Effects of Selective African Spitting Cobra Venoms and Their Three-Finger Toxins on the Modulation of Platelet Function and Blood Clotting.

Venoms of African spitting cobras, including Naja mossambica, N. nigricincta, and N. pallida, are widely recognised for their cytotoxicity. However, their effects on platelets and blood coagulation remain poorly characterised. To address this gap, we characterised their enzymatic profiles and evaluated their effects on haemostasis and cell viability using functional blood-based and cellular assays, respectively. All three venoms markedly impaired haemostatic regulation by affecting intrinsic coagulation, significantly inhibiting platelet function, and inducing haemolysis. They also exerted potent myotoxic effects on cultured myoblasts/myotubes while causing only minimal cytotoxicity towards platelets. Fractionation by reversed-phase HPLC followed by mass spectrometry identified three-finger toxins that reproduced the potent platelet-inhibitory and myotoxic activities of the crude venoms but only partially accounted for the haemolytic and anticoagulant effects. These findings demonstrate that African spitting cobra venoms induce coordinated, multifaceted effects on human blood, with three-finger toxins serving as key functional mediators alongside other potential venom components. Overall, this study advances our understanding of the effects of spitting cobra envenoming, provides a foundation for developing improved snakebite therapies, and highlights venom-derived components as potential scaffolds for developing novel antithrombotic agents.