Aquilaria subintegra Ding Hou (agarwood) tea has a high market value. Previous research found that agarwood leaf extract displayed potent anti-diabetic properties. However, the assessment of its safety is limited. In this work, the safety information at the no-observed-effect-level (NOEL) and the human equivalent dose (HED) of A. subintegra tea leaf extract for repeated-dose 28-day consumption was investigated. The tea leaves were extracted with hot water according to the usual method of consumption. The extract at 5, 50, and 300 g/kg body weight was orally administered daily up to 28 days in both genders of Wistar rat. The clinical signs and symptoms of toxicity were inspected including mortality, morbidity, and behavioral and functional integrity. Animal blood samples were checked for hematological and biochemical parameters, and internal organs (liver, spleen, kidney, lung, heart, ovary, and testis) were examined for any gross lesions and maintained for histopathological studies. Results showed that repeated oral dose (5, 50, and 300 mg/kg) for 28 days did not affect any of the measured toxicity parameters. The NOAEL of the extract was noted as more than 300 mg/kg body weight. The estimated HED was found to be approximately 40 mg/kg body weight. The results proved that A. subintegra tea is considered safe as there was no adverse effect related to its use.
Key words: Agarwood; Aquilaria subintegra; Human equivalent dose (HED); No-observed-effect-level (NOEL); Safety; Toxicological study