Adani R


Full name : Adani Rachel

First name : Rachel

Mail : Division of Medicinal Chemistry, Israel Institute for Biological Research, PO Box 19, Ness Ziona 74100

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Country : Israel

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References (16)

Title : Characterization of asymmetric fluorogenic phosphonates as probes for developing organophosphorus hydrolases with broader stereoselectivity - Amitai_2008_Chem.Biol.Interact_175_249
Author(s) : Amitai G , Adani R , Limanovich O , Teitlboim S , Yishay S , Tveria L , Yacov G , Meshulam H , Raveh L
Ref : Chemico-Biological Interactions , 175 :249 , 2008
Abstract : Organophosphorus hydrolases (OPH) such as mammalian plama paraoxonase (PON1) detoxify asymmetric toxic organophosphorus (OP) nerve agents by preferentially hydrolyzing the less toxic P(+) optical isomer. In order to develop new OPHs with broader stereoselectivity we have prepared a series of asymmetric fluorogenic organophosphonates (Flu-OPs). Such Flu-OPs may serve as molecular probes for screening large libraries of OP hydrolases during directed evolution. Flu-OPs were prepared as methylphosphonates (MPs) diesters containing either ethyl (E), isopropyl (I), cyclohexyl (C) or pinacolyl (P) groups that are structural congeners of the nerve agents VX, sarin, cyclosarin and soman, respectively. The second ester bond was formed with fluorescent moieties that are either 3-cyano-4-methyl-7-hydroxy coumarin (MeCyC) or 1,3-dichloro-7-hydroxy 9,9-dimethyl-9H-acridin-2-one (DDAO). To further characterize the Flu-OPs as surrogates of their respective nerve agents, we have studied the reactivation of Flu-OP-inhibited AChE using 2-PAM and toxogonin (TOX). AChE was 90-95% inhibited by all Flu-OPs (0.36-0.9(M) and then was reactivated by either 2-PAM or TOX. TOX caused a more rapid reactivation than 2-PAM with the following rank order; EMP>IMP>CMP. TOX was also shown to be a better reactivator than 2-PAM for AChE inhibited by the nerve agents VX and cyclosarin. PMP-AChE could not be reactivated by either TOX or 2-PAM, similarly to aging of PMP-AChE formed by inhibition with soman. Racemic CMP-MeCyC was used for screening two new PON1 variants from a neutral library of PON1. These multiple mutation variants include replacement of active site amino acid residues. Neither mutation in these new variants appeared in PON1 variants previously discovered by directed evolution using symmetric Flu-OP. Detoxification rate of cylcosarin by these new PON1 variants was rather slow indicating the need to further screen PON1 clones using optically active Flu-OPs. Therefore, we have separated enzymatically the P(-) enantiomer of CMP-MeCyC and determined its 98% purity using chiral HPLC.
ESTHER : Amitai_2008_Chem.Biol.Interact_175_249
PubMedSearch : Amitai_2008_Chem.Biol.Interact_175_249
PubMedID: 18588863

Title : Asymmetric fluorogenic organophosphates for the development of active organophosphate hydrolases with reversed stereoselectivity - Amitai_2007_Toxicology_233_187
Author(s) : Amitai G , Adani R , Yacov G , Yishay S , Teitlboim S , Tveria L , Limanovich O , Kushnir M , Meshulam H
Ref : Toxicology , 233 :187 , 2007
Abstract : In order to enhance the enzymatic detoxification rate of organophosphorus (OP) nerve agents we have searched for more active variants of recombinant mammalian paraoxonase (PON1). We have previously identified three key positions in PON1 that affect OP hydrolysis: Leu69, Val346 and His115, that significantly enhance the hydrolysis of cyclosarin (GF), soman, chlorpyrifos-oxon (ChPo), O-isopropyl-O-(p-nitrophenyl)methylphosphonate (IMP-pNP) and diisopropyl fluorophosphate (DFP). GC/FPD analysis compared to residual AChE inhibition assay displayed stereoselective hydrolysis of GF, soman and IMP-pNP, indicating that wild type PON1 and its variant V346A are more active toward the less toxic P(+) optical isomer. In order to obtain new PON1 variants with reversed stereoselectivity, displaying augmented activity toward the more toxic isomer P(-) of nerve agents, we synthesized new asymmetric fluorogenic OPs (Flu-OPs). Six Flu-OPs were prepared containing either ethyl (E), cyclohexyl (C) or pinacolyl (P) alkyl radicals attached to methyl-phosphonyl (MP) moiety analogous to the structure of VX, GF and soman, respectively. The fluorescent moieties are either 3-cyano-4-methyl-7-hydroxy coumarin (MeCyC) or 1,3-dichloro-7-hydroxy-9,9-dimethyl-9H-acridin-2-one (DDAO). The kinetics of AChE and BChE inhibition by these new Flu-OPs display k(i) values 8.5x10(4) to 8.5x10(7) and 5x10(4) to 2x10(6)M(-1)min(-1), respectively. EMP-MeCyC and EMP-DDAO are the most active inhibitors of AChE whereas CMP-MeCyC and CMP-DDAO are better inhibitors of BChE than AChE, indicating accommodation of bulky cyclohexyl group inside the active site of BChE. PMP-MeCyC and PMP-DDAO are the least active inhibitors of both AChE and BChE. CMP-MeCyC and CMP-DDAO were significantly detoxified only by the five-site mutations PON1 variant L69V/S138L/S193P/N287D/V346A. Degradation kinetics of Flu-OPs measured by increase in absorbance of the released fluorogenic group was fit by a two exponential function, indicating faster hydrolysis of the less toxic optical isomer. Interestingly, wt PON1 caused only 50% degradation of racemic EMP-MeCyC, CMP-MeCyC and CMP-DDAO indicating complete hydrolysis of P(+) isomer. This remarkable stereoselectivity was used for the enzymatic separation of the P(-) isomer of CMP-MeCyC. The bimolecular rate constant k(i) for human AChE inhibition by the isolated P(-) isomer of CMP-MeCyC is five-fold larger than that of its P(+) isomer. The marked preference of wt PON1 toward P(+) stereo-isomer of CMP-MeCyC and CMP-DDAO renders their P(-) stereo-isomers suitable for the selection of new OP hydrolase variants with reversed stereoselectivity.
ESTHER : Amitai_2007_Toxicology_233_187
PubMedSearch : Amitai_2007_Toxicology_233_187
PubMedID: 17129656

Title : Enhanced stereoselective hydrolysis of toxic organophosphates by directly evolved variants of mammalian serum paraoxonase - Amitai_2006_FEBS.J_273_1906
Author(s) : Amitai G , Gaidukov L , Adani R , Yishay S , Yacov G , Kushnir M , Teitlboim S , Lindenbaum M , Bel P , Khersonsky O , Tawfik DS , Meshulam H
Ref : Febs J , 273 :1906 , 2006
Abstract : We addressed the ability of various organophosphorus (OP) hydrolases to catalytically scavenge toxic OP nerve agents. Mammalian paraoxonase (PON1) was found to be more active than Pseudomonas diminuta OP hydrolase (OPH) and squid O,O-di-isopropyl fluorophosphatase (DFPase) in detoxifying cyclosarin (O-cyclohexyl methylphosphonofluoridate) and soman (O-pinacolyl methylphosphonofluoridate). Subsequently, nine directly evolved PON1 variants, selected for increased hydrolytic rates with a fluorogenic diethylphosphate ester, were tested for detoxification of cyclosarin, soman, O-isopropyl-O-(p-nitrophenyl) methyl phosphonate (IMP-pNP), DFP, and chlorpyrifos-oxon (ChPo). Detoxification rates were determined by temporal acetylcholinesterase inhibition by residual nonhydrolyzed OP. As stereoisomers of cyclosarin and soman differ significantly in their acetylcholinesterase-inhibiting potency, we actually measured the hydrolysis of the more toxic stereoisomers. Cyclosarin detoxification was approximately 10-fold faster with PON1 mutants V346A and L69V. V346A also exhibited fourfold and sevenfold faster hydrolysis of DFP and ChPo, respectively, compared with wild-type, and ninefold higher activity towards soman. L69V exhibited 100-fold faster hydrolysis of DFP than the wild-type. The active-site mutant H115W exhibited 270-380-fold enhancement toward hydrolysis of the P-S bond in parathiol, a phosphorothiolate analog of parathion. This study identifies three key positions in PON1 that affect OP hydrolysis, Leu69, Val346 and His115, and several amino-acid replacements that significantly enhance the hydrolysis of toxic OPs. GC/pulsed flame photometer detector analysis, compared with assay of residual acetylcholinesterase inhibition, displayed stereoselective hydrolysis of cyclosarin, soman, and IMP-pNP, indicating that PON1 is less active toward the more toxic optical isomers.
ESTHER : Amitai_2006_FEBS.J_273_1906
PubMedSearch : Amitai_2006_FEBS.J_273_1906
PubMedID: 16640555

Title : Bifunctional compounds eliciting anti-inflammatory and anti-cholinesterase activity as potential treatment of nerve and blister chemical agents poisoning - Amitai_2006_J.Appl.Toxicol_26_81
Author(s) : Amitai G , Adani R , Fishbein E , Meshulam H , Laish I , Dachir S
Ref : J Appl Toxicol , 26 :81 , 2006
Abstract : Certain organophosphorus (OP) nerve agents (e.g. soman) induce neuroinflammatory processes during acute poisoning. An increased level of typical inflammation markers was also observed in poisoning by alkylating agents such as sulfur mustard (HD). The therapeutic potential of new bifunctional compounds was investigated, eliciting activity of non-steroidal anti-inflammatory drug (NSAID) and anti-cholinesterase (anti-ChE) activity, as an antidotal treatment for both soman and HD poisoning in mice. Three bifunctional compounds were used that include the ChE inhibitor pyridostigmine (PYR) coupled to either ibuprofen (IBU) or diclofenac (DICLO) through an eight (octyl) or ten (decyl) hydrocarbon chain spacer: IBU-PO, IBU-PD and DICLO-PD. These compounds are 15-25 fold less toxic than PYR in mice and exert peripheral and central anti-inflammatory and anti-ChE activity in vivo. IBU-PO (4 mg kg(-1), i.p.), IBU-PD (4 mg kg(-1), i.p.) and PYR (0.13 mg kg(-1), i.p.) reduced to control levels the brain edema in soman-poisoned mice (1.1 LD50, s.c.). Pre-treatment with IBU-PO, IBU-PD and DICLO-PD 4-5 h before soman challenge (2.2-2.3 LD50, s.c.) combined with antidotal treatment (atropine, 11 mg kg(-1), 2-PAM-Cl, 25 mg kg(-1), i.m.) afforded a longer 24 h survival rate (SR) than with PYR pre-treatment. DICLO-PD exhibited the largest protection efficacy (SR = 70% vs 17% with PYR). These results indicate a longer duration of action of bifunctional compounds compared with PYR. DICLO-PD (5% in propyleneglycol) reduced significantly the HD-induced edema in mouse ear-skin (51% increase in biopsy weight compared with 100% without treatment). Quantitative evaluation of ear-skin sections showed that only following DICLO-PD treatment was there a marked decrease in edema. DICLO-PD also elicited a significant decrease in HD-induced vesication as displayed by the reduced sub-epidermal blister level. The data indicate possible use of NSAID-ChEI bifunctional compounds for the medical treatment of both nerve and alkylating chemical agents.
ESTHER : Amitai_2006_J.Appl.Toxicol_26_81
PubMedSearch : Amitai_2006_J.Appl.Toxicol_26_81
PubMedID: 16167317

Title : The anti-inflammatory and cholinesterase inhibitor bifunctional compound IBU-PO protects from beta-amyloid neurotoxicity by acting on Wnt signaling components - Farias_2005_Neurobiol.Dis_18_176
Author(s) : Farias GG , Godoy JA , Vazquez MC , Adani R , Meshulam H , Avila J , Amitai G , Inestrosa NC
Ref : Neurobiol Dis , 18 :176 , 2005
Abstract : Changes in signal transduction are implicated in neuronal responses to the Alzheimer's amyloid-beta-peptide (Abeta), which include neurotransmitter systems and pathways involved in the maintenance of the nervous system. We report here that a new bifunctional compound IBU-PO, which combines a non-steroidal anti-inflammatory drug (NSAID) (Ibuprofen) and a cholinesterase (ChE) inhibitor (Octyl-Pyridostigmine), is neuroprotective against Abeta-neurotoxicity, and its activity is associated to Wnt signaling components in rat hippocampal and mouse cortical neurons. IBU-PO (0.01-1 microM) inhibits glycogen-synthase-kinase-3beta (GSK-3beta) and stabilizes cytoplasmic beta-catenin reverting the silencing of the Wnt pathway caused by Abeta-toxicity and GSK-3beta overexpression. In addition, IBU-PO enhances, dose-dependently, the non-amyloidogenic amyloid precursor protein (APP) cleavage by increasing secreted APP and decreasing endogenous Abeta1-40 in rat hippocampal neurons.
ESTHER : Farias_2005_Neurobiol.Dis_18_176
PubMedSearch : Farias_2005_Neurobiol.Dis_18_176
PubMedID: 15649708

Title : Bifunctional compounds eliciting both anti-inflammatory and cholinergic activity as potential drugs for neuroinflammatory impairments - Nizri_2005_Neurosci.Lett_376_46
Author(s) : Nizri E , Adani R , Meshulam H , Amitai G , Brenner T
Ref : Neuroscience Letters , 376 :46 , 2005
Abstract : We tested two novel bifunctional compounds: ibuprofen-N-octyl-pyridostigmine bromide (IBU-PO) and ibuprofen-N-decyl-pyridostigmine bromide (IBU-PD). They both contain a non-steroidal anti-inflammatory drug (NSAID), ibuprofen (IBU) and pyridostigmine (PO), a cholinesterase inhibitor that acts as a cholinergic up-regulator (CURE). The two moieties are conjugated by a hydrocarbon spacer consisting of 8 (octyl) and 10 (decyl) carbons, respectively. The compounds were tested for their efficiency in reducing the neurological symptoms observed in experimental autoimmune encephalomyelitis induced in mice by myelin oligodendrocyte glycoprotein (MOG). IBU-PO and IBU-PD significantly ameliorated the clinical score (a 40-50% reduction in disease severity) over a period of 30 days, following daily administration of 1 and 0.1mg/kg, i.p., respectively. Clinical improvement was accompanied by reduced responsiveness of MOG-specific T-cells. In addition, IBU-PO and IBU-PD down-regulated the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in cultured astrocytes. To determine which moiety was responsible for these effects, we tested each of the two components, IBU and PO. Our findings indicate that combining NSAID with cholinergic intervention contributes an added therapeutic value for each distinct entity and that these bifunctional compounds act both on the peripheral immunological system and on the central nervous system (CNS) inflammatory pathways.
ESTHER : Nizri_2005_Neurosci.Lett_376_46
PubMedSearch : Nizri_2005_Neurosci.Lett_376_46
PubMedID: 15694272

Title : Bifunctional compounds eliciting both anti-inflammatory and cholinergic activity as potential drugs for CNS disorders. -
Author(s) : Amitai G , Adani R , Rabinovitz I , Beit-Yanai E , Shohami E , Sod-Moriah G , Meshulam H
Ref : Cholinergic Mechanisms, CRC Press :277 , 2004

Title : Poster (56) The bifunctional compound IBU-PO elicits prolonged anti-inflammatory and cholinesterase inhibition in vivo -
Author(s) : Amitai G , Adani R , Rabinovitz I , Shohami E , Sod-Moriah G , Meshulam H
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :350 , 2004

Title : Poster (64) Chloroperoxidases catalyzes the degradation of VX and sulfur mustard. -
Author(s) : Amitai G , Adani R , Hershkovitz M , Bel P , Rabinovitz I , Meshulam H
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :354 , 2004

Title : Poster (80) The anti-inflammatory-cholinergic bifunctional compound ibu-po protects at sub-micromolar levels rat hippocampal cells from a beta-induced apoptosis and beta-catenin depletion -
Author(s) : Godoy JA , Adani R , Meshulam H , Inestrosa NC , Amitai G
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :363 , 2004

Title : The anti-inflammatory bifunctional compound IBU-PO protects rat hippocampal neurons from A-beta-induced cytotoxicity and beta-catenin depletion -
Author(s) : Godoy JA , Adani R , Meshulam H , Inestrosa NC , Amitai G
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :135 , 2004

Title : Determination of therapeutic doses of bisquaternary oximes in large animals - Chen_2001_J.Appl.Toxicol_21_285
Author(s) : Chen R , Raveh L , Zomber G , Rabinovitz I , Cohen G , Adani R , Amitai G
Ref : J Appl Toxicol , 21 :285 , 2001
Abstract : This report presents a non-lethal method for estimating a range of therapeutic doses of bisquaternary oximes that serve as antidotes against organophosphorus poisoning. We have estimated therapeutic oxime doses that are equivalent in their relative toxicity rather than selecting arbitrary fractions of their LD(50). Thus, toxic signs of the oximes HI-6, HLo-7, Toxogonin, AB-8 and AB-13 were monitored quantitatively in baboon monkeys and beagle dogs. Using Toxogonin as a reference oxime, a calculated unit of equivalent dose (CED) was defined as the oxime dose equal to the ratio between its minimal toxic dose (MTD) and the therapeutic ratio (TR) of Toxogonin i.e. CED = MTD/TR. Assuming that the tails of dose-response curves of toxicity for bisquaternary oximes are shallow and similar to one another, one could substitute the ED(10) for the MTD. The ED(10) values for bisquaternary oximes were estimated using the log-log model following experimental observations and quantitative scoring of toxic signs in dogs and monkeys. The MTD values then were calculated using the ED(10) values and the experimental therapeutic dose of the reference oxime Toxogonin. The following CED values were obtained for AB-8, AB-13, Toxogonin, HI-6 and HLo-7 in dogs (d) and monkeys (m): 98.7, 74.2, 30.0, 14.5 and 12.1 (d) and 281.9, 232.1, 41.7, 192.9 and 92.9 (m) micromol kg(-1), respectively. The antidotal efficacy of these oximes against poisoning by the nerve agent tabun was determined in dogs and monkeys. These dose-dependent efficacy data were obtained at 0.3 x CED, 1 x CED and 3 x CED of oximes in combination with atropine. These data provide comparative therapeutic values using oxime doses based on their relative toxicity. The highest antidotal efficacy against tabun in dogs was obtained for toxogonin, whereas HLo-7 and AB-13 were most efficacious in monkeys.
ESTHER : Chen_2001_J.Appl.Toxicol_21_285
PubMedSearch : Chen_2001_J.Appl.Toxicol_21_285
PubMedID: 11481661

Title : Oxidative biodegradation of phosphorothiolates by fungal laccase - Amitai_1998_FEBS.Lett_438_195
Author(s) : Amitai G , Adani R , Sod-Moriah G , Rabinovitz I , Vincze A , Leader H , Chefetz B , Leibovitz-Persky L , Friesem D , Hadar Y
Ref : FEBS Letters , 438 :195 , 1998
Abstract : Organophosphorus (OP) insecticides and nerve agents that contain P-S bond are relatively more resistant to enzymatic hydrolysis. Purified phenol oxidase (laccase) from the white rot fungus Pleurotus ostreatus (Po) together with the mediator 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) displayed complete and rapid oxidative degradation of the nerve agents VX and Russian VX (RVX) and the insecticide analog diisopropyl-Amiton with specific activity: k(sp) = 2200, 667 and 1833 nmol min(-1) mg(-1), respectively (pH 7.4, 37 degrees C). A molar ratio of 1:20 for OP/ABTS and 0.05 M phosphate at pH 7.4 provided the highest degradation rate of VX and RVX. The thermostable laccase purified from the fungus Chaetomium thermophilium (Ct) in the presence of ABTS caused a 52-fold slower degradation of VX with k(sp) = 42 nmol min(-1) mg(-1). The enzymatic biodegradation products were identified by 31P-NMR and GC/MS analysis.
ESTHER : Amitai_1998_FEBS.Lett_438_195
PubMedSearch : Amitai_1998_FEBS.Lett_438_195
PubMedID: 9827544

Title : Inhibition of acetylcholinesterase and butyrylcholinesterase by chlorpyrifos-oxon - Amitai_1998_Biochem.Pharmacol_56_293
Author(s) : Amitai G , Moorad DR , Adani R , Doctor BP
Ref : Biochemical Pharmacology , 56 :293 , 1998
Abstract : Phosphorothionate insecticides such as parathion (O,O-diethyl O-p-nitrophenyl phosphorothioate) and chlorpyrifos (CPS; O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate; Dursban) are metabolically converted by oxidative desulfuration into paraoxon and chlorpyrifos-oxon (CPO). The insecticidal action of chlorpyrifos stems from inhibition of acetylcholinesterase (AChE) by CPO, resulting in severe cholinergic toxicity. Sensory peripheral neuropathy was observed in people exposed environmentally to chlorpyrifos sprayed in confined areas. We have examined the kinetics of inhibition of AChE and butyrylcholinesterase (BChE) by paraoxon and CPO. The bimolecular rate constants (ki) for inhibition by paraoxon of recombinant human (rH) AChE, recombinant mouse (rM) AChE, and fetal bovine serum (FBS) AChE were 7.0, 4.0, and 3.2 x 10(5) M(-1) min(-1). The ki values for the inhibition by CPO of rH AChE, fetal bovine serum AChE, human RBC AChE, Torpedo AChE, and recombinant mouse (rM) AChE were 9.3, 2.2, 3.8, 8.0, and 5.1 x 10(6) M(-1) min(-1), respectively. Inhibition of human serum BChE, rH BChE, and rM BChE by CPO yielded ki values of 1.65, 1.67, and 0.78 x 10(9) M(-1) min(-1), respectively. The ki values obtained for BChE from various species were 160- to 750-fold larger than those of AChE from parallel sources. Inhibition of the single-site mutant A328Y of rH BChE by CPO displayed a 21-fold lower rate than that of wild-type rH BChE (ki, 7.9 x 10(7) vs 1.67 x 10(9) M(-1) min(-1)). The double mutant of acyl pocket residues of rH AChE, F295L/F297V, was inhibited by CPO with a 150-fold larger ki than wild type (1.5 x 10(9) vs 1.0 x 10(7) M(-1) min(-1)). The increased rate obtained with the double mutant displaying characteristics of the BChE active center provides a rationale for higher efficacy of CPO scavenging by BChE, compared with AChE.
ESTHER : Amitai_1998_Biochem.Pharmacol_56_293
PubMedSearch : Amitai_1998_Biochem.Pharmacol_56_293
PubMedID: 9744565

Title : Quaternary-Lipophilic Carbamates with Blood Brain Barrier Permeability as Potential Drugs for the Treatment of Diseases Associated with Cholinergic Deficiency -
Author(s) : Amitai G , Adani R , Rabinovitz I , Sod-Moriah G , Brandeis R , Rachaman E , Heldman E
Ref : In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases , (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp. :277 , 1998

Title : Bisquaternary Oximes as Antidotes against Tabun and Soman Poisoning -
Author(s) : Amitai G , Rabinovitz I , Zomber G , Chen R , Cohen G , Adani R , Raveh L
Ref : In Enzyme of the Cholinesterase Family - Proceedings of Fifth International Meeting on Cholinesterases , (Quinn, D.M., Balasubramanian, A.S., Doctor, B.P., Taylor, P., Eds) Plenum Publishing Corp. :345 , 1995