GlyH-101

The cystic fibrosis (CF) gene encodes a cAMP-regulated chloride channel, the CF transmembrane conductance regulator (CFTR). CFTR inhibitor II, also known as GlyH-101, is a glycine hydrazide that selectively and reversibly blocks the CFTR channel (K_i = 4.3 μM). This compound binds to a site at the external pore of CFTR, occluding the pore and rapidly preventing chloride transport. Intraluminal CFTR inhibitor II greatly reduces intestinal fluid secretion induced by cholera toxin. It is effective in cells in culture and also in nasal and intestinal epithelia in vivo.

A cell-permeable glycinyl hydrazone compound that acts as a potent, selective and reversible open-channel blocker of CFTR with intermediate speed (<1 min; 95% inhibition at 50 μM; K_i = 4.3 μM in CFTR-expressing FRT cells for apical membrane Cl^- current) and exhibits desirable aqueous solubility. Shown to produce inwardly rectifying CFTR Cl^- currents with reduced mean channel open time and suggested to directly interact with the channel pore at the extracellular side of the membrane. Displays minimal effects on P-glycoprotein and non-CFTR-mediated Cl^- currents, and is effective in nasal and intestinal epithelia in vivo.