Identification of Polyphenols in <i>Mallotus peltatus</i> (Geiseler) Mull. Arg. Based on UPLC‐MS/MS and Their Protective Effects on H ₂ O ₂ ‐Induced Liver Injury

Background: Liver cells are particularly susceptible to mitochondrial dysfunction due to external stimuli, leading to excess reactive oxygen species (ROS) and redox imbalance. The aim of this study was to extract and purify the polyphenolic fractions of Mallotus peltatus (Geiseler) Mull. Arg. and evaluate their potential protective effect against H 2 O 2 ‐induced oxidative stress injury in hepatocytes. Methods: The extraction process of polyphenols in MPMA was optimized by the response surface method. Then, we purified the crude extracts with macroporous resin HPD600 to obtain MPMAP‐I, MPMAP‐II, and MPMAP‐III. The physical properties and component composition of the samples were analyzed by FT‐IR and UPLC‐MS/MS. An in vitro H 2 O 2 ‐induced oxidative stress injury model in hepatocytes was established to investigate the protective effect of MPMAP‐I on L02 cells. The effect was assessed by measuring cell survival rate, enzyme activities, intracellular ROS levels, cell apoptosis rate, mitochondrial membrane potential, and the mRNA expression of related signaling pathways. Results: The results showed that the optimized extraction conditions of MPMA were 60% ethanol, 140 min, 85°C, and liquid‐to‐solid ratio of 30 mL/g. All three purified fractions contained different polyphenols (such as kaempferol 3‐O‐sophoroside, corilagin, and cirsiliol) and had great antioxidant activities. MPMAP‐I treatment could increase the activities of SOD, CAT, and GPx in H 2 O 2 ‐induced L02 cells, reduce the content of MDA, the activities of transaminases, the production of intracellular ROS, and the rate of cell apoptosis, and restore mitochondrial function. Furthermore, these effects might be related to the inactivation of the Bcl2/Bax/caspase‐3 apoptotic pathway and the activation of the Nrf2/γ‐GCL antioxidant pathway. Conclusion: Our study provided a theoretical basis for the protective effect of MPMA polyphenols on liver injury, which is helpful to improve the development and application of MPMA in medicine and healthcare products.