Catechin-zinc-complex: synthesis, characterization and biological activity assessment

Flavonoids have been the subject of research due to their abundance and versatility, which have been attributed to therapeutic benefits. Flavonoids have the potential to form metal complexes, which have been the focus of research due to their potential bioactivity and pharmacological effects. They often form complexes with a metal to ligand (M:L) molar ratio of 1:2 or 1:1, which have strong stability constants. The effectiveness with which flavonoids attach to metal ions is strongly connected with the type and state of transition metal ions. In this paper we displayed some of the methods of synthesizing flavonoid-metal complex and the biological activity assessment. The antioxidant effects were evaluated against free radicals (iron chelation and hydroxyl radical tests) and the inhibition of lipoxygenase. On the other hand, the antidiabetic potential was investigated by using alpha-amylase and alpha-glucosidase assays. The infrared, UV spectrophotometry and the scanning electronic microscopy results indicated the formation of small acicular crystals with specific absorption bands confirming the obtaining of the catechin-zinc complex (Cat-Zn complex). The antioxidant assays indicated changes in the potential of the newly formed complex, with different intensity of action depending on the test, whereas the inhibition of alpha-amylase and alpha-glucosidase showed better activity for the complex as compared to catechin and zinc acetate. In conclusion, maintaining or improving the antioxidant or enzymatic inhibitory properties of catechin, after complexation with zinc ions, may represent a benefit for the use of such compounds in preclinical studies, but further testing is necessary to fully understand the in vivo potential.