Comparison of oximes K203 and K027 based on Benchmark dose analysis of rat diaphragmal acetylcholinesterase reactivation

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.

BODIPY-labelled acetylcholinesterase reactivators can be encapsulated into ferritin nanovehicles for enhanced bioavailability in the CNS

The BODIPY-labelled oxime reactivator was prepared and used to study its biodistribution into central nervous system. The newly synthesized oxime was found to be weak inhibitor of acetylcholinesterase and strong inhibitor of butyrylcholinesterase. Its reactivation ability for organophosphate inhibited acetylcholinesterase was found similar to a parent oxime. The BODIPY-labelled oxime was further encapsulated into recombinant human H-ferritin and evaluated in vitro and in vivo. The oxime or encapsulated oxime were found to be bioaccumulated primarily in liver and kidneys of mice, but some amount was distributed also to the brain, where it was detectable even after 24 h. The BODIPY-labelled oxime encapsulated to human H-ferritin showed better CNS bioaccumulation and tissue retention at 8 and 24 h time points compared to free oxime, although the fluorescence results might be biased due to BODIPY metabolites identified in tissue homogenates. Taken together, the study demonstrates the first utilization of recombinant ferritins for changing the unfavourable pharmacokinetics of oxime reactivators and brings promising results for follow-up studies.

Oxidative stress, metallomics and blood toxicity after subacute low-level lead exposure in Wistar rats: Benchmark dose analyses

Exposure to lead (Pb) is still rising concern worldwide, having in mind that even low-dose exposure can induce various harmful effects. Thus, in-depth knowledge of the targets of Pb toxicity and corresponding mechanisms is essential. In the presented study, the six groups (male Wistar rats, n = 6) received 0.1; 0.5; 1; 3; 7; 15 mg Pb/kg body weight/day for 28 days, each day by oral gavage, while the control group received distilled water only. All animals were sacrificed 24 h after the treatment, and blood was collected for the analysis of hematological, biochemical, oxidative status and essential elements levels. An external and internal dose-response relationship was performed using PROASTweb 70.1 software. The results showed that low doses of Pb affect hematological parameters and lipid profile after 28 days. The possible mechanisms at examined Pb dose levels were a decrease in SOD, O₂^•- and Cu and an increase in Zn levels. The dose-dependent nature of changes in cholesterol, HDL cholesterol, O₂^.-, SOD, AOPP in serum and hemoglobin, Fe, Zn, Cu in blood were obtained in this study. The most sensitive parameters that were alerted are Cu blood levels (BMDL₅: 1.4 ng/kg b.w./day) and SOD activity (BMDL₅: 0.5 μg/kg b.w./day). The presented results provide information that may be useful in further assessing the health risks of low-level Pb exposure.