Optimisation of the flash extraction process for male catkins of Corylus heterophylla and evaluation of their oxidative stress resistance

The fruit of Corylus heterophylla Fisch is an important nut, while its male catkins remain underutilised despite being rich in various bioactive compounds. To develop this potential resource, this study optimised the extraction process of C. heterophylla male catkins and investigated their antioxidant stress resistance. The results showed that the optimal extraction conditions were: extraction time of 53 s, ethanol concentration of 82%, and a liquid-solid ratio of 33 mL/g. In vitro experiments showed that C. heterophylla male catkin extract (ChCE) reduced ROS production and elevated SOD, CAT activities and GSH content in t-BHP-induced HepG2 cells. Additionally, ChCE promoted the phosphorylation of MAPKs, mediating decreased Keap1 expression in the cytoplasm and increased Nrf2 expression. In vivo experiments confirmed that ChCE alleviated alcohol-induced hepatic oxidative stress in mice. These findings suggest that the male catkins of C. heterophylla represent a valuable resource for applications in the food and pharmaceutical industries.