Study On Extraction, Purification, Antioxidant Acticity And Stability Of Polyphenols From Blue Honeysuckle (Lonicera Caerulea L.)

Blue honeysuckle(Lonicera caerulea L.) contain abundant polyphenols whose content is much high than those of other fruits and vegetables. However, it has obviously regional and seasonal characteristics, short fruiting period and thin peel, and it is hard to control its quality during transportation and storage. Therefore, the separation and purification of polyphenols from blue honeysuckle(Lonicera caerulea L.) are of great significance. Taking raw material from blue honeysuckle(Lonicera caerulea L.) growing near Changbai Mountain, this paper optimizes the extraction and purification technology of polyphenols and researches the antioxidant capacity of the extracted polyphenols, and carries out a study on its refined product in terms of stability and antioxidant activity. The results were as follows:Through ultrasonic-assisted extraction method, the extraction technology of polyphenols from blue honeysuckle(Lonicera caerulea L.) were optimized by single factor experiments and response surface methodology involving three independent variables at three different levels. The optimum conditions for polyphenol extraction were determined as follows:the extraction solvent was 50% ethanol with a solvent to solid ratio of 1:25 (g/mL), and the extraction was performed at 40 ℃ with a microwave power of 500 W for 90 min. Under these conditions, the extraction yield of polyphenols from blue honeysuckle was 7.52 mg/g.By analyzing the antioxidant activity in vitro of polyphenols from blue honeysuckle (Lonicera caerulea L.), the results showed that the extracted polyphenols had a strong scavenging capacity against superoxide anion, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ehtylbenzothiazoline-6-sulfonic acid)diammonium salt radical (ABTS+·)free radicals. Highly significant positive correlation was found between total polyphenol content and superoxide anion or DPPH free radical scavenging capacity (P<0.01) and the correlation with ABTS+·free radical scavenging capacity was positive significantly (P<0.05).By comparing and investigating the adsorption and desorption of 6 types of macroporous resins towards polyphenols from blue honeysuckle(Lonicera caerulea L.). Results showed that the adsorption process of XAD-7 resin towards polyphenols from blue honeysuckle (Lonicera caerulea L.) was an exothermic reaction and well fitted to Langmuir and Freundlich isotherms, and the optimal static adsorption and desorption conditions were adsorption time was 4 h, desorption time 2 h, sample concentration 2.03 mg/mL, sample pH 4, pH 7 of 95% ethanol as the desorption solvent. The optimal dynamic adsorption and desorption conditions were sample loading amount was 510 mL, washing water amount of 4 BV at a flow rate of 2 BV/h. Under these conditions, the purity of polyphenols from blue honeysuckle (Lonicera caerulea L.) was increased from 10.05% to 81.97%.The experment researched the effects of pH value, light, temperature, H2O2, Na2SO3, sodium benzoate and glucose, sucrose, D-fructose on the stability of the refined polyphenols from blue honeysuckle (Lonicera caerulea L.). The results showed that the refined polyphenols from blue honeysuckle (Lonicera caerulea L.) had better preservation when the pH value was less than 3, at low temperature and in dark, the polyphenols had a certain resistance to reduction but not strong oxidation of resistance, sodium benzoate had no obvious impact on the stability of the refined polyphenols (P>0.05), and carbohydrate increased the stability of the refined polyphenols.Through determining the total antioxidant capacity (T-AOC), the antioxidant activity of the refined polyphenols from blue honeysuckle (Lonicera caerulea L.) were analyzed in different conditions. The results concluded that pH value, light, temperature and H2O2 and carbohydrate at different concentrations had obvious effects on antioxidant activity of the refined polyphenols from blue honeysuckle (P<0.05).