Inhibitors of enzymes of androgen biosynthesis: cytochrome P450(17) alpha and 5 alpha-steroid reductase

Exploring the Potential of Sulfur Moieties in Compounds Inhibiting Steroidogenesis

This study reports on the synthesis and evaluation of novel compounds replacing the nitrogen-containing heterocyclic ring on the chemical backbone structure of cytochrome P450 17α-hydroxylase/12,20-lyase (CYP17A1) inhibitors with a phenyl bearing a sulfur-based substituent. Initial screening revealed compounds with marked inhibition of CYP17A1 activity. The selectivity of compounds was thereafter determined against cytochrome P450 21-hydroxylase, cytochrome P450 3A4, and cytochrome P450 oxidoreductase. Additionally, the compounds showed weak inhibitory activity against aldo-keto reductase 1C3 (AKR1C3). The compounds' impact on steroid hormone levels was also assessed, with some notable modulatory effects observed. This work paves the way for developing more potent dual inhibitors specifically targeting CYP17A1 and AKR1C3.

A combination therapy for androgenic alopecia based on quercetin and zinc/copper dual-doped mesoporous silica nanocomposite microneedle patch

A nanocomposite microneedle (ZCQ/MN) patch containing copper/zinc dual-doped mesoporous silica nanoparticles loaded with quercetin (ZCQ) was developed as a combination therapy for androgenic alopecia (AGA). The degradable microneedle gradually dissolves after penetration into the skin and releases the ZCQ nanoparticles. ZCQ nanoparticles release quercetin (Qu), copper (Cu²⁺) and zinc ions (Zn²⁺) subcutaneously to synergistically promote hair follicle regeneration. The mechanism of promoting hair follicle regeneration mainly includes the regulation of the main pathophysiological phenomena of AGA such as inhibition of dihydrotestosterone, inhibition of inflammation, promotion of angiogenesis and activation of hair follicle stem cells by the combination of Cu²⁺ and Zn²⁺ ions and Qu. This study demonstrates that the systematic intervention targeting different pathophysiological links of AGA by the combination of organic drug and bioactive metal ions is an effective treatment strategy for hair loss, which provides a theoretical basis for development of biomaterial based anti-hair loss therapy.

The synthesis of cardenolide and bufadienolide aglycones, and related steroids bearing a heterocyclic subunit

Covering: early studies through to March 2016Cardenolides and bufadienolides constitute an attractive class of biologically active steroid derivatives which have been used for the treatment of heart disease in traditional remedies as well as in modern medicinal therapy. Due to their application as therapeutic agents and their unique molecular structures, bearing unsaturated 5- or 6-membered lactones (or other heterocycles) attached to the steroid core, cardio-active steroids have received great attention, which has intensified during the last decade, in the synthetic organic community. Advances in the field of cross-coupling reactions have provided a powerful tool for the attachment of lactone subunits to the steroid core. This current review covers a methodological analysis of synthetic efforts to cardenolide and bufadienolide aglycones. Special emphasis is given to cross-coupling reactions applied for the attachment of lactone subunits at sterically very hindered positions of the steroid core. The carefully selected partial and total syntheses of representative cardio-active steroids will also be presented to exemplify recent achievements (improvements) in the field.

Determination of 17α-hydroxylase-C17,20-lyase (P45017α) enzyme activities and their inhibition by selected steroidal picolyl and picolinylidene compounds

17α-hydroxylase-C17,20-lyase (P45017α) is a key regulator enzyme of the steroid hormone biosynthesis in both the adrenals and the testes. Inhibition of this enzyme can block androgen synthesis in an early step, and may thereby be useful in the treatment of several androgen-dependent diseases. We developed radio-substrate in vitro incubation methods for the determination of the distinct 17α-hydroxylase and C17,20-lyase activities of the enzyme using rat testicular homogenate as enzyme source. With this method we have studied the inhibiting activity of selected steroidal picolyl and picolinylidene compounds. Tests revealed a substantial inhibitory action of the 17-picolinyliden-androst-4-en-3-one compound.

Steroidal 5α-reductase and 17α-hydroxylase/17,20-lyase (CYP17) inhibitors useful in the treatment of prostatic diseases

The role of steroidal inhibitors of androgen biosynthesis as potential weapons in the treatment of prostatic diseases, such as benign prostatic hyperplasia and prostatic cancer will be reviewed. Two enzymes have been targeted in the development of inhibitors that potentially could be useful in the management of such conditions. 5α-Reductase is primarily of interest in benign prostatic disease, though some role in the chemoprevention of prostatic carcinoma have been considered, whereas the 17α-hydroxylase/17,20-lyase (CYP17) enzyme is of interest in the treatment of malignant disease. An overview of the main achievements obtained during the past years will be presented, however special focus will be made on steroidal molecules that reached clinical trials or have been commercially launched. Relevant examples of such drugs are finasteride, dutasteride, abiraterone acetate and galeterone (TOK-001, formerly known as VN/124-1). This article is part of a Special Issue entitled "Synthesis and biological testing of steroid derivatives as inhibitors".

Anticancer steroids: linking natural and semi-synthetic compounds

Steroids, a widespread class of natural organic compounds occurring in animals, plants and fungi, have shown great therapeutic value for a broad array of pathologies. The present overview is focused on the anticancer activity of steroids, which is very representative of a rich structural molecular diversity and ability to interact with various biological targets and pathways. This review encompasses the most relevant discoveries on steroid anticancer drugs and leads through the last decade and comprises 668 references.

Modeling androgen receptor flexibility: a binding mode hypothesis of CYP17 inhibitors/antiandrogens for prostate cancer therapy

Prostate Cancer (PCa), a leading cause of cancer death worldwide (www.cancer.gov), is a complex malignancy where a spectrum of targets leads to a diversity of PCa forms. A widely pursued therapeutic target is the Androgen Receptor (AR). As a Steroid Hormone Receptor, AR serves as activator of transcription upon binding to androgens and plays a central role in the development of PCa. AR is a structurally flexible protein, and conformational plasticity of residues in the binding-pocket is a key to its ability to accommodate ligands from various chemical classes. Besides direct modulation of AR activity by antagonists, inhibition of cytochrome CYP17 (17α-hydroxylase/17,20-lyase), essential in androgen biosynthesis, has widely been considered an effective strategy against PCa. Interestingly, Handratta et al. (2005) discovered new, potent inhibitors of CYP17 (C-17 steroid derivatives) with pure AR antagonistic properties. Although the antiandrogenic activity of their lead compound (VN/124-1) has been experimentally proven both in vitro and in vivo, no structural data are currently available to elucidate the molecular determinants responsible for these desirable dual inhibitory properties. We implemented a Structure-based Drug Design (SBDD) approach to generate a valuable hypothesis as to the binding modes of steroidal CYP17 inhibitors/antiandrogens against the AR. To deal with the plasticity of residues buried in the Ligand Binding Domain (LBD), we developed a flexible-receptor Docking protocol based on Induced-Fit (IFD) methodology (www.schrodinger.com/). Our results constitute an ideal starting point for the rational design of next-generation analogues of CYP17 inhibitors/antiandrogens as well as an attractive tool to suggest novel chemical classes of AR antagonists.

Discovery of orteronel (TAK-700), a naphthylmethylimidazole derivative, as a highly selective 17,20-lyase inhibitor with potential utility in the treatment of prostate cancer

A novel naphthylmethylimidazole derivative 1 and its related compounds were identified as 17,20-lyase inhibitors. Based on the structure-activity relationship around the naphthalene scaffold and the results of a docking study of 1a in the homology model of 17,20-lyase, the 6,7-dihydro-5H-pyrrolo[1,2-c]imidazole derivative (+)-3c was synthesized and identified as a potent and highly selective 17,20-lyase inhibitor. Biological evaluation of (+)-3c at a dose of 1mg/kg in a male monkey model revealed marked reductions in both serum testosterone and dehydroepiandrosterone concentrations. Therefore, (+)-3c (termed orteronel [TAK-700]) was selected as a candidate for clinical evaluation and is currently in phase III clinical trials for the treatment of castration-resistant prostate cancer.

CYP17 inhibitors for prostate cancer therapy

Prostate cancer (PC) is now the second most prevalent cause of death in men in the USA and Europe. At present, the major treatment options include surgical or medical castration. These strategies cause ablation of the production of testosterone (T), dihydrotestosterone (DHT) and related androgens by the testes. However, because these procedures do not affect adrenal, prostate and other tissues' androgen production, they are often combined with androgen receptor antagonists to block their action. Indeed, recent studies have unequivocally established that in castration-resistant prostate cancer (CRPC) many androgen-regulated genes become re-expressed and tissue androgen levels increase despite low serum levels. Clearly, inhibition of the key enzyme which catalyzes the biosynthesis of androgens from pregnane precursors, 17α-hydroxy/17,20-lyase (hereafter referred to as CYP17) could prevent androgen production from all sources. Thus, total ablation of androgen production by potent CYP17 inhibitors may provide effective treatment of prostate cancer patients. This review highlights the role of androgen biosynthesis in the progression of prostate cancer and the impact of CYP17 inhibitors, such as ketoconazole, abiraterone acetate, VN/124-1 (TOK-001) and TAK-700 in the clinic and in clinical development. Article from the special issue on Targeted Inhibitors.

Determination of rat 5alpha-reductase type 1 isozyme activity and its inhibition by novel steroidal oxazolines

The 5alpha-reductase type 1 isozyme is a key enzyme in the metabolism of the androgen steroid hormones and inhibitors of this enzyme represent a new pharmacological treatment for several androgen dependent diseases. We developed a radiosubstrate in vitro incubation method for the determination of 5alpha-reductase type 1 activity using rat liver microsomes as an enzyme source. With this method we have studied the inhibiting activity of novel (5' S)-17beta-(4,5-dihydrooxazol-5-yl)androst-5-en-3-one compounds containing various derivatized phenyl substituents coupled to the exo -heterocyclic moiety. Tests revealed moderate inhibitory actions compared to finasteride, nevertheless, results provide interesting structure-activity relationship data.

Neighboring group participation Part 17 Stereoselective synthesis of some steroidal 2-oxazolidones, as novel potential inhibitors of 17alpha-hydroxylase-C(17,20)-lyase

During the alkaline methanolysis of 3beta-acetoxy-21-chloropregn-5-ene-20beta-N-phenylurethane (4a), and its 4-monosubstituted (4b-e) and 3,5-disubstituted (4f) phenyl derivatives, cyclization occurs, in the course of which 17beta-[3-(N-phenyl)-2-oxazolidon-5-yl]androst-5-en-3beta-ol (5a) and its substituted phenyl derivatives (5b-f) are formed. The cyclization takes place with (N(-)-5) neighboring group participation. The reaction of 3beta-acetoxy-21-azidopregn-5-en-20beta-ol (3d) with triphenylphosphine gave 3beta-acetoxy-21-phosphiniminopregn-5-en-20beta-ol, which reacted in situ with carbon dioxide with the participation of the sterically favored 20beta-OH to give the unsubstituted steroidal cyclic carbamate (8). Oppenauer oxidation of the 3beta-hydroxy-exo-heterocyclic steroids (5a-f, 9) yielded the corresponding Delta(4)-3-ketosteroids (7a-f, 10). The inhibitory effects (IC(50)) of these compounds on rat testicular C(17,20)-lyase were investigated with an in vitro radioligand incubation technique. The N-unsubstituted 17beta-(2-oxazolidon-5-yl)-androst-4-en-3-one derivative (10) was found to be a potent inhibitor (IC(50)=3.0 microM).

Synthesis of novel C17 steroidal carbamates. Studies on CYP17 action, androgen receptor binding and function, and prostate cancer cell growth

We have exploited the reaction of 1,1'-carbonylbis(2-methylimidazole) (CBMI) with several 17beta-hydroxy androstanes to synthesize a series of novel C17 steroidal carbamates. Structural elucidation features have been provided for the final compounds based on 1D and 2D NMR techniques, IR spectroscopy, and related literature. The new compounds were tested for inhibition of human cytochrome 17alpha-hydroxylase-C17,20-lyase (CYP17) and androgen receptor (AR) binding and function effects. Their inhibitory potential against PC-3 cell proliferation was also evaluated. Compounds 11 and 23 were found to inhibit CYP17 with IC50 values of 17.1 and 11.5 microM, respectively. The carbamate moiety at C17 allowed tight binding of the synthesized compounds to both wild-type (wt-) and mutated AR. When bound to the mutated AR, the compounds were found to have a dual effect, stimulating transcription at low concentrations while almost fully blocking it at the higher concentrations tested, in the presence of the natural androgen dihydrotestosterone (DHT). Compounds 8 and 12 were the most active against PC-3 cell proliferation with EC50 values of 2.2 and 0.2 microM, respectively.

Synthesis and evaluation of novel 17-indazole androstene derivatives designed as CYP17 inhibitors

A series of novel 1H- and 2H-indazole derivatives of the commercially available dehydroepiandrosterone acetate have been synthesized and tested for inhibition of human cytochrome 17alpha-hydroxylase-C(17,20)-lyase (CYP17), androgen receptor (AR) binding affinity, and cytotoxic potential against three prostate cancer (PC) cell lines.

3,3-Diphenylpentane skeleton as a steroid skeleton substitute: Novel inhibitors of human 5α-reductase 1

We designed and synthesized novel type 1 5alpha-reductase inhibitors by using 3,3-diphenylpentane skeleton as a substitute for the usual steroid skeleton. 4-(3-(4-(N-Methylacetamido)phenyl)pentan-3-yl)phenyl dibenzylcarbamate (11k) is a competitive 5alpha-reductase inhibitor with the IC(50) value of 0.84 microM.

Inhibition of 17alpha-hydroxylase/C17,20-lyase (CYP17) from rat testis by green tea catechins and black tea theaflavins

In the course of screening for 17alpha-hydroxylase/C17,20-lyase inhibitors from food ingredients, the methanol soluble fraction of green tea and black tea, which were expected to be rich in catechin and theaflavin content, showed potent inhibitory activity. (-)-Epigallocathechin gallate and theaflavin 3-O-gallate with a pirogallol moiety significantly inhibited C17,20-lyase activity on IC50 values of 24.5 microM and 11.5 microM respectively. They had potent cytotoxicity against human prostate cancer LNCaP cells (IC50=28.1 microM and 37.4 microM).

Stereoselective synthesis of some 17beta-dihydrooxazinyl steroids, as novel presumed inhibitors of 17alpha-hydroxylase-C17,20-lyase

17beta-Dihydrooxazinyl steroids 5a-l and 6a-l were synthetized. The acid-catalyzed reactions of 21-azidomethyl-20-hydroxy- and 21-hydroxymethyl-20-azidosteroids with substituted aromatic aldehydes led to the formation of androst-5-en-3beta-ols substituted in position 17beta with dihydrooxazine residues. The inhibitory effects of these compounds on rat testicular C(17,20)-lyase were investigated with an in vitro radioincubation technique.

Synthesis and CYP24 inhibitory activity of 2-substituted-3,4-dihydro-2H-naphthalen-1-one (tetralone) derivatives

The synthesis of novel 2-benzyl- and 2-benzylidene-3,4-dihydro-2H-naphthalen-1-one (tetralone) derivatives and their inhibitory activity versus kidney mitochondrial 25-hydroxyvitamin D(3) 24-hydroxylase (CYP24) is described. The 2-benzylidenetetralone derivatives were found to be very weak inhibitors (IC(50) 20 >100 microM), whereas the 2-benzyltetralone derivatives showed promising inhibitory activity (IC(50) 0.9 microM for the most active derivative) compared with ketoconazole (IC(50) 20 microM).

C(17,20)-lyase inhibitors. Part 2: design, synthesis and structure-activity relationships of (2-naphthylmethyl)-1H-imidazoles as novel C(17,20)-lyase inhibitors

A series of 1- and 4-(2-naphthylmethyl)-1H-imidazoles (3 and 4) has been synthesized and evaluated as C(17,20)-lyase inhibitors. Several 6-methoxynaphthyl derivatives showed potent C(17,20)-lyase inhibition, suppression of testosterone biosynthesis in rats and reduction in the weight of prostate and seminal vesicles in rats, whereas most of these compounds increased the liver weight after consecutive administrations. The effect on the liver weight was removed by incorporation of a hydroxy group and an isopropyl group at the methylene bridge, as seen in (S)-28d and (S)-42. Selectivity for C(17,20)-lyase over 11beta-hydroxylase is also discussed, and (S)-42 was found to be a more than 260-fold selective inhibitor. Furthermore, (S)-42 showed a potent suppression of testosterone biosynthesis after a single oral administration in monkeys. These data suggest that (S)-42 may be a promising agent for the treatment of androgen-dependent prostate cancer.

C17,20-lyase inhibitors I. Structure-based de novo design and SAR study of C17,20-lyase inhibitors

Novel nonsteroidal C(17,20)-lyase inhibitors were synthesized using de novo design based on its substrate, 17 alpha-hydroxypregnenolone, and several compounds exhibited potent C(17,20)-lyase inhibition. However, in vivo activities were found to be short-lasting, and in order to improve the duration of action, a series of benzothiophene derivatives were evaluated. As a result, compounds 9h, (S)-9i, and 9k with nanomolar enzyme inhibition (IC(50)=4-9 nM) and 9e (IC(50)=27 nM) were identified to have powerful in vivo efficacy with extended duration of action. The key structural determinants for the in vivo efficacy were demonstrated to be the 5-fluoro group on the benzothiophene ring and the 4-imidazolyl moiety. Superimposition of 9k and 17 alpha-hydroxypregnenolone demonstrated their structural similarity and enabled rationalization of the pharmacological results. In addition, selected compounds were also identified to be potent inhibitors of human enzyme with IC(50) values of 20-30 nM.

Rooster feathering, androgenic alopecia, and hormone-dependent tumor growth: what is in common?

Different epithelial organs form as a result of epithelial-mesenchymal interactions and share a common theme modulated by variations (Chuong ed. In Molecular Basis of Epithelial Appendage Morphogenesis, 1998). One of the major modulators is the sex hormone pathway that acts on the prototype signaling pathway to alter organ phenotypes. Here, we focus on how the sex hormone pathway may interface with epithelia morphogenesis-related signaling pathways. We first survey these sex hormone-regulated morphogenetic processes in various epithelial organs. Sexual dimorphism of hairs and feathers has implications in sexual selection. Diseases of these pathways result in androgenic alopecia, hirsutism, henny feathering, etc. The growth and development of mammary glands, prostate glands, and external genitalia essential for reproductive function are also dependent on sex hormones. Diseases affecting these organs include congenital anomalies and hormone-dependent breast and prostate cancers. To study the role of sex hormones in new growth in the context of system biology/pathology, an in vivo model in which organ formation starts from stem cells is essential. With recent developments (Yu et al. (2002) The morphogenesis of feathers. Nature 420:308-312), the growth of tail feathers in roosters and hens has become a testable model in which experimental manipulations are possible. We show exemplary data of differences in their growth rate, proliferative cell population, and signaling molecule expression. Working hypotheses are proposed on how the sex hormone pathways may interact with growth pathways. It is now possible to test these hypotheses using the chicken model to learn fundamental mechanisms on how sex hormones affect organogenesis, epithelial organ cycling, and growth-related tumorigenesis.

Effects of novel 17alpha-hydroxylase/C17, 20-lyase (P450 17, CYP 17) inhibitors on androgen biosynthesis in vitro and in vivo

Aiming at the development of new drugs for the treatment of prostate cancer, the effects of steroidal compounds and one non-steroidal substance on androgen biosynthesis were evaluated in vitro and in vivo. Sa 40 [17-(5-pyrimidyl)androsta-5,16-diene-3beta-ol], its 3-acetyl derivate Sa 41 and BW 19 [3,4-dihydro-2-(4-imidazolylmethyl)-6-methoxy-1-methyl-naphthalene] are compounds from our group, which have been developed as inhibitors of CYP 17 (17alpha-hydroxylase-C17, 20-lyase, the key enzyme in androgen biosynthesis). They have been compared with CB 7598 [abiraterone: 17-(3-pyridyl)androsta-5,16-diene-3beta-ol], its 3-acetyl compound CB 7630 and ketoconazole, compounds which already have been used clinically. The most potent compound toward human CYP 17 (testicular microsomes) was Sa 40 (IC(50) value of 24 nM), followed by Sa 41, CB 7598, BW 19, CB 7630 and ketoconazole. Sa 40 shows a type II difference spectrum and a non-competitive type of inhibition (K(i) value of 16 nM). No recovery of enzyme activity was observed after preincubation of CYP 17 with Sa 40 and subsequent charcoal treatment. In Escherichia coli cells coexpressing human CYP 17 and NADPH-P450 reductase, Sa 40 was more active than CB 7598 and BW 19, whereas the acetyl compounds were not active. The latter three compounds were equally active towards rat CYP 17. Male Sprague-Dawley (SD) rats were administered daily for 14 days BW 19 and the acetyl derivatives Sa 41 and CB 7630 as prodrugs (0.1 mmol/kg intraperitoneally). The test compounds strongly reduced plasma testosterone concentration, as well as prostate and seminal vesicles weights. They showed moderate inhibitory effects on the weights of levator ani, bulbocavernosus and testes, whereas they led to an increase in adrenal and pituitary weights. The only exception was BW 19 which did not change pituitary weights. Based on its superiority on the human enzyme, it was concluded that Sa 40 in its 3beta-acetate form (Sa 41) could be a promising candidate for clinical evaluation.

Inhibition of CYP 17, a new strategy for the treatment of prostate cancer

Androgens are growth factors for approximately 80 percent of all prostate cancers. Suppressing androgen biosynthesis is therefore an important therapeutic strategy in order to inhibit tumor growth. Unfortunately, the drugs currently applied to lower androgen levels only affect testicular androgen production. Since androgens are also synthesized in the adrenal glands, tumor stimulation cannot be blocked completely. A new therapeutic target, CYP 17 (P450 17, 17alpha-hydroxylase-C17, C20 lyase), is likely to improve this situation. CYP 17 is a P450 enzyme and catalyzes the last step of androgen biosynthesis in both testes and adrenals. Inhibition of this enzyme will therefore result in a complete block of androgen production. This paper gives an overview of the current situation in this novel field of drug research and focuses on the development of steroidal and non-steroidal inhibitors of CYP 17.

Synthesis and evaluation of steroidal hydroxamic acids as inhibitors of P450 17 (17 alpha-hydroxylase/C17-20-lyase)

With the aim of developing new inhibitors of 17 alpha-hydroxylase/C17,20-lyase (P450 17, CYP 17), two steroidal hydroxamic acids (compounds 2 and 3) were synthesized and evaluated as inhibitors of CYP 17. The synthesis was performed using carboxylic acids as starting material to give acid chlorides which were reacted with N,N,O-tris(trimethylsilyl) hydroxylamine. Using microsomal fractions of human and rat testes and progesterone as a substrate, both compounds moderately inhibited the human and rat enzyme.

6-Substituted 1H-quinolin-2-ones and 2-methoxy-quinolines: synthesis and evaluation as inhibitors of steroid 5alpha reductases types 1 and 2

A Negishi-type coupling reaction between 6-bromo-2-methoxyquinoline (1a) and various 4-bromo-N,N-dialkyl-benzamides gave access to 6-substituted 2-methoxy-quinolines 1-3 and 1H-quinolin-2-ones 4-12. Most of these compound proved to be inhibitors of steroid 5alpha reductases with activity and selectivity both being strongly dependent on the features of the heterocycle and the size of the N,N-dialkylamide substituent. The most active inhibitor for the human type 2 isozyme was 6-[4-(N,N-diisopropylcarbamoyl)phenyl]-1H-quinolin-2-one 4 (Ki 800 +/- 85 nM), showing mostly competitive inhibitory patterns. A type 1 selective inhibitor could be identified with 6-[4-(N,N-diisopropylcarbamoyl)phenyl]-N-methyl-quinolin-2-one (5, IC50 510 nM).

Novel imidazolyl and triazolyl substituted biphenyl compounds: synthesis and evaluation as nonsteroidal inhibitors of human 17alpha-hydroxylase-C17, 20-lyase (P450 17)

The synthesis of a new series of P450 17 inhibitors is described. The imidazol-1-yl compounds 5 showed strong inhibition of P450 17 rat and especially human enzyme, the most active compounds being 5ax, 5ay and 5bx with IC50 values of 0.17, 0.24 and 0.25 microM, respectively (ketoconazole: 0.74 microM). The 1,2,4-triazol-1-yl compounds 6 were less active, while the 1,2,4-triazol-4-yl compounds 7 were inactive. The title compounds showed little inhibition of P450 arom. The most active P450 17 inhibitors 5ax and 5ay markedly decreased the testosterone plasma concentration of SD rats 2 h after application of 0.019 mmol/kg. After 6 h, 5ay still exhibited a strong effect.

Imidazole substituted biphenyls: a new class of highly potent and in vivo active inhibitors of P450 17 as potential therapeutics for treatment of prostate cancer

3- And 4-imidazol-1-yl-methyl substituted biphenyl compounds (named as meta- and para-substituted compounds) were synthesized bearing additional substituents in 3'-/4'-position as inhibitors of P450 17 (17alpha-hydroxylase-C17,20-lyase). P450 17 is the key enzyme of androgen biosynthesis. Its inhibition is a novel therapeutic strategy for treatment of prostate cancer (PC). Twenty-nine compounds were synthesized by Ar-Mg-Br, Negishi or Suzuki aryl-aryl cross coupling and tested toward human and rat enzyme. Most of the compounds showed moderate to excellent activity against one of the enzymes (0.087 microM < or = IC50 < or = 7.7 microM (ketoconazole: 0.74 microM) for the human enzyme, 0.63 microM < or = IC50 < or = 32 microM (ketoconazole: 67 microM) for the rat enzyme). Interestingly, strong species differences were observed. In addition compounds were tested for inhibition toward P450 arom. The 3-imidazol-1-yl-methyl substituted compounds showed good inhibitory activity of P450 arom, while for the 4-substituted compounds negligible inhibition was found. For the most active group of P450 17 inhibitors, (i.e. the 4-imidazol-1-yl-methyl substituted compounds) a QSAR study was performed for inhibition of the human enzyme leading to the result that a hydrophilic substituent in 3'-/4'-position is very important. The most promising compounds (with respect to activity toward both enzymes) were tested in vivo using SD-rats for reduction of plasma testosterone concentrations 2 and 6 h after single i.p. application. The fluorine substituted compound 8c decreased the testosterone plasma concentration to castration level (after 2 h; 5 mg/kg) showing a biological half live of about 6 h.