Synthesis and antiproliferative activity of basic thioanalogues of merbarone

New pyranopyrazole based derivatives: Design, synthesis, and biological evaluation as potential topoisomerase II inhibitors, apoptotic inducers, and antiproliferative agents

A new series of pyranopyrazole-based derivatives were designed and synthesized. The synthesized compounds were assessed for their cytotoxic efficacy against A549 human lung carcinoma and MCF-7 human breast carcinoma cell lines. Three compounds (1b, 4b, and 7b) exhibited 1.3- to 2.3-fold more antiproliferative activity than that of doxorubicin against the A549 cell line. In comparison to doxorubicin, compounds 1d and 3b were 4.1- and 1.04-fold, respectively more powerful against MCF-7 cancer cells. All the synthesized compounds were found to be more selective toward A549 cancer cells than the normal human fibroblast BJ cells. Of interest, compounds 1b and 7b exhibited promising cytotoxicity and SIs of 27.72 and 25.30, respectively, towards A549 cancer cells, higher than that of doxorubicin (SI 4.81). The most potent compounds 1b, 1d, 3b, 4b, and 7b were then subjected to in vitro Topo II inhibition assay. They showed IC50 values in the range of 2.07 to 8.86 µM. Of particular interest, compound 7b (IC50 = 2.07 µM), exhibited higher Topo II inhibitory activity than that of doxorubicin (IC50 = 2.56 µM). The significant Topo II inhibition of compound 7b was explained by molecular docking simulations into the Topo II active site. Compound 7b halted the cell cycle in the S phase in A549 cancer cells. It induced total apoptosis and necrosis of 20.73- and 4-fold, respectively, greater than the control. This evidence was supported by a 3.59-fold increase in the level of apoptotic caspase-9 and a remarkable elevation of the Bax/BCL-2 ratio. The physiochemical parameters of compound 7b were aligned with Lipinski's rule of five.

Design, synthesis, and anti-hepatocellular carcinoma of thiopyrimidine/chalcone hybrids as dual STAT3/STAT5 inhibitors

Among the promising therapeutic targets for treating cancer are the continuously active STAT proteins, which are important in the progression of many malignancies. Here, we detail the STAT3/5 inhibitory action and thiopyrimidine/chalcone hybrid design, production, and anti-hepatocellular carcinoma activity. The prepared hybrids were assessed for their cytotoxic effect on HepG2 and Huh7 liver cancer cells. The most active compounds 5e and 5h (IC50 range from 0.55 to 2.58 μM) were further evaluated against normal THLE cells to examine their safety profiles. The hybrids 5e and 5h were additionally tested for their potential to inhibit STAT3 and STAT5a. They showed dual inhibitory action, with a decrease in the level of STAT3 by 65 and 87 times, respectively, and a decrease in the level of STAT5 by 60 and 79.5 times, respectively, compared to the control. Additionally, western blot analysis of compound 5h revealed inhibition of STAT3 and STAT5 phosphorylation at Tyr705 and Tyr694, respectively, with only a slight decrease in the total expression of STAT3 and STAT5 proteins. And lastly, molecular docking research provided additional insight on the 5h binding mechanism in the STAT3 and STAT5 SH2 domains.

Thioethers: An Overview

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Spreading rapidly in recent years, cancer has become one of the causes of the highest mor-tality rates after cardiovascular diseases. The reason for cancer development is still not clearly under-stood despite enormous research activities in this area. Scientists are now working on the biology of cancer, especially on the root cause of cancer development. The aim is to treat the cancer disease and thus cure the patients. The continuing efforts for the development of novel molecules as potential anti-cancer agents are essential for this purpose. The main aim of this review was to present a survey on the medicinal chemistry of thioethers and provide practical data on their cytotoxicities against various cancer cell lines. The research articles published between 2001-2020 were consulted to pre-pare this review article; however, patent literature has not been included. The thioether-containing heterocyclic compounds may emerge as a new class of potent and effective anti-cancer agents in the future.

2-Thiopyrimidine/chalcone hybrids: design, synthesis, ADMET prediction, and anticancer evaluation as STAT3/STAT5a inhibitors

A novel 2-thiopyrimidine/chalcone hybrid was designed, synthesised, and evaluated for their cytotoxic activities against three different cell lines, K-562, MCF-7, and HT-29. The most active cytotoxic derivatives were 9d, 9f, 9n, and 9p (IC50=0.77-1.74 µM, against K-562 cell line), 9a and 9r (IC50=1.37-3.56 µM against MCF-7 cell line), and 9a, 9l, and 9n (IC50=2.10 and 2.37 µM against HT-29 cell line). Compounds 9a, 9d, 9f, 9n, and 9r were further evaluated for their cytotoxicity against normal fibroblast cell line WI38. Moreover, STAT3 and STAT5a inhibitory activities were determined for the most active derivatives 9a, 9d, 9f, 9n, and 9r. Dual inhibitory activity was observed in compound 9n (IC50=113.31 and 50.75 µM, against STAT3 and STAT5a, respectively). Prediction of physicochemical properties, drug likeness score, pharmacokinetic and toxic properties was detected.

Design, Synthesis, Dynamic Docking, Biochemical Characterization, and in Vivo Pharmacokinetics Studies of Novel Topoisomerase II Poisons with Promising Antiproliferative Activity

We previously reported a first set of hybrid topoisomerase II (topoII) poisons whose chemical core merges key pharmacophoric elements of etoposide and merbarone, which are two well-known topoII blockers. Here, we report on the expansion of this hybrid molecular scaffold and present 16 more hybrid derivatives that have been designed, synthesized, and characterized for their ability to block topoII and for their overall drug-like profile. Some of these compounds act as topoII poison and exhibit good solubility, metabolic (microsomal) stability, and promising cytotoxicity in three cancer cell lines (DU145, HeLa, A549). Compound 3f (ARN24139) is the most promising drug-like candidate, with a good pharmacokinetics profile in vivo. Our results indicate that this hybrid new chemical class of topoII poisons deserves further exploration and that 3f is a favorable lead candidate as a topoII poison, meriting future studies to test its efficacy in in vivo tumor models.

Bicyclic 6 + 6 systems: the chemistry of pyrimido[4,5-d]pyrimidines and pyrimido[5,4-d]pyrimidines

The present study provides an overview of the chemistry and biological significance of pyrimido[4,5-d]pyrimidine and pyrimido[5,4-d]pyrimidine analogs as types of bicyclic [6 + 6] systems. The main sections include: (1) synthesis methods; (2) the reactivities of the substituents linked to the ring carbon and nitrogen atoms; and (3) biological applications. A discussion demonstrating the proposed mechanisms of unexpected synthetic routes is intended. The aim of this study is to discuss the synthetic significance of the titled compounds and to establish the biological characteristics of this class of compounds as studied to date, where the compounds have been applied on a large scale in the medical and pharmaceutical fields. This survey will help researchers in the fields of synthetic organic and medicinal chemistry to undertake and improve new approaches for the construction of new standard biological components.

Pharmacoinformatics analysis of merbarone binding site in human topoisomerase IIα

Merbarone is a derivative of thiobarbituric acid, possessing catalytic inhibitory potential against human topoisomerase IIα (hTopoIIα). Merbarone was reported to inhibit DNA cleavage by hTopoIIα. It is important to understand the molecular mechanism of hTopoIIα inhibition by merbarone, as these details guide the rational design of new ligands. In this work, a systematic pharmacoinformatics analysis has been reported to analyze the merbarone-hTopoIIα interactions and to identify merbarone analogs as potential hTopoIIα inhibitors. The reported crystal structure of hTopoIIα-DNA complex (PDB ID: 4FM9) is not suitable for analyzing the merbarone-binding domain, because it is a biological assembly of hTopoIIα in C-gate open conformation. Therefore, 3D structure of hTopoIIα-DNA complex suitable for molecular modeling analysis at merbarone binding site was first generated. Using this generated complex, molecular docking analysis and molecular dynamics simulations were performed to explore the effect of merbarone on hTopoIIα-DNA complex. The binding energy for the enol form of merbarone with hTopoIIα-DNA was estimated to be -51.28 kcal/mol. The explored binding site and identified molecular recognition interactions were in accordance with the previously reported interference in the DNA-cleavage by merbarone. Virtual screening was performed using drug likeness filters, toxicity filters and ADMET descriptor based filters followed by molecular docking (ZINC database). Sixteen compounds were identified as merbarone-functional analogs suitable for hTopoIIα inhibition. These identified molecules can be considered for further evaluation of their anti-hTopoIIα activity.

Cytotoxic activity of 3-nitropyrazolo[5,1-c][1,2,4]benzotriazine derivatives: a new series of anti-proliferative agents

We report the synthesis and biological evaluation of a new series of 3-nitropyrazolo[5,1-c][1,2,4]benzotriazine derivatives (compounds 1-4) bearing appropriate substitutions in positions 7 and/or 8. The objective of this investigation was to study the effects of these substitutions on the cytotoxic activity of four new compounds against established human cancer cell lines (i.e. HT29 and HCT-8, colon carcinoma, MCF7, breast carcinoma, and A549, lung carcinoma cells). The inhibitory effects of compounds 1-4 on cell growth were assessed by the sulforhodamine B assay. Also, the effects of these compounds on cell cycle distribution of human colon carcinoma cells (HCT-8) were analyzed by flow cytometry. 3-Nitropyrazolo[5,1-c][1,2,4]benzotriazine derivatives displayed IC(50) values in the micromolar range on the growth of the four cell lines tested. Cell cycle perturbations induced on HCT-8 cells by study compounds at the IC(50) values consisted prevalently of a slight accumulation of cells in G(0)/G(1) phase and a slight decrease in G(2)/M phase. However, compound 3 induced a marked accumulation of cells into S phase with concomitant decrease in G(0)/G(1) and G(2)/M phases. Cytotoxicity data, compared to those obtained with 3-cyano-8-chloropyrazolo[5,1-c][1,2,4]benzotriazine 5-oxide (compound 5, NSC 683334) and other compounds previously synthesized in our laboratory, demonstrated a similar or even improved cytotoxic potency. Cell cycle perturbations caused by these compounds support the hypothesis that they may act by a direct or an indirect inhibition of DNA synthesis.