Showing papers by "Shiro Suzuki published in 2002"

Stereochemical Diversity in Lignan Biosynthesis of Arctium lappa L.

Abstract: The stereochemistry of lignan biosynthesis in Arctium lappa L. is regulated organ-specifically. (+)-Secoisolariciresinol [81% enantiomeric excess (e.e.)] was isolated from A. lappa petioles. In sharp contrast, lignans whose predominant enantiomers have the opposite absolute configuration to that of (+)-secoisolariciresinol [i.e., (-)-matairesinol (>99% e.e.), (-)-arctigenin (>99% e.e.), and (-)-secoisolariciresinol (65% e.e.)] were isolated from seeds of the species. The stereochemical diversity of secoisolariciresinol was demonstrated with enzyme preparations from A. lappa petioles and seeds. Thus, a petiole enzyme preparation catalyzed the formation of (+)-pinoresinol (33% e.e.), (+)-lariciresinol (30% e.e.), and (+)-secoisolariciresinol (20% e.e.) from achiral coniferyl alcohol in the presence of NADPH and H202, whereas that from ripening seeds catalyzed the formation of (-)-pinoresinol (22% e.e.), (-)-lariciresinol (>99% e.e.), and (-)-secoisolariciresinol (38% e.e.) under the same conditions. In addition, the ripening seed enzyme preparation mediated the selective formation of the optically pure (>99% e.e.) (-)-enantiomer of matairesinol from racemic (+/-)-secoisolariciresinols in the presence of NADP. These results indicate that the stereochemical mechanism for lignan biosynthesis in A. lappa varies with organs, suggesting that multiple lignan-synthesizing isozymes are involved in the stereochemical control of lignan formation in A. lappa.

Survey and enzymatic formation of lignans ofAnthriscus sylvestris

Abstract: Gas chromatography — mass spectrometry analysis of the β-glucosidase-treated MeOH extracts ofAnthriscus sylvestris showed, based on comparison of the mass spectra and retention times with those of authentic samples, the presence of lignans, yatein, secoisolariciresinol, lariciresinol, matairesinol, hinokinin, and pluviatolide. The existence of small amounts of bursehernin was suggested by mass chromatography. In addition, nemerosin and deoxypodophyllotoxin were tentatively identified by comparing the mass spectra with those reported in the literature. Enzyme preparations fromA. sylvestris catalyzed the formation of secoisolariciresinol and lariciresinol from coniferyl alcohol. Furthermore, the enzyme preparation catalyzed the formation of lariciresinol from (±)-pinoresinols and the formation of secoisolariciresinol from (±)-lariciresinols. Thus, pinoresinol/lariciresinol reductase (PLR) activity was detected. Chiral high-performance liquid chromatography analysis showed selective formation of (+)-lariciresinol and (−)-secoisolariciresinol from (±)pinoresinols with theA. sylvestris PLR preparation, indicating that the stereochemical property ofA. sylvestris PLR-catalyzed reduction was similar to those ofForsythia PLR andArctium lappa ripening seed PLR.

Lignan production in Daphne odora cell cultures

Abstract: Lignan production in callus and cell suspension cultures ofDaphne odora is reported for the first time. The cell suspension culture produced pinoresinol, lariciresinol, secoisolariciresinol, matairesinol, and wikstromol. The production of matairesinol in the cell suspension culture was much higher than that inDaphne odora stem tissues.

First in vitro Norlignan Formation with Asparagus officinalis Enzyme Preparation.

Abstract: We report for the first time that an enzyme preparation from fungal-elicited Asparagus officinalis cultured cells catalyses the formation of a norlignan, (Z)-hinokiresinol, from two non-identical phenylpropanoid monomers, 4-coumaryl alcohol and 4-coumaroyl CoA, and from a dimer, 4-coumaryl 4-coumarate, without any additional cofactors.

Norlignan Biosynthesis in Asparagus officinalis L.: The Norlignan Originates from Two Non‐Identical Phenylpropane Units.

Abstract: Little is known about the biosynthetic mechanism(s) of norlignans with C6–C5–C6 skeletons in spite of their important contributions to heartwood formation in conifers. To clarify the mechanism(s), we have established cell-suspension cultures of Asparagus officinalis that produce a norlignan, (Z)-hinokiresinol, after fungal elicitor treatment. Feeding experiments with ring- or side chain-13C- and/or 2H-labelled phenylpropanoid monomers show that two units of L-phenylalanine, cinnamic acid, 4-coumaric acid, or 4-coumaryl alcohol are efficiently incorporated into the norlignan. 13C NMR of (Z)-hinokiresinols isolated after individual administration of [7-13C]cinnamic acid, [8-13C]cinnamic acid, and [9-13C]cinnamic acid conclusively demonstrate that the side chain 7-C, 8-C, and 9-C atoms of cinnamic acid are incorporated into C-1 and C-3, C-2 and C-4, and C-5 of (Z)-hinokiresinol, respectively. Thus, ring- and side-chain-labelled tracer results indicate that all carbon atoms of (Z)-hinokiresinol are found to originate from C6–C3 (phenylpropanoid) monomers, and this compound is formed with a loss of one carbon atom at the 9-position of one of the coupling monomers. Furthermore, a competitive tracer experiment with simultaneous administration of 4-[ring-13C6]coumaric acid and 4-[7,9,9-2H3]coumaryl alcohol indicates that the C6–C3 moiety of (Z)-hinokiresinol is derived from 4-coumaryl alcohol, while the C6–C2 moiety originates from a 4-coumaroyl compound such as 4-coumaroyl CoA and not directly from 4-coumaryl alcohol.