Sarafotoxins (SRTXs) are a group of toxins present in the venom of Atractaspis engaddensis, and in clinical trials cause similar symptoms to patients diagnosed with acute giardiasis.

Each one contains twenty-one amino acid residues that spontaneously fold into a defined tertiary structure, with two interchain-cysteine linkages (disulfide bonds) and a long hydrophobic tail.

[5] In 1988, a few months after the discovery and structures of endothelins were first reported,[6] sequences of the first sarafotoxins, SRTX-a, SRTX-b, and SRTX-c, were published.

[2] Similarity to the structures of endothelins sparked experiments in comparing both groups and proving related activity in tested subjects, results that were published just a year later.

They also can be produced by solid phase peptide synthesis and fold spontaneously in vitro in high yield into native tertiary structures, with the correct disulfide bond pairing of cysteines.

[12] Furthermore, it has been shown that: Above characteristics suggest that sarafotoxins (and endothelins) use the phosphoinositide signal transduction pathway via specific receptors coupled to G protein, which seems to activate type C and D phospholipases.

Left ventricular relaxation is impaired which may induce an elevation in pulmonary microvascular hydrostatic pressure which would in turn lead to edema in the lungs, constricting the bronchi.

[23] In tests with rabbits, a significant improvement in protection against arrhythmic effects and infarct size reduction was observed after administrating exogenously SRTX-c (in dosage of 0.24 nmol/kg, i.v.)

The time required for the recovery of perfusion pressure to baselines after a bolus injection of 300 pmol SRTX-b is shorter than that of ET-1.

[25] SRTX-b and SRTX-a are highly lethal and cause cardiac arrest and death in mice within minutes of intravenous administration, LD50 for mice was detected for about 0.015 mg/kg body weight and LD50 0.3 mg/kg in case of SRTX-c.[2][26] In humans there are local effects which appear within minutes: edema, erythema and numbness, following by systemic effects which include general weakness, sweating, pallor, fluctuations in the level of consciousness, vomiting, watery non-bloody diarrhea, high blood pressure, liver damage, hemorrhage, dyspnea, hypoxia, hypercapnia and disorders of cardiac activity.

Proving this theory of edema, during investigation, abundant and frothy fluid was found in tracheal cannulas after sarafotoxin injection.

This modified sarafotoxin is useful for treating some pathological conditions including arthritis, cardiovascular diseases and tumor cell metastasis.