| Pomegranate (Punica granatun L.) has been cultured for more than two thousand yearsin China. Pomegranate possesses of substantial amounts of bioactive components, which areuseful to the human health. In recent years, as people are more and more aware ofpomegranate’s nutritional and medicinal values, research on pomegranate has become a hottopic. In the thesis, pomegranate peel and seed were chosen as the research objects. Extractionof ellagic acid from pomegranate peel, as well as antioxidant, antiseptic, skin whitening andanti-wrinkle activities have been investigated systematically. The extraction methods, themain constituents and stability of pomegranate seed oil have also been discussed.(1) In the work, preparation of ellagic acid from pomegranate peel by hydrolysis wasdeveloped. Pomegranate peel powder was extracted with60%ethanol by means ofultrasonic-assisted extraction to obtain crude extract. After removal of lipophilic ingredientswith petroleum ether, crude extract was extracted with ethyl acetate, and the ethyl acetatefraction was hydrolyzed to produce ellagic acid. With the ultra performance liquidchromatography-mass spectrometry, the main ingredients in the ethyl acetate fraction wereidentified as castalagin, punicalagin, granatin A, corilagin, granatin B and ellagic acid, and thehydrolysis product was identified as ellagic acid. The hydrolysis process was monitored bycapillary electrophoresis. It has been found that with the increase of hydrolysis time, thenumber of peaks in electropherogams was reduced, while the weight of ellagic acid increased.With the orthogonal experiment, the influences of hydrolysis time, hydrolysis temperature, aswell as acid concentration on the ellagic acid yield was investigated. The optimum conditionsof hydrolysis were as follows: hydrolysis time for6h, hydrolysis at100℃, and sulfuric acidof1.0mol/L. Under the optimum conditions, the ellagic acid yield was32.7%.(2) The reduction power and scavenging ability on DPPH, OH and O2-radicals withellagic acid were investigated in vitro experiments. The results showed that ellagic acid had astrong ability for reduction of Fe3+and scavenging radicals. Ellagic acid as a naturalantioxidant used in cosmetics has far-reaching prospects. The effect of ellagic acid on skinwhitening was evaluated by inhibition of tyrosinase activity in vitro. The antimicrobialactivity against Staphylococcus aureus and Escherichia coli were conducted by usinginhibition zone. The results indicated that ellagic acid would be a potential as a naturalpreservative and whitening agent in cosmetic products.(3) The inhibition of ellagic acid on elastase and the mechanism of interaction betweenellagic acid and elastase were studied in the present work. The results showed that theinhibition rate of ellagic acid on elastase was determined by UV spectrophotometry. It hasbeen found that ellagic acid has obvious inhibitory effect on elastase. The interactionmechanism between ellagic acid and elastase has been investigated with fluorescence spectra.The results revealed the fluorescence quenching of elastase based chiefly on static quenchingowing to formation of the complex as the concentration of ellagic acid was lower than4.0×10-5mol/L. The ratio of dynamic quenching increased in higher drug concentration.Interaction forces between ellagic acid and elastase were mainly van der Waals or hydrogen bonding. The binding site was2.86nm away from tryptophan residues in elastase. The effectof ellagic acid on the conformation of elastase was analyzed by synchronous fluorescencespectra, which turned out that the polarity of elastase increased and hydrophobicity reduced asellagic acid was added. Ellagic acid as a natural inhibitor of elastase can be used in skinanti-wrinkle cosmetics.(4) Pomegranate seed oils were extracted by reflux, cold maceration and ultrasonication,respectively. GC-MS had been applied to analyze the composition of pomegranate seed oil.The results showed that oil yield by three extraction methods were close. Pomegranate seedoil was composed of eight kinds of fatty acids, which were palmitic acid, stearic acid, oleicacid, linoleic acid, punicic acid, α-elaeostearic acid, catalpic acid and β-elaeostearic acid. Thecomposition of fatty acid extracted by cold maceration and ultrasonication were similar andand the content of punicic acid reached more than47%. The main constitutes of fatty acidextracted by reflux was different, and the content of punicic acid was only13.19%.Pomegranate seed oil vesicles were prepared by melting and the stability of pomegranate seedoil was investigated. The results showed that pomegranate seed oil vesicles could significantlyimprove the stability of pomegranate seed oil. It can provide the experimental basis for theapplication of pomegranate seed oil in food and cosmetics. |
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