Preparation of the Enzymatic Hydrolysates from Chlorella vulgaris Protein and Assessment of Their Antioxidant Potential Using Caenorhabditis elegans.

This study aimed to assess the antioxidant potential of Chlorella vulgaris protein-derived enzymatic hydrolysate using Caenorhabditis elegans. Protein extraction was performed using an alkali solution after complete C. vulgaris swelling and hydrolysis using four commercial proteases (alcalase, neutrase, protamex, and flavourzyme). The results showed that the flavourzyme hydrolysates exhibited the strongest antioxidant activity both in vitro and in vivo. Under the optimum conditions of the enzymatic hydrolysis, the half-maximal effective concentration of the hydrolysates for superoxide and hydroxyl radicals was 0.323 mg/mL and 0.139 mg/mL, respectively. The hydrolysates could significantly extend the lifespan, improve the resistance to methyl viologen-induced oxidative stress, reduce the levels of reactive oxygen species, and enhance the activity of catalase and superoxide dismutase in C. elegans.

Pumpkin polysaccharide preparation, simulated gastrointestinal digestion, and in vivo biodistribution.

We employed a single factor and response surface methodology based on Box-Behnken design (BBD) to optimize the extraction of pumpkin polysaccharides. We then simulated pumpkin polysaccharide gastrointestinal digestion in vitro and investigated their biodistribution in mice. The optimal extraction conditions, with a yield of 7.38 ±â€¯0.21%, were as follows: a concentration of NaOH 1.20%, a ratio of material to liquid of 1:11, and an extraction time of 2.1 h, respectively, according to single factor and BBD experiments. In the gastrointestinal experiment in vitro, the molecular weight of the polysaccharides markedly decreased after gastric digestion for 30 min, suggesting the decline is due to the breakdown of polysaccharide glycosidic bonds. The simulated intestinal fluid had little effect on polysaccharides digestion within 240 min. Analysis of the biodistribution in mice indicated that the polysaccharides distribute in the duodenum, jejunum, and ileum 30 to 60 min after intragastrical administration, and are absorbed in the jejunum and ileum after 60 to 360 min. These results provide information on the digestion and biodistribution of pumpkin polysaccharides and offer a theoretical basis for further understanding the absorption mechanisms in vivo.

Preparation of Chlorella vulgaris polysaccharides and their antioxidant activity in vitro and in vivo.

In the present study, six different polysaccharides (RFPs, MAPs, UWPs, AEPs, HWPs and CEPs) were extracted from Chlorella vulgaris using repeated freeze-thawing, microwave-assisted-, ultrasonic wave-, alkali-, hot water-, and cellulase-based methods; and antioxidant property assays were performed both in vitro and in vivo. Radical-scavenging capacity (using DPPH, superoxide and hydroxyl radicals) and metal chelating ability were assessed in vitro; Caenorhabditis elegans was used to assess antioxidant effects in vivo. Based on the in vitro screening tests, UWPs exhibited high antioxidant capacity. The UWP yield was 17.1% ±â€¯2.2%; the DPPH-, superoxide-, and hydroxyl radical-scavenging rates were 65.1% ±â€¯2.4%, 61.2% ±â€¯2.7%, and 56.2% ±â€¯2.2%, respectively, and the metal chelating ability was 63.6% ±â€¯2.5% at a concentration of 0.4 mg/mL. UWPs also exhibited high antioxidant activity in vivo. UWPs significantly increased the lifespan of C. elegans under oxidative stress induced by hydrogen peroxide compared with the control group, enhanced stress-resistance-related enzymes, including catalase and superoxide dismutase by 7.29% ±â€¯1.8% and 24.41% ±â€¯4.8%, respectively. The results of the present study indicate that the extraction methods of C. vulgaris polysaccharides were a key factor influencing antioxidant activity.

Preparation of the controlled acid hydrolysates from pumpkin polysaccharides and their antioxidant and antidiabetic evaluation.

Pumpkin polysaccharides (PPe) have various biological activities. This research was to optimize the acid hydrolysis process of PPe with OH scavenging ability based on central composite design (CCD), and to explore the antioxidant and antidiabetic activities of the acid hydrolysates (PPe-H). A rat model of type 2 diabetes mellitus (T2DM) using high-fat diet and low-dose streptozotocin were established to assess the bioactivities. Both PPe and PPe-H could distinctly reduce fasting blood glucose level, prevent the weight loss in T2DM rats, and exhibited the remarkable ability to enhance the activities of the antioxidant enzymes (CAT and GR, p < 0.01, p < 0.01) and the level of GSH (p < 0.05, p < 0.01). Besides, PPe-H could significantly decrease the level of MDA (p < 0.05). Furthermore, PPe-H could cause an evident improvement to glucose stimulated GLP-1 secretion from 0 min to 30 min (p < 0.05). PPe and PPe-H were both the heteropolysaccharide and composed of rhamnose, arabinose, glucose and galactose, their molecular weight were 104.27 kDa and 37.58 kDa, respectively. The potential antidiabetic mechanism of PPe-H might be related to stimulating the secretion of endogenous GLP-1, decreasing oxidative damages, and then slowing down the process of diabetes.

Antioxidant and anti-diabetic effects of Auricularia auricular polysaccharides and their degradation by artificial gastrointestinal digestion - Bioactivity of Auricularia auricular polysaccharides and their hydrolysates.

BACKGROUND: Auricularia auricular polysaccharides (AAPs) derived from the dried fruit body of A. auricular are valuable compounds with many bioactivities. This research aimed to investigate the antioxidant and anti- diabetic activities of these polysaccharides and their artificial gastrointestinal fluid hydrolysates (AAPHs). METHODS: Artificially simulated gastrointestinal fluid was used to obtain polysaccharide-de- rived fragments, and a rat model of type 2 diabetes mellitus (T2DM) using a high-fat diet and low-dose streptozotocin (STZ) was established to assess their antioxidant and anti-diabetic effects. RESULTS: It was found that AAPs and AAPHs were both heteropolysaccharides and were comprised of arab- inose, xylose, mannose, 2-deoxy-glucose, glucose and glucosamine, but at different mole ratios. AAPHs was purified by Sephadex G-100 chromatography to produce three fractions, namely, AAPHs1, AAPHs2, and AAPHs3. The molecular weights of these three fractions were 320, 169, and 62 kDa respectively. Both AAPs and AAPHs exhibited the evident ability to enhance the activities of antioxidant enzymes and the level of GSH, while increasing the content of liver glycogen and plasma C-peptide compared with the diabetic model group (p < 0.05). Furthermore, AAPHs could cause a marked improvement in glucose-stimulated GLP-1 secretion from 0 min to 30 min (p < 0.05). CONCLUSIONS: The possible mechanism was that AAPHs could partly restore the STZ-induced impairment of GLP-1 secretion, and inhibit the oxidative stress pathway, and thereby alleviate the progression of diabetes. This data demonstrated that the molecular mole ratio and molecular weight had a definite effect on antioxi- dant and anti-diabetic activities.

Preparation of the Auricularia auricular polysaccharides simulated hydrolysates and their hypoglycaemic effect.

The anti-diabetic effect of the Auricularia auricular polysaccharides simulated hydrolysates (APSHs) obtained from the dried fruiting body of Auricularia auricular was studied in this paper. The APSHs were administered intragastrically (i.g.) at the dose of 0.15g/kg b.w. to the streptozotocin (STZ) -induced diabetic male SD rats for 7 weeks. The results showed that fasting blood glucose level was significantly reduced (p<0.05), whereas the glucose tolerance was remarkable improvement in STZ-induced diabetic rats through APSHs administration, and loss in body weight was also prevented in diabetic mice (p<0.05). Moreover, APSHs could increase hepatic glycogen and pancreatic insulin level (p<0.01), as well as decrease the levels of serum TG and LDL-C compared to the diabetic control group (p<0.05). APSHs had no significant effects on the total cholesterol and HDL-C levels. APSHs were composed of arabinose, xylose, mannose, glucose, galactose and glucosamine with the molar ratio of 1.91:0.52:2.89:1.00:0.67:0.23. These studies suggest that APSHs exerts marked antidiabetic effect in experimental diabetes mellitus, thus justifying the potential treatment for diabetic mellitus.