| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2001: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Research Abstract |
In order to clarify biosynthetic mechanism for lignans, we investigated the formation of lignans in several plant.
First, we have focused our research efforts on the formation of furofuran lignans in magnolia kobus var. borealis. With respect to enantiomeric composition of isolated lignans from M. kobus var. borealis, phenolic furofuran lignans such as pinorersinol and syringaresinol were optically impure. On the other hand, non-phenolic furofuran lignans such as eudesmin, yangambin and kobusin were optically pure. these results suggested that enantioselective enzyme are in formation of the non-phenolic furofuran lignans. Also, we examined O-methlation reactions of phenolic furofuran lignans by incubation with cell-free extracts from M. kobus var. borealis. It was shown that the cell-free extracts catalyzed the O-methylation reactions of pinoresinol syringaresinol, suggesting the conversions of pinoresinol into eudesmin, and syringaresinol into yangambin, respectively, The in vitro transmethlation reactions observed were enantioselective with the (+)-forms being the preferred substrates.
Next, we investigated lignan formation in Acanthopanax senticosus. Based on the enanyiomeric composition of their lignans, it was suggested that racemic syringaresinol formed from two molecules of sinapyl alcohol by a non-selective coupling followed by transformation into syringaresinol diglucoside with the (+)-syringaresinol being the preferred substrate.
In study of lignans flax (Linum usitatissimum), it was shown that secoisolariciresinol diglucoside does not occur in flaxseed in a free form, but rather occurs in a complex ester. Preliminary experiments have indicated that in flax plant there is an orderly biosynthetic sequence initially involving stereoselective coupling to give the furofuran lignan(+)-pinoresinol, and its subsequent transformation into tetrahydrofuran and dibenzylbutane skeleta.
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