Muscle and skin necrotizing and edema-forming activities of Duvernoy’s gland secretion of the xenodontine colubrid snake Philodryas patagoniensis from the North-east of Argentina

Abstract

Philodryas patagoniensis is a colubrid snake spread throughout South America, but very little is known about the composition and biological activities of its Duvernoy’s gland secretion. In order to characterize it, we studied edematogenic, dermonecrotic, and myonecrotic activities. For edematogenic activity, solutions containing different amounts of secretion were injected subcutaneously in the right foot pad of mice; both feet were subsequently cut off and weighed individually. For myonecrotic activity, mice were injected intramuscularly with solutions containing 40 μg of secretion, and at various time intervals mice were bled to determine serum creatine kinase activity and gastrocnemius muscles were removed for microscopic examination (Hematoxylin–Eosin stain). For dermonecrotic activity, solutions containing different amounts of secretion were injected into the shaved dorsal skin of mice; the necrotic lesion was measured on the inner surface of the skin and trimmed for microscopic examination (Hematoxylin–Eosin stain). Phospholipase A2 activity was evaluated using a kinetic method. Results showed that P. patagoniensis Duvernoy’s gland secretion exhibits high edematogenic activity and moderate myonecrotic and dermonecrotic activities, while lacking phospholipase A2 effect. Regarding edema, a 30% increase in the weight was produced by injecting 0.26 mg of Duvernoy’s gland secretion. Microscopically, myonecrosis reached its highest intensity 12 h after injection, which was also demonstrated by serum creatine kinase levels. Dermonecrosis was proportional to the amount of secretion injected, with a minimum necrotizing dose of 15.7 mg. Myonecrotic, edematogenic, and dermonecrotic activities were inhibited when the secretion was pre-incubated with 1 mM Na₂EDTA. This suggests that the enzymes responsible for those activities are mostly metalloproteinases. All the studies carried out up to now demonstrate the potential toxicity of P. patagoniensis Duvernoy’s gland secretion (which inhabits the northeast region of Argentina) and that the local lesions caused by this colubrid snake are very similar to those found in bothropic accidents. This latter suggests a more careful evaluation of the victims when considering the medical treatment to be adopted.