单丛茶水提物清除DPPH和ABTS自由基的光谱学研究

研究了白叶和风凰两种单从茶水提物清除DPPH和ABTS自由基的能力及其光谱学特征.采用分光光度法测定单从茶水提物清除ABTS自由基的测定波长为734 nm,体系稳定时间为6 min;清除DPPH自由基的测定波长为515 nm,体系稳定时间为30 min.单丛茶水提物具有良好的抗氧化活性,能有效、快速地抑制溶液中DPPH和ABTS自由基的形成及其特征吸收峰.在选定的反应体系中,白叶单丛茶(Ⅰ,Ⅱ)、凤凰单丛茶(Ⅲ,Ⅳ)和标准抗氧化剂Trolox对ABTS自由基的半数抑制浓度(IC50)分别为26.9,25.5,28.0,31.7和85.2 μg·mL-1,说明单丛茶水提物的总抗氧化活性明显优于Trolox.对于DPPH自由基,4种单丛茶的IC50值分别为49.8,41.6,47.3和64.5 μg·mL-1.实验结果显示,单丛茶水提物具有优良的抗氧化活性,且对水溶性自由基的抑制率明显高于脂溶性自由基,作为功能食品具有广阔的开发和应用前景.

Spectrometric investigation of the antioxidant activities of dangcong tea aqueous extracts against DPPH and ABTS free radicals

The antioxidant activities of Dangcong tea aqueous extracts against DPPH and ABTS free radicals were evaluated using spectrometric methods. The results show that Dangcong tea aqueous extracts could effectively and rapidly inhibited the formation of ABTS and DPPH free radicals in a dose- and time-dependent manner, indicating the potent antioxidant activities of Dangcong tea aqueous extracts under both hydrophilic and hydrophobic conditions. In the optimized systems, the IC50 values of Baiye (I, II) and Fenghuang (III, IV) Dangcong teas against ABTS free radical were 26.9, 25.5, 28.0 and 31.7 microg x mL(-1), respectively, which were significantly lower than that of Trolox, the positive control (85.2 microg x mL(-1)), indicating the higher antioxidant activities of Dangcong teas. For DPPH free radical, the IC50 values for the Dangcong teas (I-IV) were 49.8, 41.6, 47.3 and 64.5 microg x mL(-1), respectively. Taken together, our results suggest the potential applications of Dangcong tea as functional food.