Chitosan functionalized thiophene-2-thiosemicarbazones, and their copper(II) complexes: synthesis, characterization, and anticancer activity

Abstract

Chitosan is a polyfunctional biomaterial that is subjected to chemical modification through functionalization to give the derivatives of remarkable anticancer activity. In this study, functionalization of low molecular weight commercial chitosan (CS) (Mw < 3000 Da, 87% DDA) and high molecular weight crab shell chitosan (CCS) (viscosity average Mw 350 kDa, 67% DDA) as chitosan thiophene-2-thiosemicarbazones (DS 63.48–64.14%) and the formation of their copper(II) complexes were established by FT-IR, 13C NMR, EPR spectroscopy, powder X ray diffraction, elemental microanalysis and magnetic susceptibility measurements. The thermal study of the compounds showed a substantial stability up to 200°C until the commencement of chitosan chain degradation. The MTT assay revealed higher activity of CS (IC50 370 μgmL−1 in MCF-7 and >400 μgmL−1 in MDCK cell line) than CCS (IC50 > 400 μgmL−1 in both cell lines), higher activity of CSTHPTSC (IC50 364 μgmL−1 in MDCK and 369 μgmL−1 in MCF-7 cell line) than CCSTHPTSC (IC50 > 400 μgmL−1 in both cell lines), higher activity of the complexes Cu-CSTHPTSC (IC50 338 μgmL−1 in MDCK and 318 μgmL−1 in MCF-7 cell line) and Cu-CCSTHPTSC (IC50 293 μgmL−1 in MDCK and >400 μgmL−1 in MCF-7 cell line) than their corresponding ligands.