中文摘要：

目的研究茜草科植物红大戟Knoxiavalerianoides根的化学成分。方法应用硅胶柱色谱、SephadexLH．20柱色谱和半制备型反相高效液相色谱等方法进行分离和纯化，通过MS、NMR等波谱数据鉴定化合物的结构。结果从红大戟干燥根的95％乙醇提取物中分离得到1个降碳三萜，结构鉴定为3-氧代-2，19-二羟基-24-降乌苏-1，4，12-三烯-28-酸（1）。结论化合物1为新化合物，命名为红大戟酸A。

英文摘要：

Objective To investigate the chemical constituents from the root tubers of Knoxia valerianoides. Methods The constituents were isolated and purified by using a combination of chromatographic techniques including column chromatography over silica gel, Sephadex LH-20, and reverse-phase HPLC. The structures were identified by spectroscopic analyses including MS, and NMR. Results A new nor-triterpenoid was isolated from the ethanol extract in the dried root rubers ofK. valerianoides, and its structure was identified as 3-oxo-2, 19-dihydroxy-24-nor-urs-1, 4, 12-trien-28-oic acid （1）. Conclusion Compound 1 is a new compound named knoxivalic acid A.