| Tannin is the main active ingredient of pomegranate husk, account for 10.4～21.3% in pomegranate husk. It has anti-tumor, antibacterial, antiviral and antioxidant activity, etc. Punicalagin is one of the main constituent of pomegranate husk tannin. It has strong antioxidant, anti-tumor and anti-atherosclerosis activities, etc. Both of them has very big development foreground in the medical and health care, functional food and cosmetics domain. The extraction and purification process of pomegranate husk tannin and punicalagin was studied in this paper. We also compared the antioxidantive activities of punicalagin, ellagic acid and the extracts prepared by different extraction methods.The best extraction conditions of pomegranate husk tannin was: the ratio of pomegranate husk (dollp) to 40% ethanol was 1:30, ultrasonic extraction for 30min (35～45℃, 50KHz), extracting twice under the same condition. The content of tannin could achieve to 59.3%, and 30.1g tannin per 100 g dry pomegranate husk. SP-700 macroporous adsorption resin it is the ideal purification medium for pomegranate husk tannin. Since it had the characteristics of high adsorption capacity, fast absorption and easily desorption when it used in tannins purification. At 25℃, with 5 mg·mL-1 loading solution, use 70% ethanol (4BV) as desorption agent, 26.5 g purified sample containing 81.9% tannin could obtained from 100 g dry pomegranate husk.The study of punicalagin extraction and purification were mainly from the perspective of industrial production. Research showed that the optimal condition of punicalagin industrial production was as follows: the ratio of 70% methanol to dry pomegranate husk was 1:6, using refluxing extraction extracting for 3h at 60℃. Then add 5-folds 70% methanol to the residue extract for another 2 hours at the same condition as the first time. Punicalagin purity and yield of the extract were 23% and more than 10%, which was 10% and 8% higher than that of extracted by water, respectively. AB-8 resin had a good selective adsorption for punicalagin and its adsorption capacity was 20mg/g resin. Using 30% methanol or 30～40% ethanol as desorption agent, the product purity can get 2.5 times of the crude extract.In addition, this paper studied the antiodant activities of punicalagin, ellagic acid and extracts prepared by different extraction methods (refluxing extraction, ultrasonic extraction, microwave assisted extraction, enzymatic extraction, semi-bionic extraction). The results show that at the same molarity, the order of the antioxidant activity was as follows: Punicalagin > ellagic acid > Vc. Ultrasonic extraction get the extractings with the highest antioxidant activities, and refluxing extraction was the next one. Through the research of extracts composition (including polyphenols, flavonoids, polysaccharide, punicalagin, ellagic acid), we could conclude that polyphenol was the main component of pomegranate husk. The highest polyphenol content and yield of the extracts were 480 mg/g extracts and 273.6 mg/g dry pomegranate husk which is obtained by ultrasonic extraction. Apparently higher than that reported in the literature (400 mg/g crude extractings). Combining with the antioxidant activity research, we can see that the higher polyphenol content result in the stong antioxidant activity. They had significant correlation (r> 0.9, p<0.05). So ultrasonic extraction was the best method for high antioxidant extraction. Whereas refluxing extraction was the best method for punicalagin extraction. Since it could get the extract containing the highest punicalagin content (264.98 mg/g extracts) and yield (156.9 mg/g dry pomegranate husk). The results were accordant with that of in the other chapters. The study confirmed the strong antioxidant activity and industrial production value of pomegranate husk tannin and punicalagin.
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