Synthesis, spectroscopic characterizations, carbonic anhydrase II inhibitory activity, anticancer activity and docking studies of new Schiff bases of sulfa drugs

Herein we present the synthesis, and biological evaluation of new Schiff bases incorporating (2‑hydroxy-5-methylbenzaldehyde sulfisoxazole (S2M-S1) and 2‑hydroxy-5-methylbenzaldehyde sulfamethoxazole (S1M-S1) derived from sulfisoxazole (S2)/sulfamethoxazole (S1) and substituted salicylaldehyde and their Pd (II), Cu(II) complexes. The synthesized compounds were characterized by FT-IR, ¹H–¹³C NMR, LC-MS, magnetic susceptibility and conductivity measurements. The molecular structure of S2M-S1 was also determined by the single crystal X-ray diffraction technique and was found to crystallize in the monoclinic, space group P1 21/n 1. We investigated the effects of molecules on human carbonic anhydrase isoenzyme II (hCAII). Cu(S2M-S1)₂, Pb(S2M-S1)₂, Pb(S1M-S1)₂, and Cu(S1M-S1)₂, exhibited inhibitory effects with 10, 20, 42 and 67 µM IC₅₀ value, respectively. Also, molecular Docking studies performed and anticancer activities of newly synthesized compounds were evaluated against three human cancer cell lines with the sulfonamide B test. S2M-S1, S1M-S1 compounds and their Cu (II) complexes exhibited promising cytotoxic activity against all cell lines. IC₅₀ values for breast (MCF7) cells are 40 µM for S2M-S1, S1M-S1 compounds and their Cu (II) complexes.