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 beta-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 muM, respectively. The known compounds, daidzein (4) and 2'-hydroxydaidzein (6), isolated from C. pallida, inhibited of the release of lysozyme and P-glucuronidase from rat neutrophils in response to fMLP/CB with IC50 values of 26.3 +/- 5.5 and 13.7 +/- 2.6 muM, 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 muM, 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-gamma (IFN-gamma)-stimulated N9 microglial cells with IC50 values of 10.7 +/- 10.1 and 13.9 +/- 1.1 muM, 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. (C) 2003 Elsevier Ltd. All rights reserved.