The antioxidative activity of phycocyanobilin from Spirulina platensis was evaluated against oxidation of methyl
linoleate in a hydrophobic system or with phosphatidylcholine liposomes. Phycocyanobilin as well as phytochemicals
including α-tocopherol, caffeic acid and zeaxanthin, effectively inhibited the peroxidation of methyl linoleate
and produced a prolonged induction period. Oxidation of phosphatidylcholine liposomes was also controlled
markedly by adding phycocyanobilin or α-tocopherol. Phycocyanobilin was distributed outside in the liposomes
to scavenge radicals from AAPH and to prevent initiation of radical chain reactions. When the concentrations of
phycocyanin and phycocyanobilin in the reaction mixture were adjusted equally on a phycocyanobilin basis, the
activity of phycocyanobilin was almost the same as that of phycocyanin in the AAPH-containing reaction mixture.
The antioxidizing action of phycocyanin prepared from spray-dried Spirulina almost agreed with that from fresh
Spirulina in the AAPH-containing reaction mixture. These results suggest that phycocyanobilin is responsible for
the majority of the antioxidative activity of phycocyanin and may act as an effective antioxidant in a living human
body