Polymannionic acid and polygulonic acid are oligosaccharides degraded by alginate. After degradation, some biological activities of alga collagen were enhanced and even showed other special activities.
The results showed that polymannouronic acid and polyguluronic acid had good scavenging effect on hydroxyl radical and superoxide anion radical, and the scavenging effect was gradually enhanced with the increase of oligosaccharide concentration in the experimental range. With the increase of molecular weight, the free radical scavenging ability of series oligosaccharides decreased gradually, and the scavenging ability of M and G oligosaccharides with the same molecular weight range was approximately the same. In the inhibition test of lipid peroxidation, within the range of test concentration (0-0.2mg/mL), algin series oligosaccharides had a good inhibitory effect on lipid peroxidation, and the inhibitory ability was positively correlated with their respective concentrations, and the inhibitory ability of algin series oligosaccharides was gradually enhanced with the increase of molecular weight.
Polymannoglycoluronic acid and polyguluronic acid not only have good antioxidant activity, but also have biological activities such as enhancing immunity, lowering blood lipid and blood glucose, anti-senile dementia, anti-inflammatory, antibacterial and antiviral, which have broad application prospect.