Synthesis, Characterisation, and Preliminary In Vitro Studies of Vanadium(IV) Complexes with a Schiff Base and Thiosemicarbazones as Mixed Ligands

Abstract

Abstract [VO(sal‐ L ‐tryp)(H 2 O)] ( 1 , sal‐ L ‐tryp = N ‐salicylidene‐ L ‐tryptophanate) was used as a precursor to produce the new complexes [VO(sal‐ L ‐tryp)(MeATSC)] · 1.5C 2 H 5 OH [ 2 , MeATSC = 9‐Anthraldehyde‐ N (4)‐methylthiosemicarbazone], [VO(sal‐ L ‐tryp)( N ‐ethhymethohcarbthio)] · H 2 O [ 3 , N ‐ethhymethohcarbthio = ( E )‐ N ‐ethyl‐2‐(4‐hydroxy‐3‐methoxybenzylidene)hydrazinecarbothioamide] and [VO(sal‐ L ‐tryp)(acetylethTSC)] · C 2 H 5 OH { 4 , acetylethTSC = ( E )‐ N ‐ethyl‐2‐[1‐(thiazol‐2‐yl)ethylidene]hydrazinecarbothioamide} by reaction with the respective thiosemicarbazone. The chemical and structural properties of these ligands and complexes were characterised by elemental analysis, ESI‐MS, FTIR, UV/Vis, ESR and 1 H and 13 C NMR spectroscopy and X‐ray crystallography. Dimethyl sulfoxide (DMSO) and [D 6 ]DMSO solutions of 1 – 4 were oxidised in air to produce vanadium(V) species, which were verified by ESI‐MS and 51 V NMR spectroscopy. The anticancer properties of 2 – 4 were examined with three colon cancer cell lines, HTC‐116, Caco‐2 and HT‐29, and noncancerous colonic myofibroblasts, CCD18‐Co. Compounds 2 – 3 exhibited less inhibitory effects in the CCD‐18Co cells, which indicates a possible cytotoxic selectivity towards colon cancer cells. In general, compounds that exhibit antiproliferative activity to cancer cells but do not affect noncancerous cells may have a potential in chemotherapy.