Novel oxazolinyl derivatives of pregna-5,17(20)-diene as 17α-hydroxylase/17,20-lyase (CYP17A1) inhibitors

•Oxazolinyl derivatives of [17(20)E]-pregna-5,17(20)-diene bind to CYP17A1.•[17(20)E]-Pregna-5,17(20)-diene oxazolinyl derivatives inhibit CYP17A1 activity.•Docking of inhibitors to CYP17A1 yielded corresponding 17(20)Z-isomers.•Reported inhibitors can serve as templates for development of anti-cancer drugs.

New oxazolinyl derivatives of [17(20)E]-pregna-5,17(20)-diene: 2′-{[(E)-3β-hydroxyandrost-5-en-17-ylidene]methyl}-4′,5′-dihydro-1′,3′-oxazole 1 and 2′-{[(E)-3β-hydroxyandrost-5-en-17-ylidene]methyl}-4′,4′-dimethyl-4′,5′-dihydro-1′,3′-oxazole 2 were evaluated as potential CYP17A1 inhibitors in comparison with 17-(pyridin-3-yl)androsta-5,16-dien-3β-ol 3 (abiraterone). Differential absorption spectra of human recombinant CYP17A1 in the presence of compound 1 (λmax = 422 nm, λmin = 386 nm) and compound 2 (λmax = 416 nm) indicated significant differences in enzyme/inhibitors complexes. CYP17A1 activity was measured using electrochemical methods. Inhibitory activity of compound 1 was comparable with abiraterone 3 (IC50 = 0.9 ± 0.1 μM, and IC50 = 1.3 ± 0.1 μM, for compounds 1 and 3, respectively), while compound 2 was found to be weaker inhibitor (IC50 = 13 ± 1 μM). Docking of aforementioned compounds to CYP17A1 revealed that steroid fragments of compound 1 and abiraterone 3 occupied close positions; oxazoline cycle of compound 1 was coordinated with heme iron similarly to pyridine cycle of abiraterone 3. Configuration of substituents at 17(20) double bond in preferred docked position corresponded to Z-isomers of compounds 1 and 2. Presence of 4′-substituents in oxazoline ring of compound 2 prevents coordination of oxazoline nitrogen with heme iron and worsens its docking score in comparison with compound 1. These data indicate that oxazolinyl derivative of [17(20)E]-pregna-5,17(20)-diene 1 (rather than 4′,4′-dimethyl derivative 2) may be considered as potential CYP17A1 inhibitor and template for development of new compounds affecting growth and proliferation of prostate cancer cells.

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