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.