Synthesis, enzyme inhibition assay, and molecular modeling study of novel pyrazolines linked to 4-methylsulfonylphenyl scaffold: antitumor activity and cell cycle analysis

Abstract

Antitumor activity using 59 cancer cell lines and enzyme inhibitory activity of a newly synthesized pyrazoline-linked 4-methylsulfonylphenyl scaffold (compounds 18a-q) were measured and compared with those of standard drugs. Pyrazolines 18b, 18c, 18f, 18g, 18h, and 18n possessed significant antitumor activity, with a positive cytotoxic effect (PCE) of 22/59, 21/59, 21/59, 48/59, 51/59, and 20/59, respectively. The cancer cell lines HL60, MCF-7, and MDA-MB-231 were used to measure the IC₅₀ values of derivatives 18c, 18g, and 18hvia the MTT assay method, and the results were compared with those of reference drugs. Derivatives 18g and 18h showed potent and broad-spectrum antitumor activities against HL60 (IC₅₀ of 10.43, 8.99 μM, respectively), MCF-7 (IC₅₀ of 11.7 and 12.4 μM, respectively), and MDA-MB-231 (IC₅₀ of 4.07 and 7.18 μM, respectively). Compound 18c exhibited strong antitumor activity against HL60 and MDA-MB-231 cell lines with IC₅₀ values of 8.43 and 12.54 μM, respectively, and moderate antitumor activity against MCF-7 cell lines with an IC₅₀ value of 16.20 μM. Compounds 18c, 18g, and 18h remarkably inhibited VEGFR2 kinase (IC₅₀ = 0.218, 0.168, and 0.135 μM, respectively) compared with the reference drug sorafenib (IC₅₀ = 0.041 μM). Compounds 18g and 18h effectively inhibited HER2 kinase (IC₅₀ = 0.496 and 0.253 μM, respectively) compared with erlotinib (IC₅₀ = 0.085 μM). Compound 18h inhibited EGFR kinase (IC₅₀ = 0.574 μM) with a potency comparable with that of the reference drug erlotinib (IC₅₀ = 0.105 μM). Pyrazolines 18c, 18f, and 18h arrested the S/G2 phase of the cell cycle in HL-60 cells. In addition, derivatives 18c, 18f, and 18h revealed lower Bcl-2 protein expression anti-apoptotic levels and higher Bax, caspase-3, and caspase-9 expression levels. Molecular docking studies of derivative 18h into the binding sites of EGFR, HER2, and VEGFR2 kinases explored the interaction mode of these pyrazoline derivatives and their structural requirements for antitumor activity.

Fig. 1. FDA aproved receptor tyrosine kinase inhibitors as anticancer agents.

Fig. 2. Reported antitumor pyrazole, benzenesulfonyl compounds (VI–XIV), and the designed pyrazole-linked benzenesulfonyl derivatives (18a–q).

Scheme 1. Synthesis of the designed triarylpyrazolines 18a–q.

Fig. 3. Effect of pyrazolines 18c (left panel), 18g (middle panel), and 18h (right panel) on the percentage of annexin V-FITC-positive staining in HL-60 cells.

Fig. 4. Cell cycle analysis of HL-60 cells treated with pyrazolines 18c (left panel), 18g (middle panel), and 18h (right panel).

Fig. 5. Binding mode of compound 18h (grey sticks) within hEGFR (green cartoon PDB ID 1M17). In panel (A), the R-enantiomer is reported, and in panel (B), the S-enantiomer of the compound is reported. Residues in the binding sites are represented by thin sticks, and hydrogen bonds are shown as grey dotted lines. Images were generated using Maestro (Schrödinger, LLC, New York, 2020).

Fig. 6. Binding mode of compound 18h (grey sticks) within hHER2 (orange cartoon PDB ID 3RCD). In panel (A), the R-enantiomer is reported, and in panel (B), the S-enantiomer of the compound is reported. Residues in the binding sites are represented by thin sticks, hydrogen bonds are shown as black dotted lines, and the cation–π interaction and the π–π interaction as green and cyan dotted lines, respectively. Images were generated using Maestro (Schrödinger, LLC, New York, 2020).

Fig. 7. Binding mode of compound 18h (grey sticks) within hVEGFR2 (magenta cartoon PDB ID 4ASD). In panel (A), the R-enantiomer is reported, and in panel (B), the S-enantiomer of the compound is reported. Residues in the binding sites are represented by thin sticks, hydrogen bonds are shown as black dotted lines, and the π–π interaction as cyan dotted lines. Images were generated using Maestro (Schrödinger, LLC, New York, 2020).