Previous reports from this laboratory revealed that cistifolin from the antirheumatic herbal drug, gravel root (rhizome of Eupatorium purpureum), showed activity both in in vitro and in vivo models of inflammation. Data are now presented to show that, in addition to the LFA-1 and other integrin-mediated leucocyte adhesions, cistifolin inhibits the Mac-1 (CD11b/CD18)-dependent monocyte adhesion to fibrinogen in a concentration-dependent manner. Further phytochemical analysis of the crude extract also led to the isolation of three known benzofurans, euparin, euparone, 6-hydroxy-3β-methoxytrematone and a new benzofuran, 5-acetyl-6-hydroxy-2-(1-oxo-2-acetoxy-ethyl)-benzofuran. None of these compounds were active in suppressing integrin-mediated monocytic U937 cell adhesions in vitro. Copyright © 2001 John Wiley & Sons, Ltd.