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3 Acta Biochimica Polonica

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Tenocyclidine treatment in soman-poisoned rats - intriguing results on genotoxicity versus protection

100%

Petek M. J. , Berend S. , Kopjar N. , Zeljezic D. , Mladinic M. , Radic B. , Vrdoljak A. L.

Acta Biochimica Polonica

2008

tom 55

nr 1

This study aimed to evaluate the antidotal potency of tenocyclidine (TCP) that probably might protect acetylcholinesterase (AChE) in the case of organophosphate poisoning. TCP was tested alone as a pretreatment or in combination with atropine as a therapy in rats poisoned with ¼ and ½ of LD50 of soman. Possible genotoxic effects of TCP in white blood cells and brain tissue were also studied. Results were compared with previous findings on the adamantyl tenocyclidine derivative TAMORF. TCP given alone as pretreatment, 5 min before soman, seems to be superior in the protection of cholinesterase (ChE) catalytic activity in the plasma than in brain, especially after administration of the lower dose of soman. Plasma activities of the enzyme after a joint treatment with TCP and soman were significantly increased at 30 min (P < 0.001) and 24 h (P = 0.0043), as compared to soman alone. TCP and atropine, given as therapy, were more effective than TCP administered alone as a pretreatment. The above therapy significantly increased activities of the enzyme at 30 min (P = 0.046) and 24 h (P < 0.001), as compared to controls treated with ¼ LD50 of soman alone. Using the alkaline comet assay, acceptable genotoxicity of TCP was observed. However, the controversial role of TCP in brain protection of soman-poisoned rats should be studied further.

Evaluation of HI-6 oxime: potential use in protection of human acetylcholinesterase inhibited by antineoplastic drug irinotecan and its cyto-genotoxicity in vitro

100%

Radic B. , Vrdoljak A. L. , Zeljezic D. , Fuchs N. , Berend S. , Kopjar N.

nr 3

The function of acetylcholinesterase (AChE) is the rapid hydrolysis of the neurotransmitter acetylcholine (ACh), which is involved in the numerous cholinergic pathways in both the central and the peripheral nervous system. Therefore, AChE measurement is of high value for therapy management, especially during the course of intoxication with different chemicals or drugs that inhibit the enzyme. Pyridinium or bispyridinium aldoximes (oximes) are able to recover the activity of the inhibited enzyme. Since their adverse effects are not well elucidated, in this study the efficiency of HI-6 oxime in protection and/or reactivation of human erythrocyte AChE inhibited by the antineoplastic drug irinotecan as well as its cyto/genotoxicity in vitro were investigated. HI-6 was effective in protection of AChE and increased its activity up to 30%; the residual activity after irinotecan inhibition was 7%. Also, it reactivated the enzyme previously inhibited by 50% irinotecan (4.6 µg/ml) applied at ¼ of the IC50 value. The tested concentrations of HI-6 exhibited acceptable genotoxicity towards white blood cells, as estimated by the alkaline comet assay, DNA diffusion assay and cytogenetic endpoints (structural chromosome aberrations and cytokinesis-block micronucleus assay). The results obtained warrant the further investigation of HI-6 in vivo, as well as its development for possible application in chemotherapy.

A conjugate of pyridine-4-aldoxime and atropine as a potential antidote against organophosphorus compounds poisoning

84%

Lovric J. , Berend S. , Vrdoljak A. L. , Radic B. , Katalinic M. , Kovarik Z. , Zeljezic D. , Kopjar N. , Rast S. , Mesic M.

Acta Biochimica Polonica

2011

tom 58

nr 2

A conjugate of pyridine-4-aldoxime and atropine (ATR-4-OX) was synthesized and its antidotal efficiency was tested in vitro on tabun- or paraoxon-inhibited acetylcholinesterase (AChE) of human erythrocytes as well as in vivo using soman-, tabun- or paraoxon-poisoned mice. Its genotoxic profile was assessed on human lymphocytes in vitro and was found acceptable for further research. ATR-4-OX showed very weak antidotal activity, inadequate for soman or tabun poisoning. Conversely, it was effective against paraoxon poisoning both in vitro and in vivo. All animals treated with 5 % or 25 % LD50 doses of the new oxime survived after administration of 10.0 or 16.0 LD50 doses of paraoxon, respectively. Based on the persistence of toxicity symptoms in mice, the atropine moiety had questionable effects in attenuating such symptoms. It appears that ATR-4-OX has a therapeutic effect related to the reactivation of phosphylated AChE, but not to receptor antagonization.