Synthesis And Property Study Of Phloretin Methionine Schiff-base

Our study chose phloretin and methionine as materials, which were safety andfrom natural. And this study intended to get a new type of food additives throughsemi-synthesis, which have a better solubility, stability and antioxidant activity, andrelatively safe.Chapter one, the research progress of phloretin was reviewed in this part of ourstudy. The biological functions of methionine and amino acid schiff base weresummarized, finally, the purpose and meaning of this research was illuminated.Chapter two, in our study, we used phloretin as matrix, after the reaction ofdehydration synthesis with methionine, the phloretin methionine schiff base wasobtained. And the structural characterization was studied using ultraviolet spectrum,infrared spectroscopy,1HNMR spectroscopy and high-resolution mass spectrometry.Chapter three, Solubility was tested at room temperature, and the result indicatedthat the solubility of phloretin methionine schiff base was506.403mg/L, whichhigher than phloretin (28.879mg/L). And the lipid solubility was also increasedslightly. For the antioxidant activity of phloretin and its methionine schiff base werecompared with BHA. The result shown that ABTS+（IC50=1.78±0.08uM）radical scavenging and OH (IC50=258.72±0.35uM) radical scavenging abilitiesof phloretin methionine schiff base were higher than BHA(IC50=10.72±0.1uM，IC50＞1000uM), and the ABTS+radical scavenging and OH radical scavengingabilities of methionine schiff base were also increased compared to phloretin. Theresult of stability test indicated that phloretin was more sensitive to the environmentpH and lighting, it’s easy to oxidation, but after the embellishment of methionine, thestability in different pH was increased. And the result also shown that after theembellishment of methionine, the stability of schiff base was decreased in lighting,the reason of this phenomenon may relate to the light oxidation kinetics of phloretinand its methionine schiff base. The result of acute toxicity experiment shownmethionine schiff base was non-toxic actually, and the LD50is higher than5000mg.Chapter four, For the test of promoting oxidation we used lighting and heating, and samples were analyzes by gas chromatography and developing process. This partof research was designed to study the inhibitory effect of phloretin and methionineschiff base on four kinds of unsaturated fatty acid which were necessary for human.And the result showed that the inhibitory effect of methionine schiff base on fourkinds of unsaturated fatty acid was stronger than phloretin.Chapter five, Fresh milk was used as food system to study the shelf life ofpasteurized milk after the protection of methionine schiff base. The result indicatedthat methionine schiff base can decrease the degradation of unsaturated fatty acid, andalso inhibited the proliferation of microorganism in milk.