Jian Ming

Characterization and Antioxidant Activity of the Complex of Tea Polyphenols and Oat β-Glucan

Few data are available about the effects of complexation of polyphenols with polysaccharide on their bioavailability. The complex of tea polyphenols (TP) with oat β-glucan was characterized by ultraviolet-visible spectrometry, Fourier transform infrared spectrometry, differential scanning calorimetry, atomic force microscopy, and solid-state (13)C NMR spectroscopy. The results indicated that the bonds which governed the interaction between TP and oat β-glucan were strong hydrogen bonds. The in vitro antioxidant activity of TP, β-glucan, their complex, and physical mixture was assessed using four systems, namely, DPPH(•), OH(•), and O(2)(•-) scavenging activities and reducing power. The complexation and blending of TP and β-glucan exhibited different impacts on the index of in vitro and in vivo antioxidant capacities. In the concentration range of 0.5-2.5 mg mL(-1), the complex had highest O(2)(•-) scavenging activity, whereas the highest OH(•) scavenging activity was found with the physical mixture. For antioxidant testing in vivo, there was no significant difference between the complex and the physical mixture in terms of glutathione peroxidase activity and levels of malondialdehyde and total antioxidant capacity in serums. However, the complex exhibited much higher activities of superoxide dismutase and glutathione peroxidase in livers than the physical mixture. The present study provided a deeper understanding of the influence of molecular interaction between TP and oat β-glucan on their antioxidant activities.

Optimization of adsorption of tea polyphenols into oat β-glucan using response surface methodology.

Information on interactions between oat β-glucan and tea polyphenols (TP) is not available in the published literatures. Equilibrium dialysis was applied to determine the adsorption of TP into β-glucan, and response surface methodology (RSM) was employed to optimize the absorbing variables (pH, temperature, and phosphate buffered saline (PBS) buffer concentration). The equilibrium data at constant temperature were fitted with the Langmuir, Freundlich, and Redlich-Peterson models. The results showed that the Freundlich model was the best method to describe the experimental data. Parabolic curves were obtained for pH and temperature. In terms of adsorption capacity, factors including temperature, pH/temperature, and buffer concentration/temperature had the greatest influence on the response. The highest adsorption capacity of TP into β-glucan was 134.55 μg mg(-1) at the following optimized conditions: pH 5.56, PBS buffer concentration 0.13 M, and temperature 40 °C. No significant differences (p > 0.05) between the experimental and predicted values confirmed the adequacy of the response surface equations.

Carboxymethylation of polysaccharide from Morchella angusticepes Peck enhances its cholesterol-lowering activity in rats

The chemically carboxymethylated polysaccharide (CPMEP), which is derived from the purified polysaccharide from Morchella angusticepes Peck (PMEP), was prepared. The degree of substitution of CPMEP was 0.461. Fourier transform infrared spectra analysis and 13C, 1H, and DEPT135° NMR spectra indicated C6 position was partially substituted by CH2COOH. Moreover, serum total cholesterol of hypercholesterolemic rats treated with the high dose of PMEP and CPMEP was 1.54mmol/L and 1.29mmol/L compared with that of rats fed with a 2% cholesterol diet (1.74mmol/L), respectively, indicating CPMEP had a stronger cholesterol-lowering activity than PMEP. CPMEP had a trend in reducing liver total cholesterol while increasing the excretion of total fecal and intestinal bile acids, which were probably mediated by down-regulation of hepatic 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase while up-regulation of cholesterol-7α-hydroxylase. It was therefore concluded that carboxymethylation of PMEP could enhance its cholesterol-lowering ability at least in rats.

Protective effects of Coreopsis tinctoria flowers phenolic extract against D-galactosamine/lipopolysaccharide -induced acute liver injury by up-regulation of Nrf2, PPARα, and PPARγ

Coreopsis tinctoria flowers, a well-known medicinal and edible plant, have been reported to possess antioxidant and anti-inflammatory activities. However, its protective effects and underlying mechanisms on liver injury remain unclear. The aim of this study was to investigate the underlying mechanisms by which Coreopsis tinctoria flowers phenolic extract (CTP) alleviated D-galactosamine and lipopolysaccharide (D-GalN/LPS) induced acute liver injury in mice. Our results showed that pretreatment with CTP improved liver histology while decreased levels of serum aminotransferase and malondialdehyde. CTP also increased levels of glutathione in D-GalN/LPS -induced acute liver injury mice by up-regulation of nuclear factor erythroid 2-related factor 2 (Nrf2), peroxisome proliferator-activated receptor alpha (PPARα), and peroxisome proliferator-activated receptor gamma (PPARγ). In conclusion, results suggested that CTP protected against D-GalN/LPS -induced acute liver injury by up-regulation of Nrf2, PPARα, and PPARγ.