Characterization of O,O-diethylphosphoryl oximes as inhibitors of cholinesterases and substrates of phosphotriesterases
摘要:
Reactivators of organophosphate (OP)-inhibited cholinesterases (ChEs) are believed to give rise to phosphorylated oximes (POX) that reinhibit the enzyme. Diethylphosphoryl oximes (DEP-OX) that were generated In situ were demonstrated in the past to be unstable, yet were more potent inhibitors of acetylcholinesterase (AChE) than the parent OPs. In view of the inconsistencies among reported results, and the potential toxicity of POXs, it seemed important to characterize authentic DEP-OXs, and to evaluate their interference with reactivation of diethylphosphoryl-ChE (DEP-ChE) conjugates. To this end, the diethylphosphoric acid esters of 1-methyl-2-pyridinium carboxaldehyde oxime (DEP-2PAM) and 1-methyl-4 pyridinium carboxaldehyde oxime (DEP-4PAM) were synthesized and chemically defined. The half-lives of DEP-2PAM and DEP-4PAM in 10 mM Tris buffer, pH 7.8, at 29 degrees were found to be 10 and 980 sec, respectively. The two DEP-OXs inhibited ChEs with the following ranking order: for DEP-2PAM, human butyrylcholinesterase (HuBChE, k(i) = 2.03 x 10(9) M-1 min(-1)) > mouse AChE (MoAChE) congruent to fetal bovine serum AChE (FBS-AChE) congruent to equine BChE (EqBChE); for DEP-4PAM, WuBChE (k(i) = 0.71 x 10(9) M-1 min(-1)) > EqBChE > MoAChE > FBS-AChE. A dialkylarylphosphate hydrolase (phosphotriesterase; PTE) from Pseudomonas sp. catalyzed the hydrolysis of DEP-4PAM with k(cat)/K-m = 3.56 x 10(7) M-1 min(-1) and K-m = 0.78 mM. Reactivation of DEP-ChEs was enhanced by PTE when di-PAM-based oximes were used as reactivators, whereas reactivation with 2-PAM-based oximes was not affected by PTE. This observation is attributed primarily to the short half-life of DEP-OXs derived from the latter oximes. Relatively low doses of PTE can detoxify large quantities of DEP-OXs rapidly, and thereby augment the efficacy of antidotes that contain the oxime function in position 4 of the pyridine ring. (C) 1999 Elsevier Science Inc.
Ionic liquids and their use in extraction processes
申请人:BP p.l.c.
公开号:EP1854786A1
公开(公告)日:2007-11-14
There is provided a process for the extraction of at least one aromatic compound from a mixture with at least one aliphatic hydrocarbon, which process comprises contacting said mixture with a salt that is in a liquid state at a temperature below 150°C, said salt having a cation which comprises an aromatic nitrogen-containing heterocyclic ring system, in which a nitrogen atom forming part of said ring system is quaternised and in which said ring system is substituted by at least one electron-withdrawing substituent. Some of said salts are novel.
Liquid bleaching composition components are claimed which comprise
1) amphiphilic copolymers which include structural units which are derived from
a) acryloyldimethyltauric acid in free, partially neutralized or completely neutralized form with mono- or divalent inorganic or organic cations and
b) at least one hydrophobic comonomer based on ethylenically unsaturated polyalkylene alkoxylates and optionally
c) further at least monovinylically unsaturated comonomers different from a) and b), and
2) at least one bleach activator, bleach catalyst or oxygen transfer agent.