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J Nat Prod. 2003 Sep;66(9):1171-4.

Molecular structure and stereochemistry of silybin A, silybin B, isosilybin A, and isosilybin B, Isolated from Silybum marianum (milk thistle).

Author information

1
Bio-Organic and Natural Product Laboratory, McLean Hospital/Harvard Medical School, 115 Mill Street, Belmont, Massachusetts 02478, USA. dlee@mclean.harvard.edu

Erratum in

  • J Nat Prod. 2003 Dec;66(12):1632.

Abstract

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.

PMID:
14510591
DOI:
10.1021/np030163b
[Indexed for MEDLINE]

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