Evaluation of antidotal effects of adamantyl derivative Tamorf in soman poisoning

Qualitative GC-MS Assessment of TCP and Tamorf Elimination in Rats

Nerve agents are highly toxic organophosphorus (OP) compounds. They inhibit acetylcholinesterase (AChE), an enzyme that hydrolyses acetycholine (ACh) in the nervous system. Pathophysiological changes caused by OP poisonings are primarily the consequence of surplus ACh on cholinergic receptors and in the central nervous system. Standard treatment of OP poisoning includes combined administration of carbamates, atropine, oximes and anticonvulsants. In order to improve therapy, new compounds have been synthesised and tested. Tenocyclidine (TCP) and its adamantane derivative 1-[2-(2-thienyl)-2-adamantyl] morpholine (TAMORF) have shown interesting properties against soman poisoning. In this study, we developed a qualitative GC-MS method to measure elimination of TCP and TAMORF through rat urine in order to learn more about the mechanisms through which TCP protects an organism from OP poisoning and to determine the duration of this protective effect. GC-MS showed that six hours after treatment with TCP, rat urine contained only its metabolite 1-thienylcyclohexene, while urine of rats treated with TAMORF contained both TAMORF and its metabolites.

Irinotecan side effects relieved by the use of HI-6 oxime: in vivo experimental approach

Some compounds, although not primarily designed as supportive drugs in chemotherapy, are promising candidates for clinical use. The ability of HI-6 oxime to relieve the side effects of irinotecan was recently determined in vitro. In this animal study, we investigated the efficacy of HI-6 in vivo, when given as a pre-treatment and concomitantly with irinotecan. We evaluated the cholinesterase (ChE)/acetylcholinesterase (AChE) activity, the levels of oxidative stress markers, DNA damage and the radical scavenging capacity of HI-6. Both HI-6 and irinotecan inhibited ChE/AChE activity but showed different levels of ChE inhibition in plasma and AChE inhibition in the liver and brain tissue. We also observed a weak antioxidant capacity of HI-6, undiscovered until now, and found an acceptable genotoxicity profile in three types of somatic cells in rats. The in vivo erythrocyte micronucleus assay showed that HI-6 did not significantly change either the frequency of micronuclei or the ratio of polychromatic and normorchromatic erythrocytes. Taken together, our results provide a good argument in favour of HI-6 as a promising molecule for further studies and eventual use in humans.

Mechanisms of Organophosphate Toxicity and Detoxication with Emphasis on Studies in Croatia

This review comprises studies on the mechanisms of toxicity and detoxication of organophosphorus (OP) compounds done in Croatia in different research areas. One area is the synthesis of antidotes against OP poisoning and their in vivo testing in experimental animals. In vitro studies included in this review focus on the mechanisms of reversible inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), protection of cholinesterases from inhibition by OPs, and reactivation of phosphylated cholinesterases. The third area comprises distribution profiles of BChE and paraoxonase (PON) phenotypes in selected population groups and the detection of OPs and metabolites in humans. Finally, methods are described for the detection of OP compounds in human blood and other media by means of cholinesterase inhibition.

In vitro biological efficiency of tenocyclidine – TCP and its adamantane derivative TAMORF

Tenocyclidine-TCP showing a broad spectrum of pharmacological activity including antidotal effect in organophosphorus compounds poisoning, radioprotective and anticancer effects. We investigated in vitro interactions of TCP and its adamantane derivative--TAMORF with human erythrocyte acetylcholinesterase (AChE). Moreover, their genotoxicity and radioprotective activity on human white blood cells were studied using the alkaline comet assay, viability testing and the analysis of the structural chromosome aberrations. The tested compounds were found to be weak inhibitors of AChE, for TCP IC(50)=1 x 10(-5)M and for TAMORF IC(50)>1 x 10(-3)M, without reactivating and protective effects on AChE inhibited by soman. Results suggest that TCP modified by the replacement of the cyclohexyl ring with an adamantly ring and piperidine with morpholine group (TAMORF) have lower toxicity. Both compounds possess low cytotoxicity and radioprotective activity, but TAMORF also shows cell growth inhibitory effects. To clarify differences in their biological efficiency observed in vitro and in vivo, additional analyses are necessary. Since TAMORF was found to significantly inhibit cell growth and proliferation in vitro, it is reasonably to consider it as a source molecule promising for further modifications and development of more potent substances with antitumor properties rather then radioprotector or antidote in organophosphorus poisoning.