Phenolic Compounds And Antioxidant Properties Of Choerospondias Axillari As Affected By In Vitro Digestion

Choerospondias axillaris contained many bioactive ingredients such as intannins,saponins,flavonoids,polyphenols and other bioactive components were widely distributed in China.Currently,there were many reports about the bio-accessibility,bio-availability and function of phenolic compounds following simulated gastro-intestinal digestion in a few of the plants such as apples or grapes,but not in Choerospondias axillaris fruits.Therefore,we intended to study phenolic compounds of Choerospondias axillaris fruits and aqueous extract at different phases of simulated digestion(gastric and intestinal phase),using an extended in vitro model.In addition,the influence of different factors(pH,digestive enzyme digestion)on digestion was evaluated which provided the theoretical reference for the study of Choerospondias axillaris.The impact of GI digestion on total phenolics and total flavonoids showed that the amount of released phenolics decreased stepwise from gastric to intestinal digesta for Choerospondias axillaris fruit and aqueous extract(about 94%).However,the effect was not significant for flavonoids in Choerospondias axillaris fruit.In gastric phase a significant loss of total flavonoids for Choerospondias axillaris aqueous extract was observed,but increased in intestinal phase.The gastrointestinal pH environment seemed to improve accessibility of phenolic compounds in Choerospondias axillaris.The active digestive enzymes came second.In general,active enzyme digestion seemed to improve accessibility of total phenolics in Choerospondias axillaris fruit,contrary to the aqueous extract;but improved accessibility of total flavonoids in both.The changes of seven polyphenol standards during different phases of GI digestion(gastric and intestinal phase)was estimated by a UPLC method.In gastric phase,no significant changes were observed in phenolic acid compounds,however,flavonoids compounds decreased significantly.In addition to the ferulic acid and p-hydroxy benzoic acid,the amount of other phenolic compounds were decreased significantly in intestinal phase,at the same time chlorogenic acid generated new material.The mixed standards had no significant changes during gastric-intestinal digestion.However,epicatechin and gallic acid were significantly lower compared to the gastric phase(50.18%and 70.99%,respectivly).From gastric to intestinal digesta,no significant changes were observed in gallic acid,epicatechin and catechin in Choerospondias axillaris fruit.For Choerospondias axillaris fruit aqueous extract,the epicatechin and gallic acid reduced in gastric and intestinal phase,respectively.Therefore,the accessibility of three single standards in Choerospondias axillaris fruits and aqueous extract might be pH-dependent.The active digestive enzymes had no significant effect on them.In order to further evaluate the antioxidant activity of Choerospondias axillaris in vitro digestion,three antioxidant activity models(Total antioxidant activity,hydroxyl radical scavenging ability,ABTS radical scavenging capacity)were applied.The results showed that a significant loss of the antioxidant activity was observed during gastric-intestinal digestion in Choerospondias axillaris fruit.Compared to the native antioxidant activity of Choerospondias axillaris aqueous extract,total antioxidant activity test showed that increasing activity of digesta in gastric phase,contrary to the hydroxyl radical scavenging ability and ABTS radical scavenging capacity of the aqueous extract.However,in intestinal phase a significant loss of total antioxidant activity in chemistry sets and no significant changes in active digestive enzymes sets were observed;hydroxyl radical scavenging ability had no significant changes;ABTS test showed that increasing activity of digesta in intestinal phase.This study provided a protocol and plentiful of data for reasonable and effective utilization of Choerospondias axillaris.