title: Identification and stereochemical characterization of lignans in flaxseed and pumpkin seeds.
abstract: Phytoestrogens of the lignan type are widely distributed in plant-derived food items and are believed to protect against hormone-dependent cancer. The richest known dietary source of lignans is flaxseed. Flaxseed has been reported to contain glycosides of secoisolariciresinol as the major lignan, together with small amounts of matairesinol, isolariciresinol, and pinoresinol. Secoisolariciresinol, but none of the other lignans, has so far been identified in pumpkin seeds. In the present study, two different methods for the hydrolysis of lignan glycosides are compared. Artifact formation and loss of lignans under acidic conditions were observed. Lariciresinol was identified by GC-MS analysis in two different types of flaxseed (Linum usitatissimum L. and Linum flavum L.) and in pumpkin seeds (Cucurbita pepo L.) for the first time. Likewise, the novel lignan demethoxy-secoisolariciresinol was tentatively identified in the flaxseed samples. Stereochemical analysis by chiral HPLC of several lignans isolated from flaxseed showed that secoisolariciresinol, matairesinol, and lariciresinol consisted predominantly of one enantiomer.
authors.affiliation: Institute of Food Chemistry and Toxicology, Department of Chemistry, University of Karlsruhe, P.O. Box 6980, Germany.
authors.forename: Tina
authors.initials: T
authors.lastname: Sicilia
authors.forename: Heike B
authors.initials: HB
authors.lastname: Niemeyer
authors.forename: Doris M
authors.initials: DM
authors.lastname: Honig
authors.forename: Manfred
authors.initials: M
authors.lastname: Metzler
mesh_terms: D002072:Butylene Glycols / Q000032:analysis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D028464:Cucurbita / Q000737:chemistry*; D019597:Flax / Q000737:chemistry*; D005663:Furans / Q000032:analysis / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D017705:Lignans / Q000032:analysis* / Q000737:chemistry*; D008031:Lignin / Q000032:analysis / Q000737:chemistry; D012639:Seeds / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D002072:Butylene Glycols; D005663:Furans; D017705:Lignans; C068935:matairesinol; C060282:lariciresinol; D008031:Lignin; C060283:secoisolariciresinol; C103298:pinoresinol