Rice bran-modified wheat gluten nanoparticles effectively stabilized pickering emulsion: An interfacial antioxidant inhibiting lipid oxidation.

This study investigated the fabrication of Pickering emulsion stabilized by rice bran-modified wheat gluten nanoparticle (RGNP) and evaluated the effect of rice bran-modification on lipid oxidation of emulsified soybean oil, with native wheat gluten nanoparticle (CGNP) as the control. Compared with CGNP, RGNP exhibited stronger antioxidant activities due to high content of polyphenols. RGNP were roughly spherical (mean size of about 250 nm) with balanced wettability (104.6 ± 2.3°) and had excellent colloidal thermal stability. When used at a concentration of 1.5 wt%, both CGNP and RGNP could stabilize Pickering emulsions at varying oil volume fractions (0.20-0.85). For high internal phase emulsions, nanoparticles adsorbed at an oil-water interface forming an interconnected network structure, depressing the oxidation of soybean oil. RGNP as an interfacial antioxidant further improved the Pickering emulsion' oxidative stability. This work may expand the application of wheat gluten as an antioxidant solid particle in Pickering emulsion.

Effects of different extraction methods on contents, profiles, and antioxidant abilities of free and bound phenolics of Sargassum polycystum from the South China Sea.

Total phenolic content (TPC), phenolic profiles, and antioxidant activity of free and bound extracts of Sargassum polycystum, obtained by different extraction solvents and hydrolysis methods, were investigated. Aqueous acetone afforded the highest free TPC and antioxidant ability, followed by aqueous ethanol and aqueous methanol. Twelve free phenolic compounds were identified by ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS), including two hydroxycinnamic acids, seven flavonoids, one stilbene, and two phlorotannins. Three to nine different free phenolic compounds were extracted by these solvents with different compositions, including nine by 70% acetone and eight by 70% methanol, 70% ethanol, and 50% ethanol. The highest total content of free phenolic compounds determined by high-performance liquid chromatography-diode array detection was obtained from 70% ethanol. Alkaline hydrolysis afforded higher bound TPC (274.27 mg GAE/100 g DW) and antioxidant ability than acid hydrolysis. Five bound phenolic compounds were characterized by UHPLC-MS and five were released from alkaline hydrolysis, whereas two were released from acid hydrolysis. Total content of bound phenolic compounds released by alkaline hydrolysis was 14.68-fold higher than that by acid hydrolysis. The free and bound TPC, phenolic profiles, and antioxidant activities depended on the extraction solvent used. These results indicate that S. polycystum is a potentially useful antioxidant source and contribute to the development of seaweed-based functional foods. PRACTICAL APPLICATION: Phenolics are usually divided into free and bound forms based on their extractability and interaction with cell wall components. The nutritional effects of bound phenolics in algae have long been neglected. These topics contribute to the development of seaweed-based functional foods.

Structure determination, bitterness evaluation and hepatic gluconeogenesis inhibitory activity of triterpenoids from the Momordica charantia fruit.

Triterpenoids are hypoglycemic substances and flavor components of Momordica charantia L., whether their bitterness correlated with hypoglycemic potential remain unknown. Thus, triterpenoids in M. charantia were isolated by phytochemical methods and identified by spectroscopic analysis. The bitterness levels and hypoglycaemic activity of isolated triterpenoids were evaluated by electronic tongue and hepatic gluconeogenesis assay. Eighteen triterpenoids including two new ones, Momordicoside Y and Z, were identified. Among the six identified bitter triterpenoids, karaviloside III, goyaglycoside C, and momordicoside F2 were bitterer than caffeine (P < 0.05), with caffeine equivalent (CE) values of 289.19, 4.32, and 41.24 mg CE/mg, respectively. Momordicoside Y, charantoside C, momordicoside F1, and momordicoside G could inhibit hepatic gluconeogenesis by 23.9%, 36.2%, 33.4%, 34.4% at 40 µM, respectively. These four compounds could interact with active site of phosphoenolpyruvate carboxykinase in molecular docking simulation. No correlation was observed between hepatic gluconeogenesis inhibitory activity and bitterness of triterpenoids.

Effect of Storage Conditions on Phenolic Profiles and Antioxidant Activity of Litchi Pericarp.

Changes of phenolic profiles and antioxidant activity of litchi pericarp during storage at 4 °C for seven days and at room temperature (RT) for 72 h were evaluated in this study. The contents of total phenolic and procyanidin decreased by 20.2% and 24.2% at 4 °C and by 37.8% and 47.8% at RT, respectively. Interestingly, the corresponding reductions of anthocyanins were 41.3% and 73%, respectively. Four phenolic compounds, including epicatechin, procyanidin A2, procyanidin B2, and quercetin-3-O-rutinoside-7-O-α-l-rhamnosidase were detected in litchi pericarp. Their contents after storage at 4 °C and at RT were decreased by 22.1⁻49.7% and 27.6⁻48.7%, respectively. The oxygen radical absorbance capacity (ORAC) and cellular antioxidant activity (CAA) of litchi pericarp decreased by 17.6% and 58.7% at 4 °C, and by 23.4% and 66.0% at RT, respectively. The results indicated that storage at 4 °C preserved more phenolics and retained higher antioxidant activity in litchi pericarp compared to storage at RT, suggesting that storage at 4 °C should be considered as a more effective method for slowing down the degradation of litchi pericarp phenolics.

A Comparison of the Chemical Composition, In Vitro Bioaccessibility and Antioxidant Activity of Phenolic Compounds from Rice Bran and Its Dietary Fibres.

The composition, in vitro bioaccessibility and antioxidant activities of the phenolic compounds in defatted rice bran (DRB) and its soluble and insoluble dietary fibres were systematically evaluated in this study. The total phenolic content of insoluble dietary fibre from DRB (IDFDRB) was much higher than that of the soluble dietary fibre from DRB (SDFDRB) but was 10% lower than that of DRB. Bound phenolics accounted for more than 90% of the total phenolics in IDFDRB, whereas they accounted for 34.2% and 40.5% of the total phenolics in DRB and SDFDRB, respectively. Additionally, the phenolic profiles and antioxidant activities were significantly different in DRB, SDFDRB and IDFDRB. The phenolic compounds in IDFDRB were much less bioaccessibility than those in DRB and SDFDRB due to the higher proportion of bound phenolics in IDFDRB. Considering that bound phenolics could be released from food matrices by bacterial enzymes in the large intestine and go on to exert significant beneficial health effects in vivo, further studies on IDFDRB are needed to investigate the release of the phenolics from IDFDRB via gut microbiota and the related health benefits.

Lychee (Litchi chinensis Sonn.) Pulp Phenolic Extract Provides Protection against Alcoholic Liver Injury in Mice by Alleviating Intestinal Microbiota Dysbiosis, Intestinal Barrier Dysfunction, and Liver Inflammation.

Liver injury is the most common consequence of alcohol abuse, which is promoted by the inflammatory response triggered by gut-derived endotoxins produced as a consequence of intestinal microbiota dysbiosis and barrier dysfunction. The aim of this study was to investigate whether modulation of intestinal microbiota and barrier function, and liver inflammation contributes to the hepatoprotective effect of lychee pulp phenolic extract (LPPE) in alcohol-fed mice. Mice were treated with an ethanol-containing liquid diet alone or in combination with LPPE for 8 weeks. LPPE supplementation alleviated ethanol-induced liver injury and downregulated key markers of inflammation. Moreover, LPPE supplementation reversed the ethanol-induced alteration of intestinal microbiota composition and increased the expression of intestinal tight junction proteins, mucus protecting proteins, and antimicrobial proteins. Furthermore, in addition to decreasing serum endotoxin level, LPPE supplementation suppressed CD14 and toll-like receptor 4 expression, and repressed the activation of nuclear factor-κB p65 in the liver. These data suggest that intestinal microbiota dysbiosis, intestinal barrier dysfunction, and liver inflammation are improved by LPPE, and therefore, the intake of LPPE or Litchi pulp may be an effective strategy to alleviate the susceptibility to alcohol-induced hepatic diseases.

Lychee (Litchi chinensis Sonn.) Pulp Phenolic Extract Confers a Protective Activity against Alcoholic Liver Disease in Mice by Alleviating Mitochondrial Dysfunction.

Mitochondria play an important role in the initiation and development of alcoholic liver disease (ALD). Our previous studies found lychee pulp phenolic extract (LPPE) exerted protective effect against ALD partly by inhibiting fatty acid ß-oxidation, and phenolic-rich lychee pulp extract improved restraint stress-induced liver injury by inhibiting mitochondrial dysfunction. The aim of this study was to investigate whether LPPE exerted protective effect against ALD via modulating mitochondrial function. The mice were treated with an ethanol-containing liquid diet alone or in combination with LPPE for 8 weeks. LPPE supplementation significantly alleviated hepatic steatosis, suppressed serum aspartate aminotransferase activity, and decreased triglyceride levels in serum and liver. On the basis of lipid peroxidation and antioxidant enzyme analyses, LPPE supplementation inhibited serum and hepatic oxidative stress. Moreover, LPPE supplementation significantly suppressed mitochondrial 8-hydroxy-2'-deoxyguanosine level, and increased mitochondrial membrane potential, mitochondrial DNA content, activities of mitochondrial complexes I and IV, and hepatic ATP level. Furthermore, LPPE supplementation significantly inhibited cytoplasmic cytochrome c level and caspase-3 activity, repressed Bax expression and Bax/Bcl-2 ratio, and increased Bcl-2 expression in liver. In summary, LPPE exerts beneficial effects against alcoholic liver injury by alleviating mitochondrial dysfunction.