Carbon-chain length determines the binding affinity and inhibitory strength of per- and polyfluoroalkyl substances on human and rat steroid 5α-reductase 1 activity.

Per- and polyfluoroalkyl substances (PFAS) are widely used synthetic chemicals that persist in the environment and bioaccumulate in animals and humans. There is growing evidence that PFAS exposure adversely impacts neurodevelopment and neurological health. Steroid 5α-reductase 1 (SRD5A1) plays a key role in neurosteroidogenesis by catalyzing the conversion of testosterone or pregnenolone to neuroactive steroids, which influence neural development, cognition, mood, and behavior. This study investigated the inhibitory strength and binding interactions of 18 PFAS on human and rat SRD5A1 activity using enzyme assays, molecular docking, and structure-activity relationship analysis. Results revealed that C9-C14 PFAS carboxylic acid at 100 µM significantly inhibited human SRD5A1, with IC50 values ranged from 10.99 µM (C11) to 105.01 µM (C14), and only one PFAS sulfonic acid (C8S) significantly inhibited human SRD5A1 activity, with IC50 value of 8.15 µM. For rat SRD5A1, C9-C14 PFAS inhibited rat SRD5A1, showing the similar trend, depending on carbon number of the carbon chain. PFAS inhibit human and rat SRD5A1 in a carbon chain length-dependent manner, with optimal inhibition around C11. Kinetic studies indicated PFAS acted through mixed inhibition. Molecular docking revealed PFAS bind to the domain between NADPH and testosterone binding site of both SRD5A1 enzymes. Inhibitory potency correlated with physicochemical properties like carbon number of the carbon chain. These findings suggest PFAS may disrupt neurosteroid synthesis and provide insight into structure-based inhibition of SRD5A1.

Cluster Analysis of Medicinal Plants and Targets Based on Multipartite Network.

Network-based methods for the analysis of drug-target interactions have gained attention and rely on the paradigm that a single drug can act on multiple targets rather than a single target. In this study, we have presented a novel approach to analyze the interactions between the chemicals in the medicinal plants and multiple targets based on the complex multipartite network of the medicinal plants, multi-chemicals, and multiple targets. The multipartite network was constructed via the conjunction of two relationships: chemicals in plants and the biological actions of those chemicals on the targets. In doing so, we introduced an index of the efficacy of chemicals in a plant on a protein target of interest, called target potency score (TPS). We showed that the analysis can identify specific chemical profiles from each group of plants, which can then be employed for discovering new alternative therapeutic agents. Furthermore, specific clusters of plants and chemicals acting on specific targets were retrieved using TPS that suggested potential drug candidates with high probability of clinical success. We expect that this approach may open a way to predict the biological functions of multi-chemicals and multi-plants on the targets of interest and enable repositioning of the plants and chemicals.

Crystal structure of steroid reductase SRD5A reveals conserved steroid reduction mechanism.

Steroid hormones are essential in stress response, immune system regulation, and reproduction in mammals. Steroids with 3-oxo-Δ4 structure, such as testosterone or progesterone, are catalyzed by steroid 5α-reductases (SRD5As) to generate their corresponding 3-oxo-5α steroids, which are essential for multiple physiological and pathological processes. SRD5A2 is already a target of clinically relevant drugs. However, the detailed mechanism of SRD5A-mediated reduction remains elusive. Here we report the crystal structure of PbSRD5A from Proteobacteria bacterium, a homolog of both SRD5A1 and SRD5A2, in complex with the cofactor NADPH at 2.0 Å resolution. PbSRD5A exists as a monomer comprised of seven transmembrane segments (TMs). The TM1-4 enclose a hydrophobic substrate binding cavity, whereas TM5-7 coordinate cofactor NADPH through extensive hydrogen bonds network. Homology-based structural models of HsSRD5A1 and -2, together with biochemical characterization, define the substrate binding pocket of SRD5As, explain the properties of disease-related mutants and provide an important framework for further understanding of the mechanism of NADPH mediated steroids 3-oxo-Δ4 reduction. Based on these analyses, the design of therapeutic molecules targeting SRD5As with improved specificity and therapeutic efficacy would be possible.

Structure of human steroid 5α-reductase 2 with the anti-androgen drug finasteride.

Human steroid 5α-reductase 2 (SRD5A2) is an integral membrane enzyme in steroid metabolism and catalyzes the reduction of testosterone to dihydrotestosterone. Mutations in the SRD5A2 gene have been linked to 5α-reductase deficiency and prostate cancer. Finasteride and dutasteride, as SRD5A2 inhibitors, are widely used antiandrogen drugs for benign prostate hyperplasia. The molecular mechanisms underlying enzyme catalysis and inhibition for SRD5A2 and other eukaryotic integral membrane steroid reductases remain elusive due to a lack of structural information. Here, we report a crystal structure of human SRD5A2 at 2.8 Å, revealing a unique 7-TM structural topology and an intermediate adduct of finasteride and NADPH as NADP-dihydrofinasteride in a largely enclosed binding cavity inside the transmembrane domain. Structural analysis together with computational and mutagenesis studies reveal the molecular mechanisms of the catalyzed reaction and of finasteride inhibition involving residues E57 and Y91. Molecular dynamics simulation results indicate high conformational dynamics of the cytosolic region that regulate NADPH/NADP+ exchange. Mapping disease-causing mutations of SRD5A2 to our structure suggests molecular mechanisms for their pathological effects. Our results offer critical structural insights into the function of integral membrane steroid reductases and may facilitate drug development.

Expression in Escherichia Coli, Purification, and Functional Reconstitution of Human Steroid 5α-Reductases.

The potent androgen 5α-dihydrotestosterone irreversibly derives from testosterone via the activity of steroid 5α-reductases (5αRs). The major 5αR isoforms in most species, 5αR1 and 5αR2, have not been purified to homogeneity. We report here the heterologous expression of polyhistidine-tagged, codon-optimized human 5αR1 and 5αR2 cDNAs in Escherichia coli. A combination of the nonionic detergents Triton X-100 and Nonidet P-40 enabled solubilization of these extremely hydrophobic integral membrane proteins and facilitated purification with affinity and cation-exchange chromatography methods. For functional reconstitution, we incorporated the purified isoenzymes into Triton X-100-saturated dioleoylphosphatidylcholine liposomes and removed excess detergent with polystyrene beads. Kinetic studies indicated that the 2 isozymes differ in biochemical properties, with 5αR2 having a lower apparent Km for testosterone, androstenedione, progesterone, and 17-hydroxyprogesterone than 5αR1; however, 5αR1 had a greater capacity for steroid conversion, as reflected by a higher Vmax than 5αR2. Both enzymes preferred progesterone as substrate over other steroids, and the catalytic efficiency of purified reconstituted 5αR2 exhibited a sharp pH optimum at pH 5. Intriguingly, we found that the prostate-cancer drug-metabolite 3-keto-∆ 4-abiraterone is metabolized by 5αR1 but not 5αR2, which may serve as a structural basis for isoform selectivity and inhibitor design. The functional characterization results with the purified reconstituted isoenzymes paralleled trends obtained with HEK-293 cell lines stably expressing native 5αR1 and 5αR2. Access to purified human 5αR1 and 5αR2 will advance studies of these important enzymes and might help to clarify their contributions to steroid anabolism and catabolism.

Mutational analysis of SRD5A2: From gene to functional kinetics in individuals with steroid 5α-reductase 2 deficiency.

Human steroid 5α-reductase 2 (SRD5A2) plays a determinative role in the masculinization of external genitalia. To date, approximately 114 different mutations of the SRD5A2 gene have been reported; however, little information is available about their impact on catalytic function or their three-dimensional (3D) structures. We determined the effect of point mutations on the testosterone-depend kinetic constants (Km,app and Vmax,app) and structural characteristics of SRD5A2 from Mexican patients with 46,XY-steroid 5α-reductase 2 deficiency. PCR-SSCP assays identified ten distinct gene variants and sequencing analysis identified missense mutations [p.V3I, p.S14R, p.A52T, p.F118L, p.R145W, p.R171S, p.L226P, p.F229S, p.S245Y, and p.A248V]. Mutations were re-created by site-directed mutagenesis and expressed in HEK293 cells. Functional studies demonstrated that 8 variants led to partial (Km,app = 0.16-2.6 µM; Vmax,app = 224-2640 pmol/mg P/min) or complete losses of activity compared to the wild-type enzyme (Km,app = 0.7 µM; Vmax,app = 4044 pmol/mg P/min). All the mutations were assessed using multiple software tools and the results predicted that all of the mutations were associated with disease or damage. Mapping mutations on the model of a 3D structure of SRD5A2 demonstrated alterations in contact sites with their proximal amino acids. Our data show that mutations affect the catalytic efficiency (Vmax/Km) or result in residual enzymatic activity, which could be due to erroneous interactions between amino acid residues, the substrate testosterone, or NADPH.

Review of SRD5A3 Disease-Causing Sequence Variants and Ocular Findings in Steroid 5α-Reductase Type 3 Congenital Disorder of Glycosylation, and a Detailed New Case.

Steroid 5α-reductase type 3 congenital disorder of glycosylation (SRD5A3-CDG) is a severe metabolic disease manifesting as muscle hypotonia, developmental delay, cerebellar ataxia and ocular symptoms; typically, nystagmus and optic disc pallor. Recently, early onset retinal dystrophy has been reported as an additional feature. In this study, we summarize ocular phenotypes and SRD5A3 variants reported to be associated with SRD5A3-CDG. We also describe in detail the ophthalmic findings in a 12-year-old Czech child harbouring a novel homozygous variant, c.436G>A, p.(Glu146Lys) in SRD5A3. The patient was reviewed for congenital nystagmus and bilateral optic neuropathy diagnosed at 13 months of age. Examination by spectral domain optical coherence tomography and fundus autofluorescence imaging showed clear signs of retinal dystrophy not recognized until our investigation. Best corrected visual acuity was decreased to 0.15 and 0.16 in the right and left eye, respectively, with a myopic refractive error of -3.0 dioptre sphere (DS) / -2.5 dioptre cylinder (DC) in the right and -3.0 DS / -3.0 DC in the left eye. The proband also had optic head nerve drusen, which have not been previously observed in this syndrome.

In silico and functional studies reveal novel loss-of-function variants of SRD5A2, but no variants explaining excess 5α-reductase activity.

Androgens are steroid hormones essential for human male and female development. Steroid reductases 5α (SRD5As) are key enzymes in androgen biosynthesis. Mutations in the human SRD5A2 are known to cause loss-of-function and severe 46,XY undervirilization. Gain-of-function variants have been suggested in androgen excess syndromes, but have not been found so far. Therefore we searched for gain-of-function mutations in the human SRD5A2 gene which might explain hyperandrogenic disorders such as the polycystic ovary syndrome, premature adrenarche and prostate cancer. We screened databases for candidate variants and characterised them in silico with the help of a novel SRD5A2 model. We selected 9 coding SNPs (A49T, R50A, P106L, P106A, N122A, L167S, R168C, P173S, R227Q) that have not been described in manifesting individuals, and assessed their enzyme kinetic properties in HEK293 cells. SRD5A2 activity was assessed by conversion of testosterone (T), progesterone (Prog) and androstenedione (Δ4A) to their 5α-reduced metabolites. Variants R50A and P173S showed partial activity with substrates T (34% and 28%) and Δ4A (37% and 22%). With substrate Prog variants P106L, P106A, L167S and R168C in addition showed partial activity (15% to 64%). Functional testing of all other variants showed loss-of-function. As predicted in our in silico analysis, all coding SNPs affected enzyme activity, however none of them showed gain-of-function. Thus excess 5α-reductase activity might be rather regulated at the (post)-transcriptional and/or post-translational level. However through this work seven new coding SNPs were characterised which might be of clinical relevance. It is possible that individuals carrying these SNPs show a minor phenotype that is not yet identified.

Homology Modeling of 5-alpha-Reductase 2 Using Available Experimental Data.

5-Alpha-reductase 2 is an interesting pharmaceutical target for the treatment of several diseases, including prostate cancer, benign prostatic hyperplasia, male pattern baldness, acne, and hirsutism. One of the main approaches in computer aided drug design is structure-based drug discovery. However, the experimental 3D structure of 5-alpha-reductase 2 is not available at present. Therefore, a homology modeling method and molecular dynamics simulation were used to develop a reliable model of 5-alpha-reductase 2 for inhibitor pose prediction and virtual screening. Despite the low sequence identity between the target and template sequences, a useful 3D model of 5-alpha-reductase 2 was generated by the inclusion of experimental data.

The herbicide atrazine affects sperm quality and the expression of antioxidant and spermatogenesis genes in zebrafish testes.

The herbicide atrazine (ATZ) is used worldwide in the control of annual grasses and broad-leaved weeds. The present study evaluated sperm quality parameters in zebrafish Danio rerio after 11-day exposure to nominal ATZ concentrations of 2, 10, and 100 µg L-1. All ATZ concentrations caused a decrease in motility, mitochondrial functionality, and membrane integrity, as measured using conventional microscopy or fluorescence microscopy with specific probes. The DNA integrity of sperm was not affected. The levels of expression of genes related to spermatogenesis, antioxidant defenses, and DNA repair were also investigated using RT-qPCR. The ATZ caused transcriptional repression of the spermatogenesis-related genes SRD5A2 and CFTR, the antioxidant defense genes SOD2 and GPX4B, and the DNA repair gene XPC. This is the first study to show that environmentally relevant concentrations of ATZ significantly affect the sperm quality in fish, possibly resulting in reduced fertility rates. In addition, we showed that the repression of genes related to spermatogenesis and cellular defense could be part of the mechanisms involved in the ATZ toxicity in the testes of male fish.

Ziram inhibits rat neurosteroidogenic 5α-reductase 1 and 3α-hydroxysteroid dehydrogenase.

The neurotoxicity of ziram is largely unknown. In this study, we investigated the direct inhibitions of ziram on rat neurosteroid synthetic and metabolizing enzymes, 5α-reductase 1 (SRD5A1), 3α-hydroxysteroid dehydrogenase (AKR1C14), and retinol dehydrogenase 2 (RDH2). Rat SRD5A1, AKR1C14, and RDH2 were cloned and transiently expressed in COS1 cells, and the effects of ziram on these enzymes were measured. Ziram inhibited rat SRD5A1 and AKR1C14 with IC50 values of 1.556 ± 0.078 and 1.017 ± 0.072 µM, respectively, when 1000 nM steroid substrates were used. Ziram weakly inhibited RDH2 at 100 µM, when androstanediol (1000 nM) was used. Ziram competitively inhibited SRD5A1 and non-competitively inhibited AKR1C14 when steroid substrates were used. Docking study showed that ziram bound to NADPH-binding pocket of AKR1C14. In conclusion, our results demonstrated that ziram inhibited SRD5A1 and AKR1C14 activities, thus possibly interfering with neurosteroid production in rats.

Apigenin inhibits rat neurosteroidogenic 5α-reductase 1 and 3α-hydroxysteroid dehydrogenase.

Apigenin, a common flavonoid, has extensive pharmacological activities. Apigenin inhibits some steroid biosynthetic enzymes, suggesting that it may block neurosteroid synthesis. Neurosteroids play many important roles in neurological functions. The objective of the present study is to investigate effects of apigenin on neurosteroidogenic enzymes, 5α-reductase 1 (SRD5A1), 3α-hydroxysteroid dehydrogenase (AKR1C9), and retinol dehydrogenase 2 (RoDH2), in rats. SRD5A1, AKR1C9, and RoDH2 were expressed in COS-1 cells and the effects of apigenin on these enzymes and modes of action were explored using radiolabeled substrates and thin-layer chromatographic separation coupled with radiometry. Apigenin inhibited SRD5A1, AKR1C9, and RoDH2 activities with IC50 values of 100, 0.891 ± 0.065, and >100 µM, respectively. Apigenin competitively inhibited rat AKR1C9 when its substrate 5α-dihydrotestosterone was used and uncompetitively inhibited the enzyme when cofactor NADPH was used. In conclusion, apigenin is a potent inhibitor of rat AKR1C9, thereby controlling the rate of neurosteroid biosynthesis.

Studies on Chromatographic Fingerprint and Fingerprinting Profile-Efficacy Relationship of Saxifraga stolonifera Meerb.

This work investigated the spectrum-effect relationships between high performance liquid chromatography (HPLC) fingerprints and the anti-benign prostatic hyperplasia activities of aqueous extracts from Saxifraga stolonifera. The fingerprints of S. stolonifera from various sources were established by HPLC and evaluated by similarity analysis (SA), hierarchical clustering analysis (HCA) and principal component analysis (PCA). Nine samples were obtained from these 24 batches of different origins, according to the results of SA, HCA and the common chromatographic peaks area. A testosterone-induced mouse model of benign prostatic hyperplasia (BPH) was used to establish the anti-benign prostatic hyperplasia activities of these nine S. stolonifera samples. The model was evaluated by analyzing prostatic index (PI), serum acid phosphatase (ACP) activity, concentrations of serum dihydrotestosterone (DHT), prostatic acid phosphatase (PACP) and type II 5α-reductase (SRD5A2). The spectrum-effect relationships between HPLC fingerprints and anti-benign prostatic hyperplasia activities were investigated using Grey Correlation Analysis (GRA) and partial least squares regression (PLSR). The results showed that a close correlation existed between the fingerprints and anti-benign prostatic hyperplasia activities, and peak 14 (chlorogenic acid), peak 17 (quercetin 5-O-ß-d-glucopyranoside) and peak 18 (quercetin 3-O-ß-l-rhamno-pyranoside) in the HPLC fingerprints might be the main active components against anti-benign prostatic hyperplasia. This work provides a general model for the study of spectrum-effect relationships of S. stolonifera by combing HPLC fingerprints with a testosterone-induced mouse model of BPH, which can be employed to discover the principle components of anti-benign prostatic hyperplasia bioactivity.

Steroid 5ß-Reductase from Leaves of Vitis vinifera: Molecular Cloning, Expression, and Modeling.

A steroid 5ß-reductase gene corresponding to the hypothetical protein LOC100247199 from leaves of Vitis vinifera (var. 'Chardonnay') was cloned and overexpressed in Escherichia coli. The recombinant protein showed 5ß-reductase activity when progesterone was used as a substrate. The reaction was stereoselective, producing only 5ß-products such as 5ß-pregnane-3,20-dione. Other small substrates (terpenoids and enones) were also accepted as substrates, indicating the highly promiscuous character of the enzyme class. Our results show that the steroid 5ß-reductase gene, encoding an orthologous enzyme described as a key enzyme in cardenolide biosynthesis, is also expressed in leaves of the cardenolide-free plant V. vinifera. We emphasize the fact that, on some occasions, different reductases (e.g., progesterone 5ß-reductase and monoterpenoid reductase) can also use molecules that are similar to the final products as a substrate. Therefore, in planta, the different reductases may contribute to the immense number of diverse small natural products finally leading to the flavor of wine.

Hamster SRD5A3 lacks steroid 5α-reductase activity in vitro.

According to current knowledge, two steroid 5α-reductases, designated type 1 (SRD5A1) and type 2 (SRD5A2), are present in all species examined to date. These isozymes play a central role in steroid hormone physiology by catalyzing the reduction of 3-keto-4-ene-steroids into more active 5α-reduced derivatives, including the conversion of testosterone (T) to dihydrotestosterone (DHT). A third 5α-reductase (SRD5A3, -type 3), which is overexpressed in hormone-refractory prostate cancer cells, has been identified; however, its enzymatic characteristics are practically unknown. Here, we isolated a cDNA encoding hamster Srd5a3 (hSrd5a3) and performed functional metabolic assays to investigate its biochemical properties. The cloned cDNA encodes a 330 amino acid protein that is 87% identical to the homologous protein in mice and 78% to that in humans. However, hSrd5a3 exhibits low sequence homology with its counterparts hSrd5a1 (19%) and hSrd5a2 (17%). A fusion protein consisting of hSrd5a3 and green fluorescent protein provided evidence for cytoplasmic localization in transfected mammalian cells. Real-time PCR analysis revealed that, Srd5a3 mRNA was present in nearly all hamster tissues, with high expression in the cerebellum, Harderian gland and testis. Functional assays expressing hSrd5a3 cDNA in HEK-293 cells revealed that this isozyme is unable to reduce T into DHT. Further expression assays confirmed that similar to testosterone, progesterone, androstenedione and corticosterone are not reduced by hSrd5a3 or human SRD5A3. Together, these results indicate that hSrd5a3 lacks the catalytic activity to transform 3-keto-4-ene-compounds; therefore 5α-reductase type 3 may not be involved in 5α-reduction of steroids.

Caveolin-Na/K-ATPase interactions: role of transmembrane topology in non-genomic steroid signal transduction.

Progesterone and its polar metabolite(s) trigger the meiotic divisions in the amphibian oocyte through a non-genomic signaling system at the plasma membrane. Published site-directed mutagenesis studies of ouabain binding and progesterone-ouabain competition studies indicate that progesterone binds to a 23 amino acid extracellular loop of the plasma membrane α-subunit of Na/K-ATPase. Integral membrane proteins such as caveolins are reported to form Na/K-ATPase-peptide complexes essential for signal transduction. We have characterized the progesterone-induced Na/K-ATPase-caveolin (CAV-1)-steroid 5α-reductase interactions initiating the meiotic divisions. Peptide sequence analysis algorithms indicate that CAV-1 contains two plasma membrane spanning helices, separated by as few as 1-2 amino acid residues at the cell surface. The CAV-1 scaffolding domain, reported to interact with CAV-1 binding (CB) motifs in signaling proteins, overlaps transmembrane (TM) helix 1. The α-subunit of Na/K-ATPase (10 TM helices) contains double CB motifs within TM-1 and TM-10. Steroid 5α-reductase (6 TM helices), an initial step in polar steroid formation, contains CB motifs overlapping TM-1 and TM-6. Computer analysis predicts that interaction between antipathic strands may bring CB motifs and scaffolding domains into close proximity, initiating allostearic changes. Progesterone binding to the α-subunit may thus facilitate CB motif:CAV-1 interaction, which in turn induces helix-helix interaction and generates both a signaling cascade and formation of polar steroids.

5α-Reduced glucocorticoids: a story of natural selection.

5α-Reduced glucocorticoids (GCs) are formed when one of the two isozymes of 5α-reductase reduces the Δ(4-5) double bond in the A-ring of GCs. These steroids are largely viewed inert, despite the acceptance that other 5α-dihydro steroids, e.g. 5α-dihydrotestosterone, retain or have increased activity at their cognate receptors. However, recent findings suggest that 5α-reduced metabolites of corticosterone have dissociated actions on GC receptors (GRs) in vivo and in vitro and are thus potential candidates for safer anti-inflammatory steroids. 5α-Dihydro- and 5α-tetrahydro-corticosterone can bind with GRs, but interest in these compounds had been limited, since they only weakly activated metabolic gene transcription. However, a greater understanding of the signalling mechanisms has revealed that transactivation represents only one mode of signalling via the GR and recently the abilities of 5α-reduced GCs to suppress inflammation have been demonstrated in vitro and in vivo. Thus, the balance of parent GC and its 5α-reduced metabolite may critically affect the profile of GR signalling. 5α-Reduction of GCs is up-regulated in liver in metabolic disease and may represent a pathway that protects from both GC-induced fuel dyshomeostasis and concomitant inflammatory insult. Therefore, 5α-reduced steroids provide hope for drug development, but may also act as biomarkers of the inflammatory status of the liver in metabolic disease. With these proposals in mind, careful attention must be paid to the possible adverse metabolic effects of 5α-reductase inhibitors, drugs that are commonly administered long term for the treatment of benign prostatic hyperplasia.

A review on steroidal 5α-reductase inhibitors for treatment of benign prostatic hyperplasia.

Benign prostatic hyperplasia (BPH) is a kind of common noncancerous prostate gland enlargement with growing tendency in recent years. 5α-reductase is the key enzyme responsible for dihydrotestosterone biosynthesis and has been considered as an important target for designing inhibitors as potent therapeutic agents for BPH. Finasteride, the first steroidal 5α-reductase inhibitor, has been marketed worldwide as a drug for BPH. During these years, many other novel types of 5α-reductase inhibitors are being studied. This review summarizes recent advancement in steroidal 5α-reductase inhibitors.

Steroid 5α-reductase as a novel therapeutic target for schizophrenia and other neuropsychiatric disorders.

The enzyme steroid 5α reductase (S5α R) catalyzes the conversion of Δ4-3-ketosteroid precursors--such as testosterone, progesterone and androstenedione--into their 5α-reduced metabolites. Although the current nomenclature assigns five enzymes to the S5α R family, only the types 1 and 2 appear to play an important role in steroidogenesis, mediating an overlapping set of reactions, albeit with distinct chemical characteristics and anatomical distribution. The discovery that the 5α-reduced metabolite of testosterone, 5α-dihydrotestosterone (DHT), is the most potent androgen and stimulates prostatic growth led to the development of S5α R inhibitors with high efficacy and tolerability. Two of these agents, finasteride and dutasteride, have received official approval for the treatment of benign prostatic hyperplasia and are being tested for prevention of prostate cancer. Finasteride is also approved for male-pattern alopecia and has been shown to induce very limited side effects. Over the last decade, converging lines of evidence have highlighted the role of 5α-reduced steroids and their precursors in brain neurotransmission and behavioral regulation. Capitalizing on these premises, we and other groups have recently investigated the role of S5α R in neuropsychiatric disorders. Our preliminary data suggest that S5 R inhibitors may elicit therapeutic effects in a number of disorders associated to dopaminergic hyperreactivity, including psychotic disorders, Tourette syndrome and impulse control disorders. In the present article, we review emerging preclinical and clinical evidence related to these effects, and discuss some of the potential mechanisms underlying the role of S5α R in the pathophysiology of mental disorders.

Discovery of a novel hybrid from finasteride and epristeride as 5α-reductase inhibitor.

Finasteride and epristeride both inhibit 5α-reductase with high potency via competitive and non-competitive mechanism, respectively. A new hybrid of finasteride and epristeride was designed as a new 5α-reductase inhibitor based on combination principles in medicinal chemistry. Human 5ß-reductase was chosen as a plausible surrogate of 5α-reductase type II and the results indicate that although the hybrid compound possesses the main bulk of epristeride, its inhibitory mechanism is same as of finasteride. The hybrid turned out to be a potent 5α-reductase inhibitor in low IC(50) ranges.