Anti-inflammatory xanthones from the twigs of Hypericum oblongifolium wall

Two new xanthonolignoids, hypericorin A (1) and hypericorin B (2), along with five known new source compounds, a xanthonolignoid, kielcorin (3), 4-hydroxy-2,3-dimethoxyxanthone (4), 3,4,5-trihydroxyxanthone (5), 1,3-dihydroxy-5-methoxyxanthone ( 6) and 1,3,7-trihydroxyxanthone (7), were isolated from the stems (twigs) of Hypericum oblongifolium Wall. The structures of the new compounds were deduced on the basis of spectroscopic techniques (EI-MS, HREI-MS, (1)H NMR, (13)C NMR, HMQC, HMBC, and NOESY). We also report herein for the first time the single crystal X-ray structure of compound 6. Compounds 1- 7 were screened for their IN VITRO anti-inflammatory (respiratory burst) inhibiting activities using isolated human neutrophils; compounds 1, 2, 3, 5, and 7 showed significant activities (IC (50) = 816.23 ± 73.30, 985.20 ± 55.80, 965.21 ± 65.80, 907.20 ± 50.80, 975.20 ± 81.10 µM, respectively), compound 6 showed moderate activity (IC (50) = 2500.85 ± 50.50 µM), while compound 4 was totally inactive at 1000 µg/mL as compared to the positive control used, indomethacin (IC (50) = 757.99 ± 5.90 µM), and aspirin (IC (50) = 279.44 ± 4.40 µM). Compound 4 was also inactive in comparison with other tested Hypericum compounds.