Discovery and biological characterization of a novel series of androgen receptor modulators

Metal-free photosensitized intermolecular carboimination of alkenes: a green and direct access to both β-amino acids and β-amino ketones

β-Amino carbonyl substructures are privileged motifs in natural products and active pharmaceutical compounds. Here, we report a photoinduced metal-free and highly regioselective intermolecular carboimination method via the simultaneous introduction of amino and carbonyl groups into the CC double bond in one step, providing straightforward, green and general access to both β-amino acid and β-amino ketone motifs from readily available alkene feedstocks. The mild reaction conditions, excellent functional group tolerance and product diversity should make this a broadly applicable carboimination approach of very broad interest to organic and medicinal chemists.

Chemical Screening of Nuclear Receptor Modulators

Nuclear receptors are ligand-inducible transcriptional factors that control multiple biological phenomena, including proliferation, differentiation, reproduction, metabolism, and the maintenance of homeostasis. Members of the nuclear receptor superfamily have marked structural and functional similarities, and their domain functionalities and regulatory mechanisms have been well studied. Various modulators of nuclear receptors, including agonists and antagonists, have been developed as tools for elucidating nuclear receptor functions and also as drug candidates or lead compounds. Many assay systems are currently available to evaluate the modulation of nuclear receptor functions, and are useful as screening tools in the discovery and development of new modulators. In this review, we cover the chemical screening methods for nuclear receptor modulators, focusing on assay methods and chemical libraries for screening. We include some recent examples of the discovery of nuclear receptor modulators.

Synthesis and Investigation on the Antidiabetic Effect of 3-aryl-1-(5-methylisoxazol-3-ylamino)-1-(4-nitrophenyl) Propan-1-one

Background:

Diabetes mellitus is the third-largest non-communicable chronic disease worldwide. There are many effective drugs, but the long-term use of these clinical drugs may cause various side effects. Therefore, it is urgent to develop new antidiabetic molecules with higher efficacy and lower toxicity.

Methods:

Fifteen new 3-aryl-1-(5-methylisoxazol-3-ylamino)-1-(4-nitrophenyl)propan-1-one were synthesized directly through the Mannich reaction of 4-nitroacetophenone, 3-amino-5- methylisoxazole and aromatic aldehydes catalyzed by concentrated hydrochloric acid. The molecular structures of the products were fully characterized by 1H NMR, 13C NMR, ESI MS and HRMS. The peroxisome proliferator-activated receptor (PPAR) response element and α-glucosidase inhibitory activity of these compounds were evaluated in vitro. Molecular docking, molecular physical parameters calculation, and molecular toxicity prediction were performed to analyze the structure- activity relationship and evaluate the druggability of these compounds theoretically.

Results:

All compounds exhibited weak antidiabetic activities, but compound 15 showed promising as a high performance, dual-target antidiabetic lead compound with peroxisome proliferatoractivated receptor (PPAR) response element relative agonist activity of 99.55% at 27.2 nmol·mL−1 and α-glucosidase inhibitory activity of 35.21% at 13.6 nmol·mL−1. All compounds obtained may have no cardiotoxicity, no acute toxicity, no carcinogenic, and within safe range of mutagenic risk.

Conclusion:

This study identified a potential PPAR lead molecule and presented an unusual strategy for antidiabetic drug development.

G protein-coupled receptor GPR160 is associated with apoptosis and cell cycle arrest of prostate cancer cells

G protein-coupled receptors (GPCRs) represent the largest membrane protein family implicated in the therapeutic intervention of a variety of diseases including cancer. Exploration of biological actions of orphan GPCRs may lead to the identification of new targets for drug discovery. This study investigates potential roles of GPR160, an orphan GPCR, in the pathogenesis of prostate cancer. The transcription levels of GPR160 in the prostate cancer tissue samples and cell lines, such as PC-3, LNCaP, DU145 and 22Rv1 cells, were significantly higher than that seen in normal prostate tissue and cells. Knockdown of GPR160 by lentivirus-mediated short hairpin RNA constructs targeting human GPR160 gene (ShGPR160) resulted in prostate cancer cell apoptosis and growth arrest both in vitro and in athymic mice. Differential gene expression patterns in PC-3 cells infected with ShGPR160 or scramble lentivirus showed that 815 genes were activated and 1193 repressed. Functional annotation of differentially expressed genes (DEGs) revealed that microtubule cytoskeleton, cytokine activity, cell cycle phase and mitosis are the most evident functions enriched by the repressed genes, while regulation of programmed cell death, apoptosis and chemotaxis are enriched significantly by the activated genes. Treatment of cells with GPR160-targeting shRNA lentiviruses or duplex siRNA oligos increased the transcription of IL6 and CASP1 gene significantly. Our data suggest that the expression level of endogenous GPR160 is associated with the pathogenesis of prostate cancer.

Iminoenamine based novel androgen receptor antagonist exhibited anti-prostate cancer activity in androgen independent prostate cancer cells through inhibition of AKT pathway

Treatment by androgen receptor (AR) antagonists is one of the regimens for prostate cancer. The prolonged treatment with AR antagonist leads to the expression of point mutation in the ligand binding domain of the AR. This point mutation causes resistance to AR antagonist by converting them into an agonist. The T887A mutated AR was frequently expressed in androgen independent prostate cancer (AIPC) patients. Through literature survey and molecular modelling, we have identified a novel AR antagonist having a bulky β-iminoenamine BF2 complex scaffold. The tested and standard ligands were screened in AR positive (LNCaP, MCF-7 and MDA-MB-453), AR negative (PC3), and non-cancerous (3T3) cell lines through anti-proliferation assay. The ligand, ARA3 was the most potent molecule among all the tested ligands and was 7.6 folds selective for AR positive cell lines. The mechanism of anti-prostate cancer activity of ARA3 was confirmed by western blot, qPCR, and apoptotic assays in LNCaP (T887A positive AR) cells. Structural activity relationship was derived by correlating the in-vitro and in-silico data. Consequently, we have identified the essential functional groups that could prevent the resistance concerning mutant AR. The ARA3 induces the apoptosis in AIPC cells by preventing the AR mediated activation of AKT pathway. The bicalutamide did not induce the apoptosis because it failed to prevent the AR mediated activation of AKT.

Mannich bases in medicinal chemistry and drug design

The biological activity of Mannich bases, a structurally heterogeneous class of chemical compounds that are generated from various substrates through the introduction of an aminomethyl function by means of the Mannich reaction, is surveyed, with emphasis on the relationship between structure and biological activity. The review covers extensively the literature reports that have disclosed Mannich bases as anticancer and cytotoxic agents, or compounds with potential antibacterial and antifungal activity in the last decade. The most relevant studies on the activity of Mannich bases as antimycobacterial agents, antimalarials, or antiviral candidates have been included as well. The review contains also a thorough coverage of anticonvulsant, anti-inflammatory, analgesic and antioxidant activities of Mannich bases. In addition, several minor biological activities of Mannich bases, such as their ability to regulate blood pressure or inhibit platelet aggregation, their antiparasitic and anti-ulcer effects, as well as their use as agents for the treatment of mental disorders have been presented. The review gives in the end a brief overview of the potential of Mannich bases as inhibitors of various enzymes or ligands for several receptors.

Development of β-amino-carbonyl compounds as androgen receptor antagonists

AIM

Androgen receptor (AR) antagonists have proven to be useful in the early control of prostate cancer. The aim of this study was to identify and characterize a novel β-amino-carbonyl-based androgen receptor antagonist.

METHODS

Different isomers of the β-amino-carbonyl compounds were obtained by chiral separation. The bioactivities of the isomers were evaluated by AR nuclear translocation, mammalian two-hybrid, competitive receptor binding and cell proliferation assays. The expression of genes downstream of AR was analyzed with real-time PCR. The therapeutic effects on tumor growth in vivo were observed in male SCID mice bearing LNCaP xenografts.

RESULTS

Compound 21 was previously identified as an AR modulator by the high-throughput screening of a diverse compound library. In the present study, the two isomers of compound 21, termed compounds 21-1 and 21-2, were characterized as partial AR agonists in terms of androgen-induced AR nuclear translocation, prostate-specific antigen expression and cell proliferation. Further structural modifications led to the discovery of a androgen receptor antagonist (compound 6012), which blocked androgen receptor nuclear translocation, androgen-responsive gene expression and androgen-dependent LNCaP cell proliferation. Four stereoisomers of compound 6012 were isolated, and their bioactivities were assessed. The pharmacological effects of 6012, including AR binding, androgen-induced AR translocation, NH2- and COOH-terminal interaction, growth inhibition of LNCaP cells in vitro and LNCaP xenograft growth in nude mice, were mainly restricted to isomer 6012-4 (1R, 3S).

CONCLUSION

Compound 6012-4 was determined to be a novel androgen receptor antagonist with prostate cancer inhibitory activities comparable to bicalutamide both in vitro and in vivo.

Synthesis and antidiabetic performance of β-amino ketone containing nabumetone moiety

We wish to report the further design and improved synthesis that resulted in two series of target molecules, TM-1 and TM-2, with remarkably simplified structures containing β-amino ketone of discrete nabumetone moiety. These were obtained via a 'one-pot, two-step, three-component' protocol of Mannich reaction with yield up to 97%. A total of 28 out of 31 new compounds were characterized using (1)H NMR, (13)C NMR, ESI MS and HRMS techniques. Studies on their antidiabetic activities, screened in vitro at 10 μg mL(-1) level, indicate that TM-2 possesses peroxisome proliferator-activated receptor activation and α-glucosidase inhibition activity significantly stronger than that of TM-1, and also that of the series B compounds that were previously synthesized by the group. Analysis of the structure-activity relationship points to the sulfanilamide unit as the most probable potent group of β-amino ketone and, on the basis of which, a tangible strategy is presented for the development of new antidiabetic drugs.

Identification of mannich base as a novel inhibitor of Mycobacterium tuberculosis isocitrate by high-throughput screening

Mycobacterium tuberculosis (MTB) remains one of the most significant human pathogens since its discovery in 1882. An estimated 1.5 million people died from tubercle bacillus (TB) in 2006, and globally, there were an estimated 9.27 million incident cases of TB in 2007. Glyoxylate bypass pathway occurs in a wide range of pathogens and plays a key role in the pathogenesis of Mycobacterium tuberculosis. Isocitrate lyase (ICL) can catalyses the first step of this pathway, and reversibly cleaves isocitrate into succinate and glyoxylate. So, ICL may represent a good drug target for the treatment of tuberculosis. ICL was cloned, expressed, and purified, and a high-throughput screen (HTS) developed to screen active molecule from a mannich base compounds library for inhibition of ICL. This assay had signal to noise (S/N) of 650.6990 and Z' factor of 0.8141, indicating that the assay was suitable for HTS. Screening of a collection of 124 mannich base compounds resulted in the identification of one mannich base compound, which has a significant inhibitory activity. So, a new family of compound was first reported to inhibit the activity of Mycobacterium tuberculosis ICL. This family of compound might offer new avenue to explore better anti-tuberculosis and fungi drugs.

Nonsteroidal selective androgen receptor modulators enhance female sexual motivation

Women experience a decline in estrogen and androgen levels after natural or surgically induced menopause, effects that are associated with a loss of sexual desire and bone mineral density. Studies in our laboratories have shown the beneficial effects of selective androgen receptor modulators (SARMs) in the treatment of osteoporosis and muscle wasting in animal models. A series of S-3-(phenoxy)-2-hydroxy-2-methyl-N-(4-cyano-3-trifluoromethyl-phenyl)-propionamide analogs was synthesized to evaluate the effects of B-ring substitutions on in vitro and in vivo pharmacologic activity, especially female sexual motivation. The androgen receptor (AR) relative binding affinities ranged from 0.1 to 26.5% (relative to dihydrotestosterone) and demonstrated a range of agonist activity at 100 nM. In vivo pharmacologic activity was first assessed by using male rats. Structural modifications to the B-ring significantly affected the selectivity of the SARMs, demonstrating that single-atom substitutions can dramatically and unexpectedly influence activity in androgenic (i.e., prostate) and anabolic (i.e., muscle) tissues. (S)-N-(4-cyano-3-trifluoromethyl-phenyl)-3-(3-fluoro,4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide (S-23) displayed full agonist activity in androgenic and anabolic tissues; however, the remaining SARMs were more prostate-sparing, selectively maintaining the size of the levator ani muscle in castrated rats. The partner-preference paradigm was used to evaluate the effects of SARMs on female sexual motivation. With the exception of two four-halo substituted analogs, the SARMs increased sexual motivation in ovariectomized rats, with potency and efficacy comparable with testosterone propionate. These results indicate that the AR is important in regulating female libido given the nonaromatizable nature of SARMs and it could be a superior alternative to steroidal testosterone preparations in the treatment of hypoactive sexual desire disorder.

Serum testosterone bioassay evaluation in a large male cohort

OBJECTIVE

To assess if a cell-based readout of androgen action in serum demonstrates a closer association with recognized classical parameters of androgen action in men than current measures of serum testosterone (T).

DESIGN

To develop, validate and utilize a mammalian cell-based assay to measure specifically bioactive T and determine if this measure is a physiologically relevant fraction of serum T. MEASUREMENTS AND PARTICIPANTS: We have developed a specific serum T bioassay using human prostate cancer cells. A rapid 5-min exposure to 100% serum followed by serum withdrawal confers specificity of the assay to serum T and provides sufficient sensitivity to measure T in male serum samples. Matrix effects were experimentally discounted as a confounding issue. A total of 960 male serum samples from the Florey Adelaide Male Ageing Study (FAMAS) with previous comprehensive cohort data and serum measurements were utilized.

RESULTS

Bioassay T measurement in the 960 FAMAS serum samples returned a median of 10.7 nmol/l (1.7-45.4), and was most closely related to immunoassayed total T, but not immunoassayed bioavailable T or calculated free T. Immunoassayed total T demonstrated a positive association with isometric grip-strength (R(2) = 0.127, P < 0.001), self-reported sexual desire (R(2) = 0.113, P < 0.001) and erectile function (R(2) = 0.085, P < 0.05) while bioassay T did not.

CONCLUSIONS

While cellular bioassays offer a rapid and sensitive means of identifying the androgenic potential of complex environmental compounds, the utility of such assays in defining a clinically relevant fraction of serum T distinct from total T needs further investigation.

Small molecule screening reveals a transcription-independent pro-survival function of androgen receptor in castration-resistant prostate cancer

In prostate cancer (PCa) patients, initial responsiveness to androgen deprivation therapy is frequently followed by relapse due to development of treatment-resistant androgen-independent PCa. This is typically associated with acquisition of mutations in AR that allow activity as a transcription factor in the absence of ligand, indicating that androgen-independent PCa remains dependent on AR function. Our strategy to effectively target AR in androgen-independent PCa involved using a cell-based readout to isolate small molecules that inhibit AR transactivation function through mechanisms other than modulation of ligand binding. A number of the identified inhibitors were toxic to AR-expressing PCa cells regardless of their androgen dependence. Among these, some only suppressed PCa cell growth (ARTIS), while others induced cell death (ARTIK). ARTIK, but not ARTIS, compounds caused disappearance of AR protein from treated cells. siRNA against AR behaved like ARTIK compounds, while a dominant negative AR mutant that prevents AR-mediated transactivation but does not eliminate the protein showed only a growth suppressive effect. These observations reveal a transcription-independent function of AR that is essential for PCa cell viability and, therefore, is an ideal target for anti-PCa treatment. Indeed, several of the identified AR inhibitors demonstrated in vivo efficacy in mouse models of PCa and are candidates for pharmacologic optimization.