Rethinking the impact of RG-I mainly from fruits and vegetables on dietary health.

Rhamnogalacturonan I (RG-I) pectin is composed of backbone of repeating disaccharide units →2)-α-L-Rhap-(1→4)-α-D-GalpA-(1→ and neutral sugar side-chains mainly consisting of arabinose and galactose having variable types of linkages. However, since traditional pectin extraction methods damages the RG-I structure, the characteristics and health effects of RG-I remains unclear. Recently, many studies have focused on RG-I, which is often more active than the homogalacturonan (HG) portion of pectic polysaccharides. In food products, RG-I is common to fruits and vegetables and possesses many health benefits. This timely and comprehensive review describes the many different facets of RG-I, including its dietary sources, history, metabolism and potential functionalities, all of which have been compiled to establish a platform for taking full advantage of the functional value of RG-I pectin.

Structural property of extractable proteins and polysaccharides in wheat bran following a dual-enzymatic pretreatment and corresponding functionality.

The current study applied dual-enzymatic treatment via alcalase and Bacillus velezensis hydrolase for enhancing extraction of proteins and polysaccharides from wheat bran and modifying their corresponding structure. Results indicated the aqueous extract by enzymatic pretreatment (referred as EHWB) had an increased content of soluble substance, in which 18.5 % increased for carbohydrates and 11.4 % increased for proteins in the extract compared to the aqueous extract without enzymes (labeled as AEWB). Furthermore, compositions with lower molecular weight of 130 kDa and < 21.1 kDa for polysaccharides and proteins, respectively, were found in EHWB. Interestingly, EHWB had a twice higher radicals scavenging than that of AEWB, and digestive property indicated EHWB had a greater peptides production although glucose release was lower in gastric phase. Importantly, this is the first study to reveal that gut microbiota fermentation of EHWB resulted in faster generation of short-chain fatty acids at initial fermentation stage (6 h), followed a higher generation of butyrate at final fermentation stage (24 h). This fermentation property might be associated with its presence of lower molecular weight substrates and even the changes in the molecular structure induced by the enzymes. This study highlights a novel approach for developing a value-added product from wheat bran.

(1 → 3),(1 → 6) and (1 → 3)-ß-D-glucan physico-chemical features drive their fermentation profile by the human gut microbiota.

Mushroom polysaccharides consist of a unique set of polymers that arrive intact in the human large intestine becoming available for fermentation by resident gut bacteria with potential benefits to the host. Here we have obtained four glucans from two mushrooms (Pholiota nameko and Pleurotus pulmonarius) under different extraction conditions and their fermentation profile by human gut bacteria in vitro was evaluated. These glucans were isolated and characterized as (1 â†’ 3),(1 â†’ 6)-ß-D-glucans varying in branching pattern and water-solubility. An aliquot of each (1 â†’ 3),(1 â†’ 6)-ß-D-glucan was subjected to controlled smith degradation process in order to obtain a linear (1 â†’ 3)-ß-D-glucan from each fraction. The four ß-D-glucans demonstrated different water solubilities and molar mass ranging from 2.2 × 105 g.mol-1 to 1.9 × 106 g.mol-1. In vitro fermentation of the glucans by human gut microbiota showed they induced different short chain fatty acid production (52.0-97.0 mM/50 mg carbohydrates), but an overall consistent high propionate amount (28.5-30.3 % of total short chain fatty acids produced). All glucans promoted Bacteroides uniformis, whereas Anaerostipes sp. and Bacteroides ovatus promotion was strongly driven by the ß-D-glucans solubility and/or branching pattern, highlighting the importance of ß-D-glucan discrete structures to their fermentation by the human gut microbiota.

In vitro fermentation of Bangia fusco-purpurea polysaccharide by human gut microbiota and the protective effects of the resultant products on Caco-2 cells from lipopolysaccharide-induced injury.

Polysaccharide extracted from red seaweed Bangia fusco-purpurea (BFP) is a novel sulfated galactan, differed from agarans and carrageenans in fine structure. In this study, in vitro fermentation characteristics of BFP by human gut microbiota and its protective effect on lipopolysaccharide (LPS)-induced injury in Caco-2 cells were investigated. Our results showed that BFP was mainly degraded at transverse colon for 18 h fermentation by gut microbiota with reduced molecular weight. Meanwhile, BFP fermentation was associated with increased short-chain fatty acids (SCFAs) as compared to control group, especially acetic acid was increased to 129.53 ± 0.24 from 82.14 ± 0.23 mmol/L, and butyric acid was up to 1.56 ± 0.004 from 0.62 ± 0.01 mmol/L. Furthermore, BFP promoted abundances of Bacteroidetes and Firmicutes, while decreased numbers of Proteobacteria. The up-regrated beneficial differential metabolites were SCFAs, L-proline, arginine, folic acid, pyridoxamine, thiamine, etc. (p < 0.05), and their related metabolic pathways mainly included mTOR, arginine biosynthesis, and vitamin metabolism. Notably, BFP fermentation products at transverse colon significantly restored cell viability of LPS-treated Caco-2 cells from 73.79 ± 0.48 % to 93.79-99.64 %, which might be caused by increased beneficial differential metabolites (e.g., SCFAs). Our findings suggest that BFP has prebiotic potential and can enhance gut health.

Phenolic profile of jujube fruit subjected to gut microbiota fermentation and its antioxidant potential against ethyl carbamate-induced oxidative damage.

OBJECTIVES: To evaluate the composition of bioactive substances and the antioxidant effects of jujube fruit under gut microbiota fermentation (GMF), and the inhibitory effect on cytotoxicity caused by ethyl carbamate (EC). METHODS: Changes in the contents of flavonoids, polyphenols, total sugars, and reducing sugars of jujube fruit after GMF (0, 2, 6, 12, 24, and 48 h) were determined. The oxidation resistance of fermented jujube fruits (from 0 to 48 h fermentation) was evaluated using in vitro 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) and ferric reducing antioxidant power (FRAP) assays. Inhibitory effects of 48 h-fermented jujube fruit at various concentrations (0.25, 0.50, 1.00, and 2.00 mg/mL) on EC-treated toxicity and DNA damage of Caco-2 cells were estimated using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and nuclear staining assays, respectively. Effects of different concentrations of jujube fruit on EC-treated Caco-2 cells' intracellular reactive oxygen species (ROS), glutathione (GSH) levels, and mitochondrial membrane potential (MMP) were also evaluated. RESULTS: Jujube fruit has rich bioactive components after GMF and shows strong antioxidant capacity. Fermented jujube fruit can inhibit the cytotoxicity and DNA damage of Caco-2 cells caused by EC and reduce intracellular ROS generation, as well as restoring GSH and MMP. CONCLUSIONS: Fermented jujube fruit extracts produced by GMF still contain biologically active substances which retain biological activity and antioxidation capabilities.

Antioxidant and antidiabetic activity of blackberry after gastrointestinal digestion and human gut microbiota fermentation.

Blackberry fruit contains high levels of polyphenols particularly anthocyanins which contribute to its biological activities. Bioavailability of polyphenols especially anthocyanins is generally low, it has been proposed that metabolites from polyphenol biotransformation under colonic fermentation are components that exert health benefits. In this study, blackberry was subjected to simulated gastrointestinal digestion and gut microbiota fermentation at different time intervals (0-48 h) to study the changes in bioactive components, its antioxidant and antidiabetic activities. Phenolic compounds, during digestion and fermentation were also analysed. Gut metabolites of blackberry significantly increased the glucose consumption and glycogen content in HepG2 cells. Furthermore, gut metabolites ameliorated high glucose plus palmitic acid-induced ROS overproduction, mitochondrial membrane collapse, and glutathione depletion in HepG2 cells. The mechanism of antidiabetic activity of blackberry was via its potent antioxidant activity. Therefore, our results suggest that blackberry could be recommended as a functional food due to potential antioxidant and antidiabetic activity.