Chemical Modification And Physiological Activity Of Oat ?-glucan

In this study,oat?-glucan(?G)was used as a raw material.?G-H-H,?G-H-M and?G-H-L were prepared by acid degradation of?G.?G-O-H,?G-O-M and?G-O-L were obtained by oxidative degradation of?G.The properties of the degradation products such as FTIR and molecular weight were analyzed.Their antioxidant,antibacterial,swelling power,fat binding capacity,bile acid binding capacity,glucose availability,viscosity and viscoelasticity were also studied.The effects of degradation method on the physiological activity of oat?-glucan were compared.The?G-H-M and?G-O-H were selected for sulfated modification to obtain sulfated derivatives with three degrees of substitution,respectively.The in vitro fat binding capacity,bile acid binding capacity,glucose availability,and inhibition of?-glucanase activity were evaluated.The effects of sulfated modification,degree of substitution on the activity of oat?-glucan were compared.The main results were as follows:1.After degradation,the molecular weights and viscosity of oat?-glucan were reduced,the swelling ability disappeared,antioxidant and antibacterial activities were obtained,and the inhibitory effect against Staphylococcus Aureus was stronger than that against Escherichia Coli.Oat?-glucan is an ideal gel-like due to G'>G'',and its degradation products are sol in the low frequency region because of G''>G',which is a gel in the high frequency region due to G'>G''.2.The basic structure of oat?-glucan did not change after acid degradation.The molecular weight of oat?-glucan decreased from 1.34×10~5 Da to 2.75×10~4 Da,4.55×10~3Da and 1.83×10~3 Da,respectively,and the viscosity was reduced by two orders of magnitude.The fat binding capacity and the bile acid binding capacity of?G-H-M and?G-H-L were improved.The glucose availability of?G-H-H and?G-H-M were decreased.3.After oxidative degradation,the total content of carbonyl and carboxyl groups of oat?-glucan increased from 1.24 per 100 glucose units to 10.87,11.75 and 15.14,respectively.The molecular weights of?G were reduced to 4.75×10~3 Da,4.20×10~3 Da,and 3.47×10~3 Da,respectively.?G-O-H had the best antioxidant activity but was weaker than the acid degradation products.Both fat binding capacity and bile acid binding capacity were improved,and?G-O-H possessed the best above-mentioned properties.However,the availability of glucose was increased.4.The absorption peaks of S=O and C-O-S were observed on FTIR,indicating that the sulfate group was successfully bonded to the oat?-glucan.The degree of substitution of?G-H-M:0.38(?G-H-1),0.51(?G-H-2)and 0.67(?G-H-3),degree of substitution of?G-O-H:0.94(?G-O-1),0.82(?G-O-2)and 0.61(?G-O-3)were measured by a ruthenium chloride-gelatin turbidimetry.After the sulfated modification,the viscosity of the oat?-glucan increased,and the gel-sol transition point(G'=G'')was moved to the low frequency region.Their fat binding capacity and bile acid binding capacity were increased,and glucose availability was reduced.The activities of?G-H-M sulfated derivatives increased with the increasing of degree of substitution,and the activities of?G-O-H sulfated derivatives exhibited the opposite pattern.Among them,?G-H-3(DS0.67)and?G-O-1(DS 0.61)had the best physiological activities.The inhibition of?-glucosidase activity was enhanced after sulfated of oat?-glucan,and the inhibition order was:?G-H-2>?G-H-3>?G-O-2>?G-O-3>?G-O-1>?G-H-1.This study explored the effects of chemical modification methods such as degradation method and sulfated modification on the physiological activity of oat?-glucan,which provided some ideas for the application of oat?-glucan.