Background: Argenteohyla siemersi (red-spotted
Argentina frog) is a casque-headed
tree frog species
belonging to the Hylidae
family . This species has a complex combination of anti-predator
defense mechanisms that include a highly lethal
skin secretion . However, biochemical composition and
biological effects of this
secretion have not yet been studied.
Methods: The A. siemersi
skin secretion samples were analyzed by
mass spectrometry and chromatographic
analysis (
MALDI -TOF/MS, RP-
HPLC and GC-MS).
Proteins were also studied by
SDS-PAGE . Among the
biological activities evaluated, several enzymatic activities (hemolytic,
phospholipase A2 , clotting, proteolytic and amidolytic) were assessed. Furthermore, the cytotoxic activity (cytolysis and
fluorescence staining ) was evaluated on
myoblasts of the C2C12
cell line .
Results: The
MALDI -TOF/MS
analysis identified
polypeptides and
proteins in the aqueous
solution of A. siemersi
skin secretion .
SDS-PAGE revealed the presence of
proteins with molecular masses from 15 to 55 kDa.
Steroids , but no
alkaloids or
peptides (less than 5 KDa), were detected using
mass spectrometry .
Skin secretion revealed the presence of
lipids in methanolic extract, as analyzed by CG-MS. This
secretion showed hemolytic and
phospholipase A2 activities, but was devoid of amidolytic, proteolytic or clotting activities. Moreover,
dose -dependent cytotoxicity in cultured C2C12
myoblasts of the
skin secretion was demonstrated. Morphological
analysis , quantification of
lactate dehydrogenase release and
fluorescence staining indicated that the
cell death triggered by this
secretion involved
necrosis .
Conclusions: Results presented herein evidence the biochemical composition and
biological effects of A. siemersi
skin secretion and contribute to the
knowledge on the
defense mechanisms of casque-headed frogs.