Toxicity Evaluation of Camellia sinensis var. assamica and Its Fermented Miang Product

Introduction: Camellia sinensis var. assamica (Assam tea or Cha‑Miang [CM]) is widely accepted to be beneficial to health. The tea leaf is used to produce various fermented tea products such as black tea (China, India) and Miang (Thailand). Despite its medicinal properties, toxicological information regarding certain tea variety and its fermented Miang product, especially its long‑term toxicity, is currently limited. This study aimed to evaluate the potential toxicity of the extract of fresh resh Cha-Miang leaves (CM) and its fermented Miang product (FCM) in both in vitro and in vivo models. Materials and Methods: Cytotoxic effect on cell viability of HepG2, HEK293, and EA.hy926 cell lines incubated with CM or FCM extract for 24 h and 48 h was investigated by the MTT assay. After that, 14‑day repeat oral toxicity test was performed on Wistar rats. Results: No in vitro cytotoxic effect of CM and FCM extract was found in the tested cell types, at a dose up to 1000 µg/ml. For in vivo study, both CM and FCM extracts at a dose of 300 mg/kg/day did not produce any sign or symptom of toxicity; no mortality was observed. Furthermore, investigation of hematological parameters, blood chemistry, body weight, and organ weight in the treated rats revealed no significant difference compared with that of normal controls. Conclusion: The results suggested that crude extract of CM and FCM at the doses used in this study are safe, however, further evaluation of possible chronic toxicity is recommended.