Sesquiterpenes from an Egyptian herbal medicine, Pulicaria undulate, with inhibitory effects on nitric oxide production in RAW264.7 macrophage cells.

The methylene chloride-methanol (1 : 1) extract from the air-dried aerial parts of wild Pulicaria undulata collected in North Sinia, Egypt, showed inhibitory effects on lipopolysaccharide (LPS)-induced production of nitric oxide (NO) in RAW264.7 macrophages. From the extract, three new sesquiterpenes named 5α-hydroperoxyivalin, 8-epi-xanthanol, and 8-epi-isoxanthanol were isolated together with four known sesquiterpenes. The structure of each new sesquiterpenes was determined on the basis of physicochemical and chemical evidence. In addition, all the sesquiterpenoids significantly inhibited the production of NO. Ivalin (IC50=2.0 μM) and 2α-hydroxyalantolactone (1.8 μM) showed particularly strong inhibitory effects, but had strong cytotoxic effects as well. Furthermore, ivalin and 2α-hydroxyalantolactone concentration-dependently reduced inducible NO synthase (iNOS) protein levels in RAW264.7 cells.