Status epilepticus INDUCED BY MARINOBUFAGIN, A BUFADIENOLIDE ISOLATED FROM Bufo paracnemis  LUTZ (1925) PAROTID GLANDS SECRETIONS

Nogueira, R.M.D.(1), Costa, D.C. (1), Patrocínio, M.C.A. (1), Camarão, G.C. (1), Uchoa, D.E.A. (2), Silveira, E.R. (2), Scorza, F.A. (3), Santos, N.F. (3), Cavalheiro, E.A. (3), Carvalho, K.M. (4)

(1)Departamento de Fisiologia e Farmacologia, UFC, CE, (2)Química Orgânica e Inorgânica, UFC, CE, (3)Neurologia Experimental, UNIFESP, SP, (4)Ciências Fisiológicas, UECE, CE.

Objectives: The main focus of this research was the isolation of a substance with a strong convulsant action from  Bufo paracnemis Lutz (1925) parotid glands secretions, determination of  its chemical structure  and  its behavioral and electrographic effects on  central nervous system.

Methods and Results: This substance was purified  in large amounts  using a  reverse-phase high-performance liquid chromatography, with a C-18 preparative column. Its chemical structure was elucidated using high resolution Nuclear  Magnetic Resonance analysis, allowing its identification as a steroid of the bufadienolide type, already known in the literature as Marinobufagin (14b-15b-epoxy-3b,5b-dihidroxy-20,22-bufadienolide). Our results based on behavioral and electrographic  analysis  showed central effects induced by systemic administration of Marinobufagin in rats and mice. The animals presented severe neurotoxic effects, tonic-clonic seizures and death. MarinobufaginDL₅₀ was 10.5 ± l.5 mg/kg for mice and 25.0 ± 2.0 mg/kg for rats, both through intraperitoneal injection. This strong convulsant activity is dose-dependent and 5.0 mg/kg doses for mice and 20.0 mg/kg for rats, both intraperitoneal (IP), already showed behavioral changes that evolved to generalized tonic-clonic seizures. Marinobufagin induced seizures that ended up in status epilepticus that lasted more than an hour. Seizures decreased in almost 80% of the animals treated with Diazepan  (10.0 and 12.5 mg/kg, IP) even though some of these animals continued to show seizures in the electrographic recordings. Seizures induced by Marinobufagin were not affected by Phenobarbital. Phenitoin was able to block generalized tonic-clonic  seizures in all animals  of the group.

Conclusions: Our results suggest that Marinobufagin could represent a pharmacological tool for the development of an epilepsy experimental model, since it had fulfilled the following requirements: i) Marinobufagin induced epileptiform activity in electrographic recordings, ii) seizures were blocked by anticonvulsant drugs such as Diazepan and Phenitoin, an essential requirement for the evaluation of the effects of new drugs to be used in epilepsy treatment.

CORRESPONDENCE TO:

Rita Maria Dantas Nogueira, Rua José Vilar 2220 Apto 102, Fortaleza, CE, CEP: 60125-001, Brasil, Email: rita_mdnog@hotmail.com