CHEMICAL AND PHARMACOLOGICAL CHARACTERIZATION OF THE ALKALOIDS OF THE SKIN OF Epipedobates flavopictus (ANURA, DENDROBATIDAE)

Mortari, M.R.; Schwartz, C.A.; Schwartz, E.F.; Santos, M.M.; Sebben, A. 

Laboratório de Toxinologia, Departamento de Ciências Fisiológicas – Instituto de Ciências Biológicas – Universidade de Brasília, Brasília, Brasil

Objectives: The objectives of the present work were to isolate and to characterize, chemical and pharmacologically the most abundant alkaloids present in the cutaneous secretion of Epipedobates flavopictus.

Methods: The specimens were collected in Pirenópolis (Goias State, Brazil), their skins were removed and the alkaloids extracted with methanol. The alkaloids were purified by HPLC and each fraction was identified by gas chromatography and mass spectrometry. The crude extract and the identified fractions were tested on isolated frog sciatic nerve by the technique of "sucrose gap" and on isolated guinea pig ileum muscle.  

Results: Pumiliotoxin 251Da, histrionicotoxin 285Da and two decahydroquinolines: 219A and 243A were identified in E. flavopictus cutaneous secretion. The crude extract and the pumiliotoxin 251Da produced similar effects on frog sciatic nerve such as a prolongation of the potential and an elevation of the relative potential. Both produced rhythmic contractions and increased the muscular tension on isolated guinea pig ileum. Histrionicotoxin285Da and decahydroquinolines did not produced any effect on sciatic nerve or guinea pig ileum probably due to their low toxicity and also to the small amount obtained by purification.

Conclusions: In the present work we demonstrated the presence of Pumiliotoxin 251Da, histrionicotoxin285Da and two decahydroquinolines: 219A and 243A in the cutaneous secretion of the dendrobatidae frog Epipetobates flavopictus.

CORRESPONDENCE TO:

Sebben, A., Laboratóriode Toxinologia, Departamento de Ciências Fisiológicas – Instituto de Ciências Biológicas – Universidade de Brasília, Brasília, 70910-900, DF, Brasil, Email: sebben@unb.br