Rose bengal-induced photodamage to subcellular membranes and enzymes

Studies were made of photodamage (photolysis) caused by Rose Bengal + light of peroxisomes, mitochondria, and lysosomes, as well as inhibition of the respective marker enzymes: catalase, sulfite oxidase, and acid phosphatase. The time-dependence of lipid peroxidation caused by the same system and measured by the increase of thiobarbituric acid-reactive substances was also examined. The most sensitive to photolysis were the peroxisomes and the least susceptible were lysosomes as the inhibition of their marker enzymes followed this order. The sensitivity of the subcellular membranes to digitonin (a sterol binding agent) showed the opposite dependence. The importance of the cholesterol content for the membrane stability to active oxygen species, as well as the role of lipid peroxidation in photodynamic damage of the systems studied, is discussed.