Rice bean (Vigna umbellata) is a medicinal and dietary legume rich in polyphenols. In this study, the free and bound phenolics in rice bean were extracted by water, 80% methanol, and acid, base, and composite enzymatic hydrolysis, respectively. The polyphenol profiles of the extracted fractions were analyzed. The outcome demonstrated that base hydrolysis was the most effective way to liberate bound phenolics from rice bean (14.18 mg GAE/g DW), which was 16.68 and 56.72 folds higher than those extracted by acid and enzymatic hydrolysis, respectively. The bound polyphenols released by base hydrolysis contributed to 71.15% of the total phenolic content. A total of 35 individual phenolics was identified, of which isoquercitrin, procyanidin B1, rutin, taxifolin, and catechin were the main monomeric phenolics in the free fraction, while gallic acid, protocatechuic acid, p-hydroxybenzoic acid, catechin, and phloroglucinol were the main monomeric phenolics in the bound fraction. In comparison to the free phenolics extracted by water and 80% methanol and the bound phenolics extracted using acid and composite enzymatic hydrolysis, the bound phenolics from base hydrolysis had a superior antioxidant capacity. The antioxidant activity of rice bean is primarily attributed to individual phenolics such as catechin, abundant both in free and bound fractions, and also p-hydroxybenzoic acid, gallic acid, and protocatechuic acid in bound fractions. The bound phenolics of rice bean were first reported and showed large differences with the composition of free phenolics. This work suggests that the bound fraction of rice bean must be taken into account in assessing its potential benefits to health.

This study integrated analyses of gut microbiota and metabolomics to investigate the impact of ellagic acid (EA) on non-alcoholic fatty liver disease (NAFLD). Compared to the high-fructose diet (HFruD) group, the EA group exhibited reduced body weight and fat mass, alongside improvements in blood glucose and lipid metabolism. Liver metabolomics analysis revealed that EA increased the abundance of metabolites in pathways related to unsaturated fatty acids, amino acids and bile acids. Furthermore, EA induced alterations in the composition and structure of gut microbiota, notably decreasing bacterial genera enriched by HFruD while promoting beneficial bacteria such as Faecalibaculum. Correlation analysis demonstrated significant associations among NAFLD markers, gut microbiota and liver metabolites influenced by EA. This study provides new insights into the anti-NAFLD effects of EA, suggesting EA as a promising nutraceutical for improving NAFLD.

Fructus mume (FM), the processed product of Prunus mume (PM), is a traditional Chinese medicine. The release characteristics and bioactivities of phenolics from PM and FM were compared in the present study. In oral and gastric digestion, both the total polyphenols content released and the antioxidant activities of PM were much higher than those of FM, whereas the opposite trend was observed in intestinal digestion and colonic fermentation. Specifically, during colonic fermentation, the total polyphenols content released of FM was 1.43-fold higher than that of PM, with corresponding antioxidant activities (DPPH and ABTS) of FM being 1.41- and 2.91-fold higher, respectively. Twenty-four individual phenolics were found after gastrointestinal digestions with neochlorogenic acid and chlorogenic acid as the predominant ones. During colonic fermentation, a comparatively higher content of cryptochlorogenic acid and benzoic acid was detected in FM, while a higher content of 3-(3,4-dihydroxyphenyl) propionic acid was detected in PM. Notably, FM has a better effect on regulating the gut microbiota composition than PM, as evidenced by a greater enrichment of beneficial bacteria such as Bifidobacterium and Megamonas, along with a stronger suppression of the pathogenic Escherichia–Shigella. These results provided insights into the digestive properties of polyphenols from PM and FM, indicating that processing of PM into FM potentially enhance its health-improving effects on the colon.