To explore the changes in the release of phenolic substance,bioaccessibility,and antioxidant activity in fruit mulberry and leaf mulberry leaves during in vitro simulated digestion,the contents of phenolic compounds in mulberry leaves were determined by HPLC and spectrophotometry.The results revealed a gradual decrease in polyphenols,flavonoids,rutin,and chlorogenic acid in mulberry leaves during digestion,with the most significant reduction occurring during intestinal digestion.Quercetin release increased during gastric digestion compared with that before digestion,but decreased significantly after intestinal digestion.Prior to in vitro simulated digestion,bound phenols in mulberry leaves exhibited significantly higher antioxidant activity than free phenols.During the simulation digestion process,the antioxidant capacity of phenolic compounds in mulberry leaves decreased significantly (P<0.05).Following gastric and intestinal digestion stages,bioaccessibility was highest for polyphenols in fruit mulberry and quercetin in leaf mulberry,however it remained less than 1 for all phenolic compounds analyzed.Correlation analysis indicated a positive correlation between antioxidant activity of mulberry leaves and the release levels of flavonoids,polyphenols,rutin,and chlorogenic acid.In conclusion, in vitro simulated digestion affects phenolic compounds in mulberry leaves.This research provides a theoretical basis for further understanding the utilization patterns of phenolic compounds in mulberry leaves during in vivo digestion.