Trypsin and rosmarinic acid reduce the toxicity of Micrurus fulvius venom in mice

Abstract

Context. Antivenom is expensive and not always available, so alternative treatments are being investigated. Objective. The efficacy of trypsin or rosmarinic acid (RA) in treating Micrurus fulvius in a murine model is determined. Materials and methods. Design: randomized controlled blinded study. Subjects: Fifty mice (20–30 g). Study groups: Intraperitoneal injections of: 1) 2 mg/kg M. fulvius venom (approximately twice the LD50 for mice; n = 10); 2) 2 mg/kg M. fulvius venom incubated in vitro for 1 h prior to injection with RA at a 1:10 ratio (n = 17); 3) 2 mg/kg M. fulvius venom incubated in vitro for 1 h prior to injection with 1 mg of trypsin (n = 17); 4)1 mg trypsin IP without venom (n = 3); and 5) RA IP without venom (n = 3). Main outcome: time to toxicity (respiratory distress (< 25 breaths/min.), loss of spontaneous locomotor activity, or inability to upright self). Statistical analysis: Time to toxicity using Tukey–Kramer HSD; Survival to 4, 6, and 12 h using Chi-square analysis. Results. Onset of toxicity: venom + saline, 120.3 + 64.4 min; venom + rosmarinic acid, 238.1 ± 139.2 min (p = 0.15 relative to venom + saline); venom + trypsin, 319.7 + 201.0 min (p = 0.007 relative to venom + saline). Venom + trypsin but not venom + RA survival to 4 h was significant compared to venom + saline (p = 0.023). Two mice in the venom + trypsin group and one mouse in the venom + RA group survived to 12 h. Mice receiving trypsin without venom or RA without venom survived to 12 h without toxicity. Discussion. This work suggests that trypsin and RA may have efficacy in treatment M. fulvius envenomation. Conclusion. In vitro neutralization of M. Fulvius venom by trypsin justifies progressing to an in vivo model in future studies.

Keywords:

• Snakebites
• Rosmarinic acid
• Trypsin