Syringaresinol Research Articles

Stereochemistry and biosynthesis of (+)-lyoniresinol, a syringyl tetrahydronaphthalene lignan in Lyonia ovalifolia var. elliptica II: feeding experiments with 14C labeled precursors

To clarify the biosynthetic pathway for syringyl lignans, especially syringyl tetrahydronaphthalene lignans and formation of the C2–C7′ linkage, production of (+)-lyoniresinol (LYR) and its predicted intermediates [syringaresinol (SYR), 5,5′-dimethoxylariciresinol (DMLR), and 5,5′-dimethoxysecoisolariciresinol (DMSLR)] in Lyonia ovalifolia var. elliptica was investigated by means of feeding experiments with radiolabeled precursors. Following individual administration of l-[U-14C]phenylalanine (Phe), [8-14C]sinapyl alcohol (SA), and [8,8′-14C]SYR to excised young shoots of L. ovalifolia and their subsequent metabolism, free [14C]lignans and [14C]lignan glycosides were extracted with methanol from stems and leaves and were divided into ethyl acetate-soluble fractions (lignans) and aqueous fractions (lignan glycosides), respectively. Using a combination of xylanase, cellulase, and β-glucosidase, the glycosides were hydrolyzed to liberate [14C]lignans as aglycones. l-[U-14C]Phe was incorporated into (+)-[14C]SYR [stem 0.38%, 8% enantiomeric excess (e.e.)], (−)-[14C]SYR (leaves 2.75%, 72% e.e.), (+)-[14C]DMLR (stem 0.07%, 18% e.e. and leaves 0.009%, 58% e.e.), (−)-[14C]DMSLR (stem 0.03%, 46% e.e. and leaves 0.05%, 20% e.e.), (+)-[14C]LYR (leaves 0.013%, 22% e.e.) and glycosides of (+)-[14C]LYR (stem 0.036%, 50% e.e.) in 24h. Based on the percent incorporation and enantiomeric composition of the lignans, the biosynthetic pathway of (8R,8′R)-(+)-LYR was proposed as follows: a nonselective dehydrogenative dimerization of sinapyl alcohol yields (±)-SYR, which is reduced with low specificity to give (8R,8′R)-(+)-DMLR. This is cyclized to directly give (+)-LYR as well as reduced again to (8R,8′R)-(−)-DMSLR. Although further transformation of (−)-DMSLR also leads to the formation of (+)-LYR, cyclization could be a main pathway for (+)-LYR biosynthesis.

Synthesis of biologically active tetrahydro-furofuranlignan-(syringin, pinoresinol)- mono- and bis-glucosides

The naturally occurring tetrahydrofurofuran-lignan-(syringaresinol, pinoresinol)-mono- and bis-glucosides were synthesized and their structures thereby confirmed.

Characterization of (+)- and (—)-Syringaresinol Di—β—D-glucosides

Characterization of (+)- and (—)-Syringaresinol Di—β—D-glucosides

Plant Anticancer Agents XXVII: Antileukemic and Cytotoxic Constituents of Dirca occidentalis (Thymelaeaceae)

Two antileukemic daphnane esters, Pimelea factor P2 (I) and the new compound dircin (II), were isolated from the twigs and flowers of Dirca occidentalis A. Gray (Thymelaeaceae). Three lignans, (–)-medioresinol (III), (+)-syringaresinol (IV), and (–)-lariciresinol (V), as well as the coumarin daphnoretin (VI), were found to be additional cytotoxic constitents of this taxon.

Identity of eleutheroside E with acanthoside D

It was shown that eleutheroside E, one of the glycosides isolated from the prickly eleutherococcus, is identical with acanthoside D, which is one of the glycosides isolated from the cluster-flowering acanthopanax and represents the. di-β-D-glucoside of (−)-syringaresinol.