Comparison of [17(20)E]-21-Norpregnene oxazolinyl and benzoxazolyl derivatives as inhibitors of CYP17A1 activity and prostate carcinoma cells growth

Medicinal-Chemistry-Driven Approach to 2-Substituted Benzoxazole-Estradiol Chimeras: Synthesis, Anticancer Activity, and Early ADME Profile

The efficient synthesis of novel estradiol-based A-ring-fused oxazole derivatives, which can be considered as benzoxazole-steroid domain-integrated hybrids containing a common benzene structural motif, is described. The target compounds were prepared from steroidal 2-aminophenol precursors by heterocycle formation or functional group interconversion (FGI) strategies. According to 2D projection-based t-distributed stochastic neighbor embedding (t-SNE), the novel molecules were proved to represent a new chemical space among steroid drugs. They were characterized based on critical physicochemical parameters using in silico and experimental data. The performance of the compounds to inhibit cell proliferation was tested on four human cancer cell lines and non-cancerous cells. Further examinations were performed to reveal IC50 and lipophilic ligand efficiency (LLE) values, cancer cell selectivity, and apoptosis-triggering features. Pharmacological tests and LLE metric revealed that some derivatives, especially the 2-(4-ethylpiperazin-1-yl)oxazole derivative exhibit strong anticancer activity and trigger the apoptosis of cancer cells with relatively low promiscuity risk similarly to the structurally most closely-related and intensively studied anticancer agent, 2-methoxy-estradiol.

Oxazolinyl derivatives of androst-16-ene as inhibitors of CYP17A1 activity and prostate carcinoma cells proliferation: Effects of substituents in oxazolinyl moiety

Steroid derivatives modified with nitrogen containing heterocycles are known to inhibit activity of steroidogenic enzymes, decrease proliferation of cancer cells and attract attention as promising anticancer agents. Specifically, 2'-(3β-hydroxyandrosta-5,16-dien-17-yl)-4',5'-dihydro-1',3'-oxazole 1a potently inhibited proliferation of prostate carcinoma cells. In this study we synthesized and investigated five new derivatives of 3β-hydroxyandrosta-5,16-diene comprising 4'-methyl or 4'-phenyl substituted oxazolinyl cycle 1 (b-f). Docking of compounds 1 (a-f) to CYP17A1 active site revealed that the presence of substitutents at C4' atom in oxazoline cycle, as well as C4' atom configuration, significantly affect docking poses of compounds in the complexes with enzyme. Testing of compounds 1 (a-f) as CYP17A1 inhibitors revealed that the only compound 1a, comprising unsubstituted oxazolinyl moiety, demonstrated strong inhibitory activity, while other compounds 1 (b-f) were slightly active or non active. Compounds 1 (a-f) efficiently decreased growth and proliferation of prostate carcinoma LNCaP and PC-3 cells at 96 h incubation; the effect of compound 1a was the most powerful. Compound 1a efficiently stimulated apoptosis and caused PC-3 cells death, that was demonstrated by a direct comparison of pro-apoptotic effects of compound 1a and abiraterone.

Synthesis and Biological Evaluation of New Isoxazolyl Steroids as Anti-Prostate Cancer Agents

Steroids with a nitrogen-containing heterocycle in the side chain are known as effective inhibitors of androgen signaling and/or testosterone biosynthesis, thus showing beneficial effects for the treatment of prostate cancer. In this work, a series of 3β-hydroxy-5-ene steroids, containing an isoxazole fragment in their side chain, was synthesized. The key steps included the preparation of Weinreb amide, its conversion to acetylenic ketones, and the 1,2- or 1,4-addition of hydroxylamine, depending on the solvent used. The biological activity of the obtained compounds was studied in a number of tests, including their effects on 17α-hydroxylase and 17,20-lyase activity of human CYP17A1 and the ability of selected compounds to affect the downstream androgen receptor signaling. Three derivatives diminished the transcriptional activity of androgen receptor and displayed reasonable antiproliferative activity. The candidate compound, 24j (17R)-17-((3-(2-hydroxypropan-2-yl)isoxazol-5-yl)methyl)-androst-5-en-3β-ol, suppressed the androgen receptor signaling and decreased its protein level in two prostate cancer cell lines, LNCaP and LAPC-4. Interaction of compounds with CYP17A1 and the androgen receptor was confirmed and described by molecular docking.

Antiproliferative, proapoptotic, and tumor-suppressing effects of the novel anticancer agent alsevirone in prostate cancer cells and xenografts

The aim of this study was to explore the mechanisms of action of alsevirone in prostate cancer (PC) in vitro and in vivo: CYP17A1 inhibition, cytotoxic, apoptotic, and antitumor effects in comparison with abiraterone. The CYP17A1-inhibitory activity was investigated in rat testicular microsomes using high-performance liquid chromatography. Testosterone levels were evaluated using enzyme-linked immunoassay. IC₅₀ values were calculated for PC3, DU-145, LNCaP, and 22Rv1 cells using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test. The antitumor effect in vivo was studied in DU-145 and 22Rv1 subcutaneous xenografts in Balb/c nude mice. Alsevirone reduced the CYP17A1-inhibitory activity by 98% ± 0.2%. A statistically significant reduction in the testosterone concentration in murine blood was recorded after the 7th administration of 300 mg/kg alsevirone at 0.31 ± 0.03 ng/ml (p < .001) versus 0.98 ± 0.22 ng/ml (p = .392) after abiraterone administration and 1.52 ± 0.49 ng/ml in control animals. Alsevirone was more cytotoxic than abiraterone in DU-145, LNCaP, and 22Rv1 cells, with IC₅₀ values of 23.80 ± 1.18 versus 151.43 ± 23.70 μM, 22.87 ± 0.54 versus 28.80 ± 1.61 μM, and 35.86 ± 5.63 versus 109.87 ± 35.15 μM, respectively. Alsevirone and abiraterone significantly increased annexin V-positive, caspase 3/7-positive, and activated Bcl-2-positive cells. In 22Rv1 xenografts, alsevirone 300 mg/kg × 10/24 h per os inhibited tumor growth: on Day 9 of treatment, tumor growth inhibition = 59% (p = .022). Thus, alsevirone demonstrated significant antitumor activity associated with CYP17A1 inhibition, apoptosis in PC cells, and testosterone reduction.

New steroidal oxazolines, benzoxazoles and benzimidazoles related to abiraterone and galeterone

Seven new oxazoline, benzoxazole and benzimidazole derivatives were synthesized from 3β-acetoxyandrosta-5,16-dien-17-carboxylic, 3β-acetoxyandrost-5-en-17β-carboxylic and 3β-acetoxypregn-5-en-21-oic acids. Docking to active site of human 17α-hydroxylase/17,20-lyase revealed that all oxazolines, as well as benzoxazoles and benzimidazoles comprising Δ¹⁶ could form stable complexes with enzyme, in which steroid moiety is positioned similarly to that of abiraterone and galeterone, and nitrogen atom coordinates heme iron, while 16,17-saturated benzoxazoles and benzimidazoles could only bind in a position where heterocycle is located nearly parallel to heme plane. Modeling of the interaction of new benzoxazole and benzimidazole derivatives with androgen receptor revealed the destabilization of helix 12, constituting activation function 2 (AF2) site, by mentioned compounds, similar to one induced by known antagonist galeterone. The synthesized compounds inhibited growth of prostate carcinoma LNCaP and PC-3 cells at 96 h incubation; the potency of 2'-(3β-hydroxyandrosta-5,16-dien-17-yl)-4',5'-dihydro-1',3'-oxazole and 2'-(3β-hydroxyandrosta-5,16-dien-17-yl)-benzimidazole was superior and could inspire further investigations of these compounds as potential anti-cancer agents.

New azole derivatives of [17(20)E]-21-norpregnene: Synthesis and inhibition of prostate carcinoma cell growth

A number of isoxazole, 1,2,3-triazole, tetrazole, and 1,2,4-oxadiazole derivatives of [17(20)E]-21-norpregnene comprising 3β-hydroxy-5-ene and 3-oxo-4-ene fragments were prepared. Among the key steps for the synthesis of isoxazoles, 1,2,3-triazoles, and tetrazoles were (i) 1,3-dipolar cycloaddition of nitrile oxides or azides to acetylenes or nitriles and ii) dehydration of 17β-hydroxy-17α-methylene-azoles to [17(20)E]-21-norpregnene derivatives. 1,2,4-Oxadiazoles were prepared through the formation of acetimidamides. Potency of the synthesized compounds to inhibit CYP17A1 and to suppress growth of prostate carcinoma cells was investigated. Among the new azole derivatives, four compounds were found possessing high anti-proliferative activity.

Hexafluoroisopropanol-Mediated Domino Reaction for the Synthesis of Thiazolo-androstenones: Potent Anticancer Agents

A cascade reaction of thioamides with 6β-bromoandrostenedione in hexafluoroisopropanol formed substituted thiazolo-androstenones. This is a simple and mild protocol to synthesize novel molecules by using readily available reagents and substrates. Feasibility of the reaction has been rationalized by density functional theory calculations. Moreover, these compounds are potent growth inhibitors of colon, central nervous system, melanoma, ovarian, and renal cancer cell lines with 50% growth inhibition values as low as 1.04 μM.

Conjugates of 17-substituted testosterone and epitestosterone with pyropheophorbide a differing in the length of linkers

Conjugates of 17α-substituted testosterone (1 and 2) and 17β-substituted epitestosterone (3 and 4) with pyropheophorbide a were synthesized. The scheme consisted of synthesis of 17α-hydroxy-3-oxopregn-4-en-21-oic and 17β-hydroxy-3-oxopregn-4-en-21-oic acids, and their coupling with pyropheophorbide a by means of either ethylene diamine, or 1,5-diamino pentane linkers. Mutual influence of steroidal and macrocyclic fragments in conjugates molecules was dependent on configuration of C17 and length of linker, that was established by analysis of ¹H NMR spectra and molecular models of conjugates. Studies of interaction of conjugates with prostate carcinoma cells revealed that their uptake and internalization were independent on the androgen receptor activity, but dependent on the structure of conjugates, decreasing in the following row: 3 > 4 ≥ 1 > 2. Conjugates significantly decreased the LNCaP and PC-3 cells growth at 96 h incubation. Epitestosterone derivatives 3 and 4 also showed superior anti-proliferative activity versus testosterone ones. Conformationally more rigid conjugates 1 and 3, comprising short linkers, were more active than those with long linkers; conjugate 3 was the most potent.

Benign Synthesis of Thiazolo-androstenone Derivatives as Potent Anticancer Agents

An unprecedented reaction of thiourea derivatives with 6β-bromoandrostenedione has been discovered for the formation of aminothiazolo-androstenones via a simple, safer, cascade protocol that enables the syntheses of novel molecules by using readily available reagents. The reaction mechanism of product formation has been rationalized by density functional theory calculations. This benign methodology accentuates a domino protocol deploying a renewable solvent, ethanol, while generating novel compounds that display potent growth inhibitory effects in in vitro studies for several cancer cell lines at submicromolar concentrations.

[Methods for determining of cytochrome P450 isozymes functional activity]

The review is dedicated to modern methods and technologies for determining of cytochrome P450 isozymes functional activity, such as absorbance and fluorescent spectroscopy, electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), Raman, Mossbauer, and X-ray spectroscopy, surface plasmon resonance (SPR), atomic force microscopy (AFM). Methods of molecular genetic analysis were reviewed from personalized medicine point of view. The use of chromate-mass-spectrometric methods for cytochrome P450-dependent catalytic reactions' products was discussed. The review covers modern electrochemical systems based on cytochrome P450 isozymes for their catalytic activity analysis, their use in practice and further development perspectives for experimental pharmacology, biotechnology and translational medicine.