Isolation and Identification of Swainsonine from Oxytropis glabra and its Pathological Lesions to SD Rats

Locoweeds cause significant livestock poisoning and economic loss all over the world. The principal compound responsible for its toxicity is the indolizidine alkaloid swainsonine, a new potential anticancer and antiviral drug. O. glabra is a locoweed found mainly distributed throughout the inner Mongolia region of China and presents a serious hazard to the local livestock industry. The purpose of this study was to analyze the main toxic products of O. glabra first by TLC and GC-MS methods and then to evaluate its alkaloids' toxicity in vivo. Twelve Sprague-Dawley rats were randomly divided into control group and experimental group in which the rats received 0 and 800 mg kg(-1) (swainsonine content 88.64 mg) body weight day(-1) of crude alkaloid extract by intragastric administration for 65 days. Results showed that a white needle crystal was isolated and purified through systematic extraction of the alkaloid by a silica gel column and gradient sublimation from O. glabra; it was identified to be swainsonine (SW) according to physicochemical properties and spectral data analyses. Pathological lesions were revealed in the brain, heart, liver and kidney of alkaloid-treated rats. We also observed diffuse vacuolation of neurons, epithelial cells of renal tubules by electron microscope. These histopathological changes demonstrated that the main toxic ingredient of O. glabra is swainsonine.