Synthesis and the hepatoprotective activity of dibenzocyclooctadiene lignan derivatives

The halogenated and oxidized derivatives (1a–1e, 1a′–1c′, 2a–2d, 2a′–2b′, 3a–3e, 3′ and 3a′–3b′) of schizandrin (1), schizandrin B (2) and schisanhenol (3) were synthesized. The hepatoprotective effects of these dibenzocyclooctadiene lignan analogues against CCl₄-induced injury were preliminarily evaluated. Most of the analogues exhibited higher protective effects than the positive control biphenyldicarboxylate (DDB). Among these active analogues, dichloroschisanhenol (3a) exhibited the strongest protective activity (cell survival rate exceeding 98.0%).