黑加仑花色苷的分离纯化及其热降解动力学

Purification and Thermal Degradation Kinetics of Anthocyanins from Blackcurrant

摘要:

以黑加仑为原料，采用AB-8大孔树脂-Sephadex LH-20凝胶柱层析联用方法和液相色谱-质谱联用技术对黑加仑花色苷进行分离纯化和组分鉴定；分析了不同纯度花色苷在不同pH和温度下的降解动力学；通过1,1-二苯基-2-三硝基苯肼（DPPH）和2,2'-联氮基-双-（3-乙基苯并噻唑啉-6-磺酸）二铵盐（ABTS）自由基的清除评价了不同纯度花色苷的抗氧化能力。结果表明：黑加仑中包含飞燕草素-3-葡萄糖苷、矢车菊素-3-芸香糖苷、牵牛花素-3-葡萄糖苷、芍药素-3.5-二己糖苷和锦葵素-3-半乳糖苷5种组分。经分离纯化后最终获得2种花色苷，分别为飞燕草素-3-葡萄糖苷（A3）和矢车菊素-3-芸香糖苷（A4）。pH 3.0和温度50 ℃时，花色苷的热稳定性最强。不同纯度花色苷组分热降解均符合一级动力学模型。分别经大孔树脂纯化后的花色苷（A1）、乙酸乙酯萃取后的花色苷（A2）、A3和A4对DPPH自由基清除率的半数抑制浓度（IC50）分别为9.45、8.17、5.95和7.62 mg/L，而对ABTS自由基清除率的IC50分别为99.38、97.21、78.19和85.54 mg/L。

Abstract:

The anthocyanins of blackcurrant were isolated and purified by combination of AB-8 macroporous resin and Sephadex LH-20, and the liquid chromatography-mass spectrometry was employed to identified anthocyanins components of blackcurrant. The degradation kinetics of anthocyanins with different purity were analyzed under different pH values and temperatures. Besides, the antioxidant activities were assessed by hydroxyl, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-amino-di(3-ethyl-benzothiazoline sulphonic acid-6) ammonium salt(ABTS) free radical scavenging assays. The results showed that five anthocyanins were identified in terms of delphinidin-3-glucoside,cyanidin-3-rutinoside, petunidin-3-glucoside, paeoniflorin-3,5-dihexoside and malvidin-3-galactoside. The two purified anthocyanins fractions were obtained， which were identified as delphinidin-3-glucoside (A3) and cyanidin-3-rutinoside (A4), respectively. The thermal stability of anthocyanins was strongest at pH 3.0 and temperature 50 ℃. The thermal degradation of anthocyanins with different purity were fitted well to the first-order reaction kinetics, and the correlation coefficients R2 are all above 0.9. Under the same pH value, the degradation rate constant increased, but the half-life and activation energy decreased with the increase of temperature. The IC50 of DPPH free radical scavenging rate of anthocyanins purified by macroporous resin (A1), anthocyanins extracted by ethyl acetate (A2), (A3) and (A4) were 9.45, 8.17, 5.95 and 7.62 mg/L, respectively, and the IC50 of ABTS+ free radical scavenging rate of them were 99.38, 97.21, 78.19 and 85.54 mg/L, respectively. and malvidin-3-galactoside. The two purified anthocyanins fractions were obtained by combination of AB-8 macroporous resin and Sephadex LH-20, which were identified as delphinidin-3-glucoside and cyanidin-3-rutinoside, respectively. The thermal stability of anthocyanins was strongest at pH 3.0 and temperature 50 ℃. The thermal degradation of anthocyanins with different purity were fitted well to the first-order reaction kinetics. Under the same pH value, the degradation rate constant increased, but the half-life and activation energy decreased with the increase of temperature. In vitro antioxidant experiments showed that blackcurrant anthocyanins had significant scavenging abilities of DPPH and ABTS+ free radicals.