Ameliorative Effect of Ellagic Acid on Aging in Rats with the Potential Mechanism Relying on the Gut Microbiota and Urolithin A-Producing Ability.

Ellagic acid (EA) exhibits potential antiaging activity. Differences in individual ability to produce urolithins may result in large interindividual variability in the health effects of EA. Therefore, the effects and mechanism of EA on d-galactose-induced aging, considering urolithin A-producing ability, were investigated. Our results showed that EA improved cognitive impairment and hippocampal damage, increased the GABA (by 107.84-117.86%) and 5-HT (by 72.56-100.85%) levels, and suppressed the inflammatory and oxidative stress in aging rats. Thirteen plasma metabolites and 12 brain metabolites were improved by EA administration in aging rats. In particular, EA showed a better anti-aging effect in high-UroA-producing rats than in the low counterparts, while antibiotic intervention almost offset EA-alleviated aging induced by d-gal. Furthermore, the lower ratio of Firmicutes and Bacteroidota as well as the greater abundances of Akkermansia (by 139.21%), Bifidobacterium (by 88.04%), Clostridium_sensu_stricto_1 (by 183.47%), Lactobacillus (by 97.23%), and Turicibacter (by 83.06%) were observed in the high-UroA-producing group compared with the model group (p < 0.05). These findings provide novel insights into the anti-aging effects of EA and suggest that the ability of the gut microbiota responding to EA largely determines EA's anti-aging performance.

Potential of Establishing the Corresponding Human Microbial Community in Pseudo Germ-Free Mice through Fecal Microbe Transfer from Three Urolithin Metabotypes.

Three urolithin metabotypes (UMs) have been defined in the population according to final urolithins converted by gut microbiota. Currently, it is difficult to establish the cause-and-effect relationship between urolithins and microbiota in human studies. Studies on the health effects of ellagic acid (EA) in animal models rarely consider the differences in the urolithin production. Therefore, the objective of this study is to establish human microbiota-associated (HMA) mice, imitating the microbiota composition of the three UMs. Antibiotic-induced pseudo germ-free mice were gavaged with fecal bacteria of the three UM donors for four weeks. The results showed that the ability to produce corresponding urolithins was successfully transferred from the donor of the three UMs to HMA mice. The three UM HMA mice adopted a humanized microbiota profile similar to their corresponding donor. The family Eggerthellaceae and genera Eggerthella and Gordonibacter were successfully transferred and colonized from UM-A/B donors to HMA mice. Overall, the three UM HMA mouse models were successfully established, which provide a basis for exploring the health effects of EA.

A Novel Polysaccharide Isolated From Fresh Longan (Dimocarpus longan Lour.) Activates Macrophage via TLR2/4-Mediated PI3/AKT and MyD88/TRAF6 Pathways.

A novel immunomodulatory polysaccharide (LP4) with a molecular weight 6.31 × 104 g/mol was purified from fresh longan pulp. It was composed of mannose, glucose, glucuronic acid, galactose, xylose, arabinose, galacturonic acid, fucose, and rhamnose in a molar percentage of 36:31:10:7:4:4:3:2:2, and mainly linked by (1→6)-ß-Man, (1→4)-ß-Glc and (1→6)-α-Glc. LP4 can obviously enhance the phagocytosis of macrophages and promote the proliferation of lymphocytes. After treating macrophages with LP4 (12.5-50 µg/ml), the production of IL-1ß and TNF-α was significantly increased. These increases of cytokines were suppressed when the TLR2/TLR4 receptors were inhibited by anti-TLR2 and/or anti-TLR4 antibodies. Moreover, the mRNA expression of INOS, AKT, PI3K, TRAF6 and MyD88 was significantly suppressed by TLR2/TLR4 antibodies. These results indicated that LP4 induced macrophage activation mainly via the TLR2 and TLR4-induced PI3K/AKT and MyD88/TRAF6 pathways.