Vanillin as an antioxidant in rat liver mitochondria: Inhibition of protein oxidation and lipid peroxidation induced by photosensitization

Using rat liver mitochondria, as model systems, we have examined the abilit y of the natural compound and the food-flavoring agent, vanillin to protect membranes against oxidative damage induced by photosensitization at concen trations normally used in food preparations. Vanillin, at a concentration o f 2.5 mmol/L, has afforded significant protection against protein oxidation and lipid peroxidation in hepatic mitochondria induced by photosensitizati on with methylene blue plus light. The effect observed was both time- and c oncentration-dependent. The inhibitory effect is similar to ascorbic acid a nd the singlet oxygen quencher, diazabicyclo[2.2.2]octane (DABCO) but less effective than sodium azide and glutathione. Examination of possible mechan isms responsible for the observed protection, showed that vanillin has a si gnificant ability to quench singlet oxygen (O-1(2)), a reactive species res ponsible for damage induced during photosensitization by Type II mechanism. Hence, this flavoring compound, due to its antioxidant ability, may have p otential to prevent oxidative damage to membranes in mammalian tissues and thereby the ensuing diseased states.