Cytotoxicity-related effects of imidazolium and chlorinated bispyridinium oximes in SH-SY5Y cells

Novel chlorinated oxime K870 protects rats against paraoxon poisoning better than obidoxime

The aim of this study was to determine the antidotal potential of the chlorinated oxime K870 compared to obidoxime, as a monotherapy and in combination with atropine, in paraoxon (POX)-poisoned rats. The treatment doses of oximes were chosen as 20% of their LD50 values. The protective ratio (PR) of oxime K870 with atropine was significantly higher than that of obidoxime with atropine (68.8 and 125.0, respectively). In the biochemical part of the experiment POX subcutaneously (s.c.) (0.75% LD50) was administered and followed by oxime K870 or obidoxime i.m. 1 min later. Acetylcholinesterase (AChE) activity was determined spectrophotometrically in cerebrum, cerebellum, brainstem, diaphragm, and erythrocytes. Carboxylesterase activity was determined in plasma and liver. Both oximes successfully reactivated AChE in brain (cerebrum, cerebellum, and brainstem), diaphragm and erythrocytes, but the oxime K870 performed better than obidoxime. Both oximes reactivated carboxylesterase, obidoxime better in plasma and oxime K870 better in liver. In conclusion, the oxime K870, when co-administered with atropine, is a more effective antidote than the obidoxime-atropine combination in POX-poisoned rats.

Environmental exposure to glyphosate does not inhibit human acetylcholinesterase and butyrylcholinesterase

Glyphosate has remained the leading herbicide on the global market to date, despite the continuous debate between consumers, scientific community, and regulatory agencies over its carcinogenicity, genotoxicity, environmental persistence, and the role in the development of neurodegenerative disorders. Chemically, glyphosate belongs to a large family of organophosphorus pesticides, which exert a neurotoxic effect by inhibiting acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), enzymes of the cholinergic system essential for maintaining neurotransmission. Although research shows that glyphosate is a weak cholinesterase inhibitor in fish and mammals compared to other OP compounds, no conclusive data exist concerning the inhibition of human AChE and BChE. In our study we analysed its inhibitory potency on human AChE and BChE, by establishing its IC50 and reversible inhibition in terms of dissociation inhibition constants. Glyphosate concentration of 40 mmol/L caused near total inhibition of enzyme activity (approx. 10 % activity remaining). Inhibition dissociation constants (K i) of glyphosate-AChE and -BChE complexes were 28.4±2.7 mmol/L and 19.3±1.8 mmol/L, respectively. In conclusion, glyphosate shows a slight binding preference for BChE but exhibits inhibition only in a high concentration range. Our results are in line with studies reporting that its neurotoxic effect is not primarily linked to the cholinergic system.