Effect of metoclopramide and ranitidine on the inhibition of human AChE by VXin vitro

Abstract

The repeated misuse of highly toxic organophosphorus-type (OP) chemical warfare agents ('nerve agents') emphasizes the necessity for the development of effective medical countermeasures. The standard treatment with atropine and acetylcholinesterase (AChE) reactivators ('oximes') is considered to be ineffective with certain nerve agents due to low oxime efficacy. Therefore, pretreatment with carbamate-type compounds, e.g. pyridostigmine, was recommended to improve antidotal efficacy. Recently, the clinically used reversible AChE inhibitors metoclopramide (MCP) and ranitidine (RAN) were shown to exhibit some protective effect against the OP pesticide paraoxon in vitro and in vivo. The present study was undertaken to investigate a potential protective effect of MCP and RAN against inhibition of human AChE by the nerve agent VX (O-ethyl S-[2-(diisopropylamino)ethyl)methylphosphonothioate). Hemoglobin-free human erythrocyte membranes were incubated with various, human relevant MCP (0.5-2 microm) and RAN (0.5-5 microm) concentrations starting 1 min before addition of VX (1-40 nm). Both compounds failed to increase VX IC(50) values. In addition, human AChE was incubated with higher than human relevant therapeutic concentrations of MCP (1 microm-1 mm) and RAN (1 microm-2.0 mm) and inhibited by 40 nm VX. At concentrations higher than 100 microm MCP and RAN caused a concentration dependent increase of residual AChE activity 15 min after addition of VX. These data indicate that MCP and RAN may be ineffective in protecting human AChE against inhibition by the nerve agent VX at human relevant doses.

Protein Biomarkers for in Vitro Testing of Embryotoxicity

“…ID 50 , IC 50 D3, and IC 50 3T3 values are denoted together with the lower and the upper bound of the respective confidence interval. The ID50 and IC 50 values were confirmed in an independent second run (data not shown). According to expert recommendations (Reprotect), 4 the following in vivo classifications were defined: Category 1 ) strong teratogen (teratogenic in all species tested, in the absence of maternal toxicity), Category 2 ) moderate teratogen (teratogenic in some species, in the absence of maternal toxicity), Category 3 ) mild teratogen (teratogenic, but at approximately the same dosage as maternal toxicity), Category 4 ) nonteratogen.…”

“…The analysis of dose-response curves was done in the R statistical computing environment (R Development Core Team, 2009) using the R package drc. 8 In a similar fashion as ID 50 , IC 50 D3 and IC 50 3T3 are defined as 50% loss of ES cell viability or of 3T3 cell viability, respectively. To determine cytotoxic effects on ES and 3T3 cells, MTT-assays were performed in the absence of mLIF as described previously.…”

“…In another part of this project, the involvement of the G3BP in developmental toxicity-related pathways has been confirmed. 63 Taken together, this work describes a first characterization of a novel surrogate protein biomarker signature which is now 50 , concentration of test chemical reducing cell viability by 50%; ID 50 , "inhibition of differentiation", concentration of test chemical reducing contracting cardiomyocytes by 50%; IP 3 , inositol 1,4,5-trisphosphate; LIF, leukemia inducing factor; MAPK, mitogen-activated protein kinase; MALDI-TOF, matrix-assisted laser desorption ionization-time-of-flight; MeHgCl, methyl-mercury chloride; MEK, MAPK/Erk kinase, MAPK/Erk kinase, tyrosine/threonine kinase that activates the extracellular signal regulated kinases (ERK); mESC, murine embryonic stem cells; NCBI, National Center for Biotechnology Information; OECD, Organisation for Economic Co-operation and Development; PDB, Brookhaven Protein Data Bank; PIR, database of translated GenBank nucleotide sequences; PI3K, phosphoinositide 3-kinase; PMF, peptide mass fingerprint; PRF, protein sequence database by Protein Research Foundation, Osaka; Q-TOF, quadrupole timeof-flight mass spectrometer; Raf, family of proto-oncogene serine/threonine-protein kinases (rapidly growing fibrosarcoma or rat fibrosarcoma); Ran, Ras-related nuclear protein, member of the Ras superfamily; RanBP, Ran binding protein; Ras GTPas,: Rat sarcoma superfamily of guanosine triphosphate hydrolyzing enzymes; REACH, (European Union Regulation for) Registration, Evaluation, Authorisation and Restriction of Chemicals; RefSeq, Reference Sequence database of publicly available nucleotide sequences (DNA, RNA) and their protein translations; ReProTect, Integrated Project of the EU on "Development of a novel approach in hazard and risk assessment or reproductive toxicity by a combination and application of in vitro, tissue and sensor technologies"; PBS, phosphate buffered saline; SDS, sodium dodecyl sulfate; Swiss-Prot, biological database of protein sequences by the Swiss Institute of Bioinformatics and the European Bioinformatics Institute; Tris, tris(hydroxymethyl)-aminomethane; VPA, valproic acid.…”

Synthesis and in silico evaluation of 1N-methyl-1S-methyl-2-nitroethylene (NMSM) derivatives against Alzheimer disease: to understand their interacting mechanism with acetylcholinesterase

“…The Lig_1 (ID: 9725121), Lig_3 (ID: 10377907), and Lig_4 (ID: 10377911) are already available in ChemSpider database and are shown to be with anti-AChE activity, which is confirmed through their SIM-BIOSYS LASSO score (http://www.chemspider.com). The remaining Lig_2, Lig_5, and Lig_6 are novel compounds shown to be one of the derivatives of Ranitidine [54] and abovementioned group. The two-dimensional structures of all compounds are shown in Fig.…”

Ranitidine in Acute High‐Dose Organophosphate Exposure in Rats: Effect of the Time‐Point of Administration and Comparison with Pyridostigmine

“…However, in vitro results obtained by the Worek group in Germany working with organophosphonates (nerve agents) were less encouraging (Bartling et al . 2005).…”