Madhusudan Purohit

Design, synthesis and 3D-QSAR studies of new diphenylamine containing 1,2,4-triazoles as potential antitubercular agents

A new series of new diphenylamine containing 1,2,4-triazoles were synthesized from 4-arylideneamino-5-[2-(2,6-dichlorophenylamino) benzyl]-2H-1,2,4-triazole-3(4H)-thiones 3a-f. The synthesized compounds were screened for in-vitro antimycobacterial and antibacterial activities. The synthesized compounds 4a, 4e and 4d have shown potential activity against Mycobacterium tuberculosis H37Rv strain with MIC of 0.2, 1.6 and 3.125 μM respectively. To investigate the SAR of diphenylamine containing 1,2,4-triazole derivatives in more details, CoMFA (q(2)-0.432, r(2)-0.902) and CoMSIA (q(2)-0.511, r(2)-0.953) models on M. tuberculosis H37Rv were established. The generated 3D-QSAR models are externally validated and have shown significant statistical results, and these models can be used for further rational design of novel diphenylamine containing 1,2,4-triazoles as potent antitubercular agents.

Synthesis, in vitro cytotoxicity, and anti-microbial studies of 1,4-bis(4-substituted-5-mercapto-1,2,4-triazol-3-yl)butanes

Synthesis and evaluation of cytotoxicity and anti-microbial activity of a series of 1,4-bis(4-substituted-5-mercapto-1,2,4-triazol-3-yl)butane derivatives comprising thioether functionality and other pharmacophore modifications are described. All the newly synthesized compounds were characterized by IR, NMR, elemental analyses, and mass spectral studies. The compounds 4a–f, 5a–f, and 6a–f were evaluated for in vitro cytotoxicity potential using the standard MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay against a panel of three human cancer cell lines: Lung carcinoma A-549, Colon carcinoma HT-29, and Breast Cancer MDA MB-231. All the compounds were subjected to in vitro anti-bacterial activity against Bacillus subtilus (ATCC 6633), Staphylococcus aureus (ATCC-25923), Escherichia coli (ATCC-25922), and Pseudomonas aeruginosa (ATCC-27853) and their minimal inhibitory concentrations were determined.

Synthesis and cytotoxicity of bis-1,3,4-oxadiazoles and bis-pyrazoles derived from 1,4-bis[5-thio-4-substituted-1,2,4-triazol-3-yl]-butane and their DNA binding studies.

A new series of 1,4‐bis[5‐(5‐mercapto‐1,3,4‐oxadiazol‐2‐yl‐methyl)‐thio‐4‐substituted‐1,2,4‐triazol‐3‐yl]‐butane 7‐12 and 1,4‐bis[5‐(1‐oxo‐1‐(3,5 dimethyl pyrazol‐1‐yl)‐methyl)‐thio‐4‐substitued‐1,2,4‐triazol‐3‐yl]‐butane 13‐18 were prepared from 1,4‐bis(5[hydrazinocarbonylmethylthio]‐4‐substituted‐1,2,4‐triazol‐3‐yl) butane based derivativess were synthesized 1‐6. All the synthesized compounds were characterized by IR, NMR and Mass spectral studies. The synthesized compounds 7‐18 were screened for in‐vitro cytotoxicity potential using the standard MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) assay against a panel of three human cancer cell lines: Lung carcinoma A‐549, colon carcinoma HT‐29 and breast cancer MDA MB‐231. DNA binding studies were conducted for three potent molecules by absorption titration method.

Synthesis, in vitro cytotoxicity, and antibacterial studies of new asymmetric bis-1,2,4-triazoles

A series of asymmetric bis-1,2,4-triazoles (4a–l) were synthesized from respective 1,2,4-triazole-3-thiocarbohydrazides (2a, b) via base catalyzed dehydrative cyclization of thiosemicarbazide intermediates (3a–l). The synthesized compounds were characterized by IR, 1H-NMR, 13C-NMR, and Mass spectral studies. The asymmetric bis-1,2,4-triazole derivatives (4a–l) were evaluated for in vitro antioxidant activity by DPPH radical scavenging assay method. The compounds with significant antioxidant potential were evaluated for in vitro cytotoxicity by MTT assay method against HT29 (Human adenocarcinoma) and MDA-231 (Human breast cancer) cancer cell lines. All the synthesized compounds were evaluated for in vitro antibacterial activity against Bacillus subtilus (ATCC 6633), Staphylococcus aureus (ATCC-25923), Escherichia coli (ATCC-25922), and Pseudomonas aeruginosa (ATCC-27853).

Synthesis of 2-methyl N10-substituted acridones as selective inhibitors of multidrug resistance (MDR) associated protein in cancer cells.

A series of N10-substituted-2-methyl acridone derivatives are synthesized and are examined for its ability to reverse P-glycoprotein (P-gp) mediated multidrug resistance (MDR) in breast cancer cell lines MCF-7 and MCF-7/Adr. The structural requirement of in-vitro anti-cancer and reversal of drug resistance are studied. The results showed that compound 16 with four carbon spacer exhibited promising in-vitro anti-cancer and reversal of drug resistance in comparison to the other analogues.

Rational design of promiscuous binding modulators of p53 inducing E3(Ub)-ligases (Mdm2 and Pirh2) as anticancer agents: an in silico approach

In this study, for the first time, we report on in silico based development of Mdm2 and Pirh2 promiscuous binding small molecule modulators. The methodology involves capturing the important Mdm2 and Pirh2 interacting residues of p53 TAD and TET, respectively from the literature; as well as from the protein–protein docking and molecular dynamics simulations applied in the present study. The knowledge of important residues that have been already delineated was used as the benchmark for the design of Mdm2 and Pirh2 focused ligand libraries, which were obtained by pharmacophore based screening of 3.9 million compounds deposited in MMsINC® database. This was followed by 2D fingerprint similarity based filtering of focused ligand libraries with respect to a known reference set of Mdm2 inhibitors, which further confined the chemical space to 608 molecules. These included 365 Mdm2-like small molecule mimetics of p53 TAD and 243 Mdm2-like small molecule mimetics of p53 TET. Docking iterations with respective targets and reverse docking resulted in twelve potential best fit molecules that showed favourable binding interactions with both Mdm2 pBD and Pirh2 CTD. The quality of the docking protocol was assessed using experimentally determined IC50 values of the known 213 Mdm2 inhibitors and their docking scores with a set of statistical measures, which showed good correlations.

In-Vitro Cytotoxicity and Cell Cycle Analysis of Two Novel bis-1,2, 4-triazole derivatives: 1,4-bis[5-(5-mercapto-1,3,4-oxadiazol-2-yl-methyl)-thio-4-(p-tolyl)-1,2,4-triazol-3-yl]-butane (MNP-14) and 1,4-bis[5-(carbethoxy-methyl)-thio-4-(p-ethoxy phenyl)-1,2,4-triazol-3-yl]-butane (MNP-16)

In the present study, we have tested the cytotoxic and DNA damage activity of two novel bis-1,2,4 triazole derivatives, namely 1,4-bis[5-(5-mercapto-1,3,4-oxadiazol-2-yl-methyl)-thio-4-(p-tolyl)-1,2,4-triazol-3-yl]-butane (MNP-14) and 1,4-bis[5-(carbethoxy-methyl)-thio-4-(p-ethoxy phenyl) -1,2,4-triazol-3-yl]-butane (MNP-16). The effect of these molecules on cellular apoptosis was also determined. The in-vitro cytotoxicity was evaluated by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay as well as Trypan blue dye exclusion methods against human acute lymphoblastic leukemia (MOLT4) and lung cancer cells (A549). Our results showed that MNP-16 induced significant cytotoxicity (IC50 of 3–5 μM) compared with MNP-14. The cytotoxicity induced by MNP-16 was time and concentration dependent. The cell cycle analysis by flow cytometry (fluorescence-activated cell sorting [FACS]) revealed that though there was a significant increase in the apoptotic population (sub-G1 phase) with an increased concentration of MNP-14 and 16, there was no cell cycle arrest. Further, the comet assay results indicated considerable DNA strand breaks upon exposure to these compounds, thereby suggesting the possible mechanism of cytotoxicity induced by MNP-16. Hence, we have identified a novel molecule (MNP-16) which could be of great clinical relevance in cancer therapeutics.

Role of p53 circuitry in tumorigenesis: A brief review

Maintenance of genome integrity under the stressed condition is paramount for normal functioning of cells in the multicellular organisms. Cells are programmed to protect their genome through specialized adaptive mechanisms which will help decide their fate under stressed conditions. These mechanisms are the outcome of activation of the intricate circuitries that are regulated by the p53 master protein. In this paper, we provided a comprehensive review on p53, p53 homologues and their isoforms, including a description about the ubiquitin-proteasome system emphasizing its role in p53 regulation. p53 induced E3(Ub)-ligases are an integral part of the ubiquitin-proteasome system. This review outlines the roles of important E3(Ub)-ligases and their splice variants in maintaining cellular p53 protein homeostasis. It also covers up-to-date and relevant information on small molecule Mdm2 inhibitors originated from different organizations. The review ends with a discussion on future prospects and investigation directives for the development of next-generation modulators as p53 therapeutics.