EFFECT OF SOME HYDROXYCOUMARINS ON COMPLEMENT-MEDIATED HEMOLYSIS IN HUMAN SERUM

Coumarin derivatives are known to possess antiinflammatory and antimet astatic properties due to their direct action on cells, predominantly on macrophages. In the present study the interactions between esculin, esculetin, fraxin, fraxetin, as well as their acetylated and methylat ed derivatives and non-cell system participating in inflammatory proce sses, comprised of serum complement proteins, were investigated in vit ro. 7-Methylesculin, esculin 5Ac and esculetin 2Ac exhibited good inhi bition on classical pathway (CP) activity and scoparone strongly reduc ed alternative pathway (AP) activity in normal human serum (NHS). Some of the hydroxycoumarins were able to enhance hemolysis. Seven derivat ives were tested in C1 and C3 functional assays, as 7-methylesculin ap peared to be the strongest inhibitor of both activities. Esculin (En) and scopoletin (St) altered the effect of other complement activators (heat aggregated IgG, suramin, and zymosan) when applied with them sim ultaneously in vitro.