A cytochrome c-enhanced peroxidation reaction with potential use in screening dietary antioxidants

Reactive oxygen species (ROS) that result from events such as cellular respiration can cause damage to biological molecules and tissues. A variety of endogenous and dietary antioxidants function in moderating the extent of oxidative damage in the body. In this report, a pro-oxidant system is presented as an assay for screening possible antioxidant activities of dietary factors. The assay reaction involves peroxidatic oxidation of the redox indicator N,N,N',N'-tetramethyl-1,4-phenylenediamine (TMPD). It is shown that the reaction rate is enhanced by up to 10-fold in the presence of cytochrome c (cyt c), a mitochondrial electron transport protein. The extent to which selected dietary antioxidant factors inhibit the cytochrome c-enhanced peroxidatic oxidation of TMPD is also reported. Considering the known pathological consequences of mitochondrial membrane disruption and cytochrome c release in the cell, this reaction and assay may be of pathological and therapeutic relevance.