Antioxidant properties of feruloylated oligosaccharides of different degrees of polymerization from wheat bran.

In this study, four main components of feruloylated oligosaccharides (FOs),FOs-1, FOs-2, FOs-3 and FOs-4,were isolated from wheat bran by use of Amberlite XAD-2 and Sephadex LH-20. Structural characterization of FOs was determined by use of high performance liquid chromatography (HPLC), gas chromatography (GC) and fourier transform-infrared spectroscopy (FT-IR). Antioxidant properties were investigated in vitro. Average degrees of polymerization (DP) of the four components (FOs-1, FOs-2, FOs-3 and FOs-4) were approximately 10.6, 7.7, 6.1 and 3.4, respectively. In addition, DP were consistent with molar ratios of arabinose and xylose in 1:9.46, 1:5.30, 1:2.91 and 1:0.19, respectively. The presence of ß-glycosidic linkage was confirmed at 896 cm - 1 by use of FT-IR. In vitro antioxidant studies demonstrated that FOs-1, FOs-2, FOs-3 and FOs-4 possessed significant antioxidant activities in the dose-dependent manner. In addition, the degree of polymerization affected antioxidant capacity. These results have improved our understanding of the relationship between FOs with different structural types and their antioxidant activities.

Feruloylated Oligosaccharides from Maize Bran Modulated the Gut Microbiota in Rats.

Corn bran is a byproduct produced from corn milling; it is rich in ferulic acid and hemicellulose. In this research, the effects of feruloylated oligosaccharides (FOs) from maize bran on the microbial diversity and profiles in rat feces were investigated through 16S rRNA sequencing. FOs significantly increased bacterial richness and diversity compared with the control and xylooligosaccharides (XOS) alone. In comparison with the control group and the group administrated with XOS, FOs orally administered at 300 mg/kg increased OTU in feces by 57.0 and 24.8 %, and Chao value by 93.4 and 37.6 %, respectively. FOs also influenced obesity- and diabetes-associated bacteria. Oral administration of FOs at 300 mg/kg decreased the ratio of Firmicutes to Bacteroidetes from 477.7:1 to 55.1:1; greatly increased the reads of bacteria that were previously found resistant against diabetes in rats, such as Actinobacteria, Bacteroides, and Lactobacillus; whereas decreased diabetes-prone bacteria, such as Clostridium and Firmicutes.

Feruloylated oligosaccharides and ferulic acid alter gut microbiome to alleviate diabetic syndrome.

Gut microbiome has been proven to be involved in the development of type 2 diabetes (T2D). Additionally, increasing evidence showed that the composition of gut microbiome is highly associated with the outcome of T2D therapy. Previously we demonstrated that feruloylated oligosaccharides (FOs) and ferulic acid (FA) alleviated diabetic syndrome in rats, but the detailed mechanism has not been explored yet. In this study we strived to characterize how FOs and FA altered the gut microbiome and related metabolome in diabetic rats by using high-throughput sequencing of 16S rRNA and gas chromatography (GC). Our results showed that FOs reduced the abundance of Lactobacillus, Ruminococcus, Oscillibacter, and Desulfovibrio, but increased the abundance of Akkermansia, Phascolarctobacterium and Turicibacter. The structure of gut microbiome in FOs treated rats was similar with healthy rats rather than diabetic rats. Likewise, FA decreased the portion of Lactobacillus, Ruminococcus, but promoted the growth of Bacteroides, Blautia, Faecalibacterium, Parabacteroides and Phascolarctobacterium. Additionally, the short-chain fatty acids (SCFAs) and branched-chain fatty acids (BCFAs), the main bacterial lipid metabolites in gut mediating host glucose metabolism, was dramatically elevated along with FOs and FA treatment. Our findings indicated that FOs and FA attenuated diabetic syndrome in rats most likely by modulating the composition and metabolism of gut microbiome. The study gives new insight into the mechanism underlying the anti-diabetes effect of functional foods as well as facilitates the development of dietary supplements for diabetic patients.

Feruloylated Oligosaccharides Alleviate Dextran Sulfate Sodium-Induced Colitis in Vivo.

The imbalance of T lymphocyte subsets substantially conduces to disturbed intestinal immune system and succeeding colonic tissue damage in inflammatory bowel diseases. It is considered that regulation of phytochemicals on cytokine production potentially provides a broad prospect for the exploitation of immunomodulatory agents. Here, we reported that oral administration of feruloylated oligosaccharides (FOs) effectively alleviated mice colitis disease induced by dextran sulfate sodium (DSS). FOs decreased the percentage of T helper (Th)17 cells and downregulated the production of Th17-specific cytokines. In contrast, FOs increased the percentage of regulatory T (Treg) cells and elevated the production of Treg-specific cytokines in colons of DSS-challenged mice. These results indicated that FOs restored the immunologic equilibrium of Th17 and Treg subsets, hereby ameliorating the deterioration of colitis. Furthermore, FOs diminished the secretion of interleukin (IL)-23 and IL-6 but enhanced the transforming growth factor-ß1 (TGF-ß1) in dendritic cells in vitro and in vivo, which contributed to the restoration of Th17 and Treg cells immune balance. The mechanistic analysis showed that the regulation of FOs on IL-23 and IL-6 was associated with the nuclear factor-κ-gene binding signaling pathway and TGF-ß1 with mitogen-activated protein kinase-activator protein 1 signaling pathway. Taken together, oral administration of FOs exerted potent immunomodulatory effects against mice colitis via restoring the immune balance of Th17 and Treg cells.

Formation of ethyl ferulate from feruloylated oligosaccharide by transesterification of rice koji enzyme under sake mash conditions.

Formation of ethyl ferulate (EF) and ferulic acid (FA) under sake mash conditions was studied using feruloylated oligosaccharide (FO), prepared from rice grains, as the substrate for rice koji enzyme. EF and FA were produced from FO over six times faster than from alkyl ferulates however, under the same ethanol concentration, only small differences were observed between the EF/FA ratios when either FO or methyl ferulate were used as substrates. Esterification and hydrolysis of FO or methyl ferulate showed similar pH dependencies and similar EF/FA ratios for each substrate in all of the pH ranges tested. Ethanol concentration clearly affected the EF/FA ratio; the ratio increased as ethanol concentration increased. Formation of EF and FA in the sake mash simulated rice digest was accelerated by addition of exogenous FO. These results indicated that supply of FO to sake mash is a crucial step for EF and FA formation, and ethanol is an influencing factor in the EF/FA ratio. The rice koji enzyme reaction suggested that EF and FA are formed through a common feruloylated enzyme intermediate complex by transesterification or hydrolysis, and these reactions occur competitively.