Development of small bisquaternary cholinesterase inhibitors as drugs for pre-treatment of nerve agent poisonings

Pharmacological prophylaxis with pyridostigmine bromide against nerve agents adversely impact on airway function in an ex vivo rat precision-cut lung slice model

The carbamate pyridostigmine bromide (PB) is the only fielded pharmacological prophylaxis for military use against nerve agents. Previous studies have shown differences in the PB-pretreatment efficacy for various nerve agents and in the influence of post-exposure treatment with common antidotes. In the present study, the aim was to evaluate the possibility of using an ex vivo rat precision-cut lung slice model to determine the impact of PB pretreatment on VX-induced bronchoconstriction. In addition, the efficacy of post-exposure treatment with atropine sulfate following PB-prophylaxis was investigated.Bronchoconstriction was induced by electric-field stimulation and was significantly aggravated by 10 µM PB. Airway recovery was decreased by both 1 and 10 µM PB. Evaluation of acetylcholineesterese inhibition by PB showed that the lower concentration met the clinical criteria of residual enzyme activity while the higher concentration completely inhibited the activity. Exposure to VX with or without pretreatment demonstrated similar contractions. However, VX-incubation following pretreatment caused decreased airway relaxation compared to pretreatment alone. Atropine treatment following PB- and VX-exposure significantly decreased the maximum airway contraction and increased the relaxation.In conclusion, no beneficial effect of PB-prophylaxis on VX-induced contractions was observed. The atropine efficacy to relax airways was significant demonstrating the importance of efficient post-exposure therapeutics to protect against the life-threatening respiratory contractions.

para-Selective C-H Borylation of Aromatic Quaternary Ammonium and Phosphonium Salts

Aromatic ammonium and phosphonium salts are important synthetic intermediates and multifunctional materials, but para-selective functionalization of the aromatic salts remains a challenge. Here we develop an ionic ligand based on our newly designed "biphenyl-phenanthroline" skeleton and realize the Ir-catalyzed para-selective C-H borylation of seven types of aromatic quaternary ammonium and phosphonium salts. Gram-scale transformation, late-stage elaboration for drug molecule, and diversification of borylated products demonstrate the potential utility of this reaction. The mechanistic studies and computational analysis elucidate the origin of para-selectivity.

Pharmacokinetics of K117 and K127, two novel antidote candidates to treat Tabun poisoning

AIMS

K117 and K127 are bis-pyridinium aldoximes but K117 is a bis-pyridinium bis-aldoxime while K127 has only one single aldoxime in addition to its amide substituent. Is there any difference in pharmacokinetics in these compounds that otherwise have the same chemical structure? Both K117 and K127 are developed as antidotes in acetylcholinesterase and butyrylcholinesterase poisoning in terrorist attacks or intoxication with other organophosphorous compounds. Their distributions have been scouted in the bodies of rats.

MAIN METHODS

White male Wistar rats were intramuscularly injected. The animals were sacrificed, tissue samples were homogenized, and either K117 or K127 concentrations were determined using reversed-phase high-performance liquid chromatography.

KEY FINDINGS

Both K117 and K127 were present in all tissues that were analyzed including blood (serum), the brains, cerebrospinal fluid, the eyes, livers, kidneys, lungs and testes. Their pharmacokinetics and body distributions are similar.

SIGNIFICANCE

Either K117 or K127 meets the essential requirements for antidotes. Dose dependence and kinetics of their distribution were compared to that of other pyridinium aldoximes.