Toxicity of Vipera palaestinae venom and antagonistic effects of methanolic leaf extract of Eryngium creticum lam.

Vipera palaestinae is responsible for many venomous incidents in the Middle East. However, this species is not included in the antigenic pool of venoms for the production of the regionally available polyvalent antivenoms. In an attempt to develop a potential complementary alternative therapy for snakebite patients, this study is investigating the antagonistic effect of Eryngium creticum against V. palaestinae venom. In this context, the concentration of the venom as well as the electrophoretic profile, and the venom LD₅₀ were determined by intraperitoneal injection (ip). The methanolic leaf extract was prepared, and its safety on rats was examined. Adult male Sprague-Dawley rats were divided into 8 groups (n = 6); G1-G3 were injected subplantar in the right hind paws with 2.5, 3.125, and 3.75 mg kg^-1 then 200 mg kg^-1 extract ip. G4-G6 were given the same venom dose with no extract, respectively. Controls were G7 that only had the extract ip, and G8 that was injected subplantar with PBS. The swollen paws were measured at Hour 0 (before injection), Hour 1, Hour 6, and Hour 24. IL-6 and TNF-α were measured in serum using ELISA. Histopathological changes were examined in paw sections. The pooled venom concentration was 176.93 ± 35.81 mg ml^-1, revealed 10 protein bands (5-80 kDa), and the LD₅₀ via ip rout was 6.56 mg kg^-1. Paw edema peaked at Hour 1. At Hour 6, edema in G1 was significantly reduced (p < 0.05) compared to G6, while at Hour 24 there was no significant difference between all groups including the controls. Treated animals in G1-G3 expressed IL-6 significantly lower (p < 0.001) than untreated G4-G6, respectively. Levels of TNF-α in G1 and G2 were significantly (p < 0.001) lower than G3-G6, while G5 and G6 were significantly (p < 0.001) higher than G1-G4. Histopathological changes showed intensifying edema, hemorrhage, and inflammation with incrementing venom doses. Sections from treated animals expressed less adverse changes compared to untreated animals. Together, the outcomes are encouraging future utilization of E. creticum as a supportive remedy for snakebite cases.