Chemical Constituents and Antioxidant Activity from the Stems of Alyxia reinwardtii

Eight compounds were isolated from the stems of Alyxia reinwardtii, namely coumarin (1), 3-hydroxycoumarin (2), 6-hydroxycoumarin (3), 8-hydroxycoumarin (4), scopoletin (5), (+)-pinoresinol (6), zhebeiresinol (7) and p-hydroxybenzoic acid (8). The structures of all compounds were characterized by means of NMR, MS, chemical analysis and comparison with the literature data. The structure of compound 7 was also confirmed by X-ray crystallography. To the best of our knowledge, compounds 2-3, 5 and 7-8 have been isolated for the first time from this species. In terms of antioxidant activity, the isolated compounds were evaluated by various in vitro model assays, which include the DPPH radical scavenging activity, xanthine oxidase-related activity (superoxide scavenging activity and inhibitory effect on xanthine oxidase) and lipid peroxidation inhibitory activity.