Quiquelignan A-H, eight new lignoids from the rattan palm Calamus quiquesetinervius and their antiradical, anti-inflammatory and antiplatelet aggregation activities

Eight new lignin derivatives, termed quiquelignan A-H (1-8), comprising three tricin-type flavonolignans (1-3) and five 8-O-4' neolignans (4-8), were isolated from the ethanol extract of Calamus quiquesetinervius stems. Structural elucidation of the new isolates was accomplished on the basis of spectroscopic data. Compounds 1-8 showed strong-to-moderate antioxidant activity against the hydroxy radical ((OH)-O-center dot). Among them, compound 5 showed significantly higher hydroxy radical scavenging activity (IC50 4.4 mu g/mL). Compounds 2-4 and 6-8 dose-dependently suppressed the LPS-stimulated production of nitric oxide (NO) in RAW 264.7 cells. The anti-inflammatory potency of 4 and 6 was 2.7-4.5-fold higher compared with quercetin. Compounds 2-4, 6 and 8 also exhibited mild collagen-antagonistic activity, but were inactive with respect to thrombin-induced platelet aggregation. (C) 2009 Elsevier Ltd. All rights reserved.