Lee David Y-W, Liu Yanze
Bio-Organic and Natural Product Laboratory, McLean Hospital/Harvard Medical School, 115 Mill Street, Belmont, Massachusetts 02478, USA.
J Nat Prod. 2003 Sep;66(9):1171-4. doi: 10.1021/np030163b.
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 (1)H and (13)C 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.
通过硅胶柱色谱、制备型反相高效液相色谱和重结晶，成功地从水飞蓟中分离出两对非对映异构黄酮木脂素，即水飞蓟宾A、水飞蓟宾B、异水飞蓟宾A和异水飞蓟宾B。已完成这些黄酮木脂素在C-2、C-3、C-7'和C-8'处的完整立体化学归属。基于X射线晶体学分析和旋光数据，结合包括COSY、HMQC和HMBC在内的全面的¹H和¹³C NMR光谱数据解释，明确确定这些非对映异构体的立体化学结构为水飞蓟宾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，7'S，8'S。
