Subchronic And Reproductive/Development Toxicity Study Of Yunnan Pu-Erh Black Tea In Sprague Dawley Rats

1. Background:Pu-erh black tea, which is obtained by first parching crude green tea leaves in the Yunnan province and then undergoes secondary fermentation with microorganisms, has been believed to be beneficial beverages for health for nearly 2000 years in China, Japan and Taiwan area. But its potential toxicity when administered at a high dose has not been completely investigated. So this study was aimed at evaluating potential subchronic toxicity and reproductive and developmental toxicity of Pu-erh black tea (PBT) to male and female Sprague Dawley (SD) rats.2. Objectives:The present study was aimed at evaluating potential subchronic toxicity and reproductive and developmental toxicity of Pu-erh black tea (PBT) to male and female Sprague Dawley (SD) rats.3. Methods:3.1 Subchronic toxic experimentFour groups (10 males and 10 females per group) of dose levels of 1250,2500, and 5000 mg/kg/day of the test article, as well as controls (distilled water) were tested as the subchronic toxicity study. Body weights and food consumption were recorded every week. On 92-day, all rats were sacrificed. Organ weights, Hematology, blood chemistry and histopathology in every group were calculated as the evaluation of toxicity of BTE.3.2 Reproductive and development toxic experimentThe commercial Pu-erh black tea samples were collected from Yunnan Highland of China and administrated to parental SD rats for 12 consecutive weeks as doses of 2500 mg/kg/day,700 mg/kg/day and 200 mg/kg/day, respectively. For the reproductive experiment, all rats were paired, one male to two female within a group, for mating from the thirteen week. The rats were maintained on their designated diets during mating, gestation and through to necropsy after weaning. Daily observation of physical appearance, behavior and reaction to treatment were recorded. Body weight and food consumption were monitored during the premating, gestation and lactation periods. Serum chemistry, organ coefficient and pathological diagnosis were preceded after sacrifice. Reproductive indexes including were also calculated. For developmental experiment, filial embryos were removed from pregnant rats at the 19.5th day and fetal abnormal including the malformation of external appearance, visceral and skeleton were recoded. Survived filial rats with number of 96 (males and females) were administrated with PBT for 12 weeks for later toxic examination.4.Results:4.1 Subchronic toxic experimentThere were no test article related mortalities, body weight gain, feed consumption, clinical observation, organ weight changes, hematology parameters, serum chemistry, gross finding, clinical or histopathological alterations between BTE treated and control groups during the 91-day administration.4.2 Reproductive and development toxic experimentNo toxicology related abnormal were observed in the body weight, food consumption, serum chemistry, organ coefficient and pathological changes between PBT treated and control groups of parental rats. In addition, no obvious toxic symptom appeared during the gestation in PBT-treated female rats. The fecundation index was 18.2% lower in the 2500 mg/kg/day female rats than controls, but the difference was not statistically significantly (P>0.05). In the developmental experiment, the incidence of miniative embryos, as well as dysostosis, was significantly increased in PBT administration group as compared to control group in the 19.5th day of premating (P<0.05). Moreover, all groups were normal during the 12-week growing period.5.Conclusion:A dose of 5000 mg/kg/day was identified as the no-observed-adverse-effect-level (NOAEL) of BTE in the subchronic toxicity study. There were no obvious toxicological related abnormal between the PBT treated groups and control groups in all parental rats in the reproductive toxicity study. While the high dose of PBT administration could lead to significant development dysfunction of the embryos in the 19.5th day of premating. Therefore, the NOAEL of PBT of reproductive and developmental toxicity is 2500 mg/kg/day and 700 mg/kg/day, respectively.