Extraction, Enrichment And Pharmacological Activitives Of Phenolics From Pomegranate (Punica Granatum L.) Leaves

Pomegranate is a kind of deciduous shrub or small tree, which belongs to the genus Punica in the family Punicaceae. Pomegranate fruit is warm in nature, has functions of moistening dryness, astriction and combating some diseases. Pomegranate leaf is rich in many active ingredients, such as phenolics, tannins, flavonoids, alkaloids and so on. Researches have shown that pomegranate leaf has many kinds of pharmacological activites. Usually, as the edible part, pomegranate fruit attracted much attention, while the leaf was wasted. The overall objective of the current study was to find out the potential capacity of pomegranate leaf, to develop and utilize pomegranate leaf resources rationally, and to improve the comprehensive value of pomegranate. In this study, extraction, enrichment, and pharmacological of phenolics from pomegranate leaf were investigated, and main results were as follows:The contents of phenolics, tannins, flavonoids and ellagic acid of pomegranate leaf collected during different seasons and dried under different temperatures were compared. The results showed that pomegranate leaf sampled in November and dried under25℃exhibited the highest content of active ingredients, also presented the highest antioxidant activities. The results provides a certain theoretical basis for the preparation of pomegranate leaf tea. Correlation analysis results showed that antioxidant activity was closely related to polyphenol level, especially significantly correlated with tannins.The extraction process of phenolics from pomegranate leaf was optimized by single factor experiment, factorial design and response surface method. Hot reflux method was found to be the best extraction method, and50%ethanol was optimum in the four extraction solvents. Further research has found that the optimum extraction solvent, temperature and time were61%ethanol,80℃and60min, respectively. Accordingly, the extract yeild and the phenolics contents in pomegranate leaf were as high as46.683%and19.991g GAE/100g, respectively.The enrichment process of phenolics from pomegranate leaf was optimized by macroporous resin adsorption method. HPD-100resin was found to have the best adsorption and desorption capacities for phenolics from pomegranate leaf. As the pH of sample solution increased, the adsorption and desorption capacities of HPD-100resin for phenolics from pomegranate leaf decreased. Ethanol solutions of50%was found to be the best solvents to elute phenolics and the eluate (Fr.Ⅲ) exhibited the highest antioxidant activity.The anti-inflammatory activity of ethanol extract was examined using inflammatory models including both the ear edema induced by xylene and the paw edema induced by carrageenan in mice. Results showed that pomegranate leaf extract presented strong anti-inflammatory activity. Fr.Ⅲ at a dose of0.4g/kg exhibited obvious anti-inflammatory activity, similar to indomethacin at a dose of20mg/kg. In acute toxicity test, no obvious symptom of poisoning and death was observed within seven days after Fr.Ⅲ was orally administrated to mice, indicating that pomegranate leaf extract has no acute toxicity effect.