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Cyclic Glycine-Proline

Moderate Research

IGF-1 Bioavailability Regulator & Neuroprotective Peptide

Dose 20-100 μg daily (or 300mg blackcurrant extract 2x daily)
Frequency Once daily, preferably in the morning
Cycle 4-12 weeks
Storage Room temperature in sealed container, protected from moisture and light

Endogenous cyclic dipeptide found in plasma, breast milk, and cerebrospinal fluid. Functions as metabolite of IGF-1, regulating its bioavailability through competitive binding to IGFBP-3. Demonstrates neuroprotective, cognitive-enhancing, and cardioprotective properties supported by clinical trials.

Mechanism of Action

Competes with IGF-1 for IGFBP-3 binding, normalizing bioavailable IGF-1 levels. Acts as positive allosteric modulator of AMPA and GABA-A receptors. Increases BDNF levels via Akt/MDM2-p53 pathway activation.

Key Benefits

  • Neuroprotection and cognitive enhancement
  • IGF-1 optimization
  • Cardiovascular support
  • Metabolic health improvement
  • Blood-brain barrier penetration
  • Convenient oral administration
Molecular Weight
154.17 Da
Chain Length
2 amino acids (cyclic)
Type
Cyclic dipeptide (2,5-diketopiperazine)
Amino Acid Sequence
One-letter: ??
H₂N
H
? 1
O ‖ C
N
H
? 2
COOH
cyc
1

cyclo(Gly

Position 1

Pro
2

Pro)

Position 2

N-terminus C-terminus
Hydrophobic
Polar
Positive (+)
Negative (-)
Modified

Neurological

  • Cognitive Enhancement

    Higher cGP levels correlate with improved memory retention in elderly populations

  • Neuroprotection

    Protects neural stem cells from oxidative stress; efficacy demonstrated in stroke models

  • Alzheimer's Disease

    Mouse studies show reduced amyloid plaque load and improved spatial memory

  • Parkinson's Disease

    Clinical study showed increased CSF cGP and reduced anxiety/depression scores

Metabolic

  • Type-2 Diabetes

    Clinical trial improved vascular complications and normalized HbA1c%

  • Blood Pressure Regulation

    Demonstrated systolic blood pressure reduction in clinical observations

Recovery

  • Stroke Recovery

    Higher cGP/IGF-1 ratios associated with favorable clinical outcomes

  • Healthy Aging

    Maintained ratios correlate with preserved cognitive function with age

Preferred route with excellent bioavailability and blood-brain barrier crossing.

GoalDoseFrequencyRoute
General cognitive support20-40 μg1x dailyOral capsule
Neuroprotection/anti-aging40-50 μg1x dailyOral capsule
Metabolic/cardiovascular support40-100 μg1x dailyOral capsule
Via blackcurrant extract300 mg BCA2x dailyOral capsule
IGF-1

cGP is metabolite of IGF-1; regulates bioavailability through competitive IGFBP-3 binding

synergistic
BPC-157

Different pathways; BPC-157 promotes tissue repair, cGP modulates IGF-1

compatible
Semax

Both offer neuroprotection and nootropic effects through distinct pathways

compatible
Selank

Complementary cognitive effects; Selank addresses anxiety, cGP optimizes IGF-1

compatible
GH Secretagogues

Both affect growth hormone/IGF-1 axis; monitor combined effects on levels

monitor
Week 1-2

Possible subtle improvements in mental clarity

Week 2-4

Enhanced cognitive function and focus may become noticeable

Week 4-8

Neuroprotective and metabolic benefits accumulating

Week 8-12

Optimal IGF-1 regulation and sustained cognitive support

Stop Signs - Discontinue if:

  • Allergic reactions (rash, difficulty breathing, swelling)
  • Unexpected blood glucose changes
  • Unusual fatigue or weakness

Contraindications

  • Consult healthcare provider if taking IGF-1 or growth hormone medications
  • Limited long-term human data available
  • Not studied in pregnancy

Good Signs

  • Third-party tested for purity and potency
  • Clear cGP content labeling (typically in micrograms per serving)
  • Natural blackcurrant-derived sources from New Zealand
  • Sealed containers protected from moisture and light

Warning Signs

  • Products lacking clear cGP content specification

Bad Signs

  • Extreme therapeutic claims unsupported by research
  • Vague concentration descriptions
  • IGF-1 Homeostasis Regulation Study
    Scientific Reports (2014)

    cGP regulates IGF-1 bioavailability through IGFBP-3 competitive binding

  • Alzheimer's Mouse Model Study
    PMC (2023)

    Significantly improved spatial memory; reduced hippocampal plaques 42.3→14.5 per mm²

  • Parkinson's Disease Clinical Study
    PMC (2018)

    Blackcurrant supplementation increased CSF cGP 74%; reduced anxiety/depression

  • Stroke Recovery & Cognitive Function Review
    PMC (2023)

    Higher cGP/IGF-1 ratios associated with favorable stroke outcomes

Disclaimer

This information is for educational and research purposes only. Consult a healthcare professional before use.