The mode of action of helenalin appears to differ from the epoxide containing parthenolide Hall 1988 . Feverfew extract protected endothelial cells from perfusion-induced injury and increased the cAMP content of aorta segments. The results indicate feverfew may have a vasoprotective effect in addition to its effects on platelets Voyno-Yasenetskaya 1988 . Parthenolide from Paramichelia baillonii is cytotoxic to KB tumor cell culture Ruangrungsi 1987 . Feverfew extract inhibits platelet adhesion to collagen Losche 1987 .
Extracts inhibit secretion of granular contents from platelets and neutrophils.
The pattern is different from other inhibitors Heptinstall 1985 . Perturbation of lipid-protein interaction appears to have a role in activity Jain 1985 . Woynarowski 1981 . Makheja 1981 . Collier 1980 .