Acute and subchronic oral toxicities of Pu-erh black tea extract in Sprague-Dawley rats

Ethnopharmacological relevance: Pu-erh black tea, which is obtained by first parching crude green tea leaves 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 as concentrated extracts has not been completely investigated. The aim of the study: The present study was aimed at evaluating potential toxicity of Pu-erh black tea extracts (BTE) from acute and sub-chronic administration to male and female Sprague-Dawley (SD) rats. Materials and methods: A single BTE dose of 10,000 mg/kg of body weight was administered by oral gavage for acute toxicity in SD rats. Four 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. Results: No deaths and signs of toxicity occurred during the 14 days of the study. There were no test article related mortalities, body weight gain, feed consumption, clinical observation, organ weight changes, gross finding, clinical or histopathological alterations during the 91-day administration. Conclusions: The LD50 of BTE can be defined as more than 10,000 mg/kg, and a dose of 5000 mg/kg/day was identified as the no-observed-adverse-effect-level (NOAEL) in this study. (C) 2010 Elsevier Ireland Ltd. All rights reserved.