Synthesis of Macromolecular Conjugates of a Urokinase Inhibitor: Amiloride

Abstract

Amiloride is a potent inhibitor of a urokinase type plasminogen activator which is involved in the invasive process of cancer cells leading to the initiation of metastasis. Synthesis, characterization and in vitro tests of four macromolecular conjugates of Amiloride are presented. One of them is a degradable derivative, HPMA-Gly-D,l-Phe-Leu-Gly-amiloride. In this case the in vitro release of Amiloride was monitored. Other conjugates are stable containing a new amiloride derivative, 6-aminohexyl amiloride [AHA], coupled to different polymeric carriers: a branched polypeptide, poly-[Lys(AcGlu1.0-D,l-Ala4.5)] [AcEAK], poly-[N-(2-hydroxy propyl) metacrylamide] [HPMA] and poly-[1-vinyl-2-pyrrolidone- co-maleic acid] [NVP MA]. Inhibition of uPA, plasminogen activation and proteinases secreted by cancer cells was measured as well as basement membrane degradation in vitro. Each amiloride AHA and the corresponding conjugates retained their activity in these experiments.