Activity of angiotensin-converting enzyme (ACE) and intensity of ROS generation in the aorta were studied in male Wistar rats intraperitoneally injected with a mixture of (+) and (-) stereoisomers of catechin. ACE activity in aortal segments was evaluated by hydrolysis of hippuryl-histidine-leucine; ROS generation was measured by oxidation of dichlorodihydrofluorescein. The dynamics of ACE activity and intensity of ROS generation in the aorta after catechin administration and their dependence on the catechin dose were studied. The effects of dihydroquercetin and fucoidin on the studied parameters were analyzed. Catechin increased ACE activity; the maximum increase was achieved in 3 h after administration. Catechin dose producing a half-maximum increase in ACE activity was 0.04 μg/kg. The effects of catechin on ACE activity was attenuated by dihydroquercetin and completely abolished by fucoidin. Catechin did not enhance ROS production in the aorta, and in a dose of 0.1 μg/kg even inhibited this process. It is hypothesized that isomers of catechin produce opposite effects on ROS generation in the aorta.

中文翻译：

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儿茶素对大鼠主动脉血管紧张素转化酶活性及活性氧产生的影响

在腹膜内注射儿茶素的 (+) 和 (-) 立体异构体混合物的雄性 Wistar 大鼠中研究了血管紧张素转换酶 (ACE) 的活性和主动脉中 ROS 生成的强度。通过马尿苷-组氨酸-亮氨酸的水解评价主动脉段的ACE活性；通过二氯二氢荧光素的氧化来测量ROS的产生。研究了儿茶素给药后主动脉 ACE 活性的动态和 ROS 生成强度及其对儿茶素剂量的依赖性。分析了二氢槲皮素和岩藻多糖对研究参数的影响。儿茶素增加 ACE 活性；给药后 3 小时内达到最大增幅。产生 ACE 活性半最大增加的儿茶素剂量为 0.04 μg/kg。儿茶素对 ACE 活性的影响被二氢槲皮素减弱，而被岩藻多糖完全消除。儿茶素不会增加主动脉中 ROS 的产生，并且在 0.1 μg/kg 的剂量下甚至抑制了这一过程。据推测，儿茶素的异构体对主动脉中的 ROS 产生产生相反的影响。