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preclinicalCognitive & Neuro

FGL Peptide

Also known as: FGLL, FG loop peptide, NCAM mimetic peptide, EVYVVAENQQGKSKA

FGL (FG loop) peptide is a synthetic 15-amino acid peptide derived from the second fibronectin type III domain of neural cell adhesion molecule (NCAM). It mimics the interaction between NCAM and the fibroblast growth factor receptor (FGFR), activating FGFR-dependent signaling cascades that promote neurite outgrowth, synaptic plasticity, and neuronal survival. Preclinical studies demonstrate significant cognitive enhancement, neuroprotection in Alzheimer's disease models, and anti-inflammatory effects in the central nervous system.

3 cited references·5 researched benefits

Quick Answer

FGL peptide is a synthetic 15-amino acid NCAM-derived mimetic that activates fibroblast growth factor receptor (FGFR) signaling to promote neural plasticity, neurite outgrowth, and neuronal survival. Preclinical studies show it enhances memory consolidation, reverses age-related cognitive decline, reduces neuroinflammation, and protects against amyloid-beta toxicity. It represents a novel approach to neuroprotection through cell adhesion molecule signaling. No human clinical trials have been completed.

Key Facts

Mechanism
FGL peptide is derived from the FG loop of the second fibronectin type III (FnIII) module of NCAM, the region responsible for NCAM's heterophilic interaction with FGFR1. By binding directly to FGFR1, FGL activates receptor tyrosine kinase signaling cascades including the MAPK/ERK pathway and PI3K/Akt pathway. These downstream signals promote neurite outgrowth, synaptogenesis, and neuronal survival. In the hippocampus, FGL enhances long-term potentiation (LTP), the cellular mechanism underlying memory formation. Additionally, FGL modulates microglial activation and reduces pro-inflammatory cytokine release (TNF-alpha, IL-1beta), providing neuroprotection through anti-inflammatory mechanisms. Unlike the full NCAM protein, the small peptide can cross the blood-brain barrier when administered systemically, making it a viable therapeutic candidate.
Research Status
preclinical
Half-Life
Not established in humans (preclinical compound)
Molecular Formula
C₆₉H₁₁₂N₁₈O₂₅
Primary Use
Cognitive & Neuro
Table of Contents

Benefits

  • Enhanced memory consolidation — significantly improves spatial and associative memory in aged rats, with effects lasting beyond the treatment periodpreliminary
  • Reversal of age-related cognitive decline — restores hippocampal LTP and memory performance in aged animals to levels comparable to young controlspreliminary
  • Neuroprotection against amyloid-beta — protects hippocampal neurons from amyloid-beta-induced toxicity in Alzheimer's disease modelspreliminary
  • Anti-neuroinflammatory effects — reduces microglial activation and pro-inflammatory cytokine production in the CNS, addressing a key driver of neurodegenerationpreliminary
  • Promotes neurite outgrowth and synaptogenesis — stimulates new neuronal connections through FGFR-mediated signaling, supporting structural brain plasticitymoderate

Dosage Protocols

RouteDosage RangeFrequencyNotes
Subcutaneous injection (preclinical)5–10 mg/kg (animal dosing)Varied protocols in researchNo human dosing has been established. Animal studies have used various regimens including single injections and multi-day protocols. Human-equivalent doses would need to be determined through Phase I clinical trials.

Medical disclaimer

Dosage information is provided for educational reference only. Always follow your prescriber's instructions and consult a qualified healthcare provider before starting any peptide protocol.

Side Effects

  • Unknown human side effect profile — no human clinical trials have been conducted; all safety data comes from animal studiesserious
  • Theoretical FGFR-related proliferative risk — chronic activation of FGFR signaling could theoretically promote aberrant cell proliferation, though this has not been observed in animal studiesrare
  • Injection site irritation — mild local reactions observed at subcutaneous injection sites in animal studiescommon

Frequently Asked Questions

What is NCAM and why is it important for brain function?
Neural Cell Adhesion Molecule (NCAM) is a glycoprotein expressed on the surface of neurons and glial cells that plays critical roles in brain development, synaptic plasticity, and memory formation. NCAM mediates cell-cell adhesion and activates intracellular signaling cascades through interactions with FGFR, promoting neurite outgrowth, synaptogenesis, and neuronal survival. Disruptions in NCAM signaling have been implicated in Alzheimer's disease, schizophrenia, and age-related cognitive decline. FGL peptide mimics one specific NCAM-FGFR interaction to harness these neuroprotective signaling pathways.
Has FGL peptide been tested in humans?
FGL peptide has not completed human clinical trials as of the latest published data. Research has been conducted primarily in cell culture systems and rodent models by groups at the University of Copenhagen and other European institutions. A Phase I clinical trial was initiated by the company ENKAM Pharmaceuticals, but comprehensive results from human studies have not been published in the peer-reviewed literature. The peptide remains a preclinical research compound.
How does FGL peptide differ from other nootropic peptides like Cerebrolysin?
FGL peptide is a precisely defined 15-amino acid synthetic peptide with a known molecular target (FGFR1), whereas Cerebrolysin is a complex mixture of hundreds of peptides and amino acids derived from pig brain. This gives FGL a significant advantage in terms of mechanistic understanding, reproducibility, and potential for pharmaceutical development. FGL specifically activates FGFR-dependent neuroprotective pathways, while Cerebrolysin's effects arise from multiple uncharacterized mechanisms. However, Cerebrolysin has far more clinical data and decades of use in patients, while FGL remains in the preclinical stage.

References

  1. 1
    FGL, a neural cell adhesion molecule-derived peptide, promotes neurite outgrowth and memory consolidation(2008)PubMed ↗
  2. 2
    FGL peptide induces FGFR-dependent signaling and reverses age-related cognitive decline in rats(2012)PubMed ↗
  3. 3
    The neural cell adhesion molecule-derived FGL peptide reduces inflammation and promotes neuronal survival in a mouse model of Alzheimer's disease(2011)PubMed ↗

Latest Research

Last updated: 2026-02-19