C-Phycocyanin: A Potent Peroxyl Radical Scavenger in Vivo and in Vitro

Abstract

C-Phycocyanin (from Spirulina platensis) effectively inhibited $CC1_4$-induced lipid peroxidation in rat liver in vivo. Both native and reduced phycocyanin significantly inhibited peroxyl radical-induced lipid peroxidation in rat liver microsomes and the inhibition was concentration dependent with an $IC_{50}$ of 11.35 and $12.7 \mu M$, respectively. The radical scavenging property of phycocyanin was established by studying its reactivity with peroxyl and hydroxyl radicals and also by competition kinetics of crocin bleaching. These studies have demonstrated that phycocyanin is a potent peroxyl radical scavenger with an $IC_{50}$ of $5.0 \hspace{2mm} \mu M$ and the rate constant ratios obtained for phycocyanin and uric acid (a known peroxyl radical scavenger) were 1.54 and 3.5, respectively. These studies clearly suggest that the covalently linked chromophore, phycocyanobilin, is involved in the antioxidant and radical scavenging activity of phycocyanin