Antimicrobial Profile of Selected Snake Venoms and Their Associated Enzymatic Activities.

Aims: To investigate the antiviral and antibacterial profile of several crude snake venoms and to assess some of their enzymatic activities. Methodology: The antiviral activities of Naja haje, Bitis arietans, Naja nigricollis and Echis carinatus snake venoms were investigated against Herpes simplex virus type1, Rift valley fever virus and Vesicular stomatitis virus using the end point of cytopathic effect method. Antibacterial activities of Bitis arietans, Cerastes cerastes, Echis carinatus, Vipera lebetina, Naja naja, Pseudechis australis, Naja nigricollis and Naja haje venoms were examined against Staphylococcus aureus, Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa using disc diffusion method. Microdilution method was used to determine the venom's minimum inhibitory concentration. L-amino acid oxidase and phospholipase A2 activities of crude venoms were evaluated using enzymatic assays. Results: Naja nigricollis, Bitis arietans and Echis carinatus snake venoms exhibited significant antiviral activities against all test viruses, except for N. haje treated cells. The mean depletion of viral infectivity titer of venom pretreated cells was higher than its depletion post viral infection for all three venoms showing antiviral activities. Naja nigricollis exhibited the highest antiviral activity against test viruses and recorded a mean depletion of viral infectivity titer in venom pretreated cells of 3.8 log (10) / ml , 3.2 log (10) / ml and 2.5 log (10) / ml for HSV-1, RVFV and VSV, respectively. Pseudechis australis, followed by Naja naja and Naja nigricollis venoms, showed the highest inhibitory activity against test bacteria with inhibition zones ranging from 11-17 mm, 8-14 mm and 8-13 mm, respectively. Minimum inhibitory concentrations of test venoms against different bacterial strains ranged from 156 μg / ml to 1.25 mg / ml. Maximum L- amino oxidase activity was detected in Naja naja, Cerastes cerastes and Pseudechis australis. The highest Phospholipase A2 activity was identified in Bitis arietans, Pseudechis australis, Naja naja and Naja nigricollis. Conclusion: It can be concluded that snake venoms or their bioactive derivatives can be promising therapeutic agents against some microbial infections. Further investigations will be carried out for purification and more characterization of the biologically active components in snake venoms.

Antimicrobial activity of an L-amino acid oxidase isolated from Bothrops leucurus snake venom

Some snake venom proteins present enzymatic activities, such as L-amino acid oxidase (LAAO). The aim of this paper was to investigate the effect of Bothrops leucurus total venom (BleuTV) and its fraction LAAO (BleuLAAO) on bacteria, yeast, and promastigote forms of Leishmania amazonensis and Leishmania chagasi, and epimastigote forms of Trypanosoma cruzi. BleuTV was isolated with a Protein Pack 5PW® (Waters Corporation, USA), and several fractions were obtained. BleuLAAO was purified to high molecular homogeneity, and its N-terminal amino acid sequence shared a high degree of amino acid conservation with other LAAOs. BleuTV inhibited Staphylococcus aureus growth in a dose-dependent manner, with a minimum inhibitory concentration (MIC) of 25 ìg/mL, which corresponded to its minimum lethal concentration (MLC). BleuTV also inhibited the growth of promastigote forms of L. chagasi and L. amazonensis, with respective IC50 values of 1.94 ìg/mL and 5.49 ìg/mL. Furthermore, it repressed T. cruzi growth with an IC50 of 1.14 ìg/mL. However, BleuLAAO did not inhibit the growth of the microorganisms studied and was not toxic to macrophages. BleuTV had low toxicity against macrophages at the concentrations studied. In conclusion, whole venom from Bothrops leucurus inhibited the growth of some microorganisms, including S. aureus, Leishmania sp., and T. cruzi.