Abstract

Green tea catechins (GTC), polyphenols extracted from the stalks and leaves of Camellia sinensis, are found in the different types of tea beverages and as antioxidant additives to many foods, snacks, fats and fatty oils. As a part of their safety assessment, subchronic toxicity was investigated in male and female F344 rats with dietary administration at concentrations of 0 (control), 0.3%, 1.25% and 5.0% for 90 days. The average daily intakes of GTC in each group were 180, 764 and 3525 mg/kg body weight/day, respectively for males, and 189, 820 and 3542 mg/kg body weight/day, respectively for females. No mortality or obvious clinical signs were observed throughout the experimental period but body weights were reduced from week 1 to the end of the experiment in 5.0% males. In serum biochemistry, alanine transaminase and alkaline phosphatase in 5.0% males and females and aspartate transaminase in 5.0% females were increased, together with the relative liver weights in both sexes receiving 5.0%. Although decreases were evident for total cholesterol in 0.3–5.0% males and triglycerides in 1.25% and 5.0% males and 5.0% females, these changes were not considered to be adverse. Hematology and histopathological observation revealed no GTC-related toxicological changes. Based on above findings, the no observed adverse effect level (NOAEL) of GTC was estimated to be 1.25% (764 mg/kg body weight/day for males and 820 mg/kg body weight/day for females).

Keywords: Subchronic toxicity; Green tea catechins; F344 rats

Abbreviations: A/G, albumin/globulin ratio; Alb, albumin; ALP, alkaline phosphatase; ALT, alanine transaminase; ANOVA, analysis of variance; AST, aspartate transaminase; BUN, blood urea nitrogen; Ca, calcium; Cl, chloride; Cre, creatinine; Ebl, reticulocyte count; EC, epicatechin; ECg, epicatechin gallate; EGC, epigallocatechin; EGCg, epigallocatechin gallate; GC, gallocatechin; GCg, gallocatechin gallate; γ-GTP, γ-glutamyl transpeptidase; GTC, green tea catechins; Hb, hemoglobin concentration; Ht, hematocrit; IP, inorganic phosphorus; K, potassium; MCH, mean corpuscular hemoglobin; MCHC, mean corpuscular hemoglobin concentration; MCV, mean corpuscular volume; Na, sodium; NOAEL, no observed adverse effect level; Plt, platelet count; RBC, red blood cell count; T-Bil, total bilirubin; T-Cho, total cholesterol; TG, triglyceride; TP, total protein; WBC, white blood cell count

Article Outline

1. Introduction

2. Materials and methods

2.1. Chemicals and formulation

2.2. Experimental animals and housing conditions

2.3. Experimental design

2.4. Statistics

3. Results

3.1. In-life parameters

3.2. Hematology/serum biochemistry

3.3. Organ weights

3.4. Necropsy/histopathology

4. Discussion

Conflict of interest statement

Acknowledgements

References