Peptide Database

BK · Kallidin precursor fragment

Bradykinin is a 9-amino-acid vasoactive peptide of the kinin-kallikrein system. It produces vasodilation, increased vascular permeability, pain, and inflammation by acting on B1 and B2 receptors. ACE inhibitors (a major drug class) lower blood pressure partly by preventing bradykinin degradation. Icatibant, a B2 antagonist, is approved for hereditary angioedema. Research also implicates bradykinin in COVID-19 pathology (bradykinin storm hypothesis).

CCK · CCK-8

Cholecystokinin (CCK) is a peptide hormone produced by duodenal I-cells and neurons in the CNS. It triggers gallbladder contraction, pancreatic enzyme secretion, and potently suppresses appetite via vagal nerve CCK1 receptors. In the brain, CCK neurons modulate anxiety, pain, memory consolidation, and dopamine release. CCK antagonists are studied for anxiety and pain; CCK agonists for obesity and eating disorders.

Corticotropin-Releasing Hormone · Corticotropin-Releasing Factor

CRH is a 41-amino-acid neuropeptide produced in the hypothalamus that drives the HPA axis stress response. It stimulates ACTH release from the anterior pituitary, ultimately triggering cortisol secretion. Beyond stress regulation, CRH receptors (CRHR1, CRHR2) are distributed throughout the brain and gut, mediating anxiety, depression, immune function, and GI motility. CRH antagonists are under development for anxiety, depression, and irritable bowel syndrome.

N-hexanoic-Tyr-Ile-(6) aminohexanoic amide · PNB-0408

Dihexa is a small peptide derived from angiotensin IV that acts as a potent agonist at the HGF/c-Met receptor system, which mediates synaptogenesis — the formation of new synaptic connections. Animal studies suggest it may be several orders of magnitude more potent than BDNF at promoting synapse formation. Research focuses on Alzheimer's disease, cognitive decline, and traumatic brain injury.

ET-1 · Big endothelin-1

Endothelin-1 (ET-1) is a 21-amino-acid vasoconstrictor peptide produced primarily by vascular endothelial cells. It is the most potent endogenous vasoconstrictor known, acting through ETA and ETB receptors on vascular smooth muscle and endothelium. Elevated ET-1 is implicated in pulmonary arterial hypertension, heart failure, and renal disease — driving the development of endothelin receptor antagonists (bosentan, ambrisentan, macitentan) as clinical drugs.

Byetta · Bydureon

Exenatide is a GLP-1 receptor agonist derived from exendin-4, a peptide found in Gila monster saliva. The first GLP-1 RA approved for type 2 diabetes, it established the GLP-1 drug class. Extended-release formulations (Bydureon) allow once-weekly dosing. Emerging research explores repurposing for Parkinson's disease, where small trials show motor improvement, and Alzheimer's disease neuroprotection.

GAL

Galanin is a 29-30 amino acid neuropeptide widely distributed throughout the CNS and peripheral nervous system. It modulates memory, mood, pain, seizures, appetite, and sleep via three receptor subtypes (GALR1–3). Research focuses on its roles in Alzheimer's disease (galanin hyperinnervation of cholinergic neurons), depression, epilepsy, and eating behavior. Both agonists and antagonists have therapeutic potential depending on the target condition.

Pralmorelin · Growth Hormone-Releasing Peptide 2

GHRP-2 is a synthetic hexapeptide and potent ghrelin receptor agonist that stimulates growth hormone release from the pituitary. It produces a strong GH pulse with some elevation of cortisol and prolactin at higher doses. Research includes GH deficiency diagnosis, body composition, sleep quality, and appetite stimulation via its ghrelin-mimetic mechanism.

C₄₅H₅₅N₉O₆ · 817.99 Da

Growth Hormone-Releasing Peptide 6 · His-DTrp-Ala-Trp-DPhe-Lys-NH₂

GHRP-6 is one of the original synthetic GHRPs, acting as a strong ghrelin receptor agonist. It produces robust GH release accompanied by significant appetite stimulation — a property that makes it both valuable for cachexia research and distinct from cleaner GHRPs like Ipamorelin. Research also shows cytoprotective and cardioprotective properties independent of GH secretion.

C₄₆H₅₆N₁₂O₆ · 873.02 Da

Glucose-dependent Insulinotropic Polypeptide · Gastric Inhibitory Polypeptide

GIP is a 42-amino-acid incretin hormone secreted by duodenal K-cells in response to fat and carbohydrate ingestion. Like GLP-1, it enhances glucose-dependent insulin secretion. Unlike GLP-1, it also promotes insulin secretion during hypoglycemia, protects β-cells, and at high doses may stimulate glucagon in a glucose-independent manner. The GIP receptor's role in energy homeostasis underlies the efficacy of dual GIP/GLP-1 agonists like tirzepatide.

GCG

Glucagon is a 29-amino-acid pancreatic alpha-cell hormone and physiological counter-regulator to insulin. It raises blood glucose through hepatic glycogenolysis and gluconeogenesis and is also lipolytic and thermogenic at supraphysiological doses. FDA-approved for hypoglycemia rescue and GI relaxation, it is now a major drug design target as a component of dual (GLP-1/glucagon) and triple agonists for obesity and NASH treatment.

GnRH · Gonadotropin-Releasing Hormone

Gonadorelin is a synthetic decapeptide identical to endogenous GnRH. When administered in pulsatile fashion it stimulates LH and FSH release from the pituitary, driving gonadal testosterone and estrogen production. Clinically used for diagnosing hypothalamic-pituitary dysfunction, treating hypogonadotropic hypogonadism, and inducing ovulation. Paradoxically, continuous administration causes receptor downregulation and hormonal suppression — the basis of GnRH agonist therapy in prostate cancer.

NNC 26-0161

Ipamorelin is a selective growth hormone secretagogue and ghrelin receptor agonist. Unlike other GHRPs, it stimulates GH release with high selectivity — producing minimal cortisol, ACTH, or prolactin elevation. It is among the most studied GHRPs for its clean GH pulse profile, making it a preferred research peptide for GH axis studies with reduced side effect concern.

C₃₈H₄₉N₉O₅ · 711.86 Da

Victoza · Saxenda

Liraglutide is a once-daily GLP-1 receptor agonist approved for type 2 diabetes (Victoza) and obesity (Saxenda). It achieves fatty acid attachment to albumin for extended half-life, enabling daily dosing. The LEADER trial established significant cardiovascular mortality benefit in high-risk patients, and research continues into neuroprotective and anti-inflammatory properties beyond metabolic indications.

Hypocretin-1 · OXA

Orexin A (Hypocretin-1) is a 33-amino-acid neuropeptide produced exclusively by lateral hypothalamic neurons. It promotes wakefulness, arousal, and energy expenditure via OX1R and OX2R receptors, and its deficiency (due to autoimmune destruction of orexin neurons) is the cause of narcolepsy with cataplexy. Orexin receptor antagonists (suvorexant, lemborexant) are approved for insomnia; orexin agonists are under development for narcolepsy.

Bremelanotide · Vyleesi

PT-141 (bremelanotide) is a cyclic heptapeptide melanocortin receptor agonist, FDA-approved for hypoactive sexual desire disorder (HSDD) in premenopausal women. Unlike PDE5 inhibitors, it acts centrally through MC3R and MC4R receptors in the hypothalamus to initiate sexual arousal, making it effective for psychological as well as physiological sexual dysfunction. Research also explores applications in male erectile dysfunction.

LY3437943

Retatrutide is a triple agonist targeting GIP, GLP-1, and glucagon receptors simultaneously. Phase 2 trials demonstrated up to 24.2% body weight reduction — the highest achieved by any pharmacotherapy to date. The addition of glucagon agonism enhances energy expenditure and lipid metabolism beyond dual incretin agonists. Phase 3 trials are underway for obesity and NASH.

Ozempic · Wegovy

Semaglutide is a long-acting GLP-1 receptor agonist approved for type 2 diabetes (Ozempic, Rybelsus) and obesity (Wegovy). By mimicking the incretin hormone GLP-1, it enhances glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying, and reduces appetite via central hypothalamic pathways. Landmark trials demonstrate up to 15–17% body weight reduction and significant cardiovascular mortality benefit.

SP · NK1 ligand

Substance P is an 11-amino-acid neuropeptide of the tachykinin family and a primary neurotransmitter of pain signaling in the spinal cord. It binds NK1 receptors to mediate neurogenic inflammation, pain hypersensitivity, and emotional processing. NK1 antagonists have been developed for pain, depression (aprepitant), and nausea. Research also implicates substance P in wound healing, immune activation, and neuroinflammation.

Mounjaro · Zepbound

Tirzepatide is the first dual GIP/GLP-1 receptor agonist, approved for type 2 diabetes (Mounjaro) and obesity (Zepbound). By co-activating both incretin receptors, it achieves superior glycemic control and weight reduction compared to GLP-1 monotherapy — SURMOUNT trials showed up to 22.5% body weight reduction. It represents a new class of metabolic peptide therapeutics with broad cardiovascular and metabolic benefits.