Scorpion Peptide SjAPI-2 Blocks the Complement Immune Cascade by Binding C4 and Limits Heart Damage in an Animal Model
Researchers at Hubei University of Medicine reported in Biomolecules on October 19, 2026 that SjAPI-2, a small peptide from scorpion venom, inhibited the classical complement pathway, part of the immune system that can damage the body's own tissue, by binding the complement proteins C4 and C4b. Mapping showed a loop between residues K30 and V38 does the work, and the peptide limited heart muscle damage in an ischemia-reperfusion injury model. The authors describe it as the first anti-complement peptide reported from scorpions; the work is preclinical.