| Apple polyphenols were a kind of physiologically active ingredients in apple. In this thesis,two extraction methods were respectively used (the solvent and ultrasound-assisted solventextraction methods) to extract the dominating healthful components from apple pomace, theapple polyphenols. The conditions of extraction were optimized by response surface method toget a higher extraction rate of apple polyphenols, based on single-factor experiments. Then theoptimal conditions were verified. Phloridzin was one of the principal functional components. Forthe sake of researching the interaction between the phloridzin and bovine serum albumin, thefluorescence, UV-visabsorbance, fourier transform infrared and circular dichroism spectrumswere used. The principal type of acting force, binding mode and so on were studied between thephloridzin and bovine serum albumin to probe the mechanisms of metabolism and transportationin vivo. The improved Langendorff technique was adopted in order to study the protective effectsof apple polyphenol extracts against the myocardial ischemia-reperfusion injury in isolated ratheart. The study preliminaries explained the cardiac protective effect of apple polyphenols on theview of oxidative stress. This study expanded the apple polyphenols a new idea for the use ofresource and provided a theory reference for developing functional foods or cardiac protectivemedicines on apple polyphenols. This study contained four chapters as follows.In the first chapter, the classification, methods of extraction and purification and thephysiological effects of apple polyphenols were introduced. Also, this chapter introduced themechanism of conjugation reaction between the phloridzin and bovine serum albumin. Thechapter concentrated on the research progress of myocardial ischemia-reperfusion injury and theapple polyphenols.In the second chapter, the polyphenols in apple pomace were extracted by solvent andultrasound-assisted solvent extraction methods. The optimum conditions of extraction werecalculated and verified (The solvent method was that, the concentration of ethyl alcohol was62.13%, the temperature was80.53℃, the time was60.45min, the ratio of liquor to material(mL: g) was50.6to2.5. The ultrasound-assisted solvent extraction method was that, theconcentration of ethyl alcohol was35.38%, the ultrasonic power was40.54%(263.51W), the time was18.99min, the ratio of liquor to material (mL: g) was77.99:2.5.). The practical yieldsof theoretical value of solvent and ultrasound-assisted solvent extraction methods wererespectively0.91mg/g and1.59mg/g. The measured value of solvent and ultrasound-assistedsolvent extraction methods were respectively0.90mg/g and1.60mg/g. It showed that theextraction effects of ultrasound-assisted solvent extraction method observably more excellentthan the other one. The extracts of apple polyphenols obtained from the ultrasound-assistedsolvent extraction method were purified by macroporous resin and the principal ingredients werequalitative analyzed on the high performance liquid chromatograph ((+)-catechinic acid,procyanidine B2, chlorogenic acid, caffeic acid, phloridzin and quercetin).In the third chapter, the mechanism of interaction between the phloridzin and bovine serumalbumin was studied by spectroscopic methods. Which, the phloridzin was one of the principalingredients of apple polyphenols. It could react between phloridzin and bovine serum albuminfrom the view of the thermodynamic parameter. The principal type of acting force waselectrostatic forces and the intermolecular distance was3.034nm. The quenching mechanism offluorescence of bovine serum albumin by phloridzin was static quenching and formingcomplexes. The binding site was site Ⅰ. Finally, the research results of three-dimensionalfluorescence, synchronous fluorescence, UV-visabsorbance, fourier transform infrared andcircular dichroism spectrums showed that, the secondary structures of bovine serum albuminwere changed by phloridzin.In the fourth chapter, the cardiac protective effect of apple polyphenol extracts against themyocardial ischemia-reperfusion injury in isolated rat heart and the mechanism was studied bythe Langendorff technique. The experimental results showed that a certain concentration of applepolyphenols could reduce the degree of ischemia-reperfusion injury which was related to thereduced degree of oxidative stress-mediated injury. The comparison between differentconcentrations of apple polyphenols showed that cardiac protective effect of apple polyphenolshad no dependence with concentrations. Among the apple polyphenol dosage groups, the middledosage group (4mg/L) had the best protective effect by observably reducing the leakage of lacticdehydrogenase, the content of malonaldehyde and increasing activity of superoxide dismutaseagainst the ischemia-reperfusion injury. Then the low dosage group was in the second place,followed by the high dosage group. The results may provide a reliable reference value for theexploitation of health products or medicines in the future. |
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