The regio- and stereospecificity of bimolecular phenoxy radical coupling reactions, of especial importance in lignin and lignan biosynthesis, are clearly controlled in some manner in vivo; yet in vitro coupling by oxidases, such as laccases, only produce racemic products. In other words, laccases, peroxidases, and comparable oxidases are unable to control regio- or stereospecificity by themselv...

Thirty three compounds were obtained from the bulbs of Urginea maritima (Liliaceae). The compounds were identified by means of fast atom bombardment mass spectrometry (FAB-MS), nuclear magnetic resonance (1H-NMR), (13C-NMR), nuclear overhauser effects (NOE) and two dimensional (2D) NMR. Ten of them were new natural compounds. Nine were bufadienolides and only one was lignan in these compounds.

For the first time callus and suspension cultures of Linum mucronatum ssp. annenum were initiated, grown in darkness at 25 degrees C and analyzed for lignans. 6-Methoxypodophyllotoxin was the main lignan besides smaller amounts of podophyllotoxin isolated and identified by chromatographic methods as well as by 1H NMR.

New naturally occurring nitrogenous compounds 1 and 2, along with a new dimeric lignan glucoside 3, have been isolated from the ethyl acetate soluble fraction of Centaurea iberica. Their structures have been elucidated through spectroscopic techniques. All the isolated compounds showed significant platelet aggregation inhibition.

A new C18 dibenzocyclooctadiene lignan, kadsumarin A (1) was isolated from Kadsura matsudai Hayata and Schizandra arisanensis Hayata. The anti-HBeAg test revealed that kadsumarin A had activity at a concentration of 40 micrograms/ml (= 90.1 microM). Its structural elucidation by spectral analysis was discussed in this note.

Dietary isoflavone and lignan phytoestrogens are potential chemopreventive agents. This has led to a need to monitor exposure to these compounds in human populations and to determine which components of a mixed diet contribute to the exposure. Typically, urinary isoflavonoid excretion is associated with soy consumption and that of lignans is associated with whole grains. However, other plant fo...

Flax (Linum usitatissimum) stems contain cells showing contrasting cell wall structure: lignified in inner stem xylem tissue and hypolignified in outer stem bast fibers. We hypothesized that stem hypolignification should be associated with extensive phenolic accumulation and used metabolomics and transcriptomics to characterize these two tissues. (1)H nuclear magnetic resonance clearly distingu...

PURPOSE Lignans such as secoisolariciresinol diglucoside in flaxseed, are metabolizes to bioactive mammalian lignans of END and ENL. Because mammalian lignans have chemical structural similarity to the natural estrogen, they are thought to behave like selective estrogen receptor modulators and therefore have anticancer effect against hormone-related cancers. We isolated a series of lignan compo...

Eight phenolic compounds including two new lignan glucopyranosides together with a known alkaloid were isolated from the stems of Cynomorium songaricum RUPR. (Cynomoriaceae). Their chemical structures were elucidated on the basis of spectral and chemical evidence. The chemotaxonomic significance of these metabolites is discussed.