Several articles have described that PCs have antioxidant and anti-inflammatory
properties (Romay et al. 1998; Pinero Estrada et al. 2001; Romay
et al. 2003), and further studies have demonstrated that PCBs, which have
structural similarities to bilirubins, act as antioxidants and play an important
role in antioxidant activities (Bhat and Madyastha 2000; Hirata et al. 2000).
However, the potential contribution of the apoprotein to the antioxidant activity
of PCs has not been clarified. Concerning its stability in light, it is difficult
to make PCs form charged complexes and generate radicals by light. But PCs
were shown to transfer electrons, which means PCs could provide electrons
if suitable electron acceptors or donors are available. Stocker et al. (1987)
showed that PCs could be used as effective photosensitizers in photodynamic
therapy. Therefore, PCs have the opposite abilities to generate and scavenge
radicals. But the factors determining the above two attributes were not
clarified.
The authors described the antioxidant activity of allophycocyanin in S.
platensis in a previous study (Zhou et al. 2005). The aims of this study were
to evaluate the changes in the antioxidant activity of PCs when they are
denatured under different conditions, and to discuss the factors to generate
and scavenge radicals, as well as the contribution of apoprotein to the antioxidant
activity of PC.