Bradykinin is a nonapeptide (sequence: H-Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg-OH, MW 1060.56) and a key mediator in the kinin-kallikrein system. It potently induces vasodilation (lowering blood pressure), increased vascular permeability, smooth muscle contraction, pain, and inflammation. As a high-purity research reagent (>98% purity, white to off-white solid), bradykinin is widely used in pharmacological and physiological studies to investigate inflammation mechanisms, pain pathways, endothelial function, and cardiovascular responses. It is also employed in diagnostic tests for hereditary angioedema (where excess bradykinin drives pathology) and to assess vascular health. Bradykinin receptor modulators are targets for analgesics, anti-inflammatories, and treatments for angioedema and hypertension.