CPG & GZK-111ЦПГ / ГЗК-111
What is it?
A grouped record for endogenous cyclo(Pro-Gly), its experimental linear precursor GZK-111 and the connection to Noopept metabolism.
Research context
A grouped record for endogenous cyclo(Pro-Gly), its experimental linear precursor GZK-111 and the connection to Noopept metabolism.
What the studies found
animal · 2022
Rats; intravenous and intragastric pharmacokinetics
GZK-111 underwent extensive conversion to CPG in rats. CPG persisted more than twice as long in plasma and reached higher concentrations than the parent compound.
Limit: Preclinical findings do not establish human benefit or safety.
Preclinical Pharmacokinetics of GZK-111, a Dipeptide with Neuroprotective Activity. ↗analytical · 1996
Rat brain extracts and rat behavioral experiments
Chromatographic and mass-spectrometric methods identified CPG in rat brain. Synthetic CPG also altered passive-avoidance performance in rats. Endogenous detection does not establish supplementation benefit.
Limit: Preclinical findings do not establish human benefit or safety.
Identification of a novel endogenous memory facilitating cyclic dipeptide cyclo-prolylglycine in rat brain. ↗animal · 1997
Rat metabolism and enzyme preparations
Rat-brain CPG increased approximately 2.5-fold one hour after GVS-111 administration. Enzyme experiments supported conversion to CPG; these findings do not prove that CPG accounts for every Noopept effect.
Limit: Preclinical findings do not establish human benefit or safety.
The major metabolite of dipeptide piracetam analogue GVS-111 in rat brain and its similarity to endogenous neuropeptide cyclo-L-prolylglycine. ↗Selected findings, not a systematic review or a treatment recommendation. Combination and related-preparation results cannot be attributed to this compound alone. See each source for access status and remaining limitations.
- Working classification
- Peptide research family
- Research collection
- Neuropeptide research · editorial grouping
- Institutional provenance
- Not established for this compound record
- Last evidence review
- Full evidence review pending; source-check scope appears with each publication below.
What do we know?
- Human research
- —No human treatment trial assessed for this family
- Study methods
- —Member-specific studies; patents and archival leads identified separately
- Independent replication
- —Independent replication not established by the records collected here
- Source access
- —Primary abstracts, selected full texts, patents and explicit retrieval targets
- Safety evidence
- —Cell and animal effects do not establish human safety; analogues may differ
These are independent review fields, not a rating. Missing evidence in this starter does not mean no research exists.
Inside this research family
Grouping supports navigation. It does not imply equivalent composition, mechanisms, effectiveness or safety.
| Member | Identity | What the source supports |
|---|---|---|
| CPG | Cyclic Pro-Gly dipeptide | Identified in rat brain; later experiments examined AMPA currents and cell protection. Neuropeptide cycloprolylglycine is an endogenous positive modulator of AMPA receptors. ↗ |
| GZK-111 | N-phenylacetyl-Gly-Pro ethyl ester | Rat pharmacokinetics support conversion to CPG; human pharmacokinetics remain unestablished here. Preclinical Pharmacokinetics of GZK-111, a Dipeptide with Neuroprotective Activity. ↗ |
| Noopept / GVS-111 | N-phenylacetyl-Pro-Gly ethyl ester | Opposite linear residue order to GZK-111; a rat metabolism study supports CPG formation. |
| pGlu-Asn-NH₂ | Separate pyroglutamyl dipeptide branch | A piracetam-inspired compound studied in rat hippocampal plasticity; neither CPG nor a Noopept alias. Pyroglutamyl-asparagine amide normalizes long-term potentiation in rat hippocampal slices. ↗ |
Interpretation and open questions
Endogenous presence is not evidence that increasing a peptide improves health.
GPE (Gly-Pro-Glu), the IGF-1-related branch, and non-Russian cyclic analogues are adjacent research targets. They are not assigned the outcomes of CPG.
Linked sources
Explore the research map and unresolved leads ↗
Preclinical Pharmacokinetics of GZK-111, a Dipeptide with Neuroprotective Activity.
Litvin AA, Kolyvanov GB, Bochkov PO, Shevchenko RV, Podol'ko AL, Kolyasnikova KN, Zherdev VP · Bulletin of experimental biology and medicine
GZK-111 underwent extensive conversion to CPG in rats. CPG persisted more than twice as long in plasma and reached higher concentrations than the parent compound.
- Population / setting
- Rats; intravenous and intragastric pharmacokinetics
- What was checked
- Primary publication metadata and indexed abstract checked via Europe PMC; full methodological review pending.
Limitations & review scope
- Preclinical findings do not establish human benefit or safety.
- Indexed abstract reviewed; full methods and independent replication require appraisal.
Source checked 2026-10-05. This is a source-linked record, not a completed evidence review.
Identification of a novel endogenous memory facilitating cyclic dipeptide cyclo-prolylglycine in rat brain.
Gudasheva TA, Boyko SS, Akparov VKh, Ostrovskaya RU, Skoldinov SP, Rozantsev GG, Voronina TA, Zherdev VP, Seredenin SB · FEBS letters
Chromatographic and mass-spectrometric methods identified CPG in rat brain. Synthetic CPG also altered passive-avoidance performance in rats. Endogenous detection does not establish supplementation benefit.
- Population / setting
- Rat brain extracts and rat behavioral experiments
- What was checked
- Primary publication metadata and indexed abstract checked via Europe PMC; full methodological review pending.
Limitations & review scope
- Preclinical findings do not establish human benefit or safety.
- Indexed abstract reviewed; full methods and independent replication require appraisal.
Source checked 2026-10-05. This is a source-linked record, not a completed evidence review.
The major metabolite of dipeptide piracetam analogue GVS-111 in rat brain and its similarity to endogenous neuropeptide cyclo-L-prolylglycine.
Gudasheva TA, Boyko SS, Ostrovskaya RU, Voronina TA, Akparov VK, Trofimov SS, Rozantsev GG, Skoldinov AP, Zherdev VP, Seredenin SB · European journal of drug metabolism and pharmacokinetics
Rat-brain CPG increased approximately 2.5-fold one hour after GVS-111 administration. Enzyme experiments supported conversion to CPG; these findings do not prove that CPG accounts for every Noopept effect.
- Population / setting
- Rat metabolism and enzyme preparations
- What was checked
- Primary publication metadata and indexed abstract checked via Europe PMC; full methodological review pending.
Limitations & review scope
- Preclinical findings do not establish human benefit or safety.
- Indexed abstract reviewed; full methods and independent replication require appraisal.
Source checked 2026-10-05. This is a source-linked record, not a completed evidence review.
Neuropeptide cycloprolylglycine is an endogenous positive modulator of AMPA receptors.
Gudasheva TA, Grigoriev VV, Koliasnikova KN, Zamoyski VL, Seredenin SB · Doklady. Biochemistry and biophysics
CPG enhanced AMPA currents in rat cerebellar Purkinje cells. A proposed downstream BDNF mechanism requires distinction from the measured electrophysiological response.
- Population / setting
- Rat Purkinje-cell electrophysiology
- What was checked
- Primary publication metadata and indexed abstract checked via Europe PMC; full methodological review pending.
Limitations & review scope
- Preclinical findings do not establish human benefit or safety.
- Indexed abstract reviewed; full methods and independent replication require appraisal.
Source checked 2026-10-05. This is a source-linked record, not a completed evidence review.
Neuroprotective Effect of the Neuropeptide Cycloprolylglycine Depends on AMPA- and TrkB-Receptor Activation.
Gudasheva TA, Koliasnikova KN, Alyaeva AG, Nikolaev SV, Antipova TA, Seredenin SB · Doklady. Biochemistry and biophysics
AMPA and Trk receptor blockers prevented the reported CPG neuroprotective effect in cultured-cell experiments. Pharmacological blockade supports pathway involvement, not a fully resolved mechanism.
- Population / setting
- Cultured-cell injury and receptor-blockade experiments
- What was checked
- Primary publication metadata and indexed abstract checked via Europe PMC; full methodological review pending.
Limitations & review scope
- Preclinical findings do not establish human benefit or safety.
- Indexed abstract reviewed; full methods and independent replication require appraisal.
Source checked 2026-10-05. This is a source-linked record, not a completed evidence review.
Neuropeptide Cycloprolylglycine Exhibits Neuroprotective Activity after Systemic Administration to Rats with Modeled Incomplete Global Ischemia and in In Vitro Modeled Glutamate Neurotoxicity.
Povarnina PY, Kolyasnikova KN, Nikolaev SV, Antipova TA, Gudasheva TA · Bulletin of experimental biology and medicine
CPG improved selected neurological and locomotor measures after incomplete global ischemia in rats and protected HT-22 cells against glutamate toxicity.
- Population / setting
- Rat ischemia model and HT-22 cells
- What was checked
- Primary publication metadata and indexed abstract checked via Europe PMC; full methodological review pending.
Limitations & review scope
- Preclinical findings do not establish human benefit or safety.
- Indexed abstract reviewed; full methods and independent replication require appraisal.
Source checked 2026-10-05. This is a source-linked record, not a completed evidence review.
Pyroglutamyl-asparagine amide normalizes long-term potentiation in rat hippocampal slices.
Kapai NA, Chepkova AN, Gudasheva TA, Morozova AA, Skrebitskii VG · Bulletin of experimental biology and medicine
Pyroglutamyl-asparagine amide facilitated weakly induced long-term potentiation and countered ethanol-impaired potentiation in rat hippocampal slices. This separate piracetam-inspired dipeptide is not CPG.
- Population / setting
- Rat hippocampal slices
- What was checked
- Primary publication metadata and indexed abstract checked via Europe PMC; full methodological review pending.
Limitations & review scope
- Preclinical findings do not establish human benefit or safety.
- Indexed abstract reviewed; full methods and independent replication require appraisal.
Source checked 2026-10-05. This is a source-linked record, not a completed evidence review.
Novel Technologies for Dipeptide Drugs Design and their Implantation.
Gudasheva TA, Ostrovskaya RU, Seredenin SB · Current pharmaceutical design
The developers distinguish drug-inspired peptide design (Noopept and Dilept) from mimicking peptide/protein turns (GB-115 and GK-2). This is a historical design framework, not evidence of a shared clinical effect.
- Population / setting
- Developer account of medicinal-chemistry programs
- What was checked
- Primary publication metadata and indexed abstract checked via Europe PMC; full methodological review pending.
Limitations & review scope
- Developer review; claims require appraisal of each original study.
- A shared design method does not establish equivalent biology or clinical benefit.
Source checked 2026-10-05. This is a source-linked record, not a completed evidence review.