Antioxidant effects of dihydroquercetin and rutin in peroxidase reactions catalyzed by cytochrome c

Abstract

The combination of cytochrome c (Cyt c) and cardiolipin is known to catalyze free radical oxidation of membrane lipids, thereby triggering the cascade of reactions that lead to programmed cell death (apoptosis). It was interesting to estimate the possibility of controlling this reaction with the use of inhibitors of free radical reactions (antioxidants). The effects of bovine heart cardiolipin (BCL) and synthetic 1,1′,2,2′-tetraoleyl cardiolipin (TOCL) on the Cyt c peroxidase activity detected by luminol-enhanced chemiluminescence (CL) were studied. The CL amplitude substantially increased in the presence of TOCL and BCL in the ranges of the cardiolipin to Cyt c molar ratios from 0 to 30 and from 0 to 50, respectively, and insignificantly increased upon further increase in these ratios to 640: 1 and 320: 1. This dependence of the CL amplitude on the cardiolipin to protein ratio may have been accounted for by saturation of the protein surface with cardiolipin molecules reached at a certain molar ratio. The effects of the antioxidants rutin and dihydroquercetin (DHQ) on the peroxidase activity of Cyt c in combination with BCL was studied in the presence of the CL activator coumarine C-525 at a BCL to Cyt c molar ratio of 32: 1. In both cases, the peroxidase activity decreased as the antioxidant content of the system increased. A 50% inhibition of the reaction was observed at DHQ and rutin concentrations of 10 and 3 μM, respectively. It is supposed that the use of antioxidants will make it possible to control the formation of lipid radicals on membrane-bound Cyt c, which is the key stage of apoptosis.