Quanhong Li

Effect of phosphorylation on antioxidant activities of pumpkin (Cucurbita pepo, Lady godiva) polysaccharide

Phosphorylated derivatives of pumpkin polysaccharide with different degree of substitution were synthesized using POCl3 and pyridine. Antioxidant activities and cytoprotective effects of unmodified polysaccharide and phosphorylated derivatives were investigated employing various in vitro systems. Results showed that high ratio of POCl3/pyridine could increase the degree of substitution and no remarkable degradation occurred in the phosphorylation process. Characteristic absorption of phosphorylation appeared both in the IR and (31)P NMR spectrum. The df values between 2.27 and 2.55 indicated the relatively expanded conformation of the phosphorylated derivatives. All the phosphorylated polysaccharides exhibited higher antioxidant activities. H2O2-induced oxidative damages on rat thymic lymphocyte were also prevented by the derivatives. In general, phosphorylation could improve the antioxidant activities of pumpkin polysaccharide both in vitro and in a cell system.

Solution properties of a heteropolysaccharide extracted from pumpkin (Cucurbita pepo, lady godiva).

A water-soluble galactoglucofucomannan was extracted from pumpkin (Cucurbita pepo, lady godiva variety). GC-MS analysis indicated that the polysaccharide was composed of 1,6-linked-glucosyl, 1,2,6-linked-mannosyl, 1,3,6-linked-mannosyl, 1,2,6-linked-galactosyl, 1,2,6-linked-galactosyl, terminal fucosyl and terminal glucose. The solution properties of the polysaccharide were studied systematically by using size-exclusion chromatography combined with multi-angle laser light scattering, viscometry and dynamic light scattering at 25 °C. The weight average molecular masses (Mw), intrinsic viscosity [η], radius of gyration (Rg) and hydrodynamic radius (Rh) were found to be 12.7 × 10(5)g/mol, 780 ml/g, 68 nm and 116 nm, respectively. The fraction dimension and value of ρ (Rg/Rh) of the polysaccharide revealed that it existed in a sphere-like conformation in distilled water. The dependence of zero shear specific viscosity on the coil overlap parameter was analyzed using different models. Furthermore, degradation of samples upon autoclaving has been observed and quantified by intrinsic viscosity determination and SEC-MALLS.

Preparation and aroma analysis of Chinese traditional fermented flour paste

Volatile compounds in Chinese fermented flour paste were extracted using simultaneous distillation and extraction (SDE) and analyzed using gas chromatography-mass spectrometry (GC-MS) with DB-5 and DB-WAX capillary columns. A total of 84 volatile compounds were identified, including 8 aldehydes, 19 esters, 14 acids, 17 hydrocarbons, 7 heterocycles, and 19 other trace compounds. The major volatiles included furfural, 5-methyl-2-phenyl-2-hexenal, 4-ethylguaiacol, 2-phenylacetaldehyde, ethyl hexadecanoate, isovaleraldehyde, palmitic acid, and 5-methylfurfural. Aroma compounds were investigated using gas chromatography-olfactometry (GC-O) and aroma extract dilution analysis (AEDA). A total of 27 olfactory regions were exposed and 18 aroma extracts were located. Altogether, 6 aroma compounds identified using GC-O showed higher flavor dilution factors (FD≥32), including isovaleraldehyde, furfural, pentanoic acid, 2-acetylfuran, 1-octen-3-ol, and 2-phenylacetaldehyde. Compared with soybean sauce, fermented flour paste has more esters and aldehydes, which contribute to the desired fruity, caramel, sweet, and roasted odors.

OPTIMIZED MICROWAVE-ASSISTED EXTRACTION OF 6-GINGEROL FROM ZINGIBER OFFICINALE ROSCOEAND EVALUATION OF ANTIOXIDANT ACTIVITY IN VITRO *

BACKGROUND 6-Gingerol is one of the most pharmacologically active and abundant components in ginger, which has a wide array of biochemical and pharmacologic activities. In recent years, the application of microwave-assisted extraction (MAE) for obtaining bioactive compounds from plant materials has shown tremendous research interest and potential. In this study, an efficient microwave-assisted extraction (MAE) technique was developed to extract 6-gingerol from ginger. The extraction efficiency of MAE was also compared with conventional extraction techniques. MATERIAL AND METHODS Fresh gingers (Zingiber officinale Rose.) were harvested at commercial maturity (originally from Shandong, laiwu, China). In single-factor experiments for the recovery of 6-gingerol, proper ranges of ratio of liquid to solid, ethanol proportion, microwave power, extraction time were determined. Based on the values obtained in single-factor experiments, a Box-Behnken design (BBD) was applied to determine the best combination of extraction variables on the yield of 6-gingerol. RESULTS The optimum extraction conditions were as follows: microwave power 528 W, ratio of liquid to solid 26 mL·g(-1), extraction time 31 s and ethanol proportion 78%. Furthermore, more 6-gingerol and total polyphenols contents were extracted by MAE than conventional methods including Maceration (MAC), Stirring Extraction (SE), Heat reflux extraction (HRE), Ultrasound-assisted extraction (UAE), as well as the antioxidant capacity. CONCLUSION Microwave-assisted extraction showed obvious advantages in terms of high extraction efficiency and antioxidant activity of extract within shortest extraction time. Scanning electron microscopy (SEM) images of ginger powder materials after different extractions were obtained to provide visual evidence of the disruption effect. To our best knowledge, this is the first report about usage of MAE of 6-gingerol extraction from ginger, which could be referenced for the extraction of other active compounds from herbal plants.

Kinetics of 5-hydroxymethylfurfural formation in chinese acacia honey during heat treatment

In this paper, the 5-hydroxymethylfurfural (HMF) contents of the acacia honeys after heat treatment were determined by HPLC; the kinetics of HMF formation was also investigated. The HMF content of acacia honey was 0.38±0.01mg/kg, but rapidly increased to the maximum of 18,320.07±14.29 mg/kg at 190°C and decreased to 1,180.24±6.54 mg/kg at 230°C after heating. The HMF content increased gradually in honey samples heated in 12 h at the temperature of 80, 100, and 120°C. The apparent frequency constant was kf =3.91×1025/h, and the apparent activation energy was Ea=173.10 kJ/mol. The HMF content in the acacia honey was related to honey composition, heating temperature, and time, and the HMF formation could also be related to the initial honey pH.

Pumpkin polysaccharide modifies the gut microbiota during alleviation of type 2 diabetes in rats

Pumpkin polysaccharide is able to alleviate diabetes, but understanding of the underlining mechanism is still limited. In this study, we hypothesized that the alleviating effects of pumpkin polysaccharide is modulated via changes in the gut microbiota and short-chain fatty acid (SCFA) production in type 2 diabetic rats. After the type 2 diabetic model successfully was established, three groups of high-fat diet induced diabetic rats were intragastrically administered pumpkin polysaccharide, metformin, or saline solution respectively. We utilized 16S rRNA gene sequencing and multivariate statistics to analyze the structural and key species of gut microbiota in the type 2 diabetic rats. The results revealed that pumpkin polysaccharide alleviated the type 2 diabetes by improving the insulin tolerance and decreasing the levels of serum glucose (GLU), total cholesterol (TC), and low-density lipoprotein (LDL-C), while increasing the levels of high-density lipoprotein (HDL-C). Simultaneously, pumpkin polysaccharide changed the structure of gut microbiota and had selective enrichment in key species of Bacteroidetes, Prevotella, Deltaproteobacteria, Oscillospira, Veillonellaceae, Phascolarctobacterium, Sutterella, and Bilophila. The correlations between the key species and SCFA production indicated the underlining mechanisms of pumpkin polysaccharide on type 2 diabetes.