Advances in the development of bradykinin receptor ligands

Kinins are blood-derived local-acting peptides that elicit specific cellular effects via the stimulation of two related G protein coupled receptors. While the B-2 receptor subtype, constitutively expressed in various tissues, is believed to mediate most of the physiological actions of kinins in healthy conditions, the B-1 receptor, highly regulated during inflammation, has been associated with the sustained actions of these peptides in various pathological situations. Potent peptide and nonpeptide modulators of both kinin receptors have been produced as pharmacological tools and potential therapeutics over the last three decades. More recently, the accumulating evidence suggesting that B-1 receptor blockade could be useful for the treatment of pain and inflammatory disorders has led to a shift in drug development efforts toward the synthesis of orally bioavailable nonpeptide B-1 receptor antagonists. Nonpeptide ligands of either receptor subtype produced by several industrial organizations often possess significant structural commonalities that can lead to the definition of a pharmacophore, especially when the receptor docking models are compared. The field of kinin receptors ligands research has reached an exciting step of its history, as the near future will reveal whether these molecules are therapeutically beneficial in various human diseases. This review will concisely summarize our current understanding of the biology of kinins and their receptors, before discussing the recent medicinal chemistry developments and challenges that bring new kinin receptor ligands closer to clinical applications.