Research On Extraction, Purification And Antioxidantion Of Tetragonia Polyphenolic

In this study, ultrasound was first applied assistedly to extract the polyphenols of Tetragonia, which was newly planted in Jilin Province. The polyphenols of Tetragonia was purified with macroporous adsorption resins, and the antioxidant activity was analyzed systematically, in order to provide a theoretical basis for the comprehensive utilization of Tetragonia tetragonoides.The main conclutions were exhibited as follows:(1) The method of ultrasonic assisted extraction was used to extract antioxidants from Tetragonia. Study extraction time, ultrasonic power, liquid-solid ratio, extraction temperature on the influence of antioxidant activity to obtain the optimum extraction univariate conditions. In order to determine the optimum extraction conditions of antioxidants from Tetragonia, response surface methodolody was utilized and the corresponding regression model was established. The Box- Benhnken design and response surface methodology were applied to get the quadratic regression equation between the ability of free radical scavenging on DPPH(Y) and extraction time(X1), ultrasonic power(X2), liquid-solid ratio(X3), extraction temperature(X4). According to the variance analysis, the optimal parameter conditions to achieve the maximum yield of the scavenging activities for DPPH free radical were determined as follows: extraction time 44 min, ultrasonic power 200 W, liquid/material ratio 5:1m L/g, and extraction temperature 41℃. Under the optimized conditions, the scavenging activites for DPPH free radical was(89.81±0.32)%, the extraction ratio of polyphenol was(17.11±0.91)%, and the gallic acid equivalent was(201.34±4.72) mg GAE/g dry matter.(2) Macroporous adsorption resins were used for separation and purification of Tetragonia polyphenols. Tetragonia polyphenols were isolated with five types of macroporous adsorption resins with different chemical and physical properties(AB-8、D-101、X-5、ADS-17、ADS-7). The adsorption and desorption properties of five kinds of macroporous resins to Tetragonia polyphenol were evaluated. Static absorption and desorption experiments showed that D-101 resin had a higher adsorption and desorption ratio than the others. Therefore, D-101 resin was selected as the best resin to isolate Tetragonia polyphenols. The time of adsorption to reach dynamic equilibrium was 140 min. The extract(at 8mg/m L concentration) of 2BV/h(1m L/min) flow rate can better finish the saturated adsorption. Tetragonia polyphenols started to break through with 4.7 bed volumes of extract loaded, and the complete desorption was achieved using 140 m L of 90% ethanol with 2BV/h(1m L/min). The results of static adsorption kinetics and thermodynamics of D-101 indicated that Langmuir adsorption isotherm equation can better describe the effect of temperature on D-101 resin adsorption of Tetragonia polyphenols, and the fitting degree was 0.99.(3) Through the methods of chemical analysis and infrared spectrum analysis, the characteristics of polyphenols of the extracts were determined, and the corresponding characteristic groups were determined according to the wavenumber of IR spectra. Tetragonia polyphenols of purification with D-101 macroporous resin was pea green powder, and the purity can reach(75.1±0.6)%.(4) The antioxidant activities of polyphenols from Tetragonia were evaluated by determining the total reducing power, the ability of free radical scavenging on DPPH, superoxide anion and hydroxyl. Polyphenols from Tetragonia have shown some antioxidant capacity in various systems, which increased as the concentration. The activity of purified extracts was higher than that of crude extracts, some of the activities can be higher than that of tea polyphenols, and it was close to the control group VC activity.