Composition and antioxidant activities of four polysaccharides extracted from Herba Lophatheri.

Four polysaccharides (BLF80-A, BLF80-B, BLF80-C and BLF80-D) were isolated by hot-water extraction and purified from the leaves of Herba Lophatheri by DEAE-Sepharose fast flow. Their chemical and physical characteristics were determined and antioxidant activities were investigated on the basis of DPPH radical assay, hydroxyl radical assay and superoxide radical assay. The results showed that four polysaccharides exhibited antioxidant activities in a concentration-dependent manner, and the higher molecular weight, the stronger antioxidant activities of polysaccharides. Besides, the monosaccharide compositions of polysaccharides also influence their antioxidant activities. BLP80-D showed the strongest scavenging ability, followed by BLP80-C, BLP80-B and BLP80-A.

Biochemical activities of 6-carboxy ß-chitin derived from squid pens.

TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated 6-carboxy ß-chitin derivatives (T-chitin) with different carboxylate content were successfully synthesized by controlling the addition level of NaClO as the primary oxidant. The structural and biochemical properties of the derivatives were investigated. The carboxylate contents of the derivatives calculated by electrical conductivity titration were 1.33, 1.68, 1.80, and 2.08 mmol/g, respectively. The yield of T-chitin with carboxylate content of 2.08 mmol/g reached 74.55%. T-chitin exhibited stronger bile acid binding capacities than that of ß-chitin. The scavenging ability of T-chitin against hydroxyl radicals improved with increasing concentration, and EC(50) values were below 1.2 mg/mL. All T-chitin exhibited a strong ferrous ion chelating effect. At 8 mg/mL, the chelating effects of T-chitin with carboxylate content of 0.81 mmol/g reached 80.15%. These results showed that T-chitin had good bile acid binding capacity and antioxidant activities and it may be a potential antioxidant in vitro.