Abstract:

We explored the effect of pretreatment and extraction conditions (repeated freeze-thawing, extraction solvent and
pH) on the superoxide anion radical scavenging capacity of phycobiliprotein from Nostoc sphaeroides Küting. The results
revealed that this activity was not affected by repeated freeze-thawing before extraction, but enhanced by using phosphate
buffer as the extraction solvent. The extracts at pH 5.6 and pH 7.3 did not show a significant difference from each other
with respect to superoxide anion radical scavenging capacity, although both slightly inferior to that obtained at pH 8.1. The
superoxide anion radical scavenging capacity of phycobiliprotein from Nostoc sphaeroides Küting became stronger with
increasing digestion time in simulated intestinal juice, but was attenuated in simulated gastric juice.

Key words: phycobiliprotein from Nostoc sphaeroides Küting, repeated freeze-thawing, pH, degradation products