Steroid 5α-reductase Inhibitors Research Articles

Synthesis of 4-trifluoromethylsteroids: A novel class of steroid 5α-reductase inhibitors

A concise synthetic approach to 4-trifluoromethyl steroids, a novel class of steroid 5α-reductase inhibitors, is described. Direct trifluoromethylation of steroid olefinic bromide with methyl fluorosulfonyl-difluoroacetate was used as a key step in the synthesis. The compound 4 exhibited highly inhibitory activity than Finasteride in in vitro assay. A novel class of steroid 5α-reductase inhibitors, 4-trifluoromethyl steroids was designed and synthesized

Steroid 5α-reductase inhibitors in androgen-dependent disorders

Inhibition of the steroid 5α-reductases shows promise in the treatment of a number of androgen-dependent disorders, such as benign prostatic hyperplasia, male pattern baldness, and acne. The design of potent and isozyme-selective inhibitors has provided biologists and clinicians with important tools for elucidating complex androgen physiology, and has already resulted in the development of one marketed drug.

FR146687, a novel steroid 5 alpha-reductase inhibitor: in vitro and in vivo effects on prostates.

Steroid 5 alpha-reductase is implicated in the pathogenesis of benign prostatic hyperplasia (BPH). We studied the in vitro and in vivo effects of FR146687, a new inhibitor of 5 alpha-reductase. Two isozymes of rat and human 5 alpha-reductases were expressed in 293 cells. In vivo effects of drugs were evaluated on rat and dog prostates. Castrated immature rats were injected with testosterone propionate (TP) or 5 alpha-dihydrotestosterone propionate (DHTP) to induce growth of the ventral prostates. Testosterone and 5 alpha-dihydrotestosterone (DHT) contents in rat and dog prostates were measured by gas chromatography-mass spectrophotometry (GC-MS). FR146687 showed noncompetitive inhibition in both isozymes and no inhibitory effects on other steroid oxidoreductases. In mature rats and castrated immature rats treated with TP, FR146687 dose-dependently reduced ventral prostate and seminal vesicle weight at doses above 0.1 mg/kg, while castrated immature rats treated with DHTP were not affected by FR146687. FR146687 showed more potent reduction of rat prostates than finasteride. DHT concentration in the prostates was significantly reduced when FR146687 was administered to rats and beagles. FR146687 is a dual inhibitor for 5 alpha-reductase isozymes and significantly reduced the growth and DHT content in the prostate.

Effects of Steroid 5α-Reductase Inhibitor ONO-9302 and Anti-Androgen Allylestrenol on the Prostatic Growth, and Plasma and Prostatic Hormone Levels in Rats

—ONO-9302 [epristeride; (-)-17β-(tert-butylcarbamoyl)androsta-3,5-diene-3-carboxylic acid] is a novel inhibitor of steroid 5α-reductase. We studied in vitro and in vivo effects of ONO-9302 on the rat prostatic tissue in comparison with those of the anti-androgen allylestrenol. ONO-9302 inhibited the rat prostatic enzyme with an IC50 value of 11 nM, whereas allylestrenol was about 80,000-fold less potent. The growth of ventral prostate, which was induced by the subcutaneous injection of testosterone propionate in the castrated rats, was significantly reduced by ONO-9302 at oral doses of 1 -100 mg/kg/day. Allylestrenol showed a significant effect only at a dose of 100 mg/kg/day. In mature male rats, ONO-9302 significantly reduced the ventral prostate weight at doses of 10-100 mg/kg/day and decreased prostatic 5α-dihydrotes-tosterone (DHT) content associated with a rise in testosterone (T) content at doses of 0.1 -100 mg/kg/day. Plasma hormone levels (i.e., T, DHT, luteinizing hormone (LH) and follicle stimulating hormone (FSH)) were not altered significantly. Allylestrenol significantly reduced the ventral prostate weight at doses of 10-100 mg/kg/day. However, unlike ONO-9302, allylestrenol reduced both the prostatic DHT and T contents and also lowered plasma T, DHT, LH and FSH levels at a dose of 30 mg/kg/day. These results suggest that ONO-9302 reduces the prostatic growth by inhibiting the conversion of T to DHT in the prostate without lowering blood T level unlike anti-androgen drugs.

Preparation and biological activity of tricyclic non-steroidal inhibitors of human steroid 5α-reductase

The synthesis and in vitro inhibitory studies against human types 1 and 2 steroid 5α-reductase of a series of 9,10-dihydrophenanthrene-2-carboxylic acids is reported. A (4-carboxy)phenyl substituent at C-7 provides a compound with activity against both isozymes. The structural features responsible for activity are discussed.

Effects of a New Non-Steroidal 5α-Reductase Inhibitor, FK143, on the Prostate Gland in Beagle Dogs

FK143 (4-[3-[3-[bis(4-isobutylphenyl)methylamino]benzoyl]-1H-indol-1-yl]-butyric acid) is a new non-steroidal inhibitor of steroid 5α-reductase (5α-reductase). The effects of FK143 on prostate size and histopathology of mature male beagle dogs were investigated and compared with those of finasteride (a steroidal 5α-reductase inhibitor), and allylestrenol and Chlormadinone acetate (CMA) (androgen receptor antagonists). FK143 was orally administered to the dogs daily for 12 weeks. At doses of 10 and 32 mg/kg, FK143 significantly reduced prostate volume to about 60% of the initial value, and dogs treated with FK143 showed a dose-dependent glandular epithelial atrophy in the prostate. FK143 showed no abnormal changes in organ weights and histopathology of the adrenal, testis, pituitary and liver. The degree of prostate reduction in the dogs treated with FK143 (10 and 32 mg/kg) was almost the same as that by finasteride (1.0 mg/kg) and smaller than that by allylestrenol (10 mg/kg) or CMA (10 mg/kg). However, allylestrenol increased liver weights, and CMA increased liver and reduced adrenal weights. These results demonstrate that FK143 can decrease the volume of the dog prostate without any influence on other organs, and they suggest that FK143 is a good candidate for the treatment for benign prostatic hyperplasia.

3-Carboxy-20-keto steroids are dual uncompetitive inhibitors of human steroid 5α-reductase types 1 and 2

Steroidal 3-carboxy-20-ketones have been prepared within two structural series, the androsta-3,5-dienes and the estra-1,3,5-trienes, as potential inhibitors of types 1 and 2 steroid 5α-reductase, the enzyme activity responsible for the final step in biosynthesis of dihydrotestosterone. These compounds are shown to be potent uncompetitive inhibitors of both human recombinant enzyme activities, defining a novel class of dual steroid 5α-reductase inhibitors.

The preparation and evaluation of (+/-)- trans-1-Diazo-8-methoxy-4a-methyl-1,2,3,4,4a,9,10,10a-octahydro-phenanthren-2-one as an inhibitor of human type-1 steroid 5α-reductase

(+/-)- trans-1-Diazo-8-methoxy-4a-methyl-1,2,3,4,4a,9,10,10a-octahydro-phenanthren-2-one has been prepared and evaluated in vitro as an inhibitor of type-1 (K i,app 120 nM) and type-2 (K i,app 2000 nM) human recombinant steroid 5α-reductases.

A comparison of steroidal and non-steroidal inhibitors of human steroid 5α-reductase: New tricyclic aryl acid inhibitors of the type-1 isozyme

A series of 9,10-dihydrophenanthrene-2-carboxylic acids has been prepared and evaluated in vitro as inhibitors of human recombinant steroid 5α-reductase. 7-Bromo-9,10-dihydrophenanthrene-2-carboxylic acid, 8c, is a potent and selective non-steroidal inhibitor of human type-1 steroid 5α-reductase (K i,app 26 nM). The inhibitory activity relationships of steroidal and non-steroidal inhibitors, with 4-aza, 6-aza, diene acid, aryl acid and nitro-alkenes functionalities, are considered.

Synthesis of 5,6,6-[ 2H 3]finasteride and quantitative determination of finasteride in human plasma at picogram level by an isotope-dilution mass spectrometric method

Finasteride is a potent inhibitor of the enzyme steroid 5α-reductase now approved as a drug for the treatment of benign prostatic hyperplasia. We describe an original method for the quantitative determination of finasteride at picogram level in human plasma by isotope-dilution gas chromatography mass spectrometry. 5,6,6-[ 2H 3]Finasteride was synthetized with an high ratio of trideuteration ( finasteride/[ 2 H 3] finasteride = 0.007) allowing its optimal use as internal standard. Plasma samples were purified in a single-step procedure on solid-phase extraction C 18 columns with a recovery ⩾90%. Samples were injected in the GC-MS instrument without any derivatization and the minimum detection level of finasteride was 50 pg with a singal-to-noise ratio of 6:1. The coefficients of variation for the 5 and 10 ng/ml (plasma) concentrations were 5.8% and 4%, respectively. the method has been applied to the determination of the plasma pharmacokinetic of finasteride in five male volunteers treated with a single 5-mg dose of the drug, affording kinetic parameters which are in good agreement with the values previously reported with a different methodology. The present method results accurate, specific, sensible and reliable for a routinely determination of finasteride at picogram levels.

A non-steroidal diene acid inhibitor of human type 2 stereoid 5α-reductase

A series of 4a-methyl-3,4,4,4a-9-tetrahydrophenanthrene-2-carboxylic acids and 2-phosphinic acids has been prepared and evaluated in vitro as inhibitors of human recombinant steroid 5α-reductase. 7-Chloro-4a-methyl-3,4,4,4a-9-tetrahydrophenanthrene-2-carboxylic acid 5, is a marginally selective inhibitor of human type 2 steroid 5α-reductase (K i,app = 260 nM). The phosphinic acid compounds, 8 and 9, are weak inhibitors of types 1 and 2 steroid 5α-reductase.

Inhibition of steroid 5α-reductase by “inverted”, competitive inhibitors

Modified steroids, in which the D-ring has been converted to a six-membered ring lactam, were designed as inverted (or backward-binding), competitive inhibitors of steroid 5α-reductase.

Epristeride is a selective and specific uncompetitive inhibitor of human steroid 5α-reductase isoform 2

Specificity of an enzyme inhibitor can have profound implications upon the compound's therapeutic potential, utility and safety profile. As potent inhibitors of human steroid 5α-reductase (SR) the 3-androstene-3-carboxylic acids, or steroidal acrylates, may be useful in treatment of diseases such as benign prostatic hyperplasia for which 5α-dihydrotestosterone (DHT) appears to be a causative agent. To determine its specificity profile, the interactions of a representative compound from this class, N-( t-butyl)androst-3,5-diene-17β-carboxamide-3-carboxylic acid (epristeride, SK&F 105657), have been studied with 7 other steroid processing enzymes and 5 steroid hormone receptors. The affinity of epristeride for each of these 12 potential targets was found to be at least 1000-fold weaker than that for SR, the intended target. In addition, using samples of the individually expressed two known forms of human SRs, epristeride has been shown to be a selective inhibitor of the recombinant human SR type 2, the predominant activity found in the prostate of man. Nonetheless, the mechanisms of SR inhibition for both isoenzymes involve formation of a ternary complex with epristeride, NADP +, and enzyme. Epristeride, consequently, has been shown to be an uncompetitive inhibitor versus steroid substrate of both human SR isoenzymes. These results suggest that this 3-androstene-3-carboxylic acid is a specific and selective inhibitor of the human type 2 SR, and that epristeride is an attractive compound for further investigation as a safe and effective therapeutic agent in the potential treatment of disease states associated with DHT-induced tissue growth.

Biosynthesis of ecdysteroid hormones by crustacean Y-organs: conversion of cholesterol to 7-dehydrocholesterol is suppressed by a steroid 5α-reductase inhibitor

A pair of glands (Y-organs) in crustaceans synthesize and secrete ecdysteroid hormones; the obligate precursor for synthesis is circulating cholesterol. Ecdysteroid output by the Y-organs is regulated negatively by an eyestalk neurosecretory peptide, molt-inhibiting hormone (MIH). The question was addressed, does MIH suppress ecdysteroid synthesis by decreasing cholesterol supply (uptake) or its utilization or both? Experiments were conducted with Y-organs in vitro from the crab, Menippe mercenaria, in the presence of labeled cholesterol, with or without the steroid 5α-reductase inhibitor, L-645390 (Merck). Other experiments superimposed the presence or absence of eyestalk extract containing MIH activity. L-645390 greatly depressed incorporation of cholesterol into an early intermediate, 7-dehydrocholesterol and into secreted ecdysteroids. At the same time, cholesterol accumulated in the Y-organs, to levels significantly higher than in untreated controls. MIH alone depressed both cholesterol uptake and incorporation. MIH together with L-645390 produced the greatest depression of cholesterol incorporation while also preventing the cholesterol accumulation seen with L-645390 alone. These results indicate that cholesterol uptake and its metabolic utilization in Y-organs are separable events representing separate sites of regulation by MIH.

Synthesis and evaluation of 3-carboxymethyl steroids as inhibitors of human prostatic steroid 5α-reductase

A series of 3-carboxymethyl steroids has been prepared and assayed in vitro as inhibitors of steroid 5α-reductase isolated from human prostatic tissue. Potent inhibition was observed with analogs from both androstene and estratriene families. Phosphonic and sulfonic acid analogs were also prepared and found to lack significant inhibitory activity.

Chemical agents and peptides affect hair growth

During the past decade we have examined both the therapeutic and the prophylactic effects of several agents on the macaque model of androgenetic alopecia. Minoxidil and diazoxide, potent hypotensive agents acting as peripheral vasodilators, are known to have a hypertrichotic side effect. Topical use of both agents induced significant hair regrowth in the bald scalps of macaques. The application of a steroid 5α-reductase inhibitor (4MA) in non-bald preadolescent macaques has prevented baldness, whereas controls developed it during 2 years of treatment. The effects of hair growth were determined by 1) phototrichogram, 2) folliculogram (micromorphometric analysis), and 3) the rate of DNA synthesis in the follicular cells. These effects were essentially a stimulation of the follicular cell proliferation, resulting in an enlargement of the anagen follicles from vellus to terminal type (therapy) or a maintenance of the prebald terminal follicles (prevention). A copper binding peptide (PC1031) had the effect of follicular enlargement on the back skin of fuzzy rats, covering the vellus follicles; the effect was similar to that of topical minoxidil.Analyzing the quantitative sequences of follicular size and cyclic phases, we speculate on the effect of agents on follicular growth. We also discuss the triggering mechanism of androgen in the follicular epithelial-mesenchymal (dermal papilla) interaction.

Hydroxylation of 5α-androstane-3β,17β-diol by rat prostate microsomes: Potent inhibition by imidazole-type antimycotic drugs and lack of inhibition by steroid 5α-reductase inhibitors

5α-Dihydrotestosterone, the principal androgen mediating prostate growth and function in the rat, is formed from testosterone by steroid 5α-reductase. The inactivation of 5α-dihydrotestosterone involves reversible reduction to 5α-androstane-3β,17β-diol by 3β-hydroxysteroid oxidoreductase followed by 6α-, 7α-, or 7β-hydroxylation. 5α-Androstane-3β,17β-diol hydroxylation represents the ultimate inactivation step of dihydrotestosterone in rat prostate and is apparently catalyzed by a single, high-affinity ( K m ~ 0.5 μM) microsomal cytochrome P450 enzyme. The present studies were designed to determine if 5α-androstane-3β,17β-diol hydroxylation by rat prostate microsomes is inhibited by agents that are known inhibitors of androgen-metabolizing enzymes. Inhibitors of steroid 5α-reductase (4-azasteroid analogs; 10 μ m) or inhibitors of 3β-hydroxy-steroid oxidoreductase (trilostane, azastene, and cyanoketone; 10 μ m) had no appreciable effect on the 6α-, 7α-, or 7β-hydroxylation of 5α-androstane-3β,17β-diol (10 μ m) by rat prostate microsomes. Imidazole-type antimycotic drugs (ketoconazole, clotrimazole, and miconazole; 0.1–10 μ m) all markedly inhibited 5α-androstane-3β,17β-diol hydroxylation in a concentration-dependent manner, whereas triazole-type antimycotic drugs (fluconazole and itraconazole; 0.1–10 μ m) had no inhibitory effect. The rank order of inhibitory potency of the imidazole-type antimycotic drugs was miconazole > clotrimazole > ketoconazole. In the case of clotrimazole, the inhibition was shown to be competitive in nature, with a K i of 0.03 μ m. The imidazole-type antimycotic drugs inhibited all three pathways of 5α-androstane-3β,17β-diol hydroxylation to the same extent, which provides further evidence that, in rat prostate microsomes, a single cytochrome P450 enzyme catalyzes the 6α-, 7α-, and 7β-hydroxylation of 5α-androstane-3β,17β-diol. These studies demonstrate that certain imidazole-type compounds are potent, competitive inhibitors of 5α-androstane-3β,17β-diol hydroxylation by rat prostate microsomes, which is consistent with the effect of these antimycotic drugs on cytochrome P450 enzymes involved in the metabolism of other androgens and steroids.

Prostates, Pates, and Pimples: The Potential Medical Uses of Steroid 5α-Reductase Inhibitors

The steroid 5 alpha-reductase enzyme is responsible for the formation of DHT from testosterone. DHT has been the major androgen implicated in the pathogenesis of benign prostatic hyperplasia, male pattern baldness, acne, and idiopathic female hirsutism. Although specific inhibitors of 5 alpha-reductase are not yet generally available for human use, it is expected that they will become available within the next several years. Based on biochemical, histologic, and anatomic information from animals given 5 alpha-reductase inhibitors, preliminary data on their use in humans, and knowledge gained from men with the inherited 5 alpha-reductase deficiency, it is expected that these 5 alpha-reductase inhibitors may have a major role in the medical management of benign prostatic hyperplasia. In addition, it is possible that these compounds will hold promise for the prevention of male pattern baldness and for the treatment of resistant acne and idiopathic hirsutism.

3-Phosphinic acid and 3-phosphonic acid steroids as inhibitors of steroid 5α-reductase: Species comparison and mechanistic studies

3-Phosphinic acid and 3-phosphonic acid steroids are presented as a new class of steroid 5α-reductase (SR) inhibitors. Representative compounds have been studied as inhibitors of prostatic SR from human, rat, and cynomolgus monkey ( Macaca fascicularis). The most potent of the phosphinic acid inhibitors of the human enzyme activity demonstrated nanomolar inhibition constants, while the affinities of the phosphonic acids were diminished. Comparison of compound potency revealed interspecies variability with the best correlation on K i K m for the two primate SRs. Results from dead-end and multiple inhibition analyses with 17β-( N,N-diisopropylcarbamoyl)androsta-3,5-diene-3-phosphinic acid ( 2a) and 17β-( N,N-diisopropylcarbamoyl)androsta-3,5-diene-3-phosphinic acid ( 3a) were consistent with the preferential binding of these compounds to an enzyme-NADP + complex. The pH profiles of solubilized rat liver SR inhibition by 2a and 3a indicated preferential binding of the phosphinic and phosphonic acids as the anion and the monoanion, respectively.

Inhibition of steroid 5α-reductase by 3-nitrosteroids: synthesis, mechanism of inhibition, and in vivo activity.

A series of A-ring unsaturated 3-nitrosteroids has been prepared and assayed in vitro as inhibitors of steroid 5α-reductase. One of these compounds, 3-nitro-5α-androst-3-ene-17β-diisopropylcarboxamide ( 4), inhibits the human enzyme with a K i of 50 nM and exhibits competitive inhibition versus testosterone. Potent oral activity of 4 was demonstrated in cynomolgus monkeys.