Neyestani Tirang R, Khalaji Niloufar, Gharavi A'azam
Laboratory of Nutrition Research, National Nutrition and Food Technology Research Institute, Shaheed Beheshti Medical University, Tehran, Iran.
J Altern Complement Med. 2007 Dec;13(10):1119-24. doi: 10.1089/acm.2007.7033.
This study evaluated the microbiologic effects of black tea, compared to green tea, alone and in conjunction with selected antibiotics against Escherichia coli, the common cause of intestinal and urinary tract infections.
This study was an in vitro evaluation of antibacterial effects of tea extracts.
Black and green tea extracts were analyzed by using high-performance liquid chromatography to compare their major polyphenol profiles. Different concentrations of the extracts or gallic acid (GA), the phenolic compound found with high concentration in the black tea extract, were employed for bacterial sensitivity tests, using pour plate and disc diffusion methods. The latter was used to evaluate the interactions between the extracts and certain anti-E. coli antibiotics.
GA in black tea extract and epigallocatechin and epigallocatechin gallate in green tea extract are present in the highest concentrations, respectively. At concentrations of 25 mg/mL, both black and green teas after 5 and 7 hours completely inhibited E. coli growth. GA at concentrations of 5, 10, and 25 microg/mL after 7, 5 and 3 hrs, respectively, inhibited bacterial growth. Both black and green tea extracts had either synergistic or antagonistic effects at different concentrations on selected antibiotics, while GA showed a synergistic effect with all the antibiotics tested in a dose-dependent manner. The effect was more prominent with amikacin and sulfamethoxazole.
The microbiologic effects of both black tea and green tea extracts on certain antibiotics against E. coli may vary, depending on the type of the tea extract (i.e., black vs. green), the amount of the extract, and the antibiotic being used.
本研究评估了红茶与绿茶单独及联合选定抗生素对大肠杆菌（肠道和尿路感染的常见病因）的微生物学影响。
本研究是对茶提取物抗菌作用的体外评估。
采用高效液相色谱法分析红茶和绿茶提取物，比较其主要多酚谱。使用倾注平板法和纸片扩散法，采用不同浓度的提取物或没食子酸（GA，红茶提取物中高浓度存在的酚类化合物）进行细菌敏感性试验。后者用于评估提取物与某些抗大肠杆菌抗生素之间的相互作用。
红茶提取物中的GA以及绿茶提取物中的表没食子儿茶素和表没食子儿茶素没食子酸酯分别以最高浓度存在。在25mg/mL的浓度下，红茶和绿茶在5小时和7小时后均完全抑制了大肠杆菌的生长。浓度为5、10和25μg/mL的GA分别在7、5和3小时后抑制了细菌生长。红茶和绿茶提取物在不同浓度下对选定抗生素均有协同或拮抗作用，而GA与所有测试抗生素均呈剂量依赖性协同作用。与阿米卡星和磺胺甲恶唑的协同作用更为显著。
红茶和绿茶提取物对某些抗大肠杆菌抗生素的微生物学影响可能因茶提取物的类型（即红茶与绿茶）、提取物的量以及所使用的抗生素而异。
