium lini, and Cunninghamella elegans. Atamestane (12), an aromatase inhibitor, was synthesized for the first time via F. lini-mediated transformation of 1 as the major product. Hydroxylation, dehydrogenation, and reduction were occurred during biocatalysis. Study indicated that F. lini was able to catalyze dehydrogenation reactions selectively. Structures of compounds 1-14 were determined through NMR, HRFAB-MS, and IR spectroscopic data. Compounds 1-14 were identified as non-cytotoxic against BJ human fibroblast cell line (ATCC CRL-2522). Metabolite 5 (81.0 ± 2.5%) showed a potent activity against TNF-α production, as compared to the substrate 1 (62.5 ± 4.4%). Metabolites 2 (73.4 ± 0.6%), 8 (69.7 ± 1.4%), 10 (73.2 ± 0.3%), 11 (60.1 ± 3.3%), and 12 (71.0 ± 7.2%), also showed a good inhibition of TNF-α production. Compounds 3 (IC50 = 4.4 ± 0.01 µg/mL), and 5 (IC50 = 10.2 ± 0.01 µg/mL) showed a significant activity against T-cell proliferation. Identification of selective inhibitors of TNF-α production, and T-cell proliferation is a step forward towards the development of anti-inflammatory drugs.

Synthesis and in vitro study of 17 beta-[N-ureylene-N,N'-disubstituted]-4-methyl-4-aza-5 alpha-androstan-3-ones as selective inhibitors of type I 5 alpha-reductase

A series of 17 beta-(N-ureylene-N,N'-disubstituted)-4-azasteroids as inhibitors of human type I 5 alpha-reductase (5 alpha-Re) were prepared from 17 beta-N-alkyl-4-methyl-4-aza-5 alpha-androstan-3-ones and various isocyanates. For the measurement of 5 alpha-Re activity, 293 cells transfected with human type I 5 alpha-Re, cDNA were used. Azasteroids with an N-cyclopropyl ring exhibited potent inhibitory activity against type I 5 alpha-Re. As the chain length increased, from the N'-ethyl to the N'-butyl chain, activity of compounds also increased and azasteroids with the N'-butyl chain showed strong inhibitory activity (IC50 = 5.3 nM). Branching of alkyl chains decreased the potency of compounds. Introduction of the 1,2-double bond significantly reduced the activity of azasteroids. Replacement of the N'-alkyl chain with the phenyl moiety gave the most active compound of this series (IC50 = 1.3 nM). Other variations such as the replacement of a N-cyclopropyl ring with the N-methyl or the N-butyl chain decreased the activity of compounds (compounds were less active compared with above). The IC50 values of N-methyl-N'-cyclohexyl- and N-butyl-N'-phenyl-ureylenes were 31.5 and 11.5 nM. respectively. In general, all azasteroids were poor inhibitors of Type II 5 alpha-Re.