Comparative study on plant latex proteases and their involvement in hemostasis: a special emphasis on clot inducing and dissolving properties

In the present study we compared the clot inducing and dissolving properties of Calotropis gigantea R. Br. (Asclepiadaceae), Synadenium grantii Hook. f. (Euphorbiaceae) and Wrightia tinctoria R. Br. (Apocynaceae) latex extracts. All the three latex extracts hydrolyzed casein, fibrinogen and crude fibrin dose-dependently. The proteolytic action on fibrinogen subunity was in the order of Aalpha > Bbeta > gamma. All extracts exhibited procoagulant activity as assayed by re-calcification time. However, thrombin like activity is restricted to C. gigantea. In addition, the extracts dose-dependently hydrolyzed blood and plasma clots. Furthermore, the hydrolyzing pattern of fibrin in the plasma clot was substantiated by SDS-PAGE. The extracts hydrolyzed all the subunits (alpha polymer, alpha-chains, gamma-gamma dimer and beta-chain) of fibrin efficiently. Both fibrinogenolytic and fibrinolytic activity potency of the extracts were in the order of C. gigantea > S. grantii > W. tinctoria. Among the three latices, C. gigantea is toxic with a minimum hemorrhagic dose (MHD) of > 75 microg, whereas S. grantii and W. tinctoria latex extracts were non-toxic and did not induce any hemorrhagic effect at the tested dose (> 200 microg). The proteolytic activity of C. gigantea latex extract on different substrates was inhibited by IAA. On the other hand, the proteolytic activities of S. grantii and W. tinctoria were inhibited by PMSF. Thus, this study provides the basis for the probable action of plant latex proteases to stop bleeding and effect wound healing as exploited in folk medicine.