There are numerous cultivars of tea (Camellia sinensis L.), but the differences in their anti-hyperglycemic-related effects are largely unknown. The inhibition of the dipeptidyl peptidase (DPP)-IV enzyme plays an essential role in controlling hyperglycemia in diabetes by blocking the degradation of incretin hormones, which is necessary for insulin secretion. In this study, we examined the DPP-IV inhibitory activity of leaf extracts from diverse Japanese green tea cultivars. The inhibitory rates differed among tea extracts. Metabolic profiling (MP), using liquid chromatography–mass spectrometry, of all cultivars revealed compositional differences among cultivars according to their DPP-IV inhibitory capacity. Epigallocatechin-3-O-(3-O-methyl)gallate, kaempferol-3-O-rutinoside, myricetin-3-O-glucoside/galactoside, and theogallin were newly identified as DPP-IV inhibitors. The bioactivity of a tea extract was potentiated by adding these ingredients in combination. Our results show that MP is a useful approach for evaluating the DPP-IV inhibitory potency of green tea and for determining bioactivity-related ingredients and combinations.

中文翻译：

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用于评估不同绿茶品种的二肽基肽酶-IV 抑制效力和确定生物活性相关成分和组合的代谢谱

茶 ( Camellia sinensis L.)的品种繁多，但其抗高血糖相关作用的差异在很大程度上是未知的。二肽基肽酶 (DPP)-IV 酶的抑制通过阻断胰岛素分泌所必需的肠促胰岛素激素的降解，在控制糖尿病患者的高血糖中发挥重要作用。在这项研究中，我们检测了来自不同日本绿茶品种的叶提取物的 DPP-IV 抑制活性。茶提取物的抑制率不同。使用液相色谱-质谱法对所有品种进行代谢分析 (MP) 揭示了品种之间根据其 DPP-IV 抑制能力的成分差异。表没食子儿茶素-3- O -(3- O-甲基)没食子酸酯、山奈酚-3- O-芸香苷、杨梅素-3- O-葡萄糖苷/半乳糖苷和茶没食子苷被新鉴定为DPP-IV抑制剂。通过组合添加这些成分来增强茶提取物的生物活性。我们的结果表明，MP 是评估绿茶 DPP-IV 抑制效力和确定生物活性相关成分和组合的有用方法。