Exploration of Novel 5α-Reductase Inhibitors for Benign Prostatic Hyperplasia by 2D/3D QSAR, Cytotoxicity Pre-ADME and Docking Studies.

BACKGROUND: 5α-Reductase (5AR), an NADPH dependent enzyme, is expressed in most of the prostate epithelial cells. By converting testosterone (T) into more potent androgen dihydrotestosterone (DHT), it plays an important role in men physiology and represents an efficient therapeutic target for androgen-dependent diseases. Over the last few years, significant efforts have been made in order to develop 5AR inhibitors (5ARI) to treat Benign Prostatic Hyperplasia because of excessive production of DHT. METHODS: In the present study, 2D and 3D QSAR pharmacophore models have been generated for 5ARI based on known IC50 values with extensive validations. The four featured 2D pharmacophore based PLS model correlated the topological interactions (SsOHE-index); semi empirical (Quadrupole2) and physicochemical descriptors (Mol. Wt, Bromines Count, Chlorines Count) with 5AR inhibitory activity, and has the highest correlation coefficient (r2 = 0.98, q2 =0.84; F = 57.87, pred r2 = 0.88). Internal and external validation was carried out using test and proposed set of compounds. The contribution plot of electrostatic field effects and steric interactions generated by 3D-QSAR showed interesting results in terms of internal and external predictability. The well-validated 2D PLS, and 3D kNN models were used to search novel 5AR inhibitors with different chemical scaffold. The compounds were further sorted by applying ADMET properties and in vitro cytotoxicity studies against prostate cancer cell lines PC-3. Molecular docking studies have also been employed to investigate the binding interactions and to study the stability of docked conformation in detail. RESULTS: Several important hydrophobic and hydrogen bond interactions with 5AR lead to the identification of active binding sites of 4AT0 protein in the docked complex, which include the gatekeeper residues ALA 63A (Chain A: ALA63), THR 60 A (Chain A: THR60), and ARG 456 A (Chain A: ARG456), at the hinge region. CONCLUSION: Overall, this study suggests that the proposed compounds have the potential as effective inhibitors for 5AR.

Target Based Designing of Anthracenone Derivatives as Tubulin Polymerization Inhibiting Agents: 3D QSAR and Docking Approach.

Novel anthracenone derivatives were designed through in silico studies including 3D QSAR, pharmacophore mapping, and molecular docking approaches. Tubulin protein was explored for the residues imperative for activity by analyzing the binding pattern of colchicine and selected compounds of anthracenone derivatives in the active domain. The docking methodology applied in the study was first validated by comparative evaluation of the predicted and experimental inhibitory activity. Furthermore, the essential features responsible for the activity were established by carrying out pharmacophore mapping studies. 3D QSAR studies were carried out for a series of 1,5- and 1,8-disubstituted10-benzylidene-10H-anthracen-9-ones and 10-(2-oxo-2-phenylethylidene)-10H-anthracen-9-one derivatives for their antiproliferation activity. Based on the pattern recognition studies obtained from QSAR results, ten novel compounds were designed and docked in the active domain of tubulin protein. One of the novel designed compounds "N1" exhibited binding energy -9.69 kcal/mol and predicted Ki 78.32 nM which was found to be better than colchicine.

Design, synthesis and ex-vivo release studies of colon-specific polyphosphazene-anticancer drug conjugates.

Colon-specific azo based polyphosphazene-anticancer drug conjugates (11-18) have been synthesized and evaluated by ex-vivo release studies. The prepared polyphosphazene drug conjugates (11-18) are stable in acidic (pH=1.2) buffer which showed that these polymer drug conjugates are protected from acidic environment which is the primary requirement of colon specific targeted drug delivery. The ex-vivo release profiles of polyphosphazene drug conjugates (11-18) have been performed in the presence as well as in the absence of rat cecal content. The results showed that more than 89% of parent drugs (methotrexate and gemcitabine) are released from polymeric backbone of polyphosphazene drug conjugates (14 and 18) having n-butanol (lipophilic moiety). The in-vitro cytotoxicity assay has also been performed which clearly indicated that these polymeric drug conjugates are active against human colorectal cancer cell lines (HT-29 and COLO 320 DM). The drug release kinetic study demonstrated that Higuchi's equation is found to be best fitted equation which showed that release of drug from polymeric backbone as square root of time dependent process based on non-fickian diffusion. Therefore, the synthesized polyphosphazene azo based drug conjugates of methotrexate and gemcitabine are the potential candidates for colon targeted drug delivery system with minimal undesirable side effects.

Linaclotide-a novel secretagogue in the treatment of irritable bowel syndrome with constipation and chronic idiopathic constipation.

Irritable bowel syndrome with constipation (IBS-C) and chronic idiopathic constipation (CIC) are highly prevalent gastrointestinal disorders. Traditional symptoms based therapies had somewhat limited success and efficacy in addressing the disorders. Recently, linaclotide emerged as novel peptide capable of improving abdominal symptoms in patients suffering from IBS-C and CIC. Guanylate cyclase C (GC-C) receptor a multi domain protein, found to be molecular target for linaclotide which acts by activating GC-C receptor on the apical surface of intestinal epithelial cells. Binding of linaclotide to GC-C receptor triggers the elevation of second messenger cGMP that elicits fluid secretion into intestinal cells which play a critical role in maintaining homeostasis through cystic fibrosis transmembrane conductance regulator (CFTR). Data from Phase II and III clinical trials demonstrated that linaclotide seems to produce a statistically significant increase in stool frequency, improved straining, decreased abdominal pain and discomfort.

Design, synthesis and ex vivo evaluation of colon-specific azo based prodrugs of anticancer agents.

Colon-specific azo based prodrugs of anticancer agents like methotrexate (6), gemcitabine (7) and analogue of oxaliplatin (RTB-4) (8) were synthesized and characterized by modern analytical techniques. The prepared prodrugs were stable in acidic (pH 1.2) and basic (pH 7.4) buffers which showed their stability in upper GIT environment. Further, an assay was performed which demonstrated the presence of azoreductase enzyme in the rat fecal material, rat cecum content and other parts of intestinal content which reduce specifically the azo bond and release the drug. The in vitro cytotoxicity assay was also performed which clearly indicated that these azo based prodrugs are active against human colorectal cancer cell lines (COLO 205, COLO 320 DM and HT-29). The release behavior of prodrugs (10, 11 and 15) was 60-70% after 24h incubation at 37°C. Therefore, the synthesized azo linked prodrugs of methotrexate, gemcitabine and RTB-4 are the potential candidates for colon targeted drug delivery system with minimal undesirable side effects.

Synthesis and characterization of 3ß-substituted amides of 17a-aza-D-homo- 4-androsten-17-one as potent 5α-reductase inhibitors and antimicrobial agents.

We herein report the synthesis of 3ß-substituted amides of 17a-aza-D-homo-4-androsten-17-one (11a-11r) from commercially available Diosgenin as the starting material. The structures of newly synthesized compounds were confirmed by IR, (1)H NMR, (13)C NMR and mass spectrometry. All the synthesized analogues were tested for their 5α- reductase inhibitory and antimicrobial activity, some of them exhibit moderate to potent activity comparable to the reference drugs. Among the synthesized derivatives the analogue (11r) 3ß-(indonlylbutanamido)-17a-aza-D-homo-4- androsten-17-one was found to be active against both 5α-reductase enzyme and microbial strains, whereas the analogue (11i) 3ß-(3,4-dimethoxy-benzamido)-17a-aza-D-homo-4-androsten-17-one was found to be the least active. The detailed 5α-reductase inhibitors and antimicrobial activities of the synthesized compounds were reported.

Enzalutamide: a novel anti-androgen with prolonged survival rate in CRPC patients.

Prostate cancer is the most common malignancy among men found to be the second leading cause of male cancer-related mortality due to development of resistance against androgen deprivation therapy (ADT). With the advancement in understanding of prostate cancer, numbers of agents have been emerged to target Androgen-Receptor (AR) signaling for the treatment of castration resistant prostate cancer (CRPC). Food and Drug Administration (FDA) has recently approved enzalutamide (XTANDI) for the treatment of CRPC. Androgen receptor promotes the prostate cancer progression after transformation. Androgen receptor signaling leads to CRPC when cellular nucleus binds to DNA and increases pro cancer gene expression. In phase ΙΙΙ clinical trial, enzalutamide showed that 160 mg once daily oral administration is well tolerated and significantly enhanced overall survival in men with CRPC after chemotherapy, demonstrated by reduction in the serum prostate specific antigen (PSA) level and increased survival rate by 4.8 months.

Aflibercept: a novel VEGF targeted agent to explore the future perspectives of anti-angiogenic therapy for the treatment of multiple tumors.

Angiogenesis is the process of formation of new blood vessels due to over expression of VEGF (vascular endothelial growth factor) which plays a critical role in the growth and development of all solid tumor types. With the advancement in understanding of tumor angiogenesis and VEGF, there have been a number of agents developed to target VEGF for the treatment of cancer. These targeted agents can affect downstream VEGF signal transduction by unique mechanisms at different cellular and extracellular levels. FDA has recently approved Aflibercept or VEGF-Trap in August 2012 for the treatment of colorectal cancer. It is a recombinant, decoy receptor fusion protein, rationally designed to block angiogenesis by targeting VEGF-A, VEGF-B and placental growth factor. VEGF-Trap exerts its antiangiogenic effects through regression of tumor vasculature, remodelling or normalization of surviving vasculature and inhibition of new tumor vessel growth. In this review, pre-clinical and clinical data have been summarized for aflibercept alone and in combination with chemotherapy to explore its efficacy and benefits in ovarian cancer, breast cancer, non-small cell lung cancer, pancreatic cancer, glioblastoma, adenocarcinoma and renal cell cancer xenograft models.

Synthesis, characterization of (Z)-N-(1-(2-(2-amino-3-(dimethylamino) methyl)phenyl)-5-phenyl-1,3,4, oxadiazol-3(2H)-yl)ethanone analogs as potent antimicrobial and hydrogen peroxide scavenging agents.

A series of (Z)-N-(1-(2-(2-amino-3-((dimethylamino) methyl) phenyl)-5-phenyl-1,3,4,oxadiazol-3(2H)- yl)ethanone derivatives was prepared and studied for its antimicrobial and antioxidant activities. Among the synthesized derivatives, compounds (7c) (Z)-N-(1-(2-(2-amino-3-((dimethylamino)methyl)phenyl)-5-phenyl-1,3,4-oxadiazol-3(2H)- yl)ethylidene)-4-chloroaniline, (7g) (Z)-N-(1-(2-(2-amino-3-((dimethylamino)methyl)phenyl)-5-phenyl-1,3,4-oxadiazol- 3(2H)-yl)ethylidene)-4-nitroaniline and (7i) (Z)-N-(1-(2-(2-amino-3-((dimethylamino)methyl)phenyl)-5-phenyl-1,3,4- oxadiazol-3(2H)-yl)ethylidene)-4-methoxyaniline were found to be the most effective antimicrobial compounds. While the compounds 7c and 7g were the most potent antioxidant compounds with significant hydrogen peroxide scavenging activity.

Cabazitaxel: a novel drug for hormone-refractory prostate cancer.

Cabazitaxel has recently been approved by FDA for the treatment of docetaxel resistant hormone-refractory prostate cancer. It has been developed by Sanofi-Aventis under the trade name of Jevtana. It is given in combination with prednisone/prednisolone and has passed the clinical trial over well-known drug mitoxantrone. This drug is a microtubule depolymerization inhibitor, which can penetrate blood brain barrier (BBB). The FDA granted fast track designation to this drug in November 2009 and thereafter, new drug application submission was done in March 2010. Priority review to this drug was granted in April 2010 and finally in July 2010 it was approved by FDA. It is available in the form of injection in the dose of 60 mg/1.5 mL, which should be diluted prior to its use by the diluents supplied along with the injection. It is a second-line drug and has proven to be effective in patients experiencing docetaxel based treatment failure.

Synthesis and characterization of (E)-N'-(substituted benzylidene)isonicotinohydrazide derivatives as potent antimicrobial and hydrogen peroxide scavenging agents.

A series of (E)-N'-(substituted benzylidene)isonicotinohydrazide derivatives were synthesized by coupling isoniazid with differently substituted aldehydes and benzophenones in the presence of absolute ethanol along with catalytic amount of glacial acetic acid. The structure of all the synthesized compounds were confirmed and characterized by using various spectral technique like IR, 1H NMR, 13C NMR and mass spectroscopy. All the synthesized compounds were evaluated for their antimicrobial activity in terms of zone of inhibition, minimum inhibitory concentration, minimum bactericidal concentration and minimum fungicidal concentration in camparison to the standard drugs. The results revealed that all synthesized compounds had shown potent to mild biological activity. Among the synthesized derivatives, (E)-N'-(3,4-dimethoxybenzylidene)isonicotinohydrazide 2e, (E)-N'-(3,4,5-trimethoxybenzylidene)isonicotinohydrazide 2f and (E)-N'-(4-hydroxy-3-methoxybenzylidene)isonicotinohydrazide 2g were found to be the most effective antimicrobial compounds, whereas compounds 2g and 2k were the most potent antioxidants with significant hydrogen peroxide scavenging activity.

Synthesis and characterization of (Z)-N-(1-[2-{3-[(dimethylamino)methyl)]-2-methoxyphenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazol-3(2H)-yl]ethylidene) benzenamine derivatives as potent antifungal agents.

In the present study, a series of (Z)-N-(1-[2-{3-[(dimethylamino)methyl)]-2-methoxyphenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazol-3(2H)-yl]ethylidene)benzenamine derivatives have been synthesized and characterized by IR, 1H NMR and 13C NMR spectra. All the synthesized compounds were evaluated for their antifungal activity and were compared with the standard drug, clotrimazole. The compounds demonstrated excellent to weak antifungal activity. Among the synthesized derivatives, 4f and 4h showed significant activity and 4c exhibited moderate activity against Candida albicans, Candida tropicalis and Aspergillus niger as compared with the standard antifungal agent - clotrimazole. The minimum inhibitory concentration of the compounds was in the range of 1.62-25 microg/mL against fungi. Furthermore, the substitution of chloro, nitro and methoxy groups at para position of benzene moiety play an important role in enhancing the antifungal activity of this class of compounds.

Synthesis, characterization and evaluation of mannich bases as potent antifungal and hydrogen peroxide scavenging agents.

In the present study, (E)-2-{ [-2-(2,4-Dinitrophenyl)hydrazono]methyl} phenol (3) was synthesized and used as key intermediate for the synthesis of new Mannich bases. All the synthesized compounds were evaluated for their antifungal activity against three fungal strains Candida albicans, Candida tropicalis and Aspergillus niger and antioxidant activity. The structure of these compounds was confirmed by IR, 1H NMR and 13C NMR studies. Most of the compounds exhibited moderate to significant activities.

Synthesis, characterization and evaluation of benzylidene analogues as a new class of potential antioxidant agents.

Seventeen analogues of benzylidene were synthesized and evaluated for in vitro hydrogen peroxide scavenging activity. The structure of the newly synthesized compounds were confirmed by elemental and spectral (IR, 1H-NMR, 13C-NMR) studies. The antioxidant activity of the titled compounds was evaluated. Compounds: 4h--N'-[2-amino-3-(morpholinomethyl)benzylidene]isonicotinohydrazide, 4p 7-(4-(2-amino-3-[(2-isonicotinoylhydrazono)methyl]benzyl}piperazin-1-yl)-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquino- line-3-carboxylic acid and 4q 7-(4-{2-amino-3-[(2 isonicotinoylhydrazono)methyl]benzyl} piperazin-1-yl)-1-ethyl-6,8-difluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid were the most active compounds with significant hydrogen peroxide scavenging activity.

Synthesis and screening of substituted thiosemicarbazone derivatives: an approach towards novel anticonvulsant search.

A series of thiosemicarbazones of halogen substituted benzaldehydes, benzophenone and acetophenone were synthesized using an appropriate synthetic route and characterized by thin layer chromatography and spectral analysis. The anticonvulsant activity of synthesized compounds was established in three seizures models which includes maximal electroshock (MES), subcutaneous pentylene tetrazole (scPTZ) induced seizures and minimal neurotoxicity test. Five compounds out of 21 exhibited protection in MES test while only one compound showed protection in scPTZ screen. Two compounds were found to be active in minimal clonic seizure (6Hz) model. Compound PS6 i.e. 2-(3-bromobenzylidene)-N-(4-chlorophenyl) hydrazinecarbothioamide emerged as the most active compound with MES ED50 of more than 50mg/kg and pI greater than 12, which is found to be better than the prototype drug, Phenytoin. The compound has shown neuroprotection in kainic acid model with IC50 value of 40.97 µM. It has also shown mild activation effect on CYP 269 and CYP 2C9 enzymes, indicating the usefulness of thiosemicarbazones as anticonvulsants.