Study the Effects of Different Concentrations of Aqueous Green Tea Extract on Rats' Livers: In vivo Study

Abstract

Green tea (Camellia sinensis) has received a considerable attention in the health benefit owing to its anti-oxidant properties both in vivo and in vitro against drug-induced toxicities. However, there are many scientific evidences suggest that green tea or its catechins at higher concentration produced pro-oxidative effect in vivo and in vitro.
This study was designed to assess whether or not the aqueous green tea extract AGTE) used in various concentrations may have pro-oxidant effect in rats liver.
Aqueous extract of green tea was freshly prepared daily by soaking the required amount of green tea leaves for 10 min in 100 ml distilled water at 90°C to obtain 2.5 %, 5 % and 10 % concentrations, respectively of aqueous solutions. Twenty four white albino rats of both sexes, weighing 200-250 g were used in this study and allocated into two groups; group I- Six rats were fed tap water by feeding bottle for 7 days; this group was served as control group; group II- Eighteen rats were fed different concentrations of AGTE by feeding bottle as only source of drinking fluid, this group was served to demonstrate the possible prooxidant
effect of AGTE on the liver of rats as follows: A-Six rats were fed 2.5% AGTE, BSix rats were fed 5 % AGTE, C-Six rats were fed 10 % AGTE.
The parameters of oxidative stress, malondialdehyde (MDA) and reduced glutathione (GSH) were evaluated in the liver tissue homogenate. Serum activities of Aspartate Aminotransferase (AST), Alanine Aminotransferase (ALT) and Alkaline Phosphates (ALP) were assessed .
Analysis of data revealed that, rats orally administered AGTE in concentrations (5 % and 10 %) produced significant reduction in the content of MDA in liver tissue homogenate (62.42 % and 12.4 % respectively) compared to control animals, while a non significant difference was observed in animals administered 2.5 % AGTE compared to control group.
Meanwhile, 10 % AGTE produced significant decrease in levels of GSH in liver tissue homogenate, while non significant differences concerning GSH levels in liver tissue homogenate in rats administered 2.5% and 5% AGTE compared to control animals (59.25%).
Regarding the serum activities of AST, ALT and ALP, rats administrated an oral concentration of 2.5% AGTE for 7 days showed a non-significant difference in the serum activity of ALT compared to control group, while there was a significant decrease in the serum AST activity (64.48%) and ALP (65.4%) compared to control group. Rats administrated an oral concentration of 5% AGTE for 7 days showed a non-significant difference in serum activity of AST, ALT and ALP compared to control group. Administration of an oral concentration of 10 % AGTE for 7 days to rats showed nonsignificant difference in the serum activity of AST, ALT compared to control group, while there was a significant decrease in the serum ALP activity (58.57 %) compared to the control
group.
According to the results obtained from this study, it could be concluded that AGTE possesses an antioxidant- rather than pro-oxidant-effect in vivo, manifested by a decrease in the content of MDA in liver tissue homogenate, and in serum activities of AST and ALP.