Enzymatic characterization and proteomic profiling of venoms from the medically important Androctonus species

Egyptian scorpions of the Androctonus genus (family Buthidae) produce life-threatening stings owing to their neurotoxic venom. However, the composition and enzymatic activities of their venoms remain poorly understood: We used electrophoresis to analyze the protein components of venoms collected from three Androctonus species: Androctonus amoreuxi, Androctonus australis, and Androctonus bicolor. Mass spectrometric analysis was performed to characterize the peptides present in these venoms. The phospholipase A₂ (PLA₂), hyaluronidase, and protease activities of the venoms were examined to gauge their potential contribution to venom toxicity. Finally, the antibacterial and hemolytic activities of the venoms were evaluated. The electrophoretic profiles of the three venoms showed features specific to each species, with distinct protein bands observed at 75, 74, 67, 48, 46, 40, and 28 kDa, along with a notable band above the 15-kDa mark. Liquid chromatography/mass spectrometry analyses were used to detect the presence of 369, 324, and 351 components in with molecular masses in the range of 500-10,000 Da in the venoms of A. amoreuxi, A. australis, and A. bicolor, respectively. Disulfide-rich peptides (three disulfide bridges) were abundant, but peptides without disulfide bonds were also detected in all venom samples. All three venoms exhibited hyaluronidase activities, whereas protease and PLA₂ activities were either weak (at 1 µg and 10 µg) or undetectable, even at higher concentrations (up to 20 µg). All assays were performed using venoms standardized by dry weight to ensure consistent protein quantities. Crude venoms of A. amoreuxi and A. australis showed antibacterial activity against E. coli and B. subtilis (5-10 μg), whereas A. bicolor required 10 μg. Hydrophobic fractions (40-55 min) of A. australis alone retained this activity. This work furthers our knowledge of the enzymatic and peptide composition of Androctonus venoms, unveiling their potential in drug delivery enhancement and other biomedical applications. These findings will inform the development of better strategies for the treatment and prevention of scorpion envenomation.