Interaction Mechanism Between Hawthorn Pectin And Polyphenols And Its Effect On Digestion And Absorption Of Polyphenols In Vitro

Hawthorn(Crataegus spp.)of Rosaceae is an edible fruit featured in China Province.It contains a variety of active substances,such as pectin and polyphenol,with high nutritional value.Epicatechin(EC)and chlorogenic acid(CA)are two polyphenol substances with relatively rich content in Fructus Crataegi,belonging to flavan-3-ol and phenolic acid polyphenol,respectively.The study found that under the action of external forces such as heating,high pressure,and drying,pectin and polyphenol would quickly and spontaneously interact,and then significantly affect the physical and chemical properties and functional characteristics of the food.However,the interaction between hawthorn pectin and polyphenol and the effect on the biological activity of polyphenol are not clear.On this basis,hawthorn pectin(HP)was taken as the research object in this paper.The interaction between HP and EC and CA was studied by establishing a hawthorn juice simulation system,to further explore the effects of the interaction between HP and polyphenols on their digestion,absorption and antioxidant activity in vitro,and to reveal the interaction mechanism of HP and polyphenols,which would provide certain theoretical guidance and reference for improving food quality and regulating the bioavailability of polyphenol substances in food matrix.The main research contents and results are as follows:(1)Study on interaction and mechanism of hawthorn pectin and polyphenolThe binding adsorption behavior of HP with EC and CA conforms to the single-layer adsorption behavior driven by chemical action,and the quasi-second-order kinetic equation and Langmuir model fit the binding adsorption behavior of HP with polyphenols well.The binding site(Qm)and adsorption capacity(Qe)of HP to EC are 75.188 and 293.627μg/mg HP,respectively,which are about 9 times and 12 times that of CA.Compared with EC and CA,HP-polyphenol has higher turbidity,particle size and lower zeta potential.At the same time,according to FT-IR analysis,it can be inferred that the interaction between HP and polyphenols is mainly chemical bonding.Thermodynamic parameters h<0,ts<0,and |ΔH|>|ΔS| indicate that the interaction between HP and polyphenols is mainly driven by hydrogen bonds and van der Waals forces.(2)Effect of interaction between hawthorn pectin and polyphenol on polyphenol digestibilityThe effects of the interaction between HP and polyphenols on the content,bioavailability and antioxidant activity of polyphenols after digestion were studied by simulated digestion test in vitro.The results showed that the content and structure changes of EC and CA in all systems after in vitro digestion were preliminarily clarified by UV-Vis and FT-IR analysis.Secondly,it is clear that HP can slow down the degradation of EC and CA in vitro digestion to a certain extent,and the protective effect is EC>CA,which may be related to the strength of their interaction.Finally,it is clear that each system has a good ability to scavenge free radicals and reduce iron ions after digestion in vitro,and it is positively correlated with the changes of EC and CA contents.(3)Effect of interaction between hawthorn pectin and polyphenol on their absorption propertiesFirstly,the Caco-2 monolayer cell model was successfully established,with TEER value of 430.46 Ω·cm2,Papp of lucifer yellow of 1.13×10-7 cm/s,and the ratio of alkaline phosphatase active AP side to BL side of 2.1.Secondly,through cytotoxicity test,EC and HP-EC intestinal digestive juice with 0 dilution ratio were selected for absorption and transport test.The results showed that at different absorption time points,the apparent permeability coefficient PappA→B of EC in intestinal digestive juice of EC and HP-EC samples showed a downward trend,PappB→A showed a downward trend at first,and then increased,and the transport rate and efflux ratio of EC showed a significant increase with time.Generally speaking,the PappA→B values of EC in the intestinal digestive juice of EC and HP-EC in each time period were all greater than 1×10-6cm/s,and the absorption of EC in the intestinal digestive juice of HP-EC system was greater than that in the intestinal digestive juice of EC system,indicating that HP promoted the absorption of EC.Finally,the mechanism of HP promoting EC absorption was studied from the protein level,and it was verified that HP could promote EC by inhibiting the expression of transport efflux proteins BCRP,P-gp and MRP2,thus inhibiting EC efflux and improving EC cell absorption.