Safety assessment of the Quercus brantii gall hydroalcoholic extract: Single and repeated oral dose toxicity studies

Quercus brantii galls (QBGs) are well-known in Iranian traditional medicine for treating various diseases. The aim of study was to assess the acute and repeated oral toxicity of the hydroalcoholic extract of QBG in female rats.

The ethanolic extract of QBG was administered in rats by gavage in both acute and repeated dose models. In the acute section of the study, a single oral dose of 2000 mg/kg was administered to female rat which were observed for physical symptoms and behavioral changes for 14 days. In the repeated dose toxicity study, the QBG extract (50, 500, and 1000 mg/kg/day) was administered for a period of 28 days to rats. On 28th day of experiment, blood sampling of animals was done for hematological and biochemical analysis and then sacrificed for histopathological examination of the harvested tissues (liver, heart, kidney, lung, spleen, stomach, ovary and uterus).

A single oral administration of the QBG extract (2000 mg/kg) did not produce mortality or significant behavioral changes during 14 days of observation. In repeated oral toxicity models, the extract significantly increased (P<0.05) the levels of mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), thyroid-stimulating hormone (TSH) and significantly decreased the levels of triiodothyronine (T3) and thyroxin (T4) in 500 and 1000 mg/kg dosage. The histopathological studies showed the absence of toxic effects of QBG (50 mg/kg dosage) and revealed evidence of microscopic lesions in the liver, kidney, stomach, heart, spleen, lung, uterus, and ovary in the 500- and 1000-mg/kg groups. 

The results indicate that the oral acute toxicity of QBG extract was of a low order with LD50 being more than 2000 mg/kg in rats. In addition, slight tissue damage was observed in some tissues in the 500 and 1000 mg/kg groups. It was found that prolonged use at higher doses i.e. 500 mg/kg/day of QBG extract should be avoided.