State-of-the-art review - A review on snake venom-derived antithrombotics: Potential therapeutics for COVID-19-associated thrombosis?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent responsible for the Coronavirus Disease-2019 (COVID-19) pandemic, has infected over 185 million individuals across 200 countries since December 2019 resulting in 4.0 million deaths. While COVID-19 is primarily associated with respiratory illnesses, an increasing number of clinical reports indicate that severely ill patients often develop thrombotic complications that are associated with increased mortality. As a consequence, treatment strategies that target COVID-associated thrombosis are of utmost clinical importance. An array of pharmacologically active compounds from natural products exhibit effects on blood coagulation pathways, and have generated interest for their potential therapeutic applications towards thrombotic diseases. In particular, a number of snake venom compounds exhibit high specificity on different blood coagulation factors and represent excellent tools that could be utilized to treat thrombosis. The aim of this review is to provide a brief summary of the current understanding of COVID-19 associated thrombosis, and highlight several snake venom compounds that could be utilized as antithrombotic agents to target this disease.

Efficacy of Silene arenosa extract on acetylcholinesterase in Bungarus sindanus (krait) venom.

OBJECTIVE: To examine the efficacy of Silene arenosa extract on acetylcholinesterase (AChE) of krait (Bungarus Sindanus) snake venom. METHODS: The present project designed to evaluate the inhibition of AChE by following standard procedures. RESULTS: Statistical analysis of the results showed that Silene arenosa exerted 73% inhibition against the krait venom acetylcholinesterase at fixed substrate acetylcholine (ACh) concentration (0.5 mM). Kinetic analysis using the Lineweaver Burk plot revealed that Silene arenosa caused a competitive type of inhibition i.e. Km values increased from 26.6 to 93.3 mM (26.6% to 93.3%) and Vmax remained constant in a concentration-dependent manner. Silene arenosa competes with the substrate to bind at the active site of the enzyme. The Kmapp of venom AChE for Silene arenosa increased from 60% to 81.6% and the Vmaxapp remains constant. Ki (inhibition constant was estimated to be 48 µg for snake venom; while the Km (Michaelis-Menten constant of AChE- substrate into AChE and product) was estimated to be 0.5 mM. The IC50 of AchE calculated for Silene arenosa was 67 µg. CONCLUSION: The present results suggest that Silene arenosa extract can be considered as an inhibitor of snake venom AChE.