CONICET | Buscador de Institutos y Recursos Humanos

Amphibian skins contain biologically active compounds such us alkaloids; whose most probably function is passive chemical defense against predators or microorganisms. Reports of the presence of alkaloids in the anurans are continuously increasing. In Argentina, Córdoba, several were characterized from the skin of Melanophryniscus stelzneri. New alkaloids were identified from other Melanophryniscus of the northeast and northwest Argentina. M. rubriventris is endemic from the eco-region of Andean Yungas, restricted to the provinces of Salta and Jujuy. Artemia salina larvae were used in bioassays, and results of LC50 tests were published for several toxins and known chemicals. The objective of the study was to determine the LC50 and acute toxicity after 24 h of exposure to alkaloids of the skin of M. rubriventris on larvae of Artemia salina and test the susceptibility of these organisms to different compound concentrations. The skins preserved in 100% methanol were cut in small pieces and triturated. Alkaloids extraction followed standard protocols. Larvae were exposed to different compound concentrations and the LC50 and adverse effects were determined. Every test was conducted three times. LC50 were determined graphically representing percent of larvae mortality by concentration of the substance to test. After 24 h, mortality of the control group was 0%. At a 0,16 mg/ml concentration mortality reached 1%; at 0,2 mg/ml mortality was 3%; at 0,26 mg/ml 30%, at 0,4 mg/ml 60%, and at 0,8 mg/ml 100%. The minimal concentration tested that showed adverse effects on Artemia larvae was 0,16%. The results confirm the susceptibility of aquatic invertebrates to the alkaloids of the skin of M. rubriventris. The LC50 from the alkaloids extract under the study conditions was 0,33 mg/ml.

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