engleski

Counteracting organophosphate-induced toxicity by improved bioscavenging capacity of BChE and damage prevention at cell level

The phosphylation of acetylcholinesterase (AChE), a pivotal enzyme in hydrolysis of the neurotransmitter acetylcholine, by nerve agents (NAs) still has no adequate or fully efficient medical countermeasures. Furthermore, oxime antidotes known for their nucleophilic properties have limited potency in the reactivation of phosphylated AChE in the central nervous system (CNS), so even after survival, long- term effects of poisoning could occur. However, the AChE related enzyme butyrylcholinesterase (BChE), typically present in the blood, serves as bioscavenger of OPs, before they reach the crucial AChE in CNS. In our study, we wanted to investigate with a combination of in silico, in vitro, and ex vivo methods, the feasibility of an approach to develop a safe bioscavenger of NAs, based on the oxime-assisted reactivation of BChE. Firstly, we identified a promising reactivator of cyclosarin- inhibited BChE as a model system with no impact on the viability of neuroblastoma cells upon 4-hour treatment. Herein, the efficient oxime-assisted catalytic BChE degradation of cyclosarin was demonstrated ex vivo. This pair was then applied to OP-treated cells and, as the result shows, it acted by, protecting cells’ homeostasis by preserving from 50% to nearly 100% of neural cells. The most significant result was obtained if the oxime and BChE pair were applied to cells before exposure to cyclosarin or in other words, as pretreatment. This result is in accordance with ex vivo effects determined in the whole blood showing up to 80% of restored phosphylated cholinesterase activity within two minutes. In conclusion, our findings showed that an antidote should act on two levels—on cholinesterase reactivity and prevention of the long- term effects of poisoning.

Cyclosarin, butyrylcholesterase, pyridinium oximes, neuroblastoma, bioscavenging

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