Comparison of physicochemical characteristics and biological activities of polysaccharides from barley (Hordeum vulgare L.) grass at different growth stages

Use of ozone oxidation in combination with deacetylation for improving the structure and gelation properties of konjac glucomannan

In this study, oxidized deacetylated konjac glucomannans with different degrees of oxidation were prepared by a combination of deacetylation and ozone oxidation. Carboxyl groups were found to be introduced into the modified konjac glucomannan while acetyl groups were removed. The backbone, branched chains, and crystal structure of modified konjac glucomannan were not significantly affected. The whiteness was enhanced to 97-99 % and the thermal degradation temperature was up to 250 °C after modification. The solubility of the modified konjac glucomannan (oxidized for 60 min) was significantly increased to 84.56 % (p < 0.05), while its viscosity and swelling power were notably decreased owing to the changes in molecular weight (from 106 to 104) and functional groups. Rheological analysis showed that oxidized deacetylated konjac glucomannan has the ability to form soft-textured gels and the potential to develop dysphagia foods. Future studies should focus on the gelation mechanisms of oxidized deacetylated konjac glucomannan.

Investigation of in vitro biological activity of young Hordeum vulgare leaf in correlation with its bioactive compounds

Young shoots of cereals are widely regarded as superfoods with health benefits attributed to their potential antioxidant activity and antioxidant-related effects (e.g. anticancer). The current study aimed to examine the chemical characteristics of Hordeum vulgare methanolic and aqueous extracts and assess their antioxidant activity using the DDPH and ORAC. Furthermore, the inhibitory effect of xanthine oxidase was screened. TLC bioautography was employed to determine the polarity of the compounds present in the extracts that exhibited the most potent free radical scavenging activity. Total flavonoid content of the methanolic and aqueous extracts was 0.14 mg QE/g and 0.012 mg QE/g, respectively. The antioxidant activity of the methanolic extract was found to be more potent, with a value of 0.97 ± 0.13 mmol TE/g than the aqueous extract which had no activity. This study presents novel findings on the xanthine inhibitory activity of H. vulgare. The methanolic extract demonstrated moderate inhibition of xanthine oxidase with a value of 23.24%. The results of our study were compared with the phytochemical and pharmacological analysis of Triticum aestivum, and further comparison was made with the data reported in the literature. Inconsistencies were observed in the chemical and pharmacological properties of H. vulgare, which could be a result of using herbal material harvested in different vegetative phases and various methods used for extraction. The findings of our study indicate that the timing of the harvest and extraction method may play crucial role in attaining the optimal phytochemical composition of H. vulgare, hence enhancing its pharmacological activity.

The effect of sequential extraction on the physicochemical and rheological properties of Naematelia aurantialba polysaccharides

To overcome the difficulty of separation and low rate of extraction caused by highly viscous polysaccharides from Naematelia aurantialba (NA), four N. aurantialba polysaccharides (NAPs) were sequentially extracted using water (enzyme-/ultrasound-assisted extraction), alkali (0.1 mol/L NaOH), and acid (0.1 mol/L HCl), and named E-NAP, U-NAP, Al-NAP, and Ac-NAP. The properties of four NAPs were different. The yields of NAPs were 26.05 % (Ac-NAP) > 20.33 % (Al-NAP) > 17.99 % (U-NAP) > 12.77 % (E-NAP), respectively. The monosaccharide composition of NAPs was composed primarily of mannose, xylose, glucose, glucuronic acid, and galactose. Sequential extraction improved the purity and solubility of NAPs, but decreased the particle size, thermal stability, water retention, and crystallinity. Two polysaccharides, U-NAP and Al-NAP, had a triple helix structure. All the NAPs were pseudoplastic fluids with concentration/frequency-dependent entangled structure. Al-NAP with the highest viscosity exhibited an elastic gel, while Ac-NAP with the lowest viscosity was a viscous gel. The behavior of NAPs differed from that predicted using the Cox-Merz rule, and in particular, E-NAP and U-NAP more significantly deviated from the rule. In this study, four NAPs with different properties were extracted sequentially, which provided a theoretical basis for the down-stream processing with high added-value and utilization of NA and NAP.

The anti-hyperlipidemic effect and underlying mechanisms of barley (Hordeum vulgare L.) grass polysaccharides in mice induced by a high-fat diet

Hyperlipidemia is a pathological disorder of lipid metabolism that can cause fatty liver, atherosclerosis, acute myocardial infarction, and other diseases, seriously endangering people's health. Polysaccharides have been shown to have lipid-lowering potential. In the current study, the anti-hyperlipidemia effect and potential mechanisms of a polysaccharide (BGP-Z31) obtained from barley grass harvested at the stem elongation stage in high-fat diet (HFD)-treated mice were investigated. Results showed that supplementation with BGP-Z31 (200 and 400 mg kg^-1) not only suppressed obesity, organ enlargement, and fat accumulation caused by HFD, but also regulated dyslipidemia, relieved liver function injury, and ameliorated the oxidative stress level. Meanwhile, BGP-Z31 increased the concentrations of acetic acid, propionic acid, butyric acid, and isovaleric acid in HFD-induced mice. Gut microbiota analysis demonstrated that BGP-Z31 had no obvious effect on the gut microbiota diversity in mice treated with HFD, but it positively remodeled the intestinal flora structure by elevating the relative abundances of Bacteroides, Muribaculaceae, and Lachnospiraceae and lowering the Firmicutes/Bacteroides value and the relative abundance of Desulfovibrionaceae. Therefore, our data suggested that BGP-Z31 can be used as a promising nutritional supplement for dietary intervention in hyperlipidemia.

Dynamics changes in physicochemical properties, volatile metabolites, non-volatile metabolites, and physiological functions of barley juice during Bifidobacterium infantis fermentation

The purpose of this research was to explore the potential of Bifidobacterium infantis fermentation to modify the composition and physiological properties of barley juices. B. infantis JFM12 showed a potent capability to decrease the total sugar contents from 0.39 ± 0.01 mg/mL to 0.35 ± 0.01 mg/mL within 24 h of fermentation. The volatile metabolite profiles were enriched after B. infantis JFM12 fermentation, leading to the changes of 13 aldehydes, 11 ketones, 10 acids, 7 alcohols, and 6 esters. A total of 98 key non-volatile metabolites were identified in the barley juice between before and after B. infantis JFM12 fermentation, including 80 non-volatile metabolites that were remarkably increased and 18 non-volatile metabolites that were remarkably reduced. Furthermore, the antioxidant activities and lipase inhibitory activities of fermented barley juice were higher than those of unfermented barley juice. Overall, B. infantis JFM12 was beneficial in increasing the quality of barley juice.

Ultrasound-Assisted Deep Eutectic Solvent Extraction of Polysaccharides from Anji White Tea: Characterization and Comparison with the Conventional Method

Deep eutectic solvent as a new green and safe solvent system has attracted more and more attention in recent years. In this study, three deep eutectic solvents (DES) were combined with ultrasound irradiation to extract tea polysaccharides (TPs) from Anji white tea, which was compared with conventional hot water extraction (HW). The physicochemical, structural, and biological properties of TPs extracted by ultrasound-assisted DES and hot water (HWP) were further investigated. Results showed that the DES system composed of choline chloride and 1,6-hexanediol (CH) with the molar ratio of 1:2 exhibited the optimal extraction yield (19.18%) and in vitro antioxidant activities for TPs (CHP). Furthermore, compared to the HWP, the CHP had a higher extraction yield and total carbohydrate content and a lower molecular weight. Monosaccharide composition analysis displayed that the molecular structure of CHP exhibited more arabinose but less glucose, mannose, galacturonic acid, and glucuronic acid than HWP. Little difference was observed in the preliminary structural characteristics between HWP and CHP from Fourier transform infrared analysis. Besides, CHP possessed better α-glucosidase inhibitory and hypoglycemic activity in L6 cells than HWP. Therefore, the ultrasound-assisted DES extraction method can be a promising strategy for extracting TPs with excellent bioactivities for future applications in functional foods.

In vitro simulated digestion affecting physicochemical characteristics and bioactivities of polysaccharides from barley (Hordeum vulgare L.) grasses at different growth stages

In this study, three polysaccharides (BGPs: BGPs-Z21, BGPs-Z23, and BGPs-Z31) were successively extracted from barley (Hordeum vulgare L.) grasses (BG) at different growth stages, including seedling (Z21), tillering (Z23), and stem elongation (Z31). The effects of in vitro simulated saliva-gastrointestinal digestion on the physicochemical characteristics and biological activities of BGPs were investigated and compared. Results showed that the simulated saliva-gastrointestinal digestion had considerable influences on reducing sugar content, chemical components, monosaccharide constituents, and molecular weights of BGPs but hardly affected their preliminarily structural characteristics. Moreover, the antioxidant activities of BGPs were weakened after the simulated saliva-gastrointestinal digestion, but their bile acid-binding capacities were remarkably enhanced. The digested BGPs-Z31 by gastric juice possessed better antioxidant benefit, and bile acid-binding capacity (80.33 %) than other digested products. Overall, these results indicated that BGPs obtained from BG are valuable for functional foods as promising bioactive ingredients.