Phytic acid extraction from rice bran with acetic acid: Optimization, antioxidant capacity and mechanism based on cellular metabolomics

In this study, response surface methodology (RSM) was employed to optimize phytic acid extraction from rice bran using acetic acid, with extraction temperature, pH, and liquid-to-solid ratio as independent variables and phytic acid yield as the response. Through experimentation and analysis, the optimal process parameters were determined as follows: extraction temperature of 43.1 °C, a pH value of 2.99, and a liquid-to-solid ratio of 8.91. Under these conditions, the predicted extraction rate of phytic acid was 4.05%. Subsequently, the hydroxyl radical scavenging ability of extracted phytic acid (EC 50 : 0.162 mg/mL) matched vitamin C (EC 50 : 0.167 mg/mL). Phytic acid's protective effect against oxidative stress was studied using a H 2 O 2 -induced HepG2 cell model. Results showed it can inhibit the generation of intracellular reactive oxygen species (ROS), while maintaining the activities of antioxidant enzymes such as SOD, GSH-Px, and CAT, indicating its ability to reduce H 2 O 2 -induced damage and reinforcing its antioxidant properties. Furthermore, cellular metabolomics identified 12 intracellular and 14 extracellular differential metabolites. These metabolites highlighted key metabolic pathways, including amino acid metabolism, glyoxylate and dicarboxylate metabolism, and glutathione metabolism intracellularly, as well as starch, sucrose, and tryptophan metabolism extracellularly. These findings elucidate the metabolic pathways underlying phytic acid's antioxidant properties. • Extraction of phytic acid from defatted rice bran using acetic acid based on RSM. • Evaluating phytic acid's effect on antioxidant enzyme system via cell experiments and indicators. • Cellular metabolomics study on the antioxidant mechanism of phytic acid.