Study Of The Antioxidant Function Of Blackcurrant Anthocyanins

In this thesis, the effects of the processing factors on the antioxidant capacity ofblackcurrant anthocyanin extract (BAE) were studied by the DPPH method. The UV-Visspectroscopy, fluorescence spectroscopy and circular dichroism spectra (CD) were used tocompare the mechanism of interaction of two different glycosidic structure of anthocyanin withbovine serum albumin (BSA), which might provide theoretical basis for the study of themechanism of anthocyanin antioxidant capacity in vivo from the molecular level, the improve ofthe anthocyanin function by the structure modification. And the Langendorff technique wasadopted to investigate the protective effect and the underline mechanisms of BAE againstmyocardial ischemia-reperfusion injury (MIRI). These studies were significant for the researchof the absorption, transport, metabolism and antioxidant functions of anthocyanin in the body aswell as the research and development of anthocyanin healthy food.This thesis mainly consists of the following four parts:1. In the chapter one, the structure, physiological function and antioxidant research methodsof the anthocyanin, the mechanism and preventive measures of the MIRI were summarized. Andthe research progress of the blackcurrant anthocyanin was also introduced.2. In the chapter two, the effects of heating temperature and food additives on theantioxidant capacity of BAE were studied by DPPH method. The results of the experimentalshowed, when the temperature was higher than70℃, the decreased amplitude of DPPH freeradical scavenging rates of BAE was larger with the extension of time, and the high temperaturemight cause the degradation of BAE and the decline of antioxidant capacity. The sucrose hadcertain protective effect on the BAE and could enhance the antioxidant capacity of BAE. Thelow concentration of sodium benzoate could enhance the antioxidant ability of the BAE, whilethe high concentrations of sodium benzoate in the opposite. And the ascorbic acid could damagethe structure of the BAE, which leaded to the severely reduced of the antioxidant capacity inBAE.3. In the chapter three, the mechanism of the binding between BSA andCyanidin-3-O-glucoside (Cy-3-glc), Cyanidin-3-O-galactoside (Cy-3-gal) were studied byfluorescence spectroscopy, UV-Vis spectroscopy and CD. Preliminary determined that thebinding of Cy-3-glc to BSA and Cy-3-gal to BSA were all static quenching. Furthermore, the quenching efficiency of Cy-3-glc to BSA was far more than that of Cy-3-gal, which mightindicate that the degree of the combination between Cy-3-glc and BSA was far more than that ofCy-3-gal and BSA. Thermodynamic parameters calculated results indicated that the binding ofCy-3-glc to BSA and Cy-3-gal to BSA were due to the hydrogen bonds and van der Waals forces,meanwhile the negative values of ΔG indicated that the binding of Cy-3-glc and Cy-3-gal to BSAwere spontaneous. The results of site marker competitive experiments showed that Cy-3-glc andCy-3-gal mainly bound to BSA in site I. The calculation results of the radiation energy transfertheory showed that the binding distance between BSA and Cy-3-glc, Cy-3-gal were2.56nm,2.82nm respectively, which also suggested that the non-radiative energy transfer was one of thereasons why the fluorescence of BSA was quenched. The results of UV-Vis, synchronousfluorescence spectrum, three-dimensional fluorescence spectra indicated that the interactionbetween Cy-3-glc, Cy-3-gal and BSA were occurred and the secondary structure of BSA waschanged in the presence of Cy-3-glc and Cy-3-gal. Furthermore, the result of CD spectra showedthat the interaction of Cy-3-glc and Cy-3-gal with BSA induced the decreased content of α-helixin the secondary structure of BSA, and the content of β-sheet, β-turn and random coil were allincreased.4. In the chapter four, the protective effect and the underline mechanisms of BAE againstMIRI was investigated by the Langendorff technique. The results of the physical and chemicaltesting showed that the BAE could reduce the injury of myocardial cells, the release of LDH, theoccurrence of lipid peroxidation, the production of MDA and increase the activity of SOD, andimprove the cardiac function, the anti-oxidation ability of myocardial cell after MIRI. Thechanges of the myocardial tissue ultrastructure were observed by transmission electronmicroscope and the results showed that the BAE could protect the isolated rat heart from MIRIthrough the mechanism of antioxidant capacity.