Abstract: This research aimed to investigate the influence of in vitro gastrointestinal simulated digestion on the stability,antioxidant and a-glucosidase inhibitory activity of A.palmatum leaves polyphenols.The contents of phenolics,flavonoids and condensed tannins as well as the DPPH·,ATBS+· scavenging ability and a-glucosidase inhibition of A.palmatum leaves polyphenols before and after digestion were analyzed.The obtained results indicated that oral and stomach digestion reduced the total flavonoids content,but had insignificant difference on the content of phenolics and condensed tannins (P>0.05).Intestinal digestion can dramatically decrease the content of bioactive constituents present in A.palmatum leaves polyphenols extract.Contents of flavonoids,phenolics and condensed tannins in samples group decreased by 99.26%,52.95% and 100%,respectively.Oral and stomach digestion decreased the radical scavenging ability and α-glucosidase inhibition of samples,but the influence was small,while,intestinal digestion resulted in sharp reduction of above bioactivity.On the test sample concentration range,the DPPH· scavenging ability and α-glucosidase inhibition of intestinal digestion sample decreased by 100% as compared to that of stomach digestion sample,and the IC₅₀ value for ATBS⁺· scavenging ability increased by 1.88 times,and insignificant difference was observed between the sample and pH group (P>0.05).Above all,gastrointestinal digestion will decrease the stability,and antioxidant and α-glucosidase inhibitory activity,which mainly occurs on the intestinal digestion phase,the change of pH is the major influence factor.

Key words: Acer palmatum leaves, in vitro simulated digestion, polyphenols, antioxidant activity, α-glucosidase inhibition