Molecular structure and stereochemistry of silybin A, silybin B, isosilybin A, and isosilybin B, isolated from Silybum marianum (milk thistle)
Molecular structure and stereochemistry of silybin A, silybin B, isosilybin A, and isosilybin B, isolated from Silybum marianum (milk thistle)
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DOI：
10.1021/np030163b
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发表时间：
2003-09-01
影响因子：
5.1
通讯作者：
Liu, YZ
中科院分区：
文献类型：
--
作者：
Lee, DYW;Liu, YZ
通过硅胶柱层析、制备反相高效液相色谱和重结晶等方法，成功地从水飞蓟中分离出水飞蓟素A、水飞蓟素B、异水飞蓟素A和异水飞蓟素B两对非对映异构体黄酮木脂素。这些黄酮木脂素在C-2， C-3, C-7‘和C-8’上完成了完整的立体化学分配。基于x射线晶体学分析和旋光性数据，结合包括COSY、HMQC和HMBC在内的H-1和C-13核磁共振光谱数据的综合解释，确定了这些非对映异构体的立体化学性质为水飞蓟宾A(4)、2R、3R、7’r、8’r；水飞蓟宾B (5), 2R, 3R, 7'S, 8'S；异水飞蓟宾A (6), 2R, 3R, 7'R, 8'R；异水飞蓟宾B (7), 2R, 3R, 7s, 8s。
Two pairs of diastereoisomeric flavonolignans, silybin A, silybin B, isosilybin A, and isosilybin B, were successfully separated from Silybum marianum by sequential silica gel column chromatography, preparative reversed-phase HPLC, and recrystallization. Complete stereochemical assignments at C-2, C-3, C-7', and C-8' of these flavonolignans have been achieved. On the basis of X-ray crystallographic analysis and optical rotation data, coupled with comprehensive H-1 and C-13 NMR spectral data interpretation including COSY, HMQC, and HMBC, the stereochemistry of these diastereoisomers was determined unambiguously as silybin A (4), 2R, 3R, 7'R, 8'R; silybin B (5), 2R, 3R, 7'S, 8'S; isosilybin A (6), 2R, 3R, 7'R, 8'R; and isosilybin B (7), 2R, 3R, 7'S, 8'S.