BQ-123

**BQ‑123** is a synthetic cyclic pentapeptide originally isolated from the fermentation broth of *Streptomyces misakiensis* in 1991. It acts as a potent and selective antagonist of the endothelin A (ETA) receptor, with an IC50 of approximately 7.3 nM. By blocking ETA receptors, BQ‑123 inhibits the vasoconstrictive and hypertensive effects mediated by endothelin‑1 (ET‑1). It has been widely used as a biochemical tool to study endothelin receptor function and vascular biology, particularly in models of hypertension, ischemia-induced acute renal failure, coronary artery disease, and myocardial infarction. While it demonstrates antihypertensive effects in animal models by reducing total peripheral resistance, its clinical development status remains investigational[1][2][3][4][5][8].

Other names

cyclo(D-trp-D-asp-pro-D-val-leu)cyclo(-D-Trp-D-Asp-Pro-D-Val-Leu-)cyclo[D-alpha-aspartyl-L-prolyl-D-valyl-L-leucyl-D-tryptophyl]136553-81-6