1. School of Pharmaceutical SciencesSouth-Central University for Nationalities Wuhan 430074 P. R. China
2. Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, School of Pharmaceutical SciencesChongqing University Chongqing 401331 P. R. China
3. Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau BiologyChinese Academy of Sciences Xining 810008 P. R. China