Dioxomolybdenum(VI) complexes with 4-benzyloxysalicylidene-N/S-alkyl thiosemicarbazones: Synthesis, structural analysis, antioxidant activity and xanthine oxidase inhibition

Eight dioxomolybdenum(VI) complexes of 4-benzyloxysalicylidene N-or S-alkyl substituted thiosemicarbazones, where alkyl is methyl, ethyl, propyl or butyl, were synthesized and characterized by analytical and spectroscopic techniques (UV, IR, H-1 NMR). As a representative example, the dioxomolybdenum(VI) complex of N-4-propyl-substituted thiosemicarbazone (3) was studied by single-crystal X-ray diffraction, revealing a distorted octahedral environment of the molybdenum center. The total antioxidant capacities of the compounds were determined using the cupric reducing antioxidant capacity (CUPRAC) method. Trolox equivalent antioxidant capacity (TEAC) values of the ONN series of thiosemicarbazones (L-5-L-8) were measured to be higher than the ONS series of ligands (L-1-L-4). The scavenging effects for the hydroxyl radical (center dot OH) and xanthine oxidase (XO) inhibition activities of these compounds were also determined.