Anti-inflammatory flavonoids and pterocarpanoid from Crotalaria pallida and C. assamica

One new isoflavone, 5,7,4′-trihydroxy-2′-methoxyisoflavone (3) and seven, and four known compounds were isolated from the barks of Crotalaria pallida and the seeds of C. assamica, respectively. The known compounds, apigenin (1) and 2′-hydroxygenistein (2), isolated from C. pallida, showed significant concentration-dependent inhibitory effects on the release of β-glucuronidase and lysozyme from rat neutrophils in response to formyl-Met-Leu-Phe/cytochalasin B (fMLP/CB) with IC50 values of 2.8±0.1 and 17.7±1.9, and 5.9±1.4 and 9.7±3.5 μM, respectively. The known compounds, daidzein (4) and 2′-hydroxydaidzein (6), isolated from C. pallida, inhibited of the release of lysozyme and β-glucuronidase from rat neutrophils in response to fMLP/CB with IC50 values of 26.3±5.5 and 13.7±2.6 μM, respectively. Compounds 1 and 4 also showed significant concentration-dependent inhibitory effects on superoxide anion generation in rat neutrophils stimulated with fMLP/CB with IC50 values of 3.4±0.3 and 25.1±5.0 μM, respectively. Compounds 1 and 5, previously isolated from C. pallida, showed the inhibition of NO production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages and LPS/interferon-γ (IFN-γ)-stimulated N9 microglial cells with IC50 values of 10.7±0.1 and 13.9±1.1 μM, respectively. Flavonoids, suppressed chemical mediators in inflammatory cells, may have value in treatment and prevention of central and peripheral inflammatory diseases associated with excess production of chemical mediators.