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A novel peptide, Cm39, was identified in the venom of the scorpion Centruroides margaritatus . Its primary structure was determined. It consists of 37 amino acid residues with a MW of 3980.2 Da. The full chemical synthesis and proper folding of Cm39 was obtained. Based on amino acid sequence alignment with different K + channel inhibitor scorpion toxin (KTx) families and phylogenetic analysis, Cm39 belongs to the α-KTx 4 family and was registered with the systematic number of α-KTx 4.8. Synthetic Cm39 inhibits the voltage-gated K + channel hK V 1.2 with high affinity (K d = 65 nM). The conductance-voltage relationship of K V 1.2 was not altered in the presence of Cm39, and the analysis of the toxin binding kinetics was consistent with a bimolecular interaction between the peptide and the channel; therefore, the pore blocking mechanism is proposed for the toxin-channel interaction. Cm39 also inhibits the Ca 2+ -activated K Ca 2.2 and K Ca 3.1 channels, with K d = 502 nM, and K d = 58 nM, respectively. However, the peptide does not inhibit hK V 1.1, hK V 1.3, hK V 1.4, hK V 1.5, hK V 1.6, hK V 11.1, mK Ca 1.1 K + channels or the hNa V 1.5 and hNa V 1.4 Na + channels at 1 μM concentrations. Understanding the unusual selectivity profile of Cm39 motivates further experiments to reveal novel interactions with the vestibule of toxin-sensitive channels.

Among other scorpion species, Colombia has two genera of the Buthidae family Centruroides and Tityus, considered to be dangerous to humans. This research shares scientific knowledge aiming to a better understanding about the pathophysiological effects of such venoms. The venom of the three species: Centruroides margaritarus , Tityus pachyurus , and T . n. sp. aff. metuendus with biomedical interest were studied. An initial pre-glycemic sample was taken from ICR mice. They were later intraperitoneally inoculated with doses of 35% and 70% of LD 50 of total venom. Poisoning signs were observed during a 6-h period to determine the level of scorpionism. After observation, a second glycemic sample was taken, and a histopathological evaluation of different organs was performed. This work revealed that all three venoms showed considerably notorious histopathological alterations in main organs such as heart and lungs; and inducing multiple organ failure, in relation to the glycemia values, only C. margaritatus and T. n. sp. aff. metuendus showed significant changes through manifestation of hyperglycemia. According to the Colombian scorpionism level; signs were mild to severe affecting the autonomous nervous system.

The Colombian scorpion Centruroides margaritatus produces a venom considered of low toxicity. Nevertheless, there are known cases of envenomation resulting in cardiovascular disorders, probably due to venom components that target ion channels. Among them, the human ether-à-go-go-Related gene (hERG1) potassium channels are critical for cardiac action potential repolarization and alteration in its functionality are associated with cardiac disorders. This work describes the purification and electrophysiological characterization of a Centruroides margaritatus venom component acting on hERG1 channels, the CmERG1 toxin. This novel peptide is composed of 42 amino acids with a MW of 4792.88 Da, folded by four disulfide bonds and it is classified as member number 10 of the γ-KTx1 toxin family. CmERG1 inhibits hERG1 currents with an IC 50 of 3.4 ± 0.2 nM. Despite its 90.5% identity with toxin ɣ-KTx1.1, isolated from Centruroides noxius , CmERG1 completely blocks hERG1 current, suggesting a more stable plug of the hERG channel, compared to that formed by other ɣ-KTx.

Centruroides margaritatus scorpion stings are common in Colombia. However, the cardiovascular toxicity of the venom has not been clarified., Aim: To study the effect and mechanisms of action of the complete venom of C. margaritatus (CmV) on the murine cardiovascular system., Methods: We evaluated the in vivo effect of CmV LD50 on the mean arterial pressure (MABP), heart rate, and surface electrocardiogram in male adult normotensive Wistar rats. Ex vivo, we evaluated the vascular reactivity of rat aortic rings to increasing concentrations (1 to 60 μg/mL) of CmV using the blockers L-NAME, indomethacin, seratrodast, and prazosin., Results: In the first hour of poisoning, CmV increased the MABP. In the second hour after poisoning, the heart rate decreased as the normalized PR interval and QT corrected increased. After that, cardiovascular shock was demonstrated by a drastic fall in the MABP and signs of cardiac conduction system block. In aortic rings, CmV caused a direct vasoconstrictor effect mediated by alpha-1 adrenergic receptors and counteracted by nitric oxide., Conclusion: The direct vascular and probably the cardiac alpha-1 effects likely explain the transient hypertension and the maintenance of cardiac function, while interval lengthening may be due to K + channel blockage. Afterwards, the effects of both the alpha-1 pathway and the K + channel pathway converged, resulting in fatal cardiovascular shock. This knowledge could aid in understanding the dynamics of the effects of the venom and in designing treatments to address its cardiovascular effects., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Scorpion venom causes renal injury and affects vascular ion-channels function. Centruroides margaritatus scorpion is found in Colombia and is frequently the cause of envenomation accidents; however, its renal impact has never been investigated., Objective: To evaluate the effects of C. margaritatus venom (CmV) on renal parameters using isolated rat kidney and renal cell culture models., Methods: Wistar rats (n = 5, weighing 240-300 g) were first perfused with Krebs-Henseleit solution containing 6 g 100 mL-1 bovine serum albumin. After 30 minutes, the kidneys were perfused with CmV to a final concentration of 10 μgmL-1; evaluation was performed by measuring Perfusion Pressure (PP), Renal Vascular Resistance (RVR), Urinary Flow (UF), Glomerular Filtration Rate (GFR), and percentage of electrolyte tubular transport. Moreover, kidney histological analyses and cell cytotoxicity in renal tubule epithelial cells (MDCK) and proximal tubular cells (LLC-MK2) were assessed., Results: CmV increased PP and RVR 60 min after perfusion. On the other hand, UF, GFR, and the percentages of sodium, potassium and chloride tubular transport decreased after experimental envenomation. UF dropped after 120 min, while GFR and percentage of electrolyte tubular transport diminished after 60, 90 and 120 min. CmV was not toxic to MDCK cell line but reduced the viability of LLC-MK2 cells at concentrations ranging from 6.25 to 200 μgmL-1. Histological analyses disclosed hydropic degeneration, edema, and protein deposits. Flow cytometry disclosed that cell death occurred predominantly by necrosis., Conclusion: Our results suggest that C. margaritatus venom can trigger renal impairment, mainly in the proximal kidney tubule., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)