Extraction, Purification Of Polyphenols From Larch Bark And Its Effects Of Anti-oxidation

Larch, known as "fir in north", is one of the most important members in Pinaceae, which is rich and widely distributed in Northeast and Inner Mongolia of China. The study showed that polyphenols were components of plants in Pinaceae, which had numerous physiological effects on human beings such as bacteria inhibited, skin protection, whitening and anti-aging. That polyphenols are extracted and applied to food industry, skin care products and medical field as far as possible has its positive meaning on people’s health.In this paper, larch barks were taken as the main research materials. On the basis of single factor experiments in extraction and purification process, response surface experiment was established about three independent factors with three levels to optimize the extraction and purification process of larch polyphenols. Taking scavenging activity of free radical with OH·、DPPH·、O22-·、H2O2、ABTS as index, crude polyphenols extracts and purified polyphenols from larch were made to evaluate its antioxidant activity in vitro, compared with Vc solution in the same conditions. Chelating ability of polyphenols with Ca2+, Zn2+was inspected simply. Antioxidant activity of chelate and purified polyphenols was compared on scavenging ability of OH·、DPPH·free radicals. The components and quantity of larch polyphenols were analyzed at last.The way of organic solvent with ultrasonic-assisted was used to abstract larch polyphenols. Factors such as the kind of reagent, temperature, ethanol concentration, the ratio of solid to liquid and ultrasonic time, respectively, were made to evaluate extraction effect of polyphenols from larch pine and cones so that the difference of polyphenols between the quantity of pine bark and cones could be measured. On the results of single factor experiments, taking bark as materials, response surface experiment was established to optimize extraction process. Results showed that the optimal technological extract conditions of polyphenols were as follows: temperature57℃, ethanol concentration49.6%, the ratio of solid to liquid1:30, ultrasonic time20.4min, in this process the yield of polyphenols extraction was112.28mg/g.Crude extracts were purified by the method of column chromatography. First of all, Adsorption and desorption experiments were carried out to select the suitable macro porous resin, X-5, for purification process. Second, as the response to recovery and purity of polyphenols,6factors such as fineness ratio, elution concentration, sample concentration, eluting speed, sample volume, and pH, were used to evaluate purification effect of polyphenols and optimize purification conditions through response surface experiment. The results showed that the optimum conditions of purification were fineness ratio1:25, elution concentration47%, sample concentration2.5mg/mL, eluting speed5mL/min, and sample volume42mL with the measured purity value75.52%.In vitro antioxidant studies, polyphenols from pine bark showed better activity on scavenging free radical. Among of which, purified polyphenols had marked effect on scavenging ABTS radicals with scavenging rate of93.04%, which was a little more than Vc solutions. However, larch polyphenols showed least scavenging rate of10.68%on H2O2which was far below than that of Vc. The oxidation resistance capability of larch bark polyphenols were in the decrease order of ABTS> OH·>DPPH·>O22->H202.Polyphenols had better chelating activity with Zn2+, which could reach a higher chelate rate of47.28%in optimum conditions than that of36.64%with Ca2+. Zinc chelate showed better capacity on scavenging DPPH·radicals while worse on OH·...