Exploring the Biological Activity of a Library of 1,2,5-Oxadiazole Derivatives Endowed With Antiproliferative Activity.

BACKGROUND/AIM: The identification of a series of oxadiazole-based compounds, as promising antiproliferative agents, has been previously reported. The aim of this study was to explore the SAR of newly-synthesized oxadiazole derivatives and identify their molecular targets. MATERIALS AND METHODS: A small library of 1,2,5-oxadiazole derivatives was synthetized and their antiproliferative activity was tested by the MTT assay. Their interaction with topoisomerase I was evaluated and a molecular docking study was performed. RESULTS: Several candidates showed cytotoxicity towards two human tumor cell lines, HCT-116 (colorectal carcinoma) and HeLa (cervix adenocarcinoma). Some derivatives exhibited inhibitory effects on the catalytic activity of topoisomerase I and this effect was supported by docking studies. CONCLUSION: The enzyme inhibition results, although not directly related to cytotoxicity, suggest that a properly modified 1,2,5 oxadiazole scaffold could be considered for the development of new anti-topoisomerase agents.

A field-based disparity analysis of new 1,2,5-oxadiazole derivatives endowed with antiproliferative activity.

A series of 1,2,5-oxadiazoles were synthesized as new potential antiproliferative agents. The in vitro cytotoxic activity evaluation of title compounds through MTT assay revealed that some of them showed significant activity against the HCT-116 cancer cell line. The field-based disparity analysis provided indications about the electrostatic, hydrophobic, and shape features underlying the cytotoxicity, suggesting that increasing the negative electrostatic field on the heterocyclic core of the structure has positive effects on the activity. The structure-activity relationships (SAR) around a particular compound can be explained allowing for a structural rationale for the differences in activity. The SAR provided by this series of compounds can be exploited to carry out further lead optimization.

An in vivo active 1,2,5-oxadiazole Pt(II) complex: A promising anticancer agent endowed with STAT3 inhibitory properties.

New Pt(II) complexes (Pt-1-3) bearing 1,2,5-oxadiazole ligands (1-3) were synthesized, characterized and evaluated for their ability to disrupt STAT3 dimerization. Ligand 3·HCl showed cytotoxic effects on HCT-116 cells (IC50 = 95.2 µM) and a selective ability to interact with STAT3 (IC50 = 8.2 µM) versus STAT1 (IC50 > 30 µM). Its corresponding platinum complex Pt-3 exhibited an increased cytotoxicity (IC50 = 18.4 µM) and a stronger interaction with STAT3 (IC50 = 1.4 µM), leading to inhibition of its signaling pathway. Pt-3 was also evaluated in cell-based assays for its action on p53 expression and on STAT3 phosphorylation. In syngeneic murine Lewis lung carcinoma (LLC) implanted in C57BL/6 mice, Pt-3 showed a higher antitumor activity with fewer side effects than cisplatin.

Identification of a new STAT3 dimerization inhibitor through a pharmacophore-based virtual screening approach.

Signal transducer and activator of transcription 3 (STAT3) plays an essential role in cell growth regulation and survival. An aberrant STAT3 activation and/or expression is implied in various solid and blood tumors as well as in other pathologies like rheumatoid arthritis and pulmonary fibrosis, thus making the search for STAT3 inhibitors a growing field of study. With the aim of identifying new inhibitors of STAT3 dimerization, we screened a database including more than 1 320 000 commercially available compounds using a receptor-based pharmacophore model comprising the key protein-protein interactions identified in the STAT3 dimer and refining the search through docking and molecular dynamic simulations studies. STAT3 binding assays revealed a significant STAT3 inhibitory activity and selectivity versus Grb2 for one of the four top-scored compounds, thus verifying the reliability of the virtual screening workflow. Moreover, such compound could already be considered as a lead for the development of new and more potent STAT3 dimerization inhibitors.