[Inhibitory effect of green and black teas ethyl acetate extracts on helicobacter pylori the causative agent of peptic ulcers]

Helicobacter pylori is the etiological agent in peptic ulcers and gastric carcinoma. The growing problem of antibiotic resistance by this organism demands the search for novel compounds from plant based sources. Tea is amongst the most popular beverages in Iran. There is no investigation regarding the inhibitory effects of tea extracts on Helicobacter pylori growth or its urease production and function. This study was conducted to evaluate the inhibitory effects of tea ethyl acetate extracts on Helicobacter pylori growth and its urease. This was an experimental study [2008, Science and Research campus] in which the extraction of samples was performed by Soxhelet extractor in methanol/water [1:1] mixture as a solution followed by final re-extraction with ethyl acetate. The minimum inhibitory concentrations of black and green tea extracts were assessed by broth dilution method and examination of urease function performed by Mc Laren method. The urease production was detected on 12% SDS polyacrylamide gel electrophoresis. Both extracts showed inhibitory effects on H. pylori growth, urease function and its production. Urease production was completely inhibited by both black and green tea extracts at concentrations of 3.5mg/ml and 2.5mg/ml, respectively. Also, the growth of H. pylori was inhibited by black tea extract at concentration of 4.5mg/ml and at 3.5mg/ml of green tea extract. Based on inhibitory effects of tea extracts on H. pylori shown in the present study, it seems that both tea extracts in particular the green tea have the potential to reduce the H. pylori population and possibly prevent from chronic gastritis and peptic ulceration

[Comparing Black and Green tea [Camellia sinensis L] extracts effects on the growth inhibition and biofilm formation of Enterobacteriacea]

Extracts of leaves from Camellia sinensis L contains polyphenolic components with antimicrobial activity. In this investigation biofilm inhibitory effects of black and green tea extracts were defined for five members of enterobacteriacea family including: Enteropathogenic Escherichia coli, Shigella flexneri, Proteus mirabilis, Klebsiella pneumoniae and Salmonella enterica serovar Typhimurium. Because tea is the most widely drunk beverage in Iran, therefore investigation of its effects on enterobacterial biofilm formation and colonization is very important. In this experimental study after extraction of samples in water/ methanol solution, further extraction took place in Ethyl acetate phase. The extracts preserved in 4°C refrigerator after sterilization by 0.44 micro filters. Well diffusion [Kirby Bauer] and broth dilution methods were used for evaluation of minimum inhibitory concentration of biofilm formation in black and green tea extracts treated cultures. Evaluation of biofilm formation was assayed by observation of colony forming unit of cultured bacteria per milliliter by sampling from Erlenmeyer flask wall scratching onto Tripticase soy agar medium and comparing the results with controls. Analysis of data was done using analysis of variance. Biofilm inhibitory effects of black tea were greater than green tea. The concentration of 4.5 mg/ml of black tea and 5mg/ml of green tea had bactericidal effects against examined bacteria. On Mueller Hinton agar, Proteus mirabilis was more sensitive to black tea; EPEC was more sensitive to green tea and Klebsiella pneumoniae showed more resistance to both extracts. Due to the fact that gastrointestinal tract is directly affected with consumed beverage, the high concentration of tea entered in lumen can reduce the number of enterobacteriaceae and can reduce their carcinogenic amine products. Thus it plays an important role in inhibition of gastrointestinal lymphoma and colon carcinoma. Also application of tea polyphenols as a food preservative can be useful