Effect of benzylic oxygen on the antioxidant activity of phenolic lignans.
It has been clarified in the present investigation that a high degree of oxidation at the benzylic position of phenolic lignans bearing a 4-hydroxy-3-methoxybenzyl group reduces their antioxidant activity and that the antioxidant activity of the bis(4-hydroxy-3-methoxybenzyl)tetrahydrofuran lignan 2 is higher than that of the corresponding gamma-butyrolactone lignan 1. This was demonstrated by comparing the antioxidant activities of compounds 1 and 2 with those of the (benzyl)(hydroxybenzyl)tetrahydrofurans 3 and 4, the bis(hydroxybenzyl)tetrahydrofurans 7 and 8, the (benzoyl)(benzyl)tetrahydrofuran 6, and the dibenzoyltetrahydrofuran 9. The activity level of compound 2 was approximately the same potency as 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. An examination of radical scavenging activity showed differences of activity between diastereomers. To make this comparison possible, compounds 1-9 were synthesized using new synthetic routes for several of these lignans. In this investigation, stereoisomers of the (benzyl)(hydroxybenzyl)tetrahydrofurans 3 and 4 and liovils 7 and 8 were synthesized for the first time.
Yamauchi
Satoshi
S
Faculty of Agriculture, Ehime University, Tarumi 3-5-7, Matsuyama, Ehime 790-8566, Japan. syamauch@agr.ehime-u.ac.jp
Hayashi
Yoshimasa
Y
Nakashima
Yuki
Y
Kirikihira
Takuya
T
Yamada
Kazuki
K
Masuda
Toshiya
T
D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D001555:Benzene Derivatives / Q000737:chemistry*; D020650:Combinatorial Chemistry Techniques; D005663:Furans / Q000737:chemistry / Q000494:pharmacology; D017705:Lignans / Q000737:chemistry / Q000494:pharmacology*; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D000975:Antioxidants; D001555:Benzene Derivatives; D005663:Furans; D017705:Lignans; D010636:Phenols; C068935:matairesinol; D010100:Oxygen