Protective effect against d-gal-induced aging mice and components of polypeptides and polyphenols in defatted walnut kernel during simulated gastrointestinal digestion

Utilization of low-grade walnut kernels for oil extraction using eco-friendly methods: a comparative analysis of oil composition, antioxidant and antimicrobial activity

Walnut oil was extracted using three different eco-friendly extraction methods, solvent extraction (using ethyl acetate [EA] and ethanol [ET]), aqueous enzymatic extraction (AEE), and ultrasound-assisted enzymatic extraction (UAEE), and their lipid yield, lipid composition, physicochemical analysis, mineral composition, total phenols, antioxidant capacity, and antimicrobial activity were analyzed and compared. The AEE technique offered a greater yield (50.6%) than the other extraction methods and gave comparatively higher linoleic acid (66.12%) content. Palmitic, oleic, linoleic, linolenic, and stearic acids were the principal components that GC/MS detected in all the oil samples. UAEE produced the most polyphenols (0.49 mgGAE/g), followed by AEE (0.46 mgGAE/g), EA (0.45 mgGAE/g), and ET (0.35 mgGAE/g). The DPPH assay results were in the order of UAEE (191 μmolTE/kg) > AEE (186 μmolTE/kg) > EA (153 μmolTE/kg) > ET (130 μmolTE/kg). The FRAP assay findings showed a similar pattern: UAEE (112 molTE/kg) > AEE (102 molTE/kg) > EA (96 molTE/kg) > ET (82 molTE/kg). Results suggested that for a higher extraction yield, AEE is the better technique and UAEE is the recommended method for enhancing walnut oil antioxidant capacity. Additionally, it was found that polyphenols considerably increased the antioxidant capacity of walnut oil and are thought to be health-promoting. The results demonstrated the antibacterial effectiveness of the extracted oil against Bacillus subtilis, Bacillus licheniformis, and Staphylococcus aureus. This study provides information about low-cost and ecofriendly technologies of walnut oil extraction for food, cosmetic, and medical uses.

Mechanistic Insights into the Biological Effects and Antioxidant Activity of Walnut (Juglans regia L.) Ellagitannins: A Systematic Review

Walnuts (Juglans regia L.) are an important source of ellagitannins. They have been linked to positive effects on many pathologies, including cardiovascular disorders, neurodegenerative syndromes, and cancer. The limited bioavailability of ellagitannins prevents them from reaching significant circulatory levels, despite their antioxidant, anti-inflammatory, and chemopreventive properties. Urolithins are ellagitannin gut microbiota-derived metabolites. They have better intestinal absorption and may be responsible for the biological activities of ellagitannins. Recent evidence showed that walnut ellagitannins and their metabolites, urolithins, could have positive outcomes for human health. This study aims to synthesize the current literature on the antioxidant activity and mechanistic pathways involved in the therapeutic potential of walnut ellagitannins and their metabolites. In the eligible selected studies (n = 31), glansreginin A, pedunculagin, and casuarictin were the most prevalent ellagitannins in walnuts. A total of 15 urolithins, their glucuronides, and sulfate metabolites have been identified in urine, blood, feces, breast milk, and prostate tissue in analyzed samples. Urolithins A and B were associated with antioxidant, anti-inflammatory, cardioprotective, neuroprotective, anticarcinogenic, and anti-aging activities, both in preclinical and clinical studies. Despite the promising results, further well-designed studies are necessary to fully elucidate the mechanisms and confirm the therapeutic potential of these compounds in human health.

The Antioxidant Activities In Vitro and In Vivo and Extraction Conditions Optimization of Defatted Walnut Kernel Extract

The objective of this study was to determine the antioxidant activities of defatted walnut kernel extract (DWE) and whole walnut kernel extract (WE) in vitro and in vivo. Three spectrophotometric methods, DPPH, ABTS, and FRAP, were used in in vitro experiments, and mice were used in in vivo experiments. In addition, response surface methodology (RSM) was used to optimize reflux-assisted ethanol extraction of DWE for maximum antioxidant activity and total phenolic content. The results of in vitro experiments showed that both extracts showed antioxidant activity; however, the antioxidant activity of DWE was higher than that of WE. Both extracts improved the mice's oxidative damage status in in vivo studies. An ethanol concentration of 58%, an extraction temperature of 48 °C, and an extraction time of 77 min were the ideal parameters for reflux-assisted ethanol extraction of DWE. The results may provide useful information for further applications of defatted walnut kernels and the development of functional foods.

Chlorogenic acid improves growth performance of weaned rabbits via modulating the intestinal epithelium functions and intestinal microbiota

This study was conducted to investigate the impacts of chlorogenic acid (CGA) on growth performance, intestinal permeability, intestinal digestion and absorption-related enzyme activities, immune responses, antioxidant capacity and cecum microbial composition in weaned rabbits. One hundred and sixty weaned rabbits were allotted to four treatment groups and fed with a basal diet or a basal diet supplemented with 400, 800, or 1,600 mg/kg CGA, respectively. After a 35-d trial, rabbits on the 800 mg/kg CGA-supplemented group had higher (p < 0.05) ADG and lower (p < 0.05) F/G than those in control (CON) group. According to the result of growth performance, eight rabbits per group were randomly selected from the CON group and 800 mg/kg CGA group to collect serum, intestinal tissue samples and cecum chyme samples. Results showed that compared with the CON group, supplementation with 800 mg/kg CGA decreased (p < 0.05) levels of D-lactate, diamine oxidase, IL-1β, IL-6, and malondialdehyde (MDA), and increased IL-10 concentration in the serum; increased (p < 0.05) jejunal ratio of villus height to crypt depth, enhanced (p < 0.05) activities of maltase and sucrase, increased (p < 0.05) concentrations of IL-10, T-AOC, MHCII and transforming growth factor-α, and decreased (p < 0.05) levels of TNF-α and MDA in the jejunum of weaned rabbits. In addition, results of high-throughput sequencing showed that CGA supplementation elevated (p < 0.05) microbial diversity and richness, and increased (p < 0.05) the abundances of butyrate-producing bacteria (including genera V9D2013_group, Monoglobus, Papillibacter, UCG-005, and Ruminococcus). These results indicated that dietary supplementation with 800 mg/kg CGA could improve the growth performance of weaned rabbits by enhancing intestinal structural integrity, improving the intestinal epithelium functions, and modulating the composition and diversity of gut microbiota.

Characteristics and Antioxidant Activity of Walnut Oil Using Various Pretreatment and Processing Technologies

This study was the first time the effects of pretreatment technology (microwave roasting, MR; oven roasting, OR; steaming roasting, SR) and processing technology (screw pressing, SP; aqueous enzymatic extraction, AEE; subcritical butane extraction, SBE) on the quality (physicochemical properties, phytochemical content, and antioxidant ability) of walnut oil were systematically compared. The results showed that the roasting pretreatment would reduce the lipid yield of walnut oil and SBE (59.53−61.19%) was the processing method with the highest yield. SR-AEE oil provided higher acid value (2.49 mg/g) and peroxide value (4.16 mmol/kg), while MR-SP oil had the highest content of polyunsaturated fatty acid (73.69%), total tocopherol (419.85 mg/kg) and total phenolic compounds (TPC, 13.12 mg/kg). The DPPH-polar and ABTS free radicals’ scavenging abilities were accorded with SBE > AEE > SP. SBE is the recommended process for improving the extraction yield and antioxidant ability of walnut oil. Hierarchical cluster analysis showed that processing technology had a greater impact on walnut oil than pretreatment technology. In addition, multiple linear regression revealed C18:0, δ-tocopherol and TPC had positive effects on the antioxidant ability of walnut oil, while C18:1n-9, C18:3n-3 and γ-tocopherol were negatively correlated with antioxidant activity. Thus, this a promising implication for walnut oil production.

Green Tea Polyphenols Upregulate the Nrf2 Signaling Pathway and Suppress Oxidative Stress and Inflammation Markers in D-Galactose-Induced Liver Aging in Mice

The beneficial effects of green tea polyphenols (GTPs) on D-galactose (D-Gal)-induced liver aging in male Kunming mice were investigated. For this purpose, 40 adult male Kunming mice were divided into four groups. All animals, except for the normal control and GTPs control, were intraperitoneally injected with D-galactose (D-Gal; 300 mg/kg/day for 5 days a week) for 12 consecutive weeks, and the D-Gal-treated mice were allowed free access to 0.05% GTPs (w/w) diet or normal diet for 12 consecutive weeks. Results showed that GTP administration improved the liver index and decreased transaminases and total bilirubin levels. Furthermore, GTPs significantly increased hepatic glutathione and total antioxidant levels, and the activities of superoxide dismutase, catalase, and glutathione S-transferase (GST). Furthermore, GTPs downregulated 8-hydroxy-2-deoxyguanosine, advanced glycation end products, and hepatic oxidative stress markers, such as malondialdehyde and nitric oxide. Additionally, GTPs abrogated dysregulation in hepatic Kelch-like ECH-associated protein 1 and nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream target gene expression [heme oxygenase 1, NAD(P)H:quinone oxidoreductase 1, and GST] and inhibited tumor necrosis factor-α, transforming growth factor-β, and interleukin (IL)-1β and IL-6 in the liver of treated mice. Finally, GTPs effectively attenuated D-Gal-induced edema, vacuole formation, and inflammatory cell infiltration. In conclusion, GTPs showed antioxidant and anti-inflammatory properties in D-Gal-induced aging mice, and may be considered a natural alternative to the effects of hepatic aging.