EXTRACT OF GRAVEL ROOT (RHIZOME OF EUPATORIUM-PURPUREUM) INHIBITS INTEGRIN-DEPENDENT U937 CELL-ADHESION

The effect of the antirheumatic herbal drug, gravel root (rhizome of E upatorium purpureum), was investigated on integrin-dependent U937 cell adhesion to endothelial cells and extracellular matrix protein, fibro nectin, In the presence of gravel root extract (6.3-200 mu g/mL), U937 sells lowered their capacity for phorbol myristate acetate (PMA)-medi ated adhesion to tumour necrosis factor-alpha (TNF)-activated endothel ial cells or ICAM-1 coated plates. Similarly, the PMA mediated, LFA-1- dependent, homotypic cell aggregation in U937 cells was potently inhib ited by gravel root extract. The alpha(4)beta(1) and alpha(5)beta(1)-m ediated adhesion of unstimulated U937 cells to fibronectin coated plat es was also inhibited by gravel root extract. Neither the TNF-induced enhancement of expression of ICAM-1 on endothelial cell surface nor th e TNF-induced endothelial adhesiveness to U937 cells was, however, inh ibited by,by graved root extract. Since all concentrations of gravel r oot extract tested failed to alter the proliferation of U937 cells, th e observed activity was unlikely to be doe to nonspecific suppression of cells. (C) 1998 John Wiley & Sons.