Subchronic oral toxicity study of rhubarb extract in Sprague-Dawley rats

The study was primarily used to evaluate subchronic oral toxicity of rhubarb extract.

The rhubarb extract was orally administered to rats at doses of 0.00, 0.65, 1.62 and 4.05 g/kg BW/day for 13 weeks with a recovery period of 4 weeks. The weight and the relative organ weight of the kidney in the 0.65 g/kg BW group were significantly increased but no significant changes were seen in renal histopathology. When the rats received rhubarb extract at 1.62 g/kg BW or above, the relative weight of the spleen and kidney were significantly increased; the kidney was also swollen and black with hydronephrosis. Histologic examination showed that there was an obvious increase in pigment deposition in renal tubular epithelial cells. No toxic related changes were observed in the 0.65 g/kg BW group, even though organ weight was increased and relative ratio to body weight of kidney were observed at 0.65 g/kg BW dosage, no significant renal histopathologic changes were detected at this dose. Based on the current study conditions and results, the no observed adverse effect level (NOAEL) of rhubarb extract in rats is 0.65 g/kg BW/day.