Synthesis, characterisation and antioxidant activity of luteolin–vanadium(II) complex

The complex formation between luteolin (L) and vanadium(IV) oxide sulphate monohydrate (VOSO4·H2O) was examined under UV–visible, infra-red spectroscopy, mass spectroscopy and NMR techniques. The spectroscopic data indicated that luteolin reacts with vanadium oxide cation (VO+2) through 4-carbonyl-5-hydroxy chelation site in the two luteolin molecule. The free radical antioxidant activity of the complex with respect to the parent molecule was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and 2,2′-azinobis 3-ethylbenzothiazoline-6-sulphonic acid diammonium salt (ABTS) methods. It was observed that the free radical scavenging activity and ferric ion reducing potential of luteolin was increased after the formation of complex with vanadium oxide (VO+2) cation.