Effect of Benzylic Oxygen on the Antioxidant Activity of Phenolic Lignans

Abstract

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.

Isochaihulactone protects PC12 cell against H2O2 induced oxidative stress and exerts the potent anti-aging effects in D-galactose aging mouse model

“…Results [34,35] . The chemical structure of isochaihulactone (sugar moiety attached to the 20 position of the triterpene dammarane) may contribute to its direct antioxidant properties [36] .…”

Radical and Superoxide Scavenging Activities of Matairesinol and Oxidized Matairesinol

“…4) As shown in scheme 1, Mat 2, Mat 3, and Mat 4 were respectively prepared from 6, 8, and 11 and Mat 5 and Mat 6 were prepared from 13. Compounds 6, 8, 11, and 13 were synthesized from L-glutamic acid.…”

“…Compounds 6, 8, 11, and 13 were synthesized from L-glutamic acid. 4) Aldol product 6 was oxidized by pyridinium chlorochromate (PCC) to ketone 7 in 95% yield. Hydrogenolysis of 7 gave Mat 2 in 86% yield.…”

“…In particular, in the case of the 3,4-dibenzyltetrahydrofuran type of lignan, a higher oxidative degree of the benzylic position decreased the antioxidant activity. 4) This present report describes the radical and superoxide scavenging activity by employing matairesinol and oxidized matairesinol. Mat 1-Mat 6, and Lio 7 were prepared to examine the effect of the chemically active 7,7 0 , and 8 0 positions on the antioxidant activity (Fig.…”

“…The relationship between the structure of lignans and their antioxidant activities has recently been reported. [2][3][4] The fact that the structure, apart from the aromatic portion, of lignans affected the degree of antioxidant activity was clarified by these reports. In particular, in the case of the 3,4-dibenzyltetrahydrofuran type of lignan, a higher oxidative degree of the benzylic position decreased the antioxidant activity.…”