E se tea aqueous-ethanol extract ameliorates D-galactose induced oxidative stress and inflammation via the Nrf2 signal pathway.

E Se tea is a traditional herbal tea produced by traditional green tea processing technique from the tender leaves of Malus toringoides (Rehd.) Hughes with anti-inflammatory and antioxidant activities. This study investigated the inhibitory effect of the aqueous-ethanol extract of E Se tea against oxidative stress induced damage on D-galactose (D-gal) induced mice. UPLC-ESI-HRMS/MS analysis resulted in the identification of eleven compounds inclusive of 1 isoflavone (9), 1 phenolic acid (2), 2 flavanols (1 and 10), 3 dihydrochalcones (5, 8, and 11), and 4 flavones (3, 4, 6, and 7). The quantitative analysis demonstrated that phlorizin (8) had the highest content, followed by phloretin (11) and kaempferol-3-O-glucoside (7). The aqueous-ethanol extract of E Se tea significantly increased the total antioxidant capacity (T-AOC) in serum, reduced MDA level, and enhanced SOD activity and GSH level in brain and liver tissues. In addition, this extract also remarkably decreased the levels of inflammatory cytokines (IL-6 and IL-1β) in serum, and inhibited the AchE activity in brain. The possible mechanism might be related to the upregulation of Nrf2, HO-1, and NQO1 the expressions by using western blotting experiment. The pearson correlation analysis revealed that phloretin was the possible antioxidant and anti-inflammatory compound, and coumaroyl quinic acid was the active compound on AChE enzyme. These findings indicated that E Se tea extract had the protective effect on D-gal induced oxidative stress damage in mice via activating the Nrf2 signal pathway.