Active oxygen intermediates and chlorophyllin bleaching

Bleaching of chlorophyllin, a water soluble copper containing porphyrin molecule, was investigated with regard to the potential role of active oxygen intermediate involvement. It was found that the bleaching was highly aerobic and also biphasic in nature. The aerobic photobleaching and the dark bleaching were effectively prevented by the addition of reductants such as ascorbate and cysteine. In addition, the reductant and peroxyl radical scavenger, Trolox, was highly effective in preventing bleaching. Catalase was moderately effective in preventing photobleaching whereas peroxidase and superoxide dismutase hastened the photobleaching process. It is concluded that the bleaching of chlorophyllin is a peroxidative process which does not involve singlet oxygen, superoxide, nor the (OH)-O-. radical. (C) 1996 Academic Press, Inc.