Pepsin A (PGA) (PGA)

Pepsin A is the primary aspartic protease in the human stomach, responsible for the initial digestion of proteins into smaller peptides (UniProt P00790). It is synthesized and secreted as the inactive precursor pepsinogen by gastric chief cells, becoming active only in the highly acidic environment of the stomach (pH 1.5 to 2.5) (StatPearls: Physiology, Pepsin). Beyond its physiological role in digestion, pepsin is a key mediator of tissue damage in extra-gastric sites during reflux episodes, such as in gastroesophageal reflux disease (GERD) and laryngopharyngeal reflux (LPR) (PubMed: 24276064). In these conditions, pepsin remains stable in the larynx or esophagus and can be reactivated by subsequent acid exposure, leading to mucosal injury. Niclosamide, an anthelmintic drug, has been shown in biophysical research to bind to pepsin, effectively inhibiting its proteolytic activity through competitive or non-competitive mechanisms (Spectrochimica Acta Part A, 2015, 137:1316-1323). This interaction suggests that niclosamide or its derivatives could potentially be explored for mitigating pepsin-induced damage in reflux-related disorders, although its primary clinical use remains the treatment of parasitic infections (PubChem CID 4477).

Other names

PepsinPepsin A-3Pepsinogen AGastric pepsin

Inhibition of the catalytic activity of the aspartic protease, preventing the cleavage of peptide bonds in dietary proteins or host tissues.