Enhanced Antioxidant Activity of Phycocyanin Oligopeptides

Phycocyanin, a phytonutrient found in blue-green algae, has various beneficial properties, including potent antioxidant effects. The goal of this study was to investigate the antioxidant potency of a novel phycocyanin oligopeptide (PC-O) compared to phycocyanin (PC). Antioxidant potency of PC-O and PC was measured using two different methods: 1) the Folin-Ciocalteu reaction assay, and 2) the Oxygen Radical Absorbance Capacity (ORAC) 6.0 assay. The Folin-Ciocalteu reaction assay (or total phenolics assay) was run using Folin-Ciocalteu’s phenol reagent and sodium carbonate. Optical absorbance was measured at 765nm in a colorimetric plate reader with gallic acid as a reference standard. The ORAC 6.0 assay was run to evaluate the antioxidant capacity of a material against six primary reactive oxygen species: peroxyl radical, hydroxyl radical, superoxide anion, singlet oxygen, peroxynitrite, and hypochlorite. Trolox was used as the reference standard, and the results were expressed as μmole Trolox equivalency per gram of a tested material. In both assays, PC-O had higher antioxidant potency than PC. In the Folin-Ciocalteu reaction assay, the cellular antioxidant capacity of PC-O (24 mg/L) was greater than PC (16 mg/L). PC-O also demonstrated consistently higher antioxidant activity in the ORAC 6.0 assay, as follows: peroxyl radicals, PC-O (477 μmole TE/gram) vs. PC (26 μmole TE/gram); hydroxyl radicals, PC-O (734 μmole TE/gram) vs. PC (62 μmole TE/gram); peroxynitrite, PC-O (40 μmole TE/gram) vs. PC (7 μmole TE/gram); super oxide anion, PC-O (172 μmole TE/gram) vs. PC (53 μmole TE/gram); singlet oxygen, PC-O (92 μmole TE/gram) vs. PC (70 μmole TE/gram); and hypochlorite, PC-O (2,805 μmole TE/gram) vs. PC (312 μmole TE/gram). These results demonstrate that phycocyanin oligopeptide (PC-O) is a superior antioxidant compared to phycocyanin (PC) as shown by its higher cellular antioxidant capacity in the Folin-Ciocalteu reaction assay and significantly higher ORAC 6.0 scores. This work was supported by Nutrition 21, LLC.