Catalase inhibition an anti cancer property of flavonoids: A kinetic and structural evaluation

Flavonoids are dietary polyphenols that present abundantly in fruits and vegetables. Flavonoids have inhibitory effects on enzymes and catalase is one among them. Catalase is a common enzyme ubiquitously found in all living organisms exposed to oxygen. It catalyzes the decomposition of hydrogen peroxide to water and oxygen (2H(2)O(2) -> 2H(2)O + O-2). Inhibition of pure and cellular catalase from K562 cells by flavonoids was similar and exhibited the following efficacy; Myrecetin > Quercetin > Kaempferol and Quercetin > Luteolin > Apigenin demonstrating structure activity relationship. Circular Dichroisrn (CD) spectra have shown distinct loss in alpha-helical structure of the catalase on interaction with the flavonoids. All flavonoids inhibited the catalase activity by uncompetitive mechanism. The K-m and V-max values of pure catalase were observed to be 294 mM(-1) and 0.222 mM(-1) s(-1) respectively and on inhibition with myrecetin the values decreased to a minimum of 23 mM(-1) and 0.014mM(-1)s(-1) respectively. Inhibition of catalase will directly results in -increased production of Reactive Oxygen Species (ROS) and pro-oxidant property of flavonoids. This inhibition was reversed in presence of Cu2+ ions because of the chelating affect of flavonoids. (C) 2017 Elsevier B.V. All rights reserved.