Plant latex proteases with potential influence on blood coagulation and fibrinolysis

Abstract

Proteases are widespread in latices of different plant families (e.g. Apocynaceae, Asteraceae, Caricacea, Convolvulaceae, Euphorbiaceae and Moraceae) [1]. Their function has not been completely clarified yet; involvement in wound healing after injury and protection from predators appear logical. Potential use of plant proteases are in the food industry (e.g. cheese production), washing industry or in the pharmaceutical industry. For the latter one possible application is the blood coagulation and fibrinolysis process. Some latex-containing plants are already under investigation in this aspect, like for example Synadenium grantii Hook (Euphorbiaceae), Wrightia tinctoria R.Br. (Apocynaceae), Ficus carica L. (Moraceae) and Euphorbia hirta L. (Euphorbiaceae) [2, 3]. We analysed the in vitro influence of the protease-containing latex of Euphorbia mauritanica L. (Euphorbiaceae) on some parts of the coagulation and fibrinolysis procedure, by using different methods like a fibrin plate assay, specific substrates or In-Gel-Digestion. It shows thombin-like activity, since it leads to an opacity in the plate assay and a moderate conversion of two thrombin-specific fluorogenic substrates. However it also shows plasmin-like activity, since it is able to dissolve small fibrin clots and coverts two plasmin-specific fluorogenic substrates. In-Gel-Digestion of fibrin and fibrinogen chains confirmed the activity, but the cleavage sites appear to be different.