A comparative study on the tissue distributions of rhubarb anthraquinones in normal and CCl4-injured rats orally administered rhubarb extract.

The present study comparatively investigated the tissue distributions of rhubarb anthraquinone derivatives (AQs) to examine whether they undergo different uptakes in normal or CCl(4)-induced liver-damaged rats, to explore possible reasons for the different toxicities of AQs in pathological model rats and normal rats at the tissue distribution level. The total rhubarb extract (14.49 g kg(-1) of body weight per day based on the quantity of crude material) was administrated orally to normal and model rats for 12 weeks. The concentrations of free AQs in tissues were quantitated by liquid chromatography-tandem mass spectrometry (LC-MS). After drug withdrawal for 4 weeks, tissue distributions were again determined. The five free AQs-aloe-emodin, rhein, emodin, chrysophanol and physcion--were detected in the liver, kidney and spleen, while only rhein, aloe-emodin and emodin reached the quantitative limit. The tissue distributions of rhein (p < 0.001), aloe-emodin (p < 0.001) and emodin (p < 0.05) in normal rats were higher than those in model rats with rhein>aloe-emodin>emodin in kidney and spleen tissues and aloe-emodin > rhein > emodin in liver tissues. Free AQs were not detected in the tissues after drug withdrawal for 4 weeks. These results suggest that the tissue toxicity of AQs in normal animals is higher than that in pathological model animals with little accumulative toxicity of rhubarb. The results are concordant with the traditional Chinese theory of You Gu Wu Yun recorded first in Su Wen, a classical Chinese medical treatise.