Effects of the serine protease inhibitors FOY and FOY 305 on phospholipase A1 (EC 3.1.1.32) activity in rat - liver lysosomes.

Rat-liver lysosomal phospholipase A1 activity is unspecifically inhibited in a pH dependent and competitive manner by the cationic amphiphilic protease inhibitors FOY (ethyl 4-6(6-guanidinohexanoyloxy) benzoate methanesulfonate) and FOY 305 (N,N-dimethylcarbamoylmethyl 4-(4-guanidinobenzoyloxy)-phenylacetate methanesulfonate) in concentrations above 10(-4)M. This inhibition may contribute to anti-inflammatory effects of these drugs in that they reduce the release by lysosomal enzymes of fatty acids from membrane phospholipids and consequently decrease the biosynthesis of bioactive oxygenated arachidonate metabolites, among them inflammatory mediators.