Department of Medical and Health Sciences, Division of Drug Research/Pharmacology, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden.
Public Health Nutr. 2010 May;13(5):730-7. doi: 10.1017/S1368980010000170. Epub 2010 Feb 10.
Tea has been reported to reduce cardiovascular mortality, but the underlying mechanisms are largely unknown. The aim of the current project was to investigate the effect of green tea (Japanese Sencha), black tea (Indian Assam B.O.P.) and Rooibos tea (South Africa) on angiotensin-converting enzyme (ACE) and nitric oxide (NO).
Seventeen healthy volunteers received a single oral dose of 400 ml green tea, black tea or Rooibos tea in a randomized, three-phase, crossover study. ACE activity and NO concentration were measured (at 0, 30, 60 and 180 min) in all phases. ACE activity was analysed by means of a commercial radioenzymatic assay. Nitrite was analysed as a marker of NO concentration. In addition, ACE genotype was determined using a PCR method.
Oral intake of a single dose of Rooibos tea significantly inhibited ACE activity after 30 min (P < 0.01) and after 60 min (P < 0.05). A significant inhibition of ACE activity was seen with green tea for the ACE II genotype 30 min after intake of the tea (P < 0.05) and for the ACE ID genotype 60 min after intake (P < 0.05). A significant inhibition of ACE activity was also seen with Rooibos tea for the ACE II genotype 60 min after intake (P < 0.05). No significant effect on NO concentration was seen.
These results suggest that green tea and Rooibos tea may have cardiovascular effects through inhibition of ACE activity.
已有报道称，茶可降低心血管疾病死亡率，但其中的具体机制尚不清楚。本研究旨在探究绿茶（日本煎茶）、红茶（印度阿萨姆邦 B.O.P.）和南非路易波士茶对血管紧张素转换酶（ACE）和一氧化氮（NO）的影响。
17 名健康志愿者参与了一项随机、三阶段、交叉研究，他们分别在每一阶段口服 400ml 的绿茶、红茶或南非路易波士茶。在所有阶段（0、30、60 和 180 分钟）都测量 ACE 活性和 NO 浓度。ACE 活性通过商业放射酶测定法进行分析。亚硝酸盐被分析为 NO 浓度的标志物。此外，还使用 PCR 方法确定 ACE 基因型。
单次摄入南非路易波士茶后 30 分钟（P < 0.01）和 60 分钟（P < 0.05），ACE 活性显著受到抑制。摄入绿茶后 30 分钟（P < 0.05）和 60 分钟（P < 0.05），ACE II 基因型的 ACE 活性显著抑制；摄入绿茶后 60 分钟（P < 0.05），ACE ID 基因型的 ACE 活性显著抑制。摄入南非路易波士茶后 60 分钟（P < 0.05），ACE II 基因型的 ACE 活性也受到显著抑制。NO 浓度未见明显变化。
这些结果表明，绿茶和南非路易波士茶可能通过抑制 ACE 活性发挥心血管保护作用。
