Biographical note of the first author: Zi-C-hun XIANG, female, born in 1972, Ph.D. candidate, majoring in pharmacognosy. Correspondence should be addressed to Prof. Yan JIANG, MD. Tel/Fax: 86-10-6302-4898. E-mail: Jiangyan03@263.net. Shun-Xing GUO, Ph.D., Tel: 86-10-62829619. E-mail: sxguo2006@yahoo, com. cn