Peptide Database
265 therapeutic peptides with research summaries, clinical findings, and regulatory status.
Octreotide (Sandostatin)
A synthetic octapeptide analog of somatostatin with a substantially longer half-life (90 minutes IV, 6 hours subcutaneous vs. 2 minutes for native somatostatin). Octreotide binds somatostatin receptors (primarily SSTR2 and SSTR5) to inhibit the secretion of GH, glucagon, insulin, gastrin, secretin, VIP, and other GI hormones. It reduces splanchnic blood flow, GI motility, and exocrine pancreatic secretion.
Lanreotide (Somatuline Depot)
A synthetic octapeptide analog of somatostatin with high affinity for SSTR2 and moderate affinity for SSTR5 receptors. Lanreotide is formulated as a supersaturated solution that forms a drug depot at the injection site, providing sustained release over 4 weeks. It inhibits GH secretion, GI hormone release, and has direct antiproliferative effects on neuroendocrine tumor cells through cell cycle arrest and apoptosis induction.
Pasireotide (Signifor)
A multireceptor-targeted somatostatin analog with high binding affinity for SSTR1, SSTR2, SSTR3, and SSTR5, particularly notable for its 40-fold greater affinity for SSTR5 compared to octreotide. This receptor profile makes pasireotide uniquely effective in Cushing's disease, where corticotroph adenomas predominantly express SSTR5. Pasireotide suppresses ACTH secretion from pituitary corticotroph tumors, reducing cortisol production.
Plecanatide (Trulance)
A synthetic 16-amino acid peptide structurally related to uroguanylin, an endogenous intestinal peptide that regulates fluid and electrolyte homeostasis in the GI tract. Plecanatide activates guanylate cyclase-C (GC-C) receptors on intestinal epithelial cells in a pH-dependent manner, preferentially in the proximal small intestine where pH is slightly acidic. GC-C activation increases intracellular and extracellular cGMP, stimulating chloride and bicarbonate secretion while reducing visceral pain signaling.
Linaclotide (Linzess)
A synthetic 14-amino acid peptide structurally related to the heat-stable enterotoxin of Escherichia coli and the endogenous peptide guanylin. Linaclotide activates guanylate cyclase-C (GC-C) on the luminal surface of intestinal epithelium, increasing intracellular cGMP to stimulate CFTR-mediated chloride and bicarbonate secretion, accelerating intestinal transit. Extracellular cGMP also reduces firing of visceral afferent pain fibers, providing analgesic effects in the gut.
Secretin
A 27-amino acid peptide hormone produced by S-cells of the duodenal and jejunal mucosa in response to acidic chyme entering the small intestine. Secretin stimulates pancreatic ductal cells to secrete bicarbonate-rich fluid, neutralizing duodenal acid, and promotes bile flow from hepatocytes. It was the first hormone ever identified (Bayliss and Starling, 1902) and serves as a key diagnostic tool in gastroenterology and endocrinology.
Larazotide
A synthetic octapeptide derived from Vibrio cholerae zonula occludens toxin that acts as a tight junction regulator. Larazotide acetate modulates intestinal permeability by preventing zonulin-mediated opening of tight junctions between enterocytes. By reducing paracellular permeability, it aims to prevent gluten peptide translocation across the intestinal barrier in celiac disease, reducing the immune-mediated inflammatory response triggered by gluten exposure.
Glucagon Receptor Antagonist Peptides
Glucagon receptor antagonist peptides are a class of molecules designed to block the glucagon receptor and prevent glucagon-mediated hepatic glucose output. These peptides typically consist of modified glucagon analogs with substitutions that convert agonist activity to antagonism. The therapeutic rationale focuses on lowering blood glucose in type 2 diabetes by reducing hepatic gluconeogenesis and glycogenolysis. Structural modifications also enhance metabolic stability and receptor selectivity.
Motilin
Motilin is a 22-amino acid endogenous peptide hormone secreted by enteroendocrine cells in the duodenum and jejunum. It binds to motilin receptors on gastrointestinal smooth muscle and enteric neurons, stimulating phase III migrating motor complexes and promoting gastric emptying. The therapeutic rationale for exogenous motilin or receptor agonists includes treatment of gastroparesis and postoperative ileus. Erythromycin acts as a motilin receptor agonist, demonstrating the clinical relevance of this pathway.
Cholecystokinin (CCK)
Cholecystokinin is an endogenous peptide hormone existing in multiple forms, most commonly as CCK-8 and CCK-33, secreted by I-cells in the duodenum and jejunum. It binds to CCK-1 and CCK-2 receptors to stimulate gallbladder contraction, pancreatic enzyme secretion, and satiety signaling. Therapeutic interest centers on diagnostic imaging applications and potential treatments for obesity and functional gastrointestinal disorders. The peptide also plays neuromodulatory roles in the central nervous system.
Gastrin
Gastrin is an endogenous peptide hormone secreted by G-cells in the gastric antrum and duodenum, existing primarily as gastrin-17 and gastrin-34. It binds to the CCK-2 receptor on parietal and enterochromaffin-like cells, stimulating gastric acid secretion and promoting gastric mucosal growth. Therapeutic applications have focused on gastrin analogs for diagnostic purposes and investigation of gastrin immunotherapy for gastrin-dependent tumors. Dysregulation of gastrin secretion occurs in conditions such as Zollinger-Ellison syndrome and atrophic gastritis.
Peptide YY (PYY 3-36)
Peptide YY 3-36 is a 34-amino acid endogenous peptide hormone secreted by L-cells in the distal small intestine and colon in response to nutrient intake. It acts primarily on the Y2 receptor in the hypothalamus to reduce appetite and slow gastric emptying, functioning as part of the ileal brake mechanism. The therapeutic rationale for exogenous PYY 3-36 administration centers on treatment of obesity through appetite suppression. Circulating levels are reduced in obesity and elevated after bariatric surgery.
Ghrelin Receptor Antagonists
Ghrelin receptor antagonists are a class of peptides and peptidomimetics designed to block the growth hormone secretagogue receptor (GHSR), also known as the ghrelin receptor. Ghrelin is a 28-amino acid orexigenic peptide that stimulates appetite and promotes food intake. By antagonizing GHSR, these agents aim to reduce hunger signals and promote satiety, with therapeutic potential in obesity and metabolic disorders. The class includes both peptide-based molecules and small-molecule antagonists targeting the same receptor.
Guanylin
Guanylin is a 15-amino acid endogenous peptide hormone that activates guanylate cyclase-C (GC-C) receptors on intestinal epithelial cells. Upon binding, it stimulates intracellular cyclic GMP production, which regulates chloride and bicarbonate secretion into the intestinal lumen and promotes fluid secretion. This mechanism enhances intestinal motility and fluid balance. Guanylin functions as a paracrine regulator of intestinal homeostasis and salt-water equilibrium.
Uroguanylin (Dolcanatide)
Uroguanylin is a 16-amino acid endogenous peptide structurally related to guanylin that also activates guanylate cyclase-C receptors in the intestinal epithelium. It regulates fluid and electrolyte secretion in the gut and plays a role in satiety signaling and metabolic homeostasis. The synthetic analog dolcanatide has been developed to mimic uroguanylin's effects with enhanced stability and bioavailability. Like guanylin, uroguanylin increases cyclic GMP levels, promoting intestinal secretion and motility.