Reactivation of sarin-inhibited pig brain acetylcholinesterase using oxime antidotes

Abstract

Introduction: Organophosphorus nerve agents inhibit the enzyme, acetylcholinesterase (AChE; EC 3.1.1.7). AChE reactivators (also known as oximes) are generally used for the reactivation of an inhibited enzyme.Methods: Two new AChE reactivators-K033 and K027-were tested for their in vitro reactivation of sarin-inhibited pig-brain AChE. Their reactivation potencies were compared with the commercially available AChE reactivators, pralidoxime, obidoxime, and HI-6.Results: Of the oximes tested, the newly developed oxime K027 achieved the highest reactivation potency (100%; concentration of the oxime −10 −2 M). However, oxime HI-6 (33%) and obidoxime (23%) seem to be the best AChE reactivators for human relevant doses (10 −4 M and lower).Conclusion: For human relevant doses, newly developed oximes (K027 and K033) do not surpass the reactivation potency of the most promising oxime, HI-6.

Pyridinium Oximes withOrtho-Positioned Chlorine Moiety Exhibit Improved Physicochemical Properties and Efficient Reactivation of Human Acetylcholinesterase Inhibited by Several Nerve Agents

“…Tables –). Although reactivation constants from previous studies differ depending on the AChE source and species, − it became apparent that K027 is an effective reactivator of AChE inhibited by various OPs. − Indeed, herein K027 showed the fastest nucleophilic displacement rates k +2 , higher than 1 min –1 in the cases of sarin-, cyclosarin-, and VX-inhibited AChE, which resulted in a high degree of enzymatic activity shortly upon the start of reactivation. Its overall reactivation rates ( k r ) would be even more efficient if the affinities of phosphylated AChE (1/ K OX ) for K027 were not as low (cf.…”

“…38 The halogenated aldoximes were then treated with monoquaternary pyridinium amides (15−17), which were prepared as previously described, 39 resulting in the final mono-or dichlorinated pyridinium oximes (7−12). The final step took at least 12 h for compounds with a double bond in the linker (9,12) and several days for compounds with a fully saturated linker (7,8,10,11). The yields were found to be better for compounds with an unsaturated linker (9,12), whereas compounds with a saturated linkage (7,8,10,11) were obtained in generally lower yields, especially when two chlorine moieties were present.…”

“…The final step took at least 12 h for compounds with a double bond in the linker (9,12) and several days for compounds with a fully saturated linker (7,8,10,11). The yields were found to be better for compounds with an unsaturated linker (9,12), whereas compounds with a saturated linkage (7,8,10,11) were obtained in generally lower yields, especially when two chlorine moieties were present. The low reactivity is related to the chlorine atoms which reduce the electron density on pyridine nitrogen, and thus they decrease the yield during the S N 2 reaction.…”

“…Research into reactivators of acetylcholinesterase, undertaken since the 1950s, has produced an enormous number of reactivators. In the past couple of decades, K-oximes, especially K027, K048, and K203 (Figure ), have been shown to be potent reactivators of AChE inhibited with various nerve agents and OP pesticides, − which reflects their universality in reactivation independent of the phosphoryl moiety attached to the active site serine, and according to both in vitro and in vivo results, − particularly significant improvement in reactivation of the tabun-AChE conjugate was achieved when compared to standard oximes used in practice (e.g., pralidoxime, trimedoxime, or asoxime; Figure ). Moreover, K027, K048, and K203 oximes showed low cytotoxic potential in different cell lines (fibroblasts and hepatic, kidney, blood, and ovary cells), , and K048 showed no significant cytotoxic or genotoxic potential .…”

Morphological and Transcriptomic Comparison of Adipose and Bone Marrow Derived Porcine Stem Cells

“…The use of an animal model, such as swine, that adequately simulates the structure and physiology of humans, provides a readily available source of mesenchymal stem cells for research, and allows for improvements in therapeutic protocols [18][19][20]. Pigs have been used as a large animal model for studying human clinical therapies as diverse as heart surgery [18], genetic disorders [21], and drug testing [22]. In addition, pigs have ample subcutaneous fat which is similar to that in humans.…”