Chemical constituents from the fruits of Alpinia oxyphylla and their neuroprotective effects

Fourteen compounds were isolated from the ethyl acetate fraction of 90% EtOH extracts of the dried fruits of Alpinia oxyphylla by silica gel, MCI, RP-18, Sephadex LH-20, TLC and semi-preparative HPLC column chromatography. Their structures were identified by HR-ESI-MS, UV, IR, NMR, ECD and X ray single crystal diffraction spectroscopic data as: (2R, 5R, 7R, 10S)-2, 7-dihydroxyl-eudesmane-3(4), 11(12)-diene (1), α-rotunol (2), diketone I (3), (1S, 4S, 5R, 7S)-1-hydroxyl-eremophilane-9(10), 11(12)-diene-8-one (4), cyperusol A₁ (5), (6R, 9S, 10S)-10-hydroxyl-11, 12, 13-trinor-cadinane-4(5)-ene-3-one (6), (2E, 4E)-6-hydroxy-2, 6-dimethylhepta-2, 4-dienal (7), oxyphyllacinol (8), yakuchinone A (9), (5R)-5-hydroxy-1, 7-diphenylhept-3-heptanone (10), (5S)-5-hydroxy-7-(4″-hydroxyphenyl)-1-phenylhept-3-heptanone (11), (5S)-5-hydroxy-7-(4″-hydroxyl-3″-methoxyphenyl)-1-phenyl-3-heptanone (12), 7-(4″-hydroxy-3″-methoxyphenyl)-1-phenyl-3, 5-heptadione (13), bis-(2-ethylhexyl) terephthalate (14). Compounds 1-6 were sesquiterpenoids in which compound 1 is a new eudesmane sesquiterpenoid and compound 7 was a monoterpenoid. Compounds 8-13 were diarylheptanoids, and compounds 2-6 and 14 were isolated from A.oxyphylla for the first time. The experiments on H₂O₂ induced SH-SY5Y cells showed that compounds 2, 6, 7, 12 and 13 had neuroprotective effects at low and medium concentrations. In particular, compound 6 showed obvious neuroprotective effect at low, medium and high concentrations whose cell viability was higher than that of the positive control.