No abstract

No abstract

Objective: To study the inhibitory activity and enzymolysis kinetics of lentinan on α-glucosidase. Methods: The enzyme-agent screening model was used to investigate the optimal conditions of α-glucosidase action. In vitro enzyme kinetics was studied by changing the substrate concentration, reaction time, pH conditions and temperature. Results: The optimal reaction conditions of α-glucosidase were reaction time 120min, reaction temperature 50°C, buffer pH 6.0, concentration of substrate PNPG 0.1089 mol/L. Conclusion: 1g/L concentration of lentinan has good inhibitory activity against α-glucosidase, and the inhibitory effect of lentinan is competitive inhibition. KEYWORDS Lentinan, α-glucosidase, enzymolysis kinetics. 100 μL of 30000 U/L enzyme solution was added to 200 μL of phosphate buffer solution and 75 mol/LPNPG was used as a substrate, followed by a water bath at 45°C for 20, 25, 30, 35, 40, 45, 50, respectively. 55 min. 100 μL of 1 mol/L sodium carbonate solution was added to terminate the reaction and the OD values were determined.

To determine the effect of different harvesting time on antioxidant capacity in Jerusalem artichoke polysaccharides (inulin), the Jerusalem artichoke before and after overwintering were collected from the same region, and then evaluate their antioxidant capacity in vitro by reducing power assay, DPPH radical-scavenging assay and hydroxyl radical-scavenging assay. Ascorbic acid at similar mass concentration was served as positive control. The results showed no significant difference were observed in reducing power when the absorbance values were about 0.3. When the mass concentrations before and after overwintering were 0.9 mg/mL and 1.7 mg/mL, the DPPH radical-scavenging rate both reached at 50%. And when the mass concentrations were both 10 mg/mL, the hydroxyl radical-scavengings were 35.8% and 27.9%, respectively. Thus, it could be concluded that the antioxidant capacity in Jerusalem artichoke polysaccharides before overwintering was higher than that after overwintering, and showed a good dose-dependent manner with its mass concentration.

Hippophae rhamnoides L. polysaccharide was optimized with flash extraction by response surface design. The optimum process conditions were: rotation rate 5000 r/min, extraction time 15 s, extraction temperature 90 °C and liquid-to-material ratio 38 mL/g, the extraction yield was 15.28 � 0.02 %. HRP-1 and HRP-2 obtained by 40 % and 60 % graded alcohol precipitation were characterized. The results indicated that HRP-1 and HRP-2 both composed of mannose, ribose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, xylose, arabinose with different molar ratio and the molecular weights were 380.59 kDa and 288.24 kDa, respectively. In addition, the in vitro antioxidant and immunoenhancement activities of HRP-1 and HRP-2 were analyzed, and the two fractions showed good free radical scavenging activity against * OH, ABTS * + , DPPH * , and extremely strong immunomodulatory activity against RAW264.7 cells. Indicating that flash extraction is suitable for extraction of HRP, the structural study of HRP provides a scientific theoretical basis for the development of Hippophae rhamnoides.

The extraction and anti-oxidation activity of polysaccharides from Lentinan were studied by an orthogonal experimental design. The optimal extraction process was solid-liquid ratio = 1:20, pH 5, 60 ºC and extraction time=3 h, with the extraction yield of 11.61%. It was proved this extraction method was simple and available, and the crude polysaccharides had high antioxidant capacity.