Benzimidazole-linked pyrazolo[1,5-a]pyrimidine conjugates: synthesis and detail evaluation as potential anticancer agents.

A library of benzimidazole briged pyrazolo[1,5-a]pyrimidine (6a-q) was designed, synthesized and subjected for evaluation for cytotoxic potential. Antiproliferative activity, ranging from 3.1-51.5 µM, was observed against a panel of cancer cell lines which included MCF-7 (breast cancer), A549 (lung cancer), HeLa (cervical cancer) and SiHa (cervical cancer). Among them, 6k, 6l, 6n and 6o have shown significant cytotoxicity and were investigated further to study their probable mechanism of action against MCF-7 cell line. Accumulation of cells at sub-G1 phase was observed in flow cytometric analysis. The detachment of cells from substratum and membrane blebbing seen under bright field microscopy supports the ability of these conjugates to induce apoptosis. Immunostaining and western blot analysis showed EGFR, p-EGFR, STAT3, and p-STAT3 significant downregulation. Western blot analysis demonstrated an elevated level of apoptotic proteins such as p53, p21, Bax, whereas a decrease in the antiapoptotic protein Bcl-2 and procaspase-9, confirming the ability of these conjugates to trigger cell death by apoptosis. EGFR kinase assay confirms the specific activity of conjugates. Molecular docking simulation study disclosed that these molecules fit well in ATP-binding pocket of EGFR. The analysis of docking poses and the atomic interactions of different conjugates rationalize the structural-activity relationship in this series. Benzimidazole-linked pyrazolo[1,5-a]pyrimidine conjugates were synthesized and evaluated for their anticancer potential. All the conjugates have significant anticancer potential. Further mechanistic studies revealed that these conjugates arrest cancer cell growth by EGFR/STAT3 inhibition.

Design, synthesis and biological evaluation of novel pyrazolochalcones as potential modulators of PI3K/Akt/mTOR pathway and inducers of apoptosis in breast cancer cells.

Cancer has been established as the "Emperor of all maladies". In recent years, medicinal chemistry has focused on identifying novel anti-cancer compounds; though discovery of these compounds appears to be a herculean task. In present study, we synthesized forty pyrazolochalcone conjugates and explored their cytotoxic activity against a panel of sixty cancer cell lines. Fifteen conjugates of the series showed excellent growth inhibition (13b-e, 13h-j, 14c-d, 15 a, 15 c-d, 16b, 16d and 18f; GI50 for MCF-7: 0.4-20 µM). Conjugates 13b, 13c, 13d, 16b and 14d were also evaluated for their cytotoxic activity in human breast cancer cell line (MCF-7). The promising candidates induced cell cycle arrest, mitochondrial membrane depolarization and apoptosis in MCF-7 cells at a 2 µM concentration. Furthermore, inhibition of PI3K/Akt/mTOR pathway-regulators such as PI3K, p-PI3K, p-AKT, and mTOR were observed; as well as upregulation of p-GSK3ß and tumor-suppressor protein, PTEN. Our study indicates that pyrazolochalcone conjugates could serve as potential leads in the development of tailored cancer therapeutics.