Inhibition of Lipopolysaccharide-Induced Nitric Oxide Production by Antofine and Its Analogues in RAW 264.7 Macrophage Cells

Based on the anti-inflammatory activity of phenanthroindolizidine alkaloids, the inhibitory effect of antofine and its analogues on lipopolysaccharide (LPS)-induced nitric oxide (NO) production was examined, and structure–activity relationships are discussed. Antofine and several analogues suppressed NO production in LPS-stimulated RAW 264.7 cells. The MeO group at C(2), and the bulkiness of the substituents at C(3) and C(6) in the phenanthrene ring might be critical for this effect. Besides, regulation of iNOS expression might be involved in the inhibitory effect of antofine on LPS-induced NO production in macrophage cells.