Fibrinogenolytic and anticoagulant activities in the tissue covering the stingers of marine stingrays Dasyatis sephen and Aetobatis narinari.

Stingray envenomation is one of the major problems in the marine and freshwater ecosystem. Accidents in human cause immediate, local and intense pain, erythema, edema, hemorrhage, tissue necrosis and secondary bacterial infection are also common. To determine the effect of two marine stingray species Dasyatis sephen and Aetobatis narinari venom extract on coagulation, fibrin(ogen)olytic, proteolytic activities. Plasma coagulation, Thrombin catalyzed fibrinocoagulation, Fibrin plate assay, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), substrate SDS-PAGE and thrombin like activity by using chromogenic substrate were used to determine the effect of venom on plasma coagulation, its fibrin(ogen)olytic and proteolytic activity. The results show the presence of fibrin(ogen)olytic, anticoagulant and gelatinolytic activity in both stingray venom extracts. D. sephen venom delays coagulation of citrated plasma more significantly than A. narinari upon using increasing concentration of the venom. The same results were obtained in the fibrinocoagulation assays. SDS-PAGE analysis of fibrinogen and fibrin after incubation with D. sephen and A. narinari venom show fibrin(ogen)olytic activity. Through SDS-PAGE analysis it is confirmed that the delaying in coagulation process by stingray venom is due to its fibrin(ogen)olytic activity and fibrinolytic activity also confirmed through fibrin plate assay. Zymogram analysis shows the presence of array of gelatinolytic and fibrinogenolytic enzymes above 43-276 kDa in the D. sephen and A. narinari venom respectively. Protease inhibitor studies show the serine and metallo proteases are responsible for these activities. From the results, fibrinogenolytic, proteolytic activity of the stingray venom is confirmed, but it has no thrombin like activity and these activities may aid in hemorrhages, tissue necrosis and secondary bacterial infections at the site of envenomation.