•XAD-16 was an effective resin for the enrichment of black garlic antioxidants.•The pseudo-second-order kinetic model was used to describe adsorption process.•Freundlich model was suitable for describing the whole exothermic process.•The 40% ethanol fraction effectively inhibited the oxidation-induced hemolysis.The black garlic juice is popular for its nutritive value. Enrichment of antioxidants is needed to make black garlic extract an effective functional ingredient. Five macroporous resins were evaluated for their capacity in adsorbing antioxidants in black garlic juice. XAD-16 resin was chosen for further study due to its high adsorption and desorption ratios. Pseudo-second-order kinetics (qe = 625 μmol Trolox equiv/g dry resin, k2 = 0.0001463) and Freundlich isotherm models (ΔH = −10.1547 kJ/mol) were suitable for describing the whole exothermic and physical adsorption processes of the antioxidants from black garlic juice on XAD-16 resin. The antioxidants and phenolics were mostly enriched in 40% ethanol fraction by XAD-16 resin column chromatography. The black garlic extract and its fractions could protect erythrocytes against AAPH-induced hemolysis in dose-dependent manners. The pretreatment of AAPH-damaged erythrocytes with 40% ethanol fractions (2.5 mg/mL) significantly decreased the hemolysis ratios from 53.58% to 3.79%. The 40% ethanol fraction possessing strong intracellular antioxidant activity could be used as a functional food ingredient.

•XAD-16, SP-207 and SP-825 resins had similar adlay phenolics adsorption behaviors.•Boundary layer and intra-particle diffusion kinetics affected adsorption processes.•Adsorption equilibriums were well-fitted to the Freundlich isotherms.•Adsorption processes were exothermic and physical.•Antioxidant-related components were effectively enriched by gradient elution.In this study, the adsorption and desorption characteristics of six macroporous resins including XAD-7HP, XAD-16, HP-20, HP-2MGL, SP-207 and SP-825 for enrichment of adlay bran free phenolics were studied. XAD-16, SP-207 and SP-825 were chosen for further study due to their strong adsorption and desorption capacities. XAD-16, SP-207 and SP-825 had similar phenolics adsorption/desorption behaviors. Pseudo-second-order kinetics model and Freundlich isotherm model were suitable for describing the whole exothermic and physical adsorption processes of adlay bran free phenolics on XAD-16, SP-207 and SP-825. After treatment with gradient elution on XAD-16 resin column, the free phenolics were mostly enriched (from 89.61 to 1015.26 mg/100 g) in 50% ethanol fraction. The oxygen radical absorbance capacity of 50% ethanol fraction was eight times higher than that of the crude extract. Therefore, the production of highly concentrated phenolics might expand the application of adlay bran used as a bioactive ingredient in functional food.

•Pinobanksin, galangin and pinocembrin showed excellent XOD inhibitory activities.•Five studied flavonoids could interact with XOD at more than one binding sites.•Inhibitory mechanism varied with substrate's or inhibitor's type and concentration.Xanthine oxidase (XOD) inhibitory activities of five dietary flavonoids pinobanksin, galangin, pinocembrin, pinocembrin-7-O-β-d-glucopyranoside and glabranin were evaluated. Enzyme kinetic studies and molecular docking simulation were conducted to investigate the mechanisms underlying the inhibitory activities. The results showed that these flavonoids exhibited excellent inhibitory activities (which were ranked in the order of pinobanksin > galangin > pinocembrin > pinocembrin-7-O-β-d-glucopyranoside > glabranin). Competitive inhibition and a mixed-type of competitive–noncompetitive inhibition were observed. The mode of inhibition was dependent on the type and concentration of the substrate and inhibitor. Fluorescence quenching data suggested that these flavonoids could interact with XOD at more than one binding site. The docking simulation revealed that galangin and pinobanksin could enter into the active site of XOD and form hydrogen bonding with amino acid residues (such as Ser-876, Asn-768, Glu-1261 and Thr-1010) and sandwiching aromatic interactions (π–π interactions) around the active site of XOD.

This is the first report on the ability of soy sauce to effectively reduce the serum uric acid levels and xanthine oxidase (XOD) activities of hyperuricemic rats. Soy sauce was partitioned sequentially into ethyl acetate and water fractions. The ethyl acetate fraction with strong XOD inhibition effect was purified further. On the basis of xanthine oxidase inhibitory (XOI) activity-guided purification, nine compounds including 3,4-dihydroxy ethyl cinnamate, diisobutyl terephthalate, harman, daidzein, flazin, catechol, thymine, genistein, and uracil were obtained. It was the first time that 3,4-dihydroxy ethyl cinnamate and diisobutyl terephthalate had been identified from soy sauce. Flazin with hydroxymethyl furan ketone group at C-1 and carboxyl at C-3 exhibited the strongest XOI activity (IC50 = 0.51 ± 0.05 mM). According to fluorescence quenching and molecular docking experiments, flazin could enter into the catalytic center of XOD to interact with Lys1045, Gln1194, and Arg912 mainly by hydrophobic forces and hydrogen bonds. Flazin, catechol, and genistein not only were potent XOD inhibitors but also held certain antioxidant activities. According to ADME (absorption, distribution, metabolism, and excretion) simulation in silico, flazin had good oral bioavailability in vivo.

•Pseudo-second-order kinetics model was suitable for evaluating the adsorption process.•The adsorption of the resins was an exothermic and physical adsorption process.•The total flavonoids and pinocembrin were enriched and bioactivities were improved.•Licorice leaf was transformed into higher-value products as nutrition supplement.The kinetics of adsorption and desorption behaviours of five macroporous resins for enriching flavonoids from Glycyrrhizaglabra L. leaf were investigated. All five resins showed similar and effective adsorption and desorption properties. A pseudo-second-order kinetics model was suitable for evaluating the whole adsorption process. Additionally, two representative resins (XAD-16 and SP825) were chosen for adsorption thermodynamics study. The adsorption of the representative resins was an exothermic and physical adsorption process. Further column chromatography of XAD-16 and SP825 showed that the total flavonoids (from 16.8% to 55.6% by XAD-16 and to 53.9% by SP825) and pinocembrin (from 5.49% to 15.2% by XAD-16 and to 19.8% by SP825) were enriched in 90% ethanol fractions. Meanwhile, the antioxidant capacities and nitrite-scavenging capacities were 2–3 times higher than those of the crude extract. The fractions with high flavonoid and pinocembrin contents could be used as biologically active ingredients in functional food.

This study aimed to explore the potential of polished adlay, brown adlay, adlay bran, and adlay hull to prevent and treat hyperuricemia. Brown adlay extract effectively decreased the serum uric acid levels of oxonate-induced hyperuricemic rats. Free and bound phenolic extracts from these materials contained significant amounts of phenolics, with free phenolics dominated by chlorogenic acid and p-coumaric acid while bound phenolics dominated by p-coumaric acid and ferulic acid. Free and bound phenolics of adlay bran exhibited significant xanthine oxidase inhibition activities, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities, oxygen radical absorbance capacities, and superoxide radical scavenging activities. Adlay bran phenolics could be effective xanthine oxidase inhibitors and radical scavengers. p-Coumaric acid is a xanthine oxidase inhibitor with strong superoxide radical scavenging activity. However, ferulic acid is a xanthine oxidase inhibitor with weak superoxide radical scavenging activity. Chlorogenic acid is a superoxide radical scavenger with weak xanthine oxidase inhibitory activity.

•Buckwheat, corn, and brown adlay free phenolics were effective cellular antioxidants.•Adlay bran free phenolics were the most effective cellular antioxidants.•Adlay phenolics inhibited MDA, MetHb and ROS generation.•Adlay phenolics activated ATPase, CAT, SOD and GSH-Px activities.The intracellular antioxidant activities of millet, rice, wheat, brown rice, oat, buckwheat, corn and adlay phenolic extracts were evaluated in an ex vivo erythrocytes system. Buckwheat, corn, and brown adlay free phenolic extracts could effectively attenuate H2O2-induced erythrocyte hemolysis. The protective effects and involved mechanisms of polished adlay, brown adlay and adlay bran phenolic extracts were studied further. The intracellular antioxidant activities of adlay phenolic extracts decreased in the following order: adlay bran > brown adlay > polished adlay. Adlay bran free phenolic extract possessed stronger intracellular antioxidant activity than chlorogenic acid, p-coumaric acid and ferulic acid. The free phenolic extracts were more effective than bound phenolic extracts to suppress hemolysis and plasma oxidation through inhibition of MDA equivalents, MetHb and ROS generation and to restore the activities of Na+K+-ATPase, Ca2+Mg2+-ATPase and intracellular antioxidant enzyme to normal levels. Adlay-rich diets could reduce the incidence of cancer, cardiovascular and neurodegenerative diseases.