Rare hydroperoxyl guaianolide sesquiterpenes from Pulicaria undulata

Abstract Pulicaria species, such as Pulicaria undulata , are rich in sesquiterpene lactones. The methylene chloride/methanol (1:1) extract of P. undulata resulted in the isolation of new sesquiterpenes ( 1 – 4 ), as well as previously reported metabolites ( 5 – 14 ). Structures were elucidated by spectroscopic analyses. Using a mouse peritoneal macrophage bioassay, lipopolysaccharide-induced nitric oxide inhibition was observed with the eudesman-type sesquiterpene 1 β ,4 β -dihydroxy-5 α H,7 α H,8 α -guaia-10(14),11(13)-dien-8 β ,12-olide ( 11 ) at an EC 50 of 7.2 μM.