| Abstract
| - It has been clarified in the present investigation that a high degree of oxidation at the benzylic positionof phenolic lignans bearing a 4-hydroxy-3-methoxybenzyl group reduces their antioxidant activity andthat the antioxidant activity of the bis(4-hydroxy-3-methoxybenzyl)tetrahydrofuran lignan 2 is higherthan that of the corresponding γ-butyrolactone lignan 1. This was demonstrated by comparing theantioxidant activities of compounds 1 and 2 with those of the (benzyl)(hydroxybenzyl)tetrahydrofurans3 and 4, the bis(hydroxybenzyl)tetrahydrofurans 7 and 8, the (benzoyl)(benzyl)tetrahydrofuran 6, andthe dibenzoyltetrahydrofuran 9. The activity level of compound 2 was approximately the same potencyas that of the tetrahydronaphthalene-tetrahydrofuran 5. These compounds possess either a 4-hydroxy-3-methoxybenzyl group or a 4-hydroxy-3-methoxybenzoyl group as the benzyl or benzoyl group. Anexamination of radical scavenging activity showed differences of activity between diastereomers. To makethis comparison possible, compounds 1−9 were synthesized using new synthetic routes for several ofthese lignans. In this investigation, stereoisomers of the (benzyl)(hydroxybenzyl)tetrahydrofurans 3 and4 and liovils 7 and 8 were synthesized for the first time.
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