| Lycium barbarum L.var.auranticarpum K.F.Ching,a variant of Lycium,contains polysaccharides,polyphenols,betaine and other bioactive components.The content and type of phenolic compounds affect the bioactivity of the sample,especially the antioxidant activity.However,the current research on the phenolic compounds of Lycium barbarum L.var.auranticarpum K.F.Ching is limited to the determination of content,and the analysis of phenolic monomers,its stability in the digestive process and the benefits to human health have not been reported.Therefore,in this study,four varieties of Lycium barbarum L.var.auranticarpum K.F.Ching(Huangguobian,W-12-30,W-11-15 and Ningxia Huangguo)were used as materials.Folin-Ciocalteu method,Sodium nitrite-Aluminum nitrate colorimetry and High performance liquid chromatography were used to determine the contents of total phenols,total flavonoids and phenolic monomer,respectively.The antioxidant activities of four samples were compared by DPPH scavenging assay,ABTS scavenging assay and iron reducing power assay.On this basis,the HPD-100 macroporous resin was used to purify the ethanol extract of Huangguobian.In vitro digestion and in vitro fermentation tests were carried out respectively to evaluate the stability of the phenolic compounds during the digestion process,and its interaction with the gut microbiota.The results of the study are as follows:(1)The order is Huangguobian> W-12-30> Ningxia Huangguo> W-11-15.The total phenol content of Huangguobian is 10.14±0.37 mg GAE/g DW and the total flavonoids content is 10.01±0.41 mg RE/g DW.The high performance liquid chromatography method was used to qualitatively quantify four phenolic compounds: epicatechin,rutin,ferulic acid and p-coumaric acid).The results of antioxidant assay showed that all the four samples had antioxidant activity.The Huangguobian had the highest antioxidant activity.And the antioxidant activity was positively correlated with the contents of total phenols and total flavonoids(p<0.01).(2)Continuous digestion in the mouth,stomach and small intestine significantly increased the content of free phenols and flavonoids(p<0.05).In addition,gastric digestion significantly promoted the release of epicatechin and rutin(p<0.05),there was no significant change in coumaric acid and ferulic acid.The contents of epicatechin and rutin decreased after intestinal digestion(p<0.05).And the contents of p-coumaric acid and ferulic acid significantly increased(p<0.05).The results of antioxidant experiments showed that the Lycium barbarum L.var.auranticarpum K.F.Ching always had high free radical scavenging ability and iron reducing ability during in vitro digestion.(3)After 24 h in vitro fermentation,the small intestinal promoted the release of phenolic compounds and flavonoids from the food matrix,and the free phenols were increased from 20.15±0.98 mg GAE/100 m L to 26.22±1.24 mg GAE/100 m L.Flavonoids increased from 15.56±0.42 mg Re /100 m L to 41.74±1.77 mg Re /100 m L.Compared with unfermented samples,in vitro fermentation for 24 h promoted the release of epicatechin,ferulic acid and caffeic acid(p<0.05).However,rutin and p-coumaric acid were significantly decreased after 24 h fermentation(p<0.05).After fermentation for 24 h,the pH decreased from 7.38 to 4.12,and the total short-chain fatty acid concentration increased from275.98±14.95 ?L/100 m L to 304.97±21.01 ?L/100 m L.In addition,the addition of sample decreased the relative abundance of Prevotella,Dialister and Clostridium,but also increased the relative abundance of Bifidobacterium and Anaerostipes,especially Bifidobacterium. |
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