Flavonoids from Rhododendron nivale Hook. f delay aging via modulation of gut microbiota and glutathione metabolism.

BACKGROUND

Rhododendron nivale Hook. f (R.n), one of the four Manna Stash used in Tibetan medicine to delay aging, possesses anti-aging pharmacological activity. However, which R.n ingredients contain anti-aging properties and the underlying mechanisms involved are unclear.

HYPOTHESIS/PURPOSE: Based on interactions between gut microbiota and natural medicines and the important role of gut microbiota in anti-aging, the study investigated the hypothesis that R.n possesses anti-aging properties and the interaction of gut microbiota with R.n is responsible for its anti-aging effects.

STUDY DESIGN

The primary active ingredients of R.n and their target function and pathway enrichment were explored. An aging mouse model was used to clarify the underlying anti-aging mechanisms of R.n.

METHODS

Chromatography, spectroscopy, nuclear magnetic technology, and pharmacology were used to reveal the major active ingredients of ethanol extract residues of R.n (RNEA). The target function and pathway enrichment of these active ingredients were explored. Plasma metabolomics coupled with intestinal flora evaluation and bioinformatics analysis was used to clarify the underlying anti-aging mechanisms of RNEA.

RESULTS

Myricetin-3-β-D-xylopyranoside, hyperin, goospetin-8-methyl ether 3-β-D-galactoside, and diplomorphanin B were separated and identified from RNEA. The network pharmacology study revealed that the active ingredients' target function and pathway enrichment focused mainly on the glutathione antioxidant system. In a D-galactose-induced mouse model of aging, RNEA was shown to possess suitable anti-aging pharmacological activity, as indicated by the amelioration of memory loss and weakened superoxide dismutase and glutathione peroxidase activities. Plasma metabolomics coupled with intestinal flora examination and bioinformatics analysis revealed that RNEA could regulate the expression of glutathione-related enzymes and ameliorate D-galactose-induced imbalances in methionine, glycine, and serine, and betaine and galactose metabolism. The results showed that RNEA reshaped the disordered intestinal flora and mitigated the D-galactose-mediated decline in glutathione oxidase expression, further confirming that the anti-aging effect of RNEA was closely related to regulation of the glutathione antioxidant system.

CONCLUSION

RNEA, consisting of myricetin-3-β-D-xylopyranoside, hyperin, goospetin-8-methyl ether 3-β-D-galactoside, and diplomorphanin B, possesses anti-aging activity. The anti-aging effect of RNEA might be due to reshaping intestinal flora homeostasis, increasing the expression of glutathione peroxidase 4 in the intestines and liver, enhancing glutathione peroxidase activity, and reinforcing the glutathione antioxidant system.