Study On Antioxidant Activity,Anti-inflammatory Activity And Simulated Absorption In Human Intestinal Epithelial Of Phenols From Sorghum Bran

Sorghum(Sorghum bicolor L.Moench)is a dietary staple for people in more than 30 countries positioning this commodity as the 5th most valuable cereal crop in the world.Sorghum bran is a by-product of sorghum processing and also a rich and diverse source of the phenolic compounds.Studies on sorghum bran were focused on procyanidins and physiological activity of its crude extract.Phenolic compounds occur mostly as insoluble forms,covalently bound to cell wall structural components in cereal,especially in bran.As far as we know,little has been reported on the distribution of phenolic compounds in sorghum bran.Accordingly,different forms of phenols were extracted from sorghum bran,and their antioxidant activity,anti-inflammatory activity and absorption properties were studied in this paper,which will provide theoretical basis for the practical application of sorghum bran phenolic compounds.At the same time,two compounds were isolated.Their structures,antioxidation and anti-inflammatory activity were also evaluated.The contents of moisture,crude protein,crude fat,crude fiber and ash in sorghum bran sample were 10.99%,9.76%,5.44%,4.31% and 3.21%,respectively.The content of free,soluble esterified,soluble glycosidic,insoluble-bound esterified,and insoluble-bound glycosidic phenols in sorghum bran were 5.85,0.37,0.31,3.97,1.28 mg GAE/g SB DW,respectively.p-coumaric acid(33.63%)is the most abundant phenolic acids in sorghum bran,followed by ferulic acid(21.65%),both of them were mainly found in insoluble-bound form.After purification on the AB-8 macroporous resin,phenol concentrations were in the following order: free phenols > insoluble bound esterified phenols > insoluble bound glycosidic phenols > soluble glycosidic phenols > soluble esterified phenols.According to the results of HPLC,the concentrations of 18 phenolic compounds were in the following order: insoluble bound esterified phenols > free phenols > insoluble bound glycosidic phenols > soluble esterified phenols > soluble glycosidic phenols.Free phenols possesses relatively high antioxidant activities,followed by insoluble bound phenols,and soluble phenols while evaluated by chemistry antioxidant activity assays.After the treatment with 200 ?g/mL insoluble bound esterified,free,insoluble bound glycosidic,or soluble esterified phenols,the rate of AAPH-induced hemolysis of erythrocytes decreased to ~10%,which was close to that of the negative control group;the AAPH hemolysis rate of erythrocytes in the soluble glycosidic phenolic(200 ?g/m L)treatment group was still 28.84%.Pretreatments with five different forms of phenols effectively reduced the concentration of malondialdehyde(MDA),increased the glutathione/glutathione disulfide(GSH/GSSG)ratio in the AAPH-treated erythrocytes,and restored the erythrocytes to the normal state.The erythrocytes with relatively low superoxide dismutase(SOD),catalase(CAT),and glutathione peroxidase(GSH-Px)activities were also protected.As for Cellular antioxidant activity,insoluble bound esterified and soluble esterified phenols had the higher CAA value(mol of QE/g powder),followed by insoluble bound glycosidic,free,soluble glycosidic phenols.Five different forms of phenols could obviously inhibit the production of NO,TNF-?,IL-6 in LPS-induced RAW264.7 cells,and free,insoluble bound phenols had stronger inhibitory effects while soluble glycosidic phenols was lower.Five different forms of phenols also showed good permeability in the Caco-2 monolayer model simulating intestinal absorption,possible to cross the intestinal barrier.And 18 phenolic compounds detected in them mainly permeated via passive diffusion,which may be affected by the synergistic or competitive mechanism of phenolic compounds.Two compounds were isolated by RP-HPLC,and identified as 8-hydroxyfurocoumari(SB-A),5-hydroxy-4?,6,7-trimethoxyflavone(SB-B).Both of them were found in sorghum bran for the first time.In vitro effectiveness against AAPH-induced erythrocyte hemolysis and cellular antioxidant activity of cells of SB-A was lower than SB-B,three methoxyl groups connected to benzene rings of SB-B might contribute for this result.SB-A and SB-B could inhibit the production of NO,TNF-?,IL-6 in LPS-induced RAW264.7 cells,having potential anti-inflammatory effect.