Cistifolin, an integrin-dependent cell adhesion blocker from the anti-rheumatic herbal drug, gravel root (rhizome of Eupatorium purpureum).

During routine screening of medicinal plants for small molecular weight inhibitors of cell adhesion, the crude ethanolic extract of the anti-rheumatic herbal drug gravel root (rhizome of Eupatorium purpureum), was identified as a potent inhibitor of some beta 1 and beta 2 integrin-mediated cell adhesions. The active principle of gravel root has now been isolated and identified as 5-acetyl-6-hydroxy-2,3-dihydro-cis-2-isopropenyl-3- tiglinoyloxybenzofuran (1). Compound 1 inhibited integrin-dependent cell-cell and cell-protein interactions in vitro with EC50 values between 7-20 micrograms/ml. As with indomethacin, 1 administered orally two hours before induction of inflammation (in rat paw) by carrageenan inhibited oedema formation in a dose (10 and 50 mg/kg)-dependent manner. It appears that 1 has therapeutic potential for diseases where integrin adhesion molecules play a significant role.