Neurotoxicity caused by snake venom phospholipase A2 (PLA2) activity derived from coral snakes (e.g., Micrurus tener, Micrurus fulvius, group IA PLA2) and some rattlesnakes (e.g., Crotalus scutulatus, group IIA PLA2) is medically significant. Of interest, the catalytic site of PLA2 also binds to activated clotting factor X, causing anticoagulation. Given that ruthenium (Ru)-containing compounds have been demonstrated to inactivate hemotoxic venoms in a solvent-dependent manner (e.g., 0.9% NaCl, phosphate-buffered saline), we wished to determine if RuCl3 would cause solvent-dependent inhibition of snake venom group IA and group IIA PLA2 in human plasma with thrombelastography. It was determined that RuCl3 significantly decreased the anticoagulant effects of group IA PLA2 derived from M. tener and M. fulvius venoms in the presence of 0.9% NaCl, but not phosphate-buffered saline. In contrast, group IIA PLA2 anticoagulant activity derived from C. scutulatus venom was inhibited by RuCl3 in both solvents. It is concluded that the different ions formed by RuCl3 in different solvents may interact with novel disulfide bridges unique to group IA and IIA PLA2 or through some other mechanism. In vivo validation of Ru-based enzyme inhibitor effects on neurotoxicity associated with either group IA or IIA remains a critical translational issue.
Nielsen et al. (Thu,) studied this question.