Synthesis and characterization of sulfonamide appended rigid phenyl-based and non-rigid 1,4-benzodioxan-based ring systems and their Pt(II) complexes towards potential therapeutic targets

Abstract

Two novel non-rigid; 1,4-benzodioxan (bzd) based and rigid; 4-methylbiphenyl (4-Mebip) based di-(2-picolyl)amine derived sulfonamide ligands, and their cis-dichloroplatinum(II) complexes have been synthesized. The ligands; L1: N(SO2)(bzd)dpa and L2: N(SO2)(4-Mebip)dpa were synthesized via N-sulfonylation of di-(2-picolyl)amine in good yield. Their platinum(II) complexes; C1: [PtCl2(N(SO2)(bzd)dpa)], C2: [PtCl2(N(SO2)(4-Mebip)dpa)]·CH3CN were synthesized and characterized by 1H NMR, FTIR, UV–Vis and fluorescence spectroscopies. Structural studies revealed that the L1 and L2 ligands coordinate Pt(II) in a bidentate mode in C1 and C2 complexes, forming an eight-membered chelate ring. Interestingly, L1 possesses two conformations because the dioxan ring exists with a 95:5 occupancy ratio. The L2 ligand crystal undergoes a phase transition to triclinic form with twinning at 90 K whereas, at 150 K, the ligand exists in a monoclinic system; the populations of the two orientations for one pyridine substituent are approximately 78:22. The 1H NMR spectra of both Pt complexes obtained in DMSO‑d6 revealed two doublets (exo-CH2 and endo-CH2) for the magnetically inequivalent methylene protons, in contrast to their uncoordinated ligands, which show a singlet peak for the methylene protons. The NCI-H292 (non-small cell lung cancer cells) and MRC-5 (human normal lung fibroblast cells) were used to examine the in vitro cytotoxic activity of all synthesized compounds. All tested compounds demonstrated notable cytotoxicity against NCI-H292 cells, with the most pronounced cytotoxic effect being displayed by [PtCl2(N(SO2)(4-Mebip)dpa)]·CH3CN (C2). Docking studies strengthen in vivo antiproliferation activity where specific interactions with AKT1, BAX, STK-11, and BCL-2 were explored. Further predictions revealed that the compounds have inhibitory effects on COX-2 and PDE10A proteins.