Abstract: To study the difference in the contents of phenolics and the antioxidant activities between two kinds of Hawk tea of different maturity levels, and to evaluate their qualities, the contents of 15 phenolic compounds were determined using LC-MS/MS method. Then, the antioxidant activities of two types of tea were evaluated using DPPH radical scavenging rate, ABTS⁺ radical scavenging rate, and Fe³⁺ ferric reducing antioxidant power(FRAP). And then, the contents of 15 phenolic compounds and the antioxidant activities between two kinds of Hawk tea of different maturity levels were analyzed by analysis of variance(ANOVA). Based on the contents of 15 phenolic compounds, hierarchical cluster analysis(HCA), principal component analysis(PCA), and orthogonal partial least square-discriminant analysis(OPLS-DA)were used to classify two kinds of Hawk tea. Finally, the contribution of different phenolic compounds in Hawk tea to antioxidation was discussed by partial least square regression analysis(PLSR). The results were as follows:(1)The contents of catechin, p-coumaric acid, isoquercitrin, hyperoside, nicotiflorin, astragalin, kaempferol, quercetin, and afzelin in tender leaf tea were significantly higher than those in old leaf tea, among which the average contents of catechin, isoquercitrin, and astragalin were higher than those in old leaf tea by 1 039.43, 169.12 and 257.35 mg·100 g^-1, respectively. The results of HCA, PCA, and OPLS-DA could distinguish two kinds of Hawk tea.(2)The ANOVA showed significant differences in DPPH radical scavenging rate, ABTS⁺ radical scavenging rate, and FRAP between two kinds of tea, with the tender leaf tea superior to the old leaf tea.(3)The PLSR suggested that isoquercitrin, catechin, astragalin, chlorogenic acid, hyperoside, p-coumaric acid, and kaempferol were the main phenolic compounds those contributed to the antioxidant activity of Hawk tea. This study can provide a reference for Hawk tea's quality control and application promotion.

Key words: Hawk tea, phenolic compounds, LC-MS/MS, antioxidant activity, correlation analysis

摘要： 为了探究两种不同成熟度老鹰茶中酚类化合物含量及抗氧化活性的差异,以对其进行辨识及质量评价,该研究利用液相色谱-串联质谱(LC-MS/MS)法测定老鹰茶中15种酚类化合物,采用DPPH自由基清除率、ABTS⁺自由基清除率、Fe³⁺还原能力评价两种茶叶抗氧化能力,再通过数据统计分析探讨两种老鹰茶酚类化合物含量及抗氧化活性的差异,并进一步探索老鹰茶中不同酚类化合物对于抗氧化的贡献。结果表明:(1)嫩叶茶中儿茶素、对香豆酸、异槲皮苷、金丝桃苷、烟花苷、紫云英苷、山奈酚、槲皮素、阿福豆苷含量显著高于老叶茶,其中儿茶素、异槲皮苷、紫云英苷平均含量比老叶茶分别高1 039.43、169.12、257.35 mg·100 g^-1。聚类分析(HCA)、主成分分析(PCA)、正交偏最小二乘判别分析(OPLS-DA)均可将二者区分。(2)方差分析(ANOVA)结果显示在抗氧化能力上,二者在DPPH自由基清除率、ABTS⁺自由基清除率、Fe³⁺还原能力之间具有显著性差异,嫩叶茶优于老叶茶。(3)偏最小二乘回归分析(PLSR)法提示老鹰茶中的异槲皮苷、儿茶素、紫云英苷、绿原酸、金丝桃苷、对香豆酸、山奈酚是其发挥抗氧化效能的主要酚类化合物。该研究结果可为老鹰茶的质量控及应用推广提供一定的参考。

关键词: 老鹰茶, 酚类化合物, LC-MS/MS, 抗氧化活性, 相关分析