Anti-inflammatory constituents and new pterocarpanoid of Crotalaria pallida.

One new pterocarpanoid, crotafuran E (1), and three known compounds were isolated from the bark of Crotalaria pallida. The structure of 1 was determined by spectral methods. Two pterocarpanoids, crotafurans A (2) and B (3), previously isolated from this plant, showed significant concentration-dependent inhibitory effects on the NO production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage-like cells, with IC(50) values of 23.0 +/- 1.0 and 19.0 +/- 0.2 microM, respectively. Compound 3 also inhibited the LPS/interferon-gamma (IFN-gamma)-stimulated NO production in N9 microglial cells with an IC(50) value of 9.4 +/- 0.9 microM. Moreover, compound 2 produced a concentration-dependent inhibition of the release of beta-glucuronidase and lysozyme from rat neutrophils in response to formyl-Met-Leu-Phe/cytochalasin B (fMLP/CB) with IC(50) values of 7.8 +/- 1.4 and 9.5 +/- 2.1 microM, respectively.