Skip to content
Peptides Codex
ENFR

Use the arrow keys to choose a result, Enter to open it, and Escape to close.

← Home
Peptide hormone

Apelin

Apelin is an endogenous peptide hormone processed from a 77-amino-acid precursor into active fragments such as apelin-13 and apelin-36.

By The Peptides Codex Editorial TeamIndividual review date not recorded

Page data last changed: . Chemistry registry snapshot: . Registry refreshes and identity assessments are separate from scientific content review.

Length
n/a
Class
Peptide hormone
Function
Endogenous ligand of the APJ (APLNR) receptor
Context
Cardiovascular and metabolic physiology research target

One of two natural ligands of the APJ receptor, linking cardiac function, fluid balance and adipocyte signaling.

Also known as: APLN · apelin-13 · apelin-36

Part of the Metabolic & GLP-1 peptides cluster

Overview

Apelin is an endogenous peptide hormone processed from a 77-amino-acid precursor into active fragments such as apelin-13 and apelin-36. It is one of two natural ligands of the G-protein-coupled APJ (APLNR) receptor and is studied for roles in cardiovascular function, fluid homeostasis and adipose signaling. This page is educational and not medical advice.

Source & context

Biological / chemical source: Cleaved from a 77-residue preproprotein (APLN gene)

Primary research or clinical context: Cardiovascular and metabolic physiology research target

Forms and receptor

The APLN gene encodes a preproprotein that is cleaved into several bioactive fragments, including apelin-36, apelin-17, apelin-13 and [Pyr1]-apelin-13. These share a conserved C-terminus that binds the APJ receptor, a class-A GPCR expressed in heart, vasculature, kidney and adipose tissue.

Why it is studied

Apelin research focuses on cardiac contractility, blood-pressure regulation, angiogenesis and glucose handling. Because the shorter fragments are rapidly cleared in vivo, much work explores the apelin-APJ axis and stabilized analogs as investigational tools rather than approved therapies.

Structure & chemistry

Molecular identity & reference confidence

Source-supported reference

Reference values are taken from the cited molecular record or curated profile. A database match is not independent laboratory verification; modifications, counter-ions, and formulations can change the measured mass.

Molecular form
Apelin (source record; form not independently established)
Species
Not established by this molecular identity audit
Termini (N / C)
Not specified / Not specified

Average reference mass

Reference policy updated: 2026-10-05

Molecular formula
C266H427N95O71S2
Average reference mass
≈ 6,156
Identifiers

Chemistry values: PubChem, IUPHAR/BPS Guide to Pharmacology · fetched 2026-10-01.

Clinical development snapshot

ClinicalTrials.gov lists 38 registered studies with “Apelin” as an intervention (snapshot 2026-10-01). A registry footprint is not evidence of efficacy or approval.

Registered studies
38
Highest phase reached
Phase 4
Active in latest 100
4
Most recent update
2026-09-30
Most recently updated studies
NCTTitlePhaseStatusUpdated
NCT03449251A Series of Pilot Studies to Evaluate the haemoDynamic and mEtabolic Effects oF apelIn aNd rElaxinPhase 2active not recruiting2026-09-30
NCT07793656mRNA Therapy to Restore Lymphatic Flow in Secondary LymphedemaPhase 2not yet recruiting2026-08-28
NCT07703345Salivary Apelin, Chemerin, Ghrelin, and Lipocalin-2 Levels in Diabetic Patients With Periodontitis—recruiting2026-07-14
NCT05562687Association Between Some Polymorphisms in Apelin/ Apelin Receptor Genes and Coronary Artery Disease in Syrian —completed2026-04-01
NCT07449663SPORT-SPECIFIC HIIT IN ELITE KICKBOXERSNot applicableactive not recruiting2026-03-04
NCT02724566Effect of Apelin on Insulin Sensitivity in Type 2 Diabetic VolunteersPhase 1completed2025-12-10
See all on ClinicalTrials.gov →
Concentration math

Apelin — reconstitution calculator

Enter how much peptide is in the vial and how much diluent (e.g. bacteriostatic water) is added. The tool returns the resulting solution concentration — and, for any amount you type, the volume it corresponds to. This is educational arithmetic, not a dosing recommendation.

Reference form: Apelin (source record; form not independently established)Average reference mass: 6,156 Da

Syringe graduation
Solution concentration
5 mg/mL5,000 mcg/mL
mcg

Enter an amount to see the volume it corresponds to.

Educational concentration mathematics only. This tool does not recommend a dose, amount, or protocol, and nothing here is medical advice. Many peptides are not authorized by Health Canada for human use — see our reconstitution and bacteriostatic-water guides for context.

Open the Apelin calculator on its own page →

FAQ about Apelin

What is Apelin?+

Apelin is an endogenous peptide hormone processed from a 77-amino-acid precursor into active fragments such as apelin-13 and apelin-36. It is one of two natural ligands of the G-protein-coupled APJ (APLNR) receptor and is studied for roles in cardiovascular function, fluid homeostasis and adipose signaling. This page is educational and not medical advice.

What Canadian product status is recorded for Apelin?+

Canadian product status for Apelin has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.

What is the typical length of Apelin?+

Apelin is not a classic amino-acid chain peptide in the same sense; see the profile for classification details.

Related peptides

Beta-endorphin
Neuropeptide
Beta-endorphin is a 31-amino-acid endogenous opioid peptide cleaved from the proopiomelanocortin (POMC) precursor. It is a foundational molecule in pain, stress, and reward neuroscience research.
Ziconotide
Conotoxin analgesic
Ziconotide is the synthetic form of an ω-conotoxin, a 25-amino-acid peptide from cone snail venom that selectively blocks N-type voltage-gated calcium channels. Delivered directly into cerebrospinal fluid by an intrathecal pump, it is an approved therapeutic for severe, refractory chronic pain. Content here is educational only.
Terlipressin
Vasopressin analog
Terlipressin is a synthetic analog of vasopressin built by adding three glycine residues to lysine-vasopressin. It acts as a slow-release prodrug, giving prolonged V1-mediated splanchnic vasoconstriction, and gained FDA approval in 2022 for hepatorenal syndrome. Content here is educational only.
Carbetocin
Oxytocin analog
Carbetocin is a synthetic long-acting analog of oxytocin. Structural modifications extend its half-life to roughly 85-100 minutes versus a few minutes for oxytocin, allowing a single dose to sustain uterine contraction, and it is an approved therapeutic for preventing postpartum hemorrhage. This page is educational and not medical advice.

References & further reading

  1. 1.Respekta et al. (2022). The Apelinergic System: Apelin, ELABELA, and APJ Action on Cell Apoptosis: Anti-Apoptotic or Pro-Apoptotic Effect?. Cells
  2. 2.Williams et al. (2023). Expanding the apelin receptor pharmacological toolbox using novel fluorescent ligands. Front Endocrinol (Lausanne)
  3. 3.Castan-Laurell et al. (2011). Apelin, diabetes, and obesity. Endocrine
  4. 4.Read et al. (2019). International Union of Basic and Clinical Pharmacology. CVII. Structure and Pharmacology of the Apelin Receptor with a Recommendation that Elabela/Toddler Is a Second Endogenous Peptide Ligand. Pharmacol Rev
  5. 5.Kamińska et al. (2024). Neuroprotective effect of apelin-13 and other apelin forms-a review. Pharmacol Rep
  6. 6.Pisarenko et al. (2023). Apelin C-Terminal Fragments: Biological Properties and Therapeutic Potential. Biochemistry (Mosc)
  7. 7.Li et al. (2025). A reactive oxygen species-responsive hydrogel loaded with Apelin-13 promotes the repair of spinal cord injury by regulating macrophage M1/M2 polarization and neuroinflammation. J Nanobiotechnology
  8. 8.Gürlek et al. (2020). Evaluation of serum apelin-13 and apelin-36 concentrations in preeclamptic pregnancies. J Obstet Gynaecol Res
  9. 9.UniProtKB — APLN, Apelin (Human) Q9ULZ1
  10. 10.Wikipedia — Apelin
Disclaimer: Educational content only. Not medical advice. Not instructions for human use. Research peptides and unapproved products may be restricted or illegal to market for human consumption in your jurisdiction. Consult qualified professionals and applicable law.
You might also like: All peptides · Atlas · Research · Tools
Cite this: Peptides Codex — Apelin educational profile.
Tip: Use browser print (Ctrl/Cmd + P) for a clean PDF of this page.