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

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 (radical dotOH). Among them, compound 5 showed significantly higher hydroxy radical scavenging activity (IC50 4.4 μg/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.