| China tops the square meters and production of persimmon list. Persimmon has economical value. Its active ingredients and biological activites are widely concerned. In this paper, extraction, purification and antioxidant activity of tannin from persimmon veneer were studied, the results of which are of important theoretical interest and also of great relevance to applications.The main research contents and results were as follows:(1) The quantitative analysis method of persimmon veneer polyphenol with the Folin-Ciocalteu method was built, and the quantitative analysis method of persimmon veneer tannins with the vanillin-sulfuric acid method were built.The method of Folin-Ciocalteu was used to determine the content of persimmon veneer phenol. With gallic acid as the standard sample, Folin-Ciocalteu and Na2CO3 wre used as chromogenic agent, the absorbance was measured at 760 nm and then standard curve was drew. The mass of gallic acid and the absorbance have good linear relationship and the regression aquation was A=12.290m+0.0336 (R2=0.9998). The results of precision, repeatability and accuracy are respectively as following:RSD=0.35%, RSD=0.35%, RSD=0.23%(the average recovery is 100.47%).The method of vanillin-sulfuric acid was used to determine the content of persimmon veneer tannin. With catechinns as standard sample, vanillin and H2SO4 were used as chromogenic agent. The regression equation was drew at 500nm. The mass of catechinns and the absorbance have good linear relationship and the regression equation is A=6.1851m+0.0066(R2:=0.9995). The results of precision, repeatability and accuracy are respectively as following: RSD=0.35%, RSD=0.22%, RSD=0.23%(the average recovery is 96.48%).(2)Tannin in Persimmon veneer was extracted with Ultrasound process. The optimum values of extraction parameters including ethanol ratio, extraction power, extraction temperature and length of extraction were determined by orthogonal array design to be:40%,360W,70℃,50min, and ethanol ratio had the most important effect on tannin yield, sequentially followed by extraction power, extraction temperature and length of extraction. Under the above optimum extraction conditions, the tannin yield was 5.6%.(3) Screen out the optimum resin and purification conditions:The best macroporous resin is HPD500, the optimum purification conditions are as follow:the feed concentration of 1.2 mg·g-1 with flow rate of 1.5mL·min-1, the desorption solvent was 60% ethanol with flow velocity of 1.5 mL·min-1.The crude extract tannin(component A)the purity of which is 5.6% was purified by solvent and macroporous resin. Eight different purity tannin components are aquired:crude extract was extracted by ethyl acetate and got component B the purity of which is 11.5%, crude extract was purified by macroporous resin and obtained component C the purity of which is 19.4%, ethyl acetate residue was purified by macroporous resin and obtained component D the purity of which is 47.4%, component B was purified by macroporous resin and obtained component E the purity of which is 53.3%, component C was extracted by mineral ether and obtained component F the purity of which is 53.68%, mineral ether residue was extracted by ethyl acetate and obtained component G the purity of which is 55.32%, ethyl acetate residue was extracted by n-butanol and obtained component H the purity of which is 62.33% and aqueous phase residue component I the purity of which is 68.66%.(4) The scavenging effect of DPPH· and ·OH by componentA, B, C, D, E were studied. The results show that the scavenging rate for DPPH·were 69.07%, 80.19%,92.96%,94.02%,94.05% respectively when the mass concentration was 1.0mg·mL-1, and their IC50 were 0.68,0.52,0.13,0.12,0.11 mg·mL-1, respectively. The maximum scavenging rates for·OH were 43.04%、73.99%、 83.00%、94.68%、96.23% respectively when the mass concentration was 0.9 mg·mL-1 respectively.(5)The antioxidant activities of component A, C, F, G, H, I were determined by POV (peroxide number) and the absorbance values of MDA (malonaldehyde) in oil system. Meanwhile, the synergistic antioxidant effect of component A, C, H, I with vitamine C (Vc) were researched, separately. The results show that the six fractions have antioxidant function, indicating that the higher antioxidant activity of tannin was extracted by solvent with greater polarity from persimmon veneers. Component A and C exhibit strong antioxidation in oil system when the dosage was 0.08% and 0.04%, respectively, but both of which have no synergistic effect with Vc. The antioxidant activity of 0.04% component H is fine and better than Vc, and it has good synergistic effect with Vc. The tannin shows strong anti-oxidation oil activity when the dosage of component I is 0.08% but it hasn’t synergistic effect with Vc. |
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