Phytochemicals from twigs of Afzelia xylocarpa and their antioxidation kinetics of oxymyoglobin.

The phytochemical investigation of crude n-hexane and ethyl acetate extracts from twigs of Afzelia xylocarpa (Kurz) led to the isolation of 14 known compounds. Their structures were elucidated by spectroscopic techniques (IR, 1H NMR, 13C NMR, and 2D NMR) as well as mass spectrometry. These structures were characterized as β-sitosterol (1), lupeol (2), vanilic acid (3), 5,7-dihydroxychromone (4), (+)-mellein (5), isoliquiritigenin (6), 7-hydroxyemodin (7), physion (8), aromadendrin (9), naringenin (10), apigenin (11), luteolin (12), chrysoeriol (13) and kaempferol (14). Compounds 4-7 and 12-13 were isolated from the genus Afzelia for the first time. The selected compounds 5, 8, 9 and 12 exhibited potent activity for antioxidation kinetics of oxymyoglobin.