RESUMEN
The inhibition of acetylcholinesterase (AChE) is a common outcome caused by organophosphorus (OPs) intoxication. Although inconsistent, the standard treatment consists of a muscarinic receptor antagonist (atropine) and AChE-reactivating molecules such as oximes. This study proposes to test unpublished compounds which contain the moieties of isatin and/or oxime have protective effects against the toxicity induced by malathion in two animal models: Artemia salina and Rattus norvegicus (Wistar rats). The lethality was assessed in A salina, and the calculated LD50 to (3Z)-5-chloro-3-(hydroxyimino) indolin-2-one oxime (Câ-HIN) and 2-(5-chloro-2-oxoindolin-3-ylidene)-hydrazinecarbothioamide (Câ-OXHS) was higher than 1000 µM while to 3-(phenylhydrazono) butan-2-one oxime (PHBO) was 38 µM. Our screening showed that Câ-HIN seems to be the most promising molecule, with low toxicity to A salina, protection against mortality (with or without atropine) and AChE inhibition induced by malathion. Similarly, the oral administration of 300 mg/kg of Câ-HIN induced low or no toxicity in rats. The plasma butyrylcholinesterase (BChE) and cortical AChE activities were reactivated by Câ-HIN (50 mg/kg, p.o.) in rats exposed to malathion (250 mg/kg, i.p). No difference was observed in paraoxonase-1 (PON-1) activity among groups treated. In conclusion, Câ-HIN restored the cholinesterase activities inhibited by malathion in A salina and rats with low toxicity in both. Thus, the data provide evidence that Câ-HIN, a compound that combines isatin and oxime functional groups, is safe and has important properties to reactivate the cholinesterases inhibited by malathion. In addition, we demonstrate the importance of a preliminary assessment in an alternative model in order to reduce the use of mammalians in drug discovery.
Asunto(s)
Inhibidores de la Colinesterasa/toxicidad , Isatina/farmacología , Malatión/toxicidad , Oximas/farmacología , Animales , Artemia , Reactivadores de la Colinesterasa/administración & dosificación , Reactivadores de la Colinesterasa/química , Reactivadores de la Colinesterasa/farmacología , Modelos Animales de Enfermedad , Descubrimiento de Drogas/métodos , Femenino , Insecticidas/toxicidad , Isatina/administración & dosificación , Isatina/química , Dosificación Letal Mediana , Masculino , Oximas/administración & dosificación , Oximas/química , Ratas , Ratas WistarRESUMEN
Isatin (1H-indole-2,3-dione) is a synthetically versatile substrate used for the synthesis of heterocyclic compounds and as a raw material for drug synthesis. Isatin and its derivatives demonstrate anticonvulsant, antibacterial, antifungal, antiviral, and anticancer properties. We evaluated the genotoxic and mutagenic effects of acute (24h) and repeated (14d) exposure to isatin in vivo, using the comet assay and the micronucleus test. Three doses (50, 100, and 150mg/kgb.w.) were administered to mice via gavage. Doses were selected according to the LD(50) of isatin, estimated in a preliminary test to be 1g/kgb.w. To evaluate the results, parametric (ANOVA/Tukey) and non-parametric (Kruskal-Wallis/Dunn's post hoc test) tests were used, according to the nature of the data distribution. At all doses (50, 100 and 150mg/kgb.w.), after acute treatment with isatin, alterations in DNA migration (comet assay) were not observed and mutagenic effects were not seen (micronucleus test on peripheral blood cells). After repeated doses, only the highest dose of isatin (150mg/kgb.w.) induced alterations in the DNA that gave rise to micronuclei in the bone marrow and peripheral blood cells of the mice. Our results show that the mutagenic and genotoxic effects of isatin depend on dose and on period of exposure.