Antioxidant properties of 8.0.4'-neolignans

A series of naturally occurring 8.0.4'-neolignans (1a-d, 1g, 2g, 2h) and their analogues (le-f, lh, 1i, 2a-f, 2i) have been synthesized in racemic form starting from commercially available phenols, such as eugenol, isoeugenol and 4-allyl-2,6-dimethoxyphenol and from aromatic aldehydes, such as piperonal, veratraldehyde and 3,4,5-trimethoxybenzaldehyde. The inhibitory activity of these compounds on superoxide anion (O2.-) release by human polymorphonuclear leukocytes (PMNLs) was tested and the structure-activity relationship was also studied.