Organotin(IV) derivatives of 4-chloro-2-methylphenoxyacetic acid: synthesis, spectral characterization, X-ray structures, anticancer, enzyme inhibition, antileishmanial, antimicrobial and antioxidant activities

Four organotin(IV) carboxylate complexes; (C₄H₉)₃SnL (1), CH₃SnL (2), (C₄H₉)₂SnL₂ (3) and (CH₃)₂SnL₂ (4) are synthesized by the condensation reaction of organotin(IV) chlorides with sodium-4-chloro-2-methylphenoxyacetate (NaL). The FT-IR spectra suggested bridging/chelating bidentate coordination of the ligand to the tin atom. Single-crystal XRD analysis authenticated the FT-IR findings for 1 and 2. The NMR study has shown no significant differences in the signals of the free and coordinated ligand except for absence of a proton and up-filed/down-field shift of the C signal of the carboxyl group in the spectra. Complexes 1-4 have shown better enzyme inhibition, antioxidant, antimicrobial, and anticancer activities compared to the free ligand acid. Complex 3 was the most active inhibitor of AChE, BChE, α-glucosidase and α-amylase with IC₅₀ values of 43.76, 102.39, 232.71 and 91.84 µg/mL, respectively. Additionally, 3 with IC₅₀ values of 7.52 and 8.77 µg/mL in the DPPH and ABTS assays, respectively was better antioxidant than the standard. Complex 4 was the most efficient inhibitor of MAO-B and COX-2 enzymes with IC₅₀ values of 106.99 and 12.98 µg/mL, respectively, while 1 (IC₅₀ = 38.97 µg/mL) has shown the highest 5-LOX inhibition potential. Complexes 1-4 with IC₅₀ values in the range 237.51-168.35 µg/mL have shown better antileishmanial activity than HL (IC₅₀ = 277.57 µg/mL). The compounds showed good to potent antiproliferative activity in malignant glioma U87 cells with IC₅₀ values in the range 12.54 ± 0.05 to 37.65 ± 0.04 µg/mL. Antimicrobial activities have shown promising results for the compounds compared to the standards in some cases.