The enzyme and inhibitors of 4-ene-3-oxosteroid 5 alpha-oxidoreductase

Virtual screening approach for the discovery of selective 5α-reductase type II inhibitors for benign prostatic hyperplasia treatment

Background: 5α-Reductase type II (5αR2) inhibition is a promising strategy for benign prostatic hyperplasia treatment. A computational approach including virtual screening, ligand-based 3D pharmacophore modeling, 2D quantitative structure-activity relationship and molecular docking simulations were adopted to develop novel inhibitors. Results: Hits were first filtered via the validated pharmacophore and 2D quantitative structure-activity relationship models. Docking on the recently determined cocrystallized structure of 5αR2 showed three promising hits. Visual inspection results were compared with finasteride ligand and dihydrotestosterone as reference, to explain the role of binding to Glu57 and Tyr91 for 5αR2 selective inhibition. Conclusion: Alignment between Hit 2 and finasteride in the binding pocket showed similar binding modes. The biological activity prediction showed antitumor and androgen targeting activity of the new hits.

Caffeic acid N-[3,5-bis(trifluoromethyl)phenyl] amide as a non-steroidal inhibitor for steroid 5α-reductase type 1 using a human keratinocyte cell-based assay and molecular dynamics

Caffeic acid derivatives containing amide moieties similar to those of finasteride and dutasteride were synthesized. An in vitro inhibitory activity evaluation of caffeic acid (1) and its amide derivatives (2 - 4) against the steroid 5α-reductase type 1 (SRD5A1) produced by human keratinocyte cells coupled with the non-radioactive high-performance thin-layer chromatography detection revealed that caffeic acid N-[3,5-bis(trifluoromethyl)phenyl] amide (4) was a promising non-steroidal suppressor, with a half-maximal inhibitory concentration (IC₅₀) of 1.44 ± 0.13 µM and relatively low cytotoxicity with an IC₅₀ of 29.99 ± 8.69 µM. The regulatory role of compound 4 against SRD5A1 involved both suppression of SRD5A1 expression and mixed mode SRD5A1 inhibition. The K_i value of compound 4 was 2.382 µM based on the whole-cell kinetic studies under specific conditions. Molecular docking and molecular dynamics simulations with AlphaFold generated the human SRD5A1 structure and confirmed the stability of compound 4 at the SRD5A1 catalytic site with greater interactions, including hydrogen bonding of the key M119 amino-acid residue than those of finasteride and dutasteride. Thus, compound 4 shows the potential for further development as an SRD5A1 suppressor for androgenic alopecia treatment.

Discovery of Natural Steroid 5 Alpha-Reductase Inhibitors

Human steroid 5 alpha-reductases (S5αRs) and NADPH irreversibly reduce testosterone to the more potent dihydrotestosterone (DHT). S5αR inhibitors are useful treatments for DHT-dependent diseases, including benign prostatic hyperplasia, androgenic alopecia and hair growth, and acne. There are three S5αR isozymes, and there is a need for safer and more isozyme selective inhibitors than finasteride and dutasteride currently licensed. In this study, we review the methods used to screen for S5αR inhibitory activity and describe studies that characterize the ability of herbal preparations and their constituents to inhibit S5αRs. We identified enormous variations between studies in IC₅₀s for finasteride and dutasteride used as standards. Accordingly, we make several recommendations: Stable isozyme specific transfection systems need creating a standardized enzyme/microsome preparation and all three isozymes, as well as androgen receptor binding, should be tested; agreed reaction conditions, especially the substrate concentrations, and separation/quantitation method optimized for high throughput screening; systematic screening of herbal compounds and most extensive use of leads to develop more potent and isozyme specific inhibitors.

Germacrene Analogs are Anti-androgenic on Androgen-dependent Cells

Anti-androgenic drugs are treatments for androgen-related disorders such as benign prostatic hyperplasia, acne, hirsutism, and androgenic alopecia. Germacrone (1), a sesquiterpene isolated from hexane extracts of Curcuma aeruginosa Roxb. rhizome, is an androgen inhibitor of steroid 5-alpha reductase in-vitro. Here, we used the similarity of germacrone's α,ß-unsaturated carbonyl to testosterone's α,ß-unsaturated carbonyl to find germacrene analogs obtained from this plant and by semi-synthesis that might be more potent steroid 5-alpha reductase inhibitors. 8-Hydroxy germacrene B (4) was ~13-fold more potent than its parent, 1 and the most potent (IC50, 0.15±0.022 mM) among 9 compounds tested. The conformation of its cyclodecadiene ring and the α,ß-unsaturated ketone/hydroxy in the germacrene molecule might be crucial role for its anti-androgen activity. Moreover, 1 and 4 showed mild cytotoxic effect on prostate cancer cells. Neither compound was cytotoxic towards human dermal papilla cells at 100 μg/mL. We show that this SAR strategy created promising anti-androgenics for androgen dependent disorders and may create further analogues with further improvements in selectivity and clinical efficacy.

5α-Reductases and Their Inhibitors

5α reductase is a key enzyme in androgen metabolism. Altered enzyme function and/or regulation is responsible for numerous human pathologies such as benign prostatic hyperplasia, acne, hirsutism and male pattern baldness. In order to block androgen action through inhibition of this enzyme, numerous compounds have been synthesized during the past two decades. Among them, 4-azasteroids and in particular finasteride have been extensively studied and used in the treatment of human diseases.

Steroidal pyrazolines and pyrazoles as potential 5α-reductase inhibitors: synthesis and biological evaluation

Taking pregnenolone as the starting material, two series of pyrazolinyl and pyrazolyl pregnenolones were synthesized through different routes. The synthesis of the analogs of both series is multistep and proceeds in good overall yields. While the key step in the synthesis of pyrazolinyl pregnenolones is the heterocyclization of benzylidine derivatives (3) in presence of hydrazine hydrate, it is the condensation of 3β-hydroxy-21-hydroxymethylidenepregn-5-en-3β-ol-20-one (5) with phenylhydrazine in the synthesis of pyrazolyl derivatives. Compounds of both the series were tested for their 5α-reductase inhibitory activities. Amongst all the compounds screened for their 5α-reductase inhibitory activities, compound 4b, 4c and 6b were found to be the most active.

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.

Targeting 5α-reductase for prostate cancer prevention and treatment

Testosterone is the most abundant circulating androgen, and can be converted to dihydrotestosterone (DHT), a more potent androgen, by the 5α-reductase enzymes in target tissues. Current treatments for prostate cancer consist of reducing androgen levels by chemical or surgical castration or pure antiandrogen therapy that directly targets the androgen receptor (AR). Although these therapies reduce tumor burden and AR activity, the cancer inevitably recurs within 18-30 months. An approach targeting the androgen-AR axis at different levels could, therefore, improve the efficacy of prostate cancer therapy. Inhibition of 5α-reductase is one such approach; however, the two largest trials to investigate the use of the 5α-reductase inhibitors (5ARIs) finasteride and dutasteride in patients with prostate cancer have shown that, although the incidence of cancer was reduced by 5ARI treatment, those cancers that were detected were more aggressive than in patients treated with placebo. Thus, the best practice for using these drugs to prevent and treat prostate cancer remains unclear.

Therapeutic options in the treatment of benign prostatic hyperplasia

Current theraputic options for the treatment of symptomatic benign prostatic hyperplasia (BPH) are reviewed. Therapeutic options for mild lower urinary tract symptoms (LUTS), as defined by the American Urological Association, are generally treated medically. Moderate to severe LUTS can be treated medically or with surgical therapy. Current medical and surgical treatments for LUTS secondary to BPH are reviewed and evolving treatments are explored.

New progesterone derivatives as inhibitors of 5α-reductase enzyme and prostate cancer cell growth

In this study we report the synthesis and pharmacological evaluation, in vivo as well as in vitro, of four new progesterone derivatives 4-7. The evaluation in vivo was carried out on gonadectomized male hamsters that were injected subcutaneously daily with 1 mg/Kg of testosterone (T) and/or 1 mg/Kg of finasteride, or with 2 mg/Kg of the novel compounds. It was observed that when testosterone (T) and finasteride or compound 4 were injected together, the weight of the prostate decreased significantly as compared to that oftestosterone-treated animals. Compounds 5-7 did not show any in vivo activity. The 5alpha-reductase inhibitory activity of the novel compounds was determined in vitro using human prostate homogenates; the steroids 4-7 inhibited the 5alpha-reductase activity with IC50 values lower than that for the reference compound finasteride. 3. The effect of compounds 4-7 on the growth of lymphocytes and prostate cancer culture cells line was that steroid 4 inhibited the growth of both cells lines at a concentration of 50 microM and showed a cytotoxic effect whereas compounds 5-7 showed a much lower inhibition. Nevertheless steroids 4-7 didn't exhibit any toxic effects in vivo since the animals remained alive during the six days of treatment.

Combination therapy for the pharmacological management of benign prostatic hyperplasia: rationale and treatment options

The management of symptomatic benign prostatic hyperplasia (BPH) continues to evolve, with new techniques and forms of medical management being introduced and traditional surgical techniques being used less frequently. Medical management of BPH has evolved from nonspecific alpha-adrenoceptor antagonists to uroselective alpha-adrenoceptor antagonists and 5-alpha reductase inhibitors. Traditionally, alpha-adrenoceptor antagonists have been used for relief of lower urinary tract symptoms (LUTS) as a result of BPH and are known for their quick onset of action. 5-alpha Reductase inhibitors have proven useful for the prevention of BPH progression as measured by prostate volume, disease progression, incidence of acute urinary retention and the need for subsequent BPH-related surgery. Recent studies have shown that the combination of an alpha-adrenoceptor antagonist and a 5-alpha reductase inhibitor has significantly better efficacy than either drug alone or placebo. Currently, alpha-adrenoceptor antagonists are used in the acute setting or for short-term relief of LUTS. The combination of an alpha-adrenoceptor antagonist and a 5-alpha reductase inhibitor is used for the longer term management of BPH symptoms and to prevent progression of BPH and perhaps avoid surgical intervention.

Methyl esters of N-(dicyclohexyl)acetyl-piperidine-4-(benzylidene-4-carboxylic acids) as drugs and prodrugs: a new strategy for dual inhibition of 5 alpha-reductase type 1 and type 2

Steroid 5alpha-reductase (5alphaR) inhibitory potency of three N-(dicyclohexyl)acetyl-piperidine-4-(benzylidene-4-carboxylic acids) and their corresponding methyl esters was monitored for type 2 isoenzyme in a benign prostatic hyperplasia cell free preparation and for type 1 isoenzyme in DU145 cells and in a cell free assay. The hydrolytic stability of the esters and their bioconversion to the corresponding acids was assessed in aqueous buffered solution (pH 7.4) and in selected biological media having measurable esterase activities. The carboxylic acids 1, 2, and 3 with high type 2 inhibitory potencies displayed only little type 1 inhibition. The esters 1a, 2a, and 3a, originally designed as prodrugs to enhance cell permeation, proved to be potent type 1 inhibitors and are therefore acting as drugs themselves. They are stable in buffered salt solution (pH 7.4), Caco-2 cells, and human plasma, whereas all esters are cleaved into the corresponding acids in benign prostatic hyperplasia tissue homogenate. Methyl esters, applied as hydrolytically stable precursor drugs to facilitate cell permeation, will yield the corresponding carboxylic acids as type 2 inhibitors after hydrolysis in the target organ. The esters themselves--stable in human plasma and Caco-2 cells--are acting as potent drugs toward 5alphaR type 1. Thus, dual inhibition of 5alphaR type 1 and type 2 can be achieved by applying a single parent compound.

Synthesis and activity of 8-substituted benzo[c]quinolizin-3-ones as dual inhibitors of human 5alpha-reductases 1 and 2

Some potent dual inhibitors of 5alpha-reductases 1 and 2, based on the benzo[c]quinolizin-3-one structure and with IC(50) values ranging between 93 and 166nM for both isozymes, were found. The presence of the F atom on the ester moiety at the position 8 was crucial. This result can help in the design of other potent, dual inhibitors to be developed as drugs in the treatment of 5alpha-reductase related diseases.

Inhibition of type 2 17beta-hydroxysteroid dehydrogenase by estradiol derivatives bearing a lactone on the D-ring: structure-activity relationships

The peripheral conversion of steroid precursors into biologically active forms can be a major source of steroid synthesis, and these steroids support the growth of hormone-dependent diseases. The 17beta-hydroxysteroid dehydrogenase (17beta-HSD) enzyme family is involved in the biosynthesis of active steroids and its inhibition constitutes an interesting approach for treating estrogen- and androgen-dependent cancers. We previously found that a compound formed by the introduction of a spiro-gamma-lactone at position 17 of estradiol (E2) produces a significant inhibition of type 2 17beta-HSD. To optimize the inhibitory potency of such compounds, we synthesized a series of estradiol derivatives bearing a lactone on the D-ring and tested their ability to inhibit the type 2 17beta-HSD transformation of 4-androstenedione into testosterone. The results of our structure-activity relationship study determined the importance of the 17beta-orientation of the oxygen atom. Indeed, the 17beta-O-isomer of spiro-gamma-lactone-E2 is a much more potent inhibitor than the 17alpha-O-analog (respectively 85 and 9% of inhibition at 1 microM). The carbonyl function is essential since the percentage of inhibition shifts from 85 to 30%, 15, or 3%, when the carbonyl group is transformed into a hydroxyl, a methoxy or a methylene (cycloether) group, respectively. Our results lead us to realize the importance of the spirolactone versus the C17beta-O/C16beta lactone (respectively 32 and 2% of inhibition at 0.1 microM, for the same size of lactone ring). The optimal size for the spirolactone was also established to be six members. All the types of substituents (methyl, dimethyl, allyl, propyl, and methoxycarbonyl) that we added on the spiro-delta-lactone moiety decreased the inhibitory activity, suggesting steric restrictions for the space that can be occupied in proximity of the spiro-delta-lactone functionality. 17-(Spiro-delta-lactone)-E2, compound 6, was thus the most potent inhibitor of type 2 17beta-HSD with a K(i) value of 29 +/- 5 nM. This compound reversibly inhibits type 2 17beta-HSD in a non-competitive manner.

Selective non-steroidal inhibitors of 5 alpha-reductase type 1

The enzyme 5 alpha-reductase (5 alpha R) catalyses the reduction of testosterone (T) into the more potent androgen dihydrotestosterone (DHT). The abnormal production of DHT is associated to pathologies of the main target organs of this hormone: the prostate and the skin. Benign prostatic hyperplasia (BPH), prostate cancer, acne, androgenetic alopecia in men, and hirsutism in women appear related to the DHT production. Two isozymes of 5 alpha-reductase have been cloned, expressed and characterized (5 alpha R-1 and 5 alpha R-2). They share a poor homology, have different chromosomal localization, enzyme kinetic parameters, and tissue expression patterns. Since 5 alpha R-1 and 5 alpha R-2 are differently distributed in the androgen target organs, a different involvement of the two isozymes in the pathogenesis of prostate and skin disorders can be hypothesized. High interest has been paid to the synthesis of inhibitors of 5 alpha-reductase for the treatment of DHT related pathologies, and the selective inhibition of any single isozyme represents a great challenge for medical and pharmaceutical research in order to have more specific drugs. At present, no 5 alpha R-1 inhibitor is marketed for the treatment of 5 alpha R-1 related pathologies but pharmaceutical research is very active in this field. This paper will review the major classes of 5 alpha R inhibitors focusing in particular on non-steroidal inhibitors and on structural features that enhance the selectivity versus the type 1 isozyme. Biological tests to assess the inhibitory activity towards the two 5 alpha R isozymes will be also discussed.

Novel 17 Substituted Pregnadiene Derivatives as 5.ALPHA.-Reductase Inhibitors and Their Binding Affinity for the Androgen Receptor

The in vitro antiandrogenic activity of four new progesterone derivatives: 4, 5, 6 and 7 (8 is a known compound) was determined. These compounds were evaluated as 5alpha-reductase inhibitors as well as by their capacity to bind to the androgen receptor in gonadectomized hamster prostate. The IC(50) value was determined using increasing concentrations of 4, 5, 6, 7 and 8 in the presence of [(3)H]T and the microsomal fraction of the hamster prostate containing the 5alpha-reductase enzyme. In this paper we also demonstrated the effect of increasing concentrations of the novel steroids upon [(3)H]DHT binding to the androgen receptors from hamster prostate which produces competition for the androgen receptor sites. The in vitro studies showed that steroids 4, 5, 6, 7 and 8 had an inhibitory activity for the 5alpha-reductase with IC(50) of: 4 (0.17 microM), 5 (0.19 microM), 6 (1 microM), 7 (4.2 microM), and 8 (2.7 microM). On the other hand, the IC(50) value for compounds 4, 5, 6, 7, 8 and DHT showed the following order of affinity for the androgen receptor: 6>7>5>DHT. Surprisingly compounds 4 and 8 did not bind to the androgen receptor. The overall data indicate that all synthesized compounds are inhibitors for the enzyme 5alpha-reductase present in the hamster prostate. In contrast, compounds 5, 6 and 7, which have a cyclohexyl group in the side chain showed a high affinity for the androgen receptor.

Epoxides, cyclic sulfites, and sulfate from natural pentacyclic triterpenoids: theoretical calculations and chemical transformations

Several triterpenic derivatives, with the A-ring functionalized, were semisynthesized from oleanolic and maslinic acids. The reactivities of sulfites, sulfate, and epoxides in these triterpene compounds were investigated under different reaction conditions. Moreover, contracted A-ring triterpenes (five-membered rings) were obtained, by different treatments of the sulfate 7. From the epoxide 8, deoxygenated and halohydrin derivatives were semisynthesized with several nucleophiles. Ozonolysis and Beckmann reactions were used to yield 4-aza compounds, from five-membered ring olanediene triterpenes. The X-ray structure of sulfate 7 is given and compared with density functional theory geometries. Theoretical (13)C and (1)H chemical shifts (gauge-invariant atomic orbital method at the B3LYP/6-31G*//B3LYP/6-31G* level) and (3)J(H,H) coupling constants were calculated for compounds 5-9 and 34-36, identifying the (R)- or (S)-sulfur and alpha- or beta-epoxide configurations together with 4-aza or 3-aza structures.

Molecular Interactions of New Pregnenedione Derivatives

The in vitro inhibitory activity of five new progesterone derivatives: 17alpha-hydroxy-16beta-methylpregna-1,4,6-triene-3,20-dione 1; 16beta-methyl-17alpha-toluoyloxypregna-1,4,6-triene-3,20-dione 2; 17alpha-hydroxy-6-methylenepregn-4-ene-3,20-dione 3; 6-methylene-17alpha-toluoyloxypregn-4ene-3,20-dione 4 and 17alpha-(p-bromobenzoyloxy)-6-methylenepregn-4-ene-3,20-dione 5 was determined. These compounds were evaluated as 5alpha-reductase inhibitors as well as antagonists for the androgen receptor. Compounds 1, 2, 3, 4 and 5 showed the following inhibitory activity for the 5alpha-reductase enzyme with IC(50) values of: 1 (1.65 microM), 2 (10 microM), 3 (19 nM), 4 (100 nM) and 5 (100 nM). The results of this study also showed the effect of increasing concentrations of the novel steroids upon [(3)H]dihydrotestosterone binding to androgen receptors from male hamster prostate. The K(i) values for compounds 1, 2, 3, 4, 5 and dihydrotestosterone showed the following order of affinity for the androgen receptor: 4>5>dihydrotestosterone>2>3>1. The overall data indicated that all synthesized compounds 1, 2, 3, 4 and 5 are inhibitors of the 5alpha-reductase enzyme present in the hamster prostate. In addition compounds 1, 2, 3, 4 and 5 also presented an affinity for the androgen receptor.

Cutaneous androgen metabolism: basic research and clinical perspectives

The skin, especially the pilosebaceous unit composed of sebaceous glands and hair follicles, can synthesize androgens de novo from cholesterol or by locally converting circulating weaker androgens to more potent ones. As in other classical steroidogenic organs, the same six major enzyme systems are involved in cutaneous androgen metabolism, namely steroid sulfatase, 3beta-hydroxy-steroid dehydrogenase, 17beta-hydroxysteroid dehydrogenase, steroid 5alpha-reductase, 3alpha-hydroxysteroid dehydrogenase, and aromatase. Steroid sulfatase, together with P450 side chain cleavage enzyme and P450 17-hydroxylase, was found to reside in the cytoplasm of sebocytes and keratinocytes. Strong steroid sulfatase immunoreactivity was observed in the lesional skin but not in unaffected skin of acne patients. 3beta-hydroxysteroid dehydrogenase has been mainly immunolocalized to sebaceous glands, with the type 1 being the key cutaneous isoenzyme. The type 2 17beta-hydroxysteroid dehydrogenase isoenzyme predominates in sebaceous glands and exhibits greater reductive activity in glands from facial areas compared with acne nonprone areas. In hair follicles, 17beta-hydroxysteroid dehydrogenase was identified mainly in outer root sheath cells. The type 1 5alpha-reductase mainly occurs in the sebaceous glands, whereby the type II isoenzyme seems to be localized in the hair follicles. 3alpha-hydroxysteroid dehydrogenase converts dihydrotestosterone to 3alpha-androstanediol, and the use of 3alpha-androstanediol glucuronide serum level to reflect the hyperandrogenic state in hirsute women may be a reliable parameter, especially for idiopathic hirsutism. In acne patients it is still controversial if 3alpha-androstanediol glucuronide or androsterone glucuronide could serve as suitable serum markers for measuring androgenicity. Aromatase, localized to sebaceous glands and to both outer as well as inner root sheath cells of anagen terminal hair follicles, may play a "detoxifying" role by removing excess androgens. Pharmacologic development of more potent specific isoenzyme antagonists may lead to better clinical treatment or even prevention of androgen-dependent dermatoses.

Type-1 steroid 5 alpha-reductase is functionally active in the hair follicle as evidenced by new selective inhibitors of either type-1 or type-2 human steroid 5 alpha-reductase

Steroid 5 alpha-reductase catalyzes the reduction of testosterone (T) into the very potent androgen dihydrotestosterone (DHT). The different tissue expression patterns of the two isoforms of 5 alpha-reductase, namely type-1 and type-2 5 alpha-reductase (5 alpha-R1 and 5 alpha-R2, respectively), have prompted studies directed towards the synthesis of selective 5 alpha-R1 or 5 alpha-R2 inhibitors. In this present work, we have performed a structure/activity study on the inhibitory potential of indole carboxylic acids against hair follicle 5 alpha-reductase activity. We have demonstrated that this class of molecules were potent inhibitors of either 5 alpha-R1 or 5 alpha-R2 or both depending on (i) substituents in positions 4, 5 or 6 and (ii) the presence of a free carboxylic group. We have also found that only 5 alpha-R1 or 5 alpha-R1/R2 inhibitors were able to inhibit 5 alpha-reductase activity in plucked hairs from female volunteers or in freshly isolated female hair follicles, selective 5 alpha-R2 inhibitors being inactive.

Caution on the use of saliva measurements to monitor absorption of progesterone from transdermal creams in postmenopausal women

OBJECTIVES

To determine the levels of progesterone in plasma, red cells and saliva as well as pregnanediol-3-glucuronide excretion in postmenopausal women using transdermal progesterone creams.

METHODS

A double-blind placebo controlled study was carried out using 24 postmenopausal women. Creams (placebo, 20 or 40 mg progesterone/g) were applied twice daily for 3 weeks followed by 1 week without before a further 3-week treatment. Morning samples were collected at 0, 1, 3, 4, 7 and 8 weeks for analysis.

RESULTS

There were small increases in plasma progesterone levels and pregnanediol-3-glucuronide excretion compared to the placebo group and red cell progesterone levels never exceeded plasma levels during progesterone cream use. Saliva progesterone levels were very high and variable in the progesterone cream groups compared to the placebo group and presented a paradox to the usual relationship observed between plasma and saliva progesterone in premenopausal women.

CONCLUSION

The absorption of progesterone from transdermal creams is low and we caution against the use of saliva measurements to monitor progesterone absorption. The low systemic absorption of progesterone may not be due to peripheral conversion by 5 alpha-reductase(s). We also conclude that the low level of progesterone associated with red cells suggests they are not important in the delivery of progesterone to target tissues.

Stable expression of human 5alpha-reductase type II in COS1 cells due to chromosomal gene integration: a novel tool for inhibitor identification

Inhibitors of human 5alpha-reductase type II are promising drug candidates for the treatment of benign prostatic hyperplasia which is associated with high prostatic DHT levels. In this study we describe the evaluation of potential inhibitors in a new cell assay. First a plasmid (pRcCMV-5alphaII) for the expression of human 5alpha-reductase type II was constructed by the use of the vector pRcCMV and transfected into the African green monkey fibroblast-like cell line COS1. By selection with G418 sulfate, ten COS1 single cell clones were obtained of which three stably exhibited high 5alpha-reductase activity. One single cell clone (COS1-5alphaIIST) was selected for further investigations. By Southern blot analysis, fluorescence in situ hybridization (FISH) and comparative PCR experiments it turned out that the expression plasmid pRcCMV-5alphaII has been integrated into the chromosome, resulting in a long-term stable expression of the foreign 5alpha-reductase gene. The newly established cell line was used for testing novel compounds on their inhibitory effect on human 5alpha-reductase type II. Using this whole cell assay, inhibitors with IC(50) values in the nanomolar range could be identified.

Effect of C-ring modifications in benzo[c]quinolizin-3-ones, new selective inhibitors of human 5 alpha-reductase 1

The synthesis and the inhibition potency of octahydro- and decahydrobenzo[c]quinolizin-3-one derivatives 3--7, as new non-steroidal selective inhibitors of human enzyme 5 alpha-reductase type 1, are reported. These compounds differ from the recently reported benzo[c]quinolizin-3-one inhibitors 2 by the presence of a fully or partially saturated C-ring. Compounds 3 and 4, with a double bond in the C-ring, were prepared by sequential rearrangement-annulation of isoxazolines 19 and 20. C-ring saturated compounds 5--7 were prepared by the Lewis acid-promoted Mannich-Michael tandem reaction of Danishefsky diene with the appropriate N-t-Boc iminium ion. Inhibition experiments were carried out on 5 alpha R-1 and 5 alpha R-2 expressed by CHO cells. Among the prepared compounds, octahydrobenzo[c]quinolizin-3-one 3, with a double bond at the position 6a--10a, was a potent and selective inhibitor of human 5 alpha R-1 (IC(50)=58 nM). The introduction of a tert-butylcarboxyamide at the position 8 (compound 4) was deleterious for the inhibition activity. The lack of the double bond in the C-ring reduced strongly the inhibition activity of compounds 5--7. The extended planarity of the most potent benzo[c]quinolizin-3-ones as well as favorable interactions of the C-ring unsaturation with the enzyme active site could account for the inhibition activity of these compounds.

Androsterone 3beta-substituted derivatives as inhibitors of type 3 17beta-hydroxysteroid dehydrogenase

Androsterone derivatives substituted at position 3 were synthesized starting from dihydrotestosterone in a short sequence of reactions. They proved to be potent inhibitors (IC50 = 57-147 nM) of type 3 17beta-hydroxysteroid dehydrogenase, a key enzyme of steroidogenesis, which catalyzes the transformation of androstenedione to steroid active androgen testosterone.

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).

New nonsteroidal steroid 5 alpha-reductase inhibitors. Syntheses and structure-activity studies on carboxamide phenylalkyl-substituted pyridones and piperidones

In the search for nonsteroidal inhibitors of 5 alpha-reductase for the treatment of benign prostatic hyperplasia (BPH), we synthesized diisopropyl (1a-8a) and tert-butyl (1b-8b) benzamides, as well as ethyl benzoates (1c, 3c), which were substituted in 4 position via variable alkyl spacer (n = 0: 1-4, n = 1: 5, 7 and n = 3: 6, 8) with a 1-methyl-2-pyridone (1, 2, 5, 6) or a 1-methyl-2-piperidone (3, 4, 7, 8) moiety mimicking steroidal ring A. The directly connected benzamides (1a-4a, 1b-4b) and benzoates (1c, 3c) were obtained by palladium-catalysed coupling reaction of diethyl(3-pyridyl)-borane with 4-bromobenzoic acid derivatives, followed by alpha-oxidation of the 1-methyl-pyridinium salt and subsequent separation of the regioisomers. Catalytic hydrogenation of the pyridones (1, 2) led to the piperidones (3, 4). The preparation of the benzamides with a methylene (5, 7) and a propylene spacer (6, 8), respectively, started with the reduction of the keto group of 5-benzoyl-1,2-dihydro-1-methyl-2(1H)-pyridone and catalytic hydrogenation of the alkene obtained by Wittig reaction of 5-formyl-1,2-dihydro-1-methyl-2(1H)-pyridone with (2-phenylethyl)triphenylphosphonium bromide, respectively. The phenyl ring was functionalized by Friedel-Crafts reaction, haloform cleavage to give the acid, formation of the acid chloride, and subsequent treatment with the appropriate amines. Again, catalytic hydrogenation of the pyridones (5, 6) led to the piperidones (7, 8). The 5 alpha-reductase inhibitory properties were determined using rat ventral prostate, as well as human BPH tissue as enzyme source, 1 beta-2 beta-[3H]testosterone as substrate and a HPLC procedure for the separation of dihydrotestosterone (DHT). Tested at a concentration of 100 microM, the inhibition values of 1-8 ranged from 0-79%. Significant differences were observed between rat and human enzyme. The most active compound was ethyl 4-(1-methyl-2-oxopiperid-5-yl)benzoate 3c (68%) for the human enzyme and N,N-bis(1-methylethyl)-4-[3-(1,2-dihydro-1-methyl-2-oxopyrid-5-yl) propyl] benzamide 6a (79%) for the rat enzyme.

N-substituted 4-(5-indolyl)benzoic acids. Synthesis and evaluation of steroid 5alpha-reductase type I and II inhibitory activity

The synthesis of N-alkyl and N-arylalkyl substituted 4-(5-indolyl)benzoic acid derivatives as inhibitors of steroid 5alpha-reductases is described. For the human type II isozyme a benzyl substituent (IC50 6.20 microM) and for the human type I isozyme a cyclohexanemethyl substituent (IC50 2.10 microM) on the indole nitrogen proved to be most efficacious, thus providing interesting leads for the development of drugs for the treatment of benign prostatic hyperplasia (BPH).

Site-directed mutagenesis studies of the NADPH-binding domain of rat steroid 5alpha-reductase (isozyme-1) I: analysis of aromatic and hydroxylated amino acid residues

Previous studies have shown that the reduced nicotinamide adenine dinucleotide phosphate (NADPH)- binding domain of rat liver microsomal steroid 5alpha-reductase isozyme-1 (r5alphaR-1) is in a highly conserved region of the polypeptide sequence (residues 160-190). In this study, we investigated, by site-directed mutagenesis, the role of hydroxylated and aromatic amino acids within the NADPH-binding domain. The r5alphaR-1 cDNA was cloned into a pCMV vector, and the double strand site-directed mutagenesis method was used to create mutants Y179F, Y179S, Y189F, Y189S, S164A, S164T, and Y187F, which were subsequently expressed in COS-1 cells. Kinetic studies of the expressed enzymes showed that the mutation Y179F resulted in an approximately 40-fold increase in the Km for NADPH versus wild-type, with only a 2-fold increase in the Km for testosterone. The mutants Y189F and S164A showed smaller increases (4 and 6-fold) in Kms for NADPH and no significant change in the Km for testosterone, whereas Y189S had kinetic properties similar to the wild-type r5alphaR-1. Mutants Y179S and S164T both resulted in inactive enzymes, whereas F187Y showed an approximately 5-fold decrease in Km for NADPH and a significant increase (approximately 18-fold) in the Km for testosterone. The results suggest that the -OH functionality of Y179 is involved in cofactor binding, but is not essential for the activity of the enzyme, whereas the -OH functionalities of Y189 and S164 play lesser roles in cofactor binding to r5alphaR-1 and may not be required for enzyme activity. On the other hand, the residue F187 may be important for the binding of both NADPH and testosterone.

Synthesis of benzanilide derivatives as dual acting agents with alpha 1-adrenoceptor antagonistic action and steroid 5-alpha reductase inhibitory activity

Synthesis of benzanilide derivatives which have dual alpha 1-adrenoceptor antagonistic action and steroid 5 alpha-reductase inhibitory activity and their structure-activity relationships is described.

Synthesis of benzo[c]quinolizin-3-ones: selective non-steroidal inhibitors of steroid 5 alpha-reductase 1

A short and efficient synthesis of novel benzo[c]quinolizin-3-one derivatives is described. The synthesis is based on the tandem Mannich-Michael cyclization between 2-silyloxy-1,3-butadienes and a N-t-Boc iminium ion. The prepared derivatives are selective inhibitors of human steroid 5 alpha-reductase isoenzyme 1, thus having potential application as drugs for treatment of male pattern baldness and other DHT-dependent skin disorders.

5 alpha-reductase inhibitors, chemical and clinical models

An active site model of 5 alpha-reductase type 2 isoenzyme on an "active-analog approach" and based on 4-azasteroidal inhibitors has been constructed to evaluate the effects on the inhibitory potency of substituents on the steroid A ring. This model has proven able to predict the potential inhibitory activity of 19-nor-10-azasteroid and 6-azasteroid compounds. A model for the evaluation of clinical efficacy of an inhibitor, based on in vitro data, has also been developed and applied to finasteride. This inhibitory potency evaluation of finasteride in human scalp homogenates, plus pharmacokinetic data, allows the calculation of a theoretical in situ inhibition value for human scalp. From the IC50 curve of finasteride in scalp homogenates, it is possible to calculate that for an inhibition level similar to that obtained in prostate with 5 mg of finasteride, the necessary plasma concentration of the drug is 1 microM, a level obtained after the acute administration of 50 mg of finasteride.

The effects of progesterone, 4,16-androstadien-3-one and MK-434 on the kinetics of pig testis microsomal testosterone-4-ene-5alpha-reductase activity

The enzyme 3-oxo-steroid: NADP+ 4-oxidoreductase (EC 1.3.1.22; 5alpha-reductase) was assayed in testicular microsomes of pigs of 3, 20 and 24 weeks of age. The activity was very low in 3-week-old animals and approximately 10-fold higher in 5- and 6-month-old pigs. The pH optimum was 6.3 in 6-month-old animals, 5.7 in 5-month-old animals, but could not be reliably determined in 3-week-old animals. The kinetic parameters for 5alpha-reductase in testis microsomes from 6-month-old animals were; K((m)(app)), 8.0 micromol/l, V((max)(app)), 6.7 nmoles/90 min/mg protein. Progesterone was a competitive inhibitor of testosterone 5alpha-reduction with an apparent K((i)(app)) of 0.86 micromol/l. However, 4,16-androstadien-3-one (dienone), which undergoes 5alpha-reduction in the biosynthesis of the pheromonally active 16-androstenes, was a comparatively poor inhibitor with a K((i)(app)) of 4.9 micromol/l. Similarly, MK434, which is a selective inhibitor of the human type 2 5alpha-reductase, but which inhibits both types 1 and 2 in the rat, was also a poor competitive inhibitor of testosterone 5alpha-reductase in the pig testis (K((i)(app)), 3.1 micromol/l). It would appear from these studies that the pig testis microsomal 5alpha-reductase corresponds to a type 1 isozyme that is not capable of reducing dienone other than under conditions where the dienone concentration would be in considerable excess of testosterone. It is, therefore, probable that substrate-specific 5alpha-reductases exist in the pig testis for the 5alpha-reduction of testosterone and dienone.

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.

Evidence for the involvement of 3-oxo-delta 4 intermediates in ecdysteroid biosynthesis

Although the involvement of 3-oxo-delta 4 compounds as intermediates in arthropod ecdysteroid biosynthesis has been postulated for a long time, it has not yet been directly demonstrated. In the present study, 3-oxo-delta 4-steroids have been synthesized and incubated in vitro with dissociated moulting gland cells from the crab Carcinus maenas. The tritiated compounds were converted into 3-dehydroecdysone, ecdysone and/or 25-deoxyecdysone, i.e. final ecdysteroids. This means that the 3-oxo-delta 4 compounds had undergone a 5 beta-reduction, to give the 5 beta-conformation of ecdysteroids. Our results suggest that the 3-oxo-delta 4-steroid 4,7-cholestadien-14 alpha-ol-3,6-dione may be an intermediate in the biosynthetic pathway. The 5 beta-reduction reaction involves a cytosolic enzyme which requires NADPH as electron donor and seems specific for 3-oxo-delta 4 substrates. This reaction was the most active in crab Y-organs, as compared with other tissues. The characteristics of the 5 beta-reductase (subcellular localization, substrate and cofactor requirements) appear similar to those of the vertebrate 3-oxo-delta 4-steroid 5 beta-reductase involved in steroid hormone catabolism and bile acid biosynthesis.

Outcome of long-term treatment with the 5 alpha-reductase inhibitor finasteride in idiopathic hirsutism: clinical and hormonal effects during a 1-year course of therapy and 1-year follow-up

OBJECTIVE

To evaluate the long-term efficacy of the 5 alpha-reductase inhibitor finasteride in idiopathic hirsutism.

DESIGN

Prospective clinical study.

SETTING

Outpatients in a university hospital.

PATIENT(S)

Fourteen young women with idiopathic hirsutism.

INTERVENTION(S)

Finasteride, 5 mg once daily, was given for 12 months.

MAIN OUTCOME MEASURE(S)

Degree of hirsutism, graded by a modified Ferriman and Gallwey score, serum sex hormones, and serum and urinary markers of 5 alpha-reductase activity. Clinical outcome was evaluated up to and including the 1-year post-treatment period.

RESULT(S)

The Ferriman and Gallwey score showed a remarkable reduction after 12 months of finasteride treatment (4.4 +/- 0.7 versus 11.8 +/- 1.0; mean +/- SEM). Serum levels of the two 5 alpha-reductase activity markers, dihydrotestosterone and 3 alpha-androstanediol glucuronide, decreased, and urinary C19 and C21 5 beta:5 alpha steroid metabolite ratios consistently increased during finasteride administration. These changes were reversed readily after cessation of treatment. No significant adverse effect was reported. Nine of 14 women completed the 1-year post-treatment follow-up. Their hirsutism scores were increased substantially as compared with values recorded at the end of therapy, but still were lower than baseline values.

CONCLUSION(S)

The 5 alpha-reductase inhibitor finasteride is effective and well tolerated in longterm treatment of women with idiopathic hirsutism. Post-treatment follow-up suggests that drug effects on hair growth are sustained in the majority of subjects with this disorder.