The derivatization and antioxidant activities of yeast mannan.

The alkaline mannan (M) was extracted from yeast cell walls, and the best extraction condition was: 100°C, 2h, 1% NaOH, solid-liquid ratio of 10:1. The purity of mannan was 96.15%. Its five derivatives were obtained by chemical modification methods, and they were: phosphorylated mannan (P-M), sulfated mannan (S-M), carboxymethylated mannan (CM-M), carboxymethylated-phosphorylated mannan (CMP-M), and carboxymethylated-sulfated mannan (CMS-M). The phosphate substitution degree of P-M and CMP-M was 0.2 and 0.1, respectively. The sulfate substitution degree of S-M and CMS-M was 0.67 and 0.65, respectively. The carboxymethyl substitution degree of CM-M, CMP-M and CMS-M were 1.11, 1.17 and 0.25, respectively. It indicated that the hydroxyl radical scavenging capacities of P-M and CMP-M were 15% higher than that of M. The anti-lipid peroxidation capacity of all derivatives increased than that of M, especially for CMP-M, its scavenging effect was 25% higher.