Testagen

updated

Testagen is a trade name that the Khavinson group of Russian short-peptide bioregulators ties to the tetrapeptide Lys-Glu-Asp-Gly, sold for natural testosterone support alongside hCG, gonadorelin and enclomiphene. No human study exists, and no study in any species measured testosterone or any gonadal endpoint: the animal work is in chickens and concerns the thyroid axis and immunity. A registered topical testosterone lotion also carries the name Testagen, and it is not this peptide.

Synthetic tetrapeptide bioregulator

  • PubChem has no record under the name Testagen. H-Lys-Glu-Asp-Gly-OH is CID 123863700, C17H29N5O9, molecular weight 447.4, with no CAS number; a 2011 abstract and a 2025 chemistry abstract tie the name to that sequence.
  • Naming warning: ClinicalTrials.gov lists a phase 2 study of Testagen TDS-Testosterone, a topical testosterone lotion that is not a peptide and not yet recruiting as of its 2026-05-27 update. It is not about this tetrapeptide.
  • The group's label of Testagen as a regulator of the male reproductive system rests on three references in its 2021 review that are not about reproduction, and the 2022 table repeats it with no reference.
  • In hypophysectomized chickens and old hens given the peptide for 40 days, thyrotropic and thyroid hormone concentrations rose and thyroid and thymus structure was restored; the abstracts give no dose, no route and no gonadal or testosterone endpoint.
  • A PubMed search on 10 October 2026 for testagen returned 2 records: a HeLa cell study and a 2025 chemistry paper testing it as a copper corrosion inhibitor.
  • Searches for the peptide with testosterone, testis, Leydig, spermatogenesis, hypogonadism or androgen terms, and with clinical trial publication types, each returned 0 records.

What is Testagen, and is it an approved drug?

Testagen is a trade name that a 2011 abstract and the Khavinson group's 2022 table tie to the tetrapeptide Lys-Glu-Asp-Gly (KEDG); PubChem does not make that link. DailyMed returns no label named Testagen, and ClinicalTrials.gov returned no study for the tetrapeptide, so no FDA record of the peptide was found. A registered topical testosterone product shares the name and is not the peptide.

A PubChem name search for Testagen returned no record. H-Lys-Glu-Asp-Gly-OH is PubChem CID 123863700, C17H29N5O9, molecular weight 447.4, with no CAS number and no Testagen synonym. The sequence tied to the name appears in a 2011 abstract (testagen, Lys-Glu-Asp-Gly, PMID 22117547) and in a 2025 chemistry abstract that calls testagen (KEDG) the tetrapeptide H-Lys-Glu-Asp-Gly-OH (PMID 40807317). The group's 2022 table lists Testagen (KEDG) as a regulator of the male reproductive system. The trade name is tied to the sequence by those sources, not by PubChem.

The 2025 chemistry abstract tested the peptide as a copper corrosion inhibitor in salt solution, with about 86% inhibition efficiency and no biological measurement.

On 10 October 2026 DailyMed returned no label named Testagen, and ClinicalTrials.gov returned 1 record for Testagen, a topical testosterone lotion, and none for a KEDG tetrapeptide. That covers FDA and registry sources and says nothing about other regulators.

PubChem: Lys-Glu-Asp-Gly identity

Chemical identity record

National Library of Medicine. PubChem compound record CID 123863700.

A PubChem name search for Testagen returned no record. H-Lys-Glu-Asp-Gly-OH is CID 123863700, C17H29N5O9, molecular weight 447.4, with no CAS number and no Testagen synonym. The sequence tied to the name appears in a 2011 abstract (testagen, Lys-Glu-Asp-Gly, PMID 22117547) and in a 2025 chemistry abstract that calls testagen (KEDG) the tetrapeptide H-Lys-Glu-Asp-Gly-OH (PMID 40807317); the group's 2022 table lists Testagen (KEDG) as a regulator of the male reproductive system. The trade name is tied to the sequence by those sources, not by PubChem.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined synthetic peptide
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

The record defines the sequence only. The link from the name Testagen to the sequence rests on the group's abstracts and table.

Read the original source
PubMed: 2 records, no testosterone measure, no clinical trial

PubMed search record

PubMed searches run 10 October 2026: testagen; (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen); (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) with clinical trial or randomized controlled trial publication types; KEDG under its sequence names. ClinicalTrials.gov and DailyMed queries, run the same day.

A PubMed search for testagen returned 2 records: the HeLa study and a 2025 chemistry paper in which the peptide was tested as a copper corrosion inhibitor in salt solution (about 86% inhibition efficiency, no biological measurement). A search for (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen) returned 0 records. A search for (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) with clinical trial or randomized controlled trial publication types returned 0 records. A search for KEDG under its sequence names returned 13 records: the 5 hypophysectomized bird papers, 4 general Khavinson peptide papers (including the HeLa study and the histone-binding paper), the 2025 corrosion paper, and 3 unrelated records. ClinicalTrials.gov returned 1 record for Testagen (the testosterone lotion) and none for a KEDG tetrapeptide. In the records reviewed there is no testosterone, luteinizing hormone, follicle-stimulating hormone, or sperm measure after the peptide in any animal or person, no study with hCG, gonadorelin, or enclomiphene, no human dose, and no human safety data.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Search run on 10 October 2026
Study design
Dated literature and registry search
Funding
not stated in the source

An absence finding as of 10 October 2026, not proof that no unpublished work exists.

Read the original source
Naming warning: a registered topical testosterone product shares the name Testagen

Trial registry record

ClinicalTrials.gov. NCT02733133, phase 2 pharmacokinetic study of Testagen TDS-Testosterone, record last updated 2026-05-27.

ClinicalTrials.gov lists NCT02733133, a phase 2 pharmacokinetic study of Testagen TDS-Testosterone, a topical testosterone product (HypoSpray lotion) from Transdermal Delivery Solutions Corp, designed to measure transfer of testosterone from dosed men to female partners by skin contact. It estimates 96 healthy adults, has a start date of 2027-01-05, and was not yet recruiting as of its 2026-05-27 update, so it has no posted results. That product is a testosterone, not a peptide, and nothing in that record involves the tetrapeptide. DailyMed returns no label named Testagen.

Participants / model
Healthy adults (registered, not yet enrolling)
Treatment
Topical testosterone lotion
Follow-up
Not applicable
Study design
Trial registry record for an unrelated product, not yet recruiting
Funding
not stated in the source

Naming warning only. This record is for a different product and is not evidence about the peptide.

Read the original source

Which product called Testagen is not this peptide?

Testagen TDS-Testosterone is a topical testosterone lotion in a registered phase 2 study that was not yet recruiting as of 27 May 2026. It is a testosterone, not a peptide, and nothing in that record involves the tetrapeptide, so it is not evidence about the peptide.

ClinicalTrials.gov lists NCT02733133, a phase 2 pharmacokinetic study of Testagen TDS-Testosterone, a topical testosterone product (HypoSpray lotion) from Transdermal Delivery Solutions Corp. It is designed to measure transfer of testosterone from dosed men to female partners by skin contact, estimates 96 healthy adults, has a start date of 2027-01-05, and was not yet recruiting as of its 2026-05-27 update, so it has no posted results.

Naming warning: that product is a testosterone, not a peptide, and nothing in that record involves the tetrapeptide. A page or listing that cites a Testagen testosterone study needs to say which Testagen it means. Nothing about the lotion is used as evidence on this page.

Naming warning: a registered topical testosterone product shares the name Testagen

Trial registry record

ClinicalTrials.gov. NCT02733133, phase 2 pharmacokinetic study of Testagen TDS-Testosterone, record last updated 2026-05-27.

ClinicalTrials.gov lists NCT02733133, a phase 2 pharmacokinetic study of Testagen TDS-Testosterone, a topical testosterone product (HypoSpray lotion) from Transdermal Delivery Solutions Corp, designed to measure transfer of testosterone from dosed men to female partners by skin contact. It estimates 96 healthy adults, has a start date of 2027-01-05, and was not yet recruiting as of its 2026-05-27 update, so it has no posted results. That product is a testosterone, not a peptide, and nothing in that record involves the tetrapeptide. DailyMed returns no label named Testagen.

Participants / model
Healthy adults (registered, not yet enrolling)
Treatment
Topical testosterone lotion
Follow-up
Not applicable
Study design
Trial registry record for an unrelated product, not yet recruiting
Funding
not stated in the source

Naming warning only. This record is for a different product and is not evidence about the peptide.

Read the original source

What did the chicken and cell studies find?

The in vivo work on this sequence is in chickens and concerns the pituitary-thyroid axis and the immune system, not the testis: in hypophysectomized chickens and old hens given the peptide for 40 days, thyroid hormone concentrations rose and thyroid and thymus structure was restored. In HeLa cells the labeled peptide entered the nucleus. No study measured testosterone or any gonadal endpoint.

Lys-Glu-Asp-Gly was synthesized on the basis of the amino acid composition of anterior pituitary peptide complexes. In hypophysectomized chickens and old hens given the peptide for 40 days, it raised thyrotropic hormone and thyroid hormone concentrations and restored thyroid structure, restored thymus structure, and normalized immune and hemostatic parameters. The effects were smaller in old hens. The abstracts give no dose, no route, and no gonadal, luteinizing hormone, follicle-stimulating hormone or testosterone endpoint.

Fluorescein-labeled testagen, epithalon and pinealon entered the cytoplasm, nucleus and nucleolus of HeLa cells, and the abstract reports that testagen binds preferentially to CAG-containing oligonucleotide sequences in a test tube. This is a mechanism-level cell result in a cervical cancer line.

A PubMed search for testagen returned 2 records, the HeLa study and the 2025 chemistry paper that has no biological measurement. A search for KEDG under its sequence names returned 13 records: the 5 hypophysectomized bird papers, 4 general Khavinson peptide papers, the 2025 corrosion paper and 3 unrelated records.

Hypophysectomized chickens and old hens: thyroid hormones and thyroid structure

Animal study

Kuznik BI et al. Bull Exp Biol Med. 2011;150(4):495-9. PMID 22268052.

Lys-Glu-Asp-Gly was synthesized on the basis of the amino acid composition of anterior pituitary peptide complexes. In hypophysectomized chickens and old hens given the peptide for 40 days, it raised thyrotropic hormone and thyroid hormone concentrations and restored thyroid structure (PMID 19024016, PMID 22268052, PMID 21809626), restored thymus structure (PMID 23658898), and normalized immune and hemostatic parameters (PMID 20731122). The effects were smaller in old hens. The abstracts give no dose, no route, and no gonadal, luteinizing hormone, follicle-stimulating hormone, or testosterone endpoint.

Participants / model
Hypophysectomized young chickens, mature chickens, and old hens or birds
Treatment
Administration for 40 days; route and dose not stated in the abstracts
Follow-up
40 days
Study design
Preclinical bird studies of the pituitary-thyroid axis, thymus and immunity
Funding
not stated in the source

The in vivo work on this sequence is about the pituitary-thyroid axis and the immune system, not the testis.

Read the original source
2011 HeLa cells: cell uptake and DNA binding

Cell study

Fedoreyeva LI et al. Biochemistry (Mosc). 2011;76(11):1210-9. PMID 22117547.

Fluorescein-labeled testagen, epithalon, and pinealon entered the cytoplasm, nucleus, and nucleolus of HeLa cells, and the abstract reports that testagen binds preferentially to CAG-containing oligonucleotide sequences in a test tube. This is a mechanism-level cell result in a cervical cancer line.

Participants / model
HeLa cells; synthetic oligonucleotides
Treatment
Labeled peptide in culture medium and in vitro mixtures
Follow-up
not stated in the source
Study design
Cell uptake and in vitro DNA-binding study
Funding
not stated in the source

Cell uptake only. It measures no hormone and no reproductive endpoint.

Read the original source
PubMed: 2 records, no testosterone measure, no clinical trial

PubMed search record

PubMed searches run 10 October 2026: testagen; (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen); (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) with clinical trial or randomized controlled trial publication types; KEDG under its sequence names. ClinicalTrials.gov and DailyMed queries, run the same day.

A PubMed search for testagen returned 2 records: the HeLa study and a 2025 chemistry paper in which the peptide was tested as a copper corrosion inhibitor in salt solution (about 86% inhibition efficiency, no biological measurement). A search for (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen) returned 0 records. A search for (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) with clinical trial or randomized controlled trial publication types returned 0 records. A search for KEDG under its sequence names returned 13 records: the 5 hypophysectomized bird papers, 4 general Khavinson peptide papers (including the HeLa study and the histone-binding paper), the 2025 corrosion paper, and 3 unrelated records. ClinicalTrials.gov returned 1 record for Testagen (the testosterone lotion) and none for a KEDG tetrapeptide. In the records reviewed there is no testosterone, luteinizing hormone, follicle-stimulating hormone, or sperm measure after the peptide in any animal or person, no study with hCG, gonadorelin, or enclomiphene, no human dose, and no human safety data.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Search run on 10 October 2026
Study design
Dated literature and registry search
Funding
not stated in the source

An absence finding as of 10 October 2026, not proof that no unpublished work exists.

Read the original source

Does Testagen support natural testosterone, with hCG, gonadorelin or enclomiphene?

No record supports it. No study measured testosterone, luteinizing hormone, follicle-stimulating hormone or any testicular endpoint after the peptide in any species, and none tested it with hCG, gonadorelin or enclomiphene. The group's male reproductive label rests on references that are not about reproduction.

Sellers promote Testagen for natural testosterone support alongside hCG, gonadorelin and enclomiphene. A PubMed search for (testagen OR Lys-Glu-Asp-Gly OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen) returned 0 records, and the same terms with clinical trial or randomized controlled trial publication types returned 0 records. In the records reviewed there is no testosterone, luteinizing hormone, follicle-stimulating hormone or sperm measure after the peptide in any animal or person, no study with hCG, gonadorelin or enclomiphene, no human dose and no human safety data.

The group's 2021 review lists KEDG, Testagen under regulation of male reproductive system function and gives three references. They are a wheat histone-binding study of six short peptides, a review of cell differentiation whose abstract places KEDG among immune-cell differentiation peptides, and a Vilon and Epitalon mouse heart microarray study that does not involve KEDG. The group's 2022 table repeats the label with no reference.

The only whole-animal result is thyroid hormone recovery in chickens whose pituitary glands had been removed. This page does not describe the peptide as acting on the testis or the hypothalamic-pituitary-gonadal axis, because no record shows that.

Every result on this page is for the synthetic tetrapeptide. The anterior pituitary peptide complexes it was designed from are a tissue extract and a separate product. Tissue-extract products sold under similar names are different things, and no PubMed record describes a Cytomax or Cytogen retail product, so nothing here is cited to those product lines.

PubMed: 2 records, no testosterone measure, no clinical trial

PubMed search record

PubMed searches run 10 October 2026: testagen; (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen); (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) with clinical trial or randomized controlled trial publication types; KEDG under its sequence names. ClinicalTrials.gov and DailyMed queries, run the same day.

A PubMed search for testagen returned 2 records: the HeLa study and a 2025 chemistry paper in which the peptide was tested as a copper corrosion inhibitor in salt solution (about 86% inhibition efficiency, no biological measurement). A search for (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen) returned 0 records. A search for (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) with clinical trial or randomized controlled trial publication types returned 0 records. A search for KEDG under its sequence names returned 13 records: the 5 hypophysectomized bird papers, 4 general Khavinson peptide papers (including the HeLa study and the histone-binding paper), the 2025 corrosion paper, and 3 unrelated records. ClinicalTrials.gov returned 1 record for Testagen (the testosterone lotion) and none for a KEDG tetrapeptide. In the records reviewed there is no testosterone, luteinizing hormone, follicle-stimulating hormone, or sperm measure after the peptide in any animal or person, no study with hCG, gonadorelin, or enclomiphene, no human dose, and no human safety data.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Search run on 10 October 2026
Study design
Dated literature and registry search
Funding
not stated in the source

An absence finding as of 10 October 2026, not proof that no unpublished work exists.

Read the original source
Hypophysectomized chickens and old hens: thyroid hormones and thyroid structure

Animal study

Kuznik BI et al. Bull Exp Biol Med. 2011;150(4):495-9. PMID 22268052.

Lys-Glu-Asp-Gly was synthesized on the basis of the amino acid composition of anterior pituitary peptide complexes. In hypophysectomized chickens and old hens given the peptide for 40 days, it raised thyrotropic hormone and thyroid hormone concentrations and restored thyroid structure (PMID 19024016, PMID 22268052, PMID 21809626), restored thymus structure (PMID 23658898), and normalized immune and hemostatic parameters (PMID 20731122). The effects were smaller in old hens. The abstracts give no dose, no route, and no gonadal, luteinizing hormone, follicle-stimulating hormone, or testosterone endpoint.

Participants / model
Hypophysectomized young chickens, mature chickens, and old hens or birds
Treatment
Administration for 40 days; route and dose not stated in the abstracts
Follow-up
40 days
Study design
Preclinical bird studies of the pituitary-thyroid axis, thymus and immunity
Funding
not stated in the source

The in vivo work on this sequence is about the pituitary-thyroid axis and the immune system, not the testis.

Read the original source
2021 review: the male reproductive label rests on three non-reproductive references

Narrative review

Khavinson VK et al. Molecules. 2021;26(22). PMID 34834147.

The group's 2021 systematic review in Molecules lists KEDG, Testagen under regulation of male reproductive system function and gives three references. Those are a wheat histone-binding study of six short peptides (PMID 23581987), a review of cell differentiation whose abstract places KEDG among immune-cell differentiation peptides (PMID 31808038), and a Vilon and Epitalon mouse heart microarray study that does not involve KEDG. The group's 2022 table repeats the regulator of the male reproductive system label with no reference.

Participants / model
Not applicable
Treatment
Not applicable
Follow-up
Not applicable
Study design
Review table
Funding
not stated in the source

The label that links the name to male reproduction rests on references that are not about reproduction.

Read the original source

How is Testagen thought to work?

No mechanism for any testosterone effect exists. In cells the labeled peptide entered the nucleus and bound CAG-containing oligonucleotides in a test tube, and the chicken abstracts report thyroid and thymus recovery without a mechanism. No pharmacokinetic data exist.

The cell work is mechanism-level only: fluorescein-labeled testagen entered the cytoplasm, nucleus and nucleolus of HeLa cells, and in a test tube it bound preferentially to CAG-containing oligonucleotide sequences. It measures no hormone and no reproductive endpoint.

In chickens whose pituitary glands had been removed, the abstracts report thyrotropic hormone rising after peptide treatment. How completely the pituitary was removed needs the full text, so no pituitary mechanism is described here. The abstracts give no dose or route, and no pharmacokinetic data were found in any species.

2011 HeLa cells: cell uptake and DNA binding

Cell study

Fedoreyeva LI et al. Biochemistry (Mosc). 2011;76(11):1210-9. PMID 22117547.

Fluorescein-labeled testagen, epithalon, and pinealon entered the cytoplasm, nucleus, and nucleolus of HeLa cells, and the abstract reports that testagen binds preferentially to CAG-containing oligonucleotide sequences in a test tube. This is a mechanism-level cell result in a cervical cancer line.

Participants / model
HeLa cells; synthetic oligonucleotides
Treatment
Labeled peptide in culture medium and in vitro mixtures
Follow-up
not stated in the source
Study design
Cell uptake and in vitro DNA-binding study
Funding
not stated in the source

Cell uptake only. It measures no hormone and no reproductive endpoint.

Read the original source
Hypophysectomized chickens and old hens: thyroid hormones and thyroid structure

Animal study

Kuznik BI et al. Bull Exp Biol Med. 2011;150(4):495-9. PMID 22268052.

Lys-Glu-Asp-Gly was synthesized on the basis of the amino acid composition of anterior pituitary peptide complexes. In hypophysectomized chickens and old hens given the peptide for 40 days, it raised thyrotropic hormone and thyroid hormone concentrations and restored thyroid structure (PMID 19024016, PMID 22268052, PMID 21809626), restored thymus structure (PMID 23658898), and normalized immune and hemostatic parameters (PMID 20731122). The effects were smaller in old hens. The abstracts give no dose, no route, and no gonadal, luteinizing hormone, follicle-stimulating hormone, or testosterone endpoint.

Participants / model
Hypophysectomized young chickens, mature chickens, and old hens or birds
Treatment
Administration for 40 days; route and dose not stated in the abstracts
Follow-up
40 days
Study design
Preclinical bird studies of the pituitary-thyroid axis, thymus and immunity
Funding
not stated in the source

The in vivo work on this sequence is about the pituitary-thyroid axis and the immune system, not the testis.

Read the original source

What is known about the safety of Testagen?

No human safety data exist for Testagen: the searches found no human dose and no study of any design in people. The chicken abstracts give no dose or route, so animal safety is not described either, and a registered topical testosterone product shares the name, so a record needs the sequence stated before it is attributed to the peptide.

A PubMed search on 10 October 2026 found no clinical trial of the peptide, so there is no human dose and no human safety data. The chicken abstracts report hormone, thyroid, thymus and immune outcomes and give no dose or route.

A topical testosterone lotion in a registered phase 2 study carries the name Testagen. It is not the peptide, and a label, trial or database record cited as Testagen needs the sequence stated to keep them apart.

PubMed: 2 records, no testosterone measure, no clinical trial

PubMed search record

PubMed searches run 10 October 2026: testagen; (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen); (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) with clinical trial or randomized controlled trial publication types; KEDG under its sequence names. ClinicalTrials.gov and DailyMed queries, run the same day.

A PubMed search for testagen returned 2 records: the HeLa study and a 2025 chemistry paper in which the peptide was tested as a copper corrosion inhibitor in salt solution (about 86% inhibition efficiency, no biological measurement). A search for (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen) returned 0 records. A search for (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) with clinical trial or randomized controlled trial publication types returned 0 records. A search for KEDG under its sequence names returned 13 records: the 5 hypophysectomized bird papers, 4 general Khavinson peptide papers (including the HeLa study and the histone-binding paper), the 2025 corrosion paper, and 3 unrelated records. ClinicalTrials.gov returned 1 record for Testagen (the testosterone lotion) and none for a KEDG tetrapeptide. In the records reviewed there is no testosterone, luteinizing hormone, follicle-stimulating hormone, or sperm measure after the peptide in any animal or person, no study with hCG, gonadorelin, or enclomiphene, no human dose, and no human safety data.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Search run on 10 October 2026
Study design
Dated literature and registry search
Funding
not stated in the source

An absence finding as of 10 October 2026, not proof that no unpublished work exists.

Read the original source
Hypophysectomized chickens and old hens: thyroid hormones and thyroid structure

Animal study

Kuznik BI et al. Bull Exp Biol Med. 2011;150(4):495-9. PMID 22268052.

Lys-Glu-Asp-Gly was synthesized on the basis of the amino acid composition of anterior pituitary peptide complexes. In hypophysectomized chickens and old hens given the peptide for 40 days, it raised thyrotropic hormone and thyroid hormone concentrations and restored thyroid structure (PMID 19024016, PMID 22268052, PMID 21809626), restored thymus structure (PMID 23658898), and normalized immune and hemostatic parameters (PMID 20731122). The effects were smaller in old hens. The abstracts give no dose, no route, and no gonadal, luteinizing hormone, follicle-stimulating hormone, or testosterone endpoint.

Participants / model
Hypophysectomized young chickens, mature chickens, and old hens or birds
Treatment
Administration for 40 days; route and dose not stated in the abstracts
Follow-up
40 days
Study design
Preclinical bird studies of the pituitary-thyroid axis, thymus and immunity
Funding
not stated in the source

The in vivo work on this sequence is about the pituitary-thyroid axis and the immune system, not the testis.

Read the original source
Naming warning: a registered topical testosterone product shares the name Testagen

Trial registry record

ClinicalTrials.gov. NCT02733133, phase 2 pharmacokinetic study of Testagen TDS-Testosterone, record last updated 2026-05-27.

ClinicalTrials.gov lists NCT02733133, a phase 2 pharmacokinetic study of Testagen TDS-Testosterone, a topical testosterone product (HypoSpray lotion) from Transdermal Delivery Solutions Corp, designed to measure transfer of testosterone from dosed men to female partners by skin contact. It estimates 96 healthy adults, has a start date of 2027-01-05, and was not yet recruiting as of its 2026-05-27 update, so it has no posted results. That product is a testosterone, not a peptide, and nothing in that record involves the tetrapeptide. DailyMed returns no label named Testagen.

Participants / model
Healthy adults (registered, not yet enrolling)
Treatment
Topical testosterone lotion
Follow-up
Not applicable
Study design
Trial registry record for an unrelated product, not yet recruiting
Funding
not stated in the source

Naming warning only. This record is for a different product and is not evidence about the peptide.

Read the original source

Why does Testagen sit in D tier?

Testagen has a defined sequence and several chicken papers, but none touches the gonadal axis. The label that links it to the male reproductive system rests on references that are not about reproduction, and a registered topical testosterone product shares its name.

The peptide has a defined sequence, a cell uptake study and several chicken papers on the thyroid axis, thymus and immunity. None measures testosterone, luteinizing hormone, follicle-stimulating hormone or a testicular endpoint, and the label that links the name to male reproduction rests on references that are not about reproduction.

No study combined it with hCG, gonadorelin or enclomiphene, and a PubMed search on 10 October 2026 found no clinical trial and no human data. The only whole-animal result is thyroid hormone recovery in chickens whose pituitary glands had been removed.

Hypophysectomized chickens and old hens: thyroid hormones and thyroid structure

Animal study

Kuznik BI et al. Bull Exp Biol Med. 2011;150(4):495-9. PMID 22268052.

Lys-Glu-Asp-Gly was synthesized on the basis of the amino acid composition of anterior pituitary peptide complexes. In hypophysectomized chickens and old hens given the peptide for 40 days, it raised thyrotropic hormone and thyroid hormone concentrations and restored thyroid structure (PMID 19024016, PMID 22268052, PMID 21809626), restored thymus structure (PMID 23658898), and normalized immune and hemostatic parameters (PMID 20731122). The effects were smaller in old hens. The abstracts give no dose, no route, and no gonadal, luteinizing hormone, follicle-stimulating hormone, or testosterone endpoint.

Participants / model
Hypophysectomized young chickens, mature chickens, and old hens or birds
Treatment
Administration for 40 days; route and dose not stated in the abstracts
Follow-up
40 days
Study design
Preclinical bird studies of the pituitary-thyroid axis, thymus and immunity
Funding
not stated in the source

The in vivo work on this sequence is about the pituitary-thyroid axis and the immune system, not the testis.

Read the original source
2021 review: the male reproductive label rests on three non-reproductive references

Narrative review

Khavinson VK et al. Molecules. 2021;26(22). PMID 34834147.

The group's 2021 systematic review in Molecules lists KEDG, Testagen under regulation of male reproductive system function and gives three references. Those are a wheat histone-binding study of six short peptides (PMID 23581987), a review of cell differentiation whose abstract places KEDG among immune-cell differentiation peptides (PMID 31808038), and a Vilon and Epitalon mouse heart microarray study that does not involve KEDG. The group's 2022 table repeats the regulator of the male reproductive system label with no reference.

Participants / model
Not applicable
Treatment
Not applicable
Follow-up
Not applicable
Study design
Review table
Funding
not stated in the source

The label that links the name to male reproduction rests on references that are not about reproduction.

Read the original source
Naming warning: a registered topical testosterone product shares the name Testagen

Trial registry record

ClinicalTrials.gov. NCT02733133, phase 2 pharmacokinetic study of Testagen TDS-Testosterone, record last updated 2026-05-27.

ClinicalTrials.gov lists NCT02733133, a phase 2 pharmacokinetic study of Testagen TDS-Testosterone, a topical testosterone product (HypoSpray lotion) from Transdermal Delivery Solutions Corp, designed to measure transfer of testosterone from dosed men to female partners by skin contact. It estimates 96 healthy adults, has a start date of 2027-01-05, and was not yet recruiting as of its 2026-05-27 update, so it has no posted results. That product is a testosterone, not a peptide, and nothing in that record involves the tetrapeptide. DailyMed returns no label named Testagen.

Participants / model
Healthy adults (registered, not yet enrolling)
Treatment
Topical testosterone lotion
Follow-up
Not applicable
Study design
Trial registry record for an unrelated product, not yet recruiting
Funding
not stated in the source

Naming warning only. This record is for a different product and is not evidence about the peptide.

Read the original source
PubMed: 2 records, no testosterone measure, no clinical trial

PubMed search record

PubMed searches run 10 October 2026: testagen; (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen); (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) with clinical trial or randomized controlled trial publication types; KEDG under its sequence names. ClinicalTrials.gov and DailyMed queries, run the same day.

A PubMed search for testagen returned 2 records: the HeLa study and a 2025 chemistry paper in which the peptide was tested as a copper corrosion inhibitor in salt solution (about 86% inhibition efficiency, no biological measurement). A search for (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen) returned 0 records. A search for (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) with clinical trial or randomized controlled trial publication types returned 0 records. A search for KEDG under its sequence names returned 13 records: the 5 hypophysectomized bird papers, 4 general Khavinson peptide papers (including the HeLa study and the histone-binding paper), the 2025 corrosion paper, and 3 unrelated records. ClinicalTrials.gov returned 1 record for Testagen (the testosterone lotion) and none for a KEDG tetrapeptide. In the records reviewed there is no testosterone, luteinizing hormone, follicle-stimulating hormone, or sperm measure after the peptide in any animal or person, no study with hCG, gonadorelin, or enclomiphene, no human dose, and no human safety data.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Search run on 10 October 2026
Study design
Dated literature and registry search
Funding
not stated in the source

An absence finding as of 10 October 2026, not proof that no unpublished work exists.

Read the original source

Studies and sources

PubChem: Lys-Glu-Asp-Gly identity

Chemical identity record

National Library of Medicine. PubChem compound record CID 123863700.

A PubChem name search for Testagen returned no record. H-Lys-Glu-Asp-Gly-OH is CID 123863700, C17H29N5O9, molecular weight 447.4, with no CAS number and no Testagen synonym. The sequence tied to the name appears in a 2011 abstract (testagen, Lys-Glu-Asp-Gly, PMID 22117547) and in a 2025 chemistry abstract that calls testagen (KEDG) the tetrapeptide H-Lys-Glu-Asp-Gly-OH (PMID 40807317); the group's 2022 table lists Testagen (KEDG) as a regulator of the male reproductive system. The trade name is tied to the sequence by those sources, not by PubChem.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined synthetic peptide
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

The record defines the sequence only. The link from the name Testagen to the sequence rests on the group's abstracts and table.

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Naming warning: a registered topical testosterone product shares the name Testagen

Trial registry record

ClinicalTrials.gov. NCT02733133, phase 2 pharmacokinetic study of Testagen TDS-Testosterone, record last updated 2026-05-27.

ClinicalTrials.gov lists NCT02733133, a phase 2 pharmacokinetic study of Testagen TDS-Testosterone, a topical testosterone product (HypoSpray lotion) from Transdermal Delivery Solutions Corp, designed to measure transfer of testosterone from dosed men to female partners by skin contact. It estimates 96 healthy adults, has a start date of 2027-01-05, and was not yet recruiting as of its 2026-05-27 update, so it has no posted results. That product is a testosterone, not a peptide, and nothing in that record involves the tetrapeptide. DailyMed returns no label named Testagen.

Participants / model
Healthy adults (registered, not yet enrolling)
Treatment
Topical testosterone lotion
Follow-up
Not applicable
Study design
Trial registry record for an unrelated product, not yet recruiting
Funding
not stated in the source

Naming warning only. This record is for a different product and is not evidence about the peptide.

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2021 review: the male reproductive label rests on three non-reproductive references

Narrative review

Khavinson VK et al. Molecules. 2021;26(22). PMID 34834147.

The group's 2021 systematic review in Molecules lists KEDG, Testagen under regulation of male reproductive system function and gives three references. Those are a wheat histone-binding study of six short peptides (PMID 23581987), a review of cell differentiation whose abstract places KEDG among immune-cell differentiation peptides (PMID 31808038), and a Vilon and Epitalon mouse heart microarray study that does not involve KEDG. The group's 2022 table repeats the regulator of the male reproductive system label with no reference.

Participants / model
Not applicable
Treatment
Not applicable
Follow-up
Not applicable
Study design
Review table
Funding
not stated in the source

The label that links the name to male reproduction rests on references that are not about reproduction.

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Hypophysectomized chickens and old hens: thyroid hormones and thyroid structure

Animal study

Kuznik BI et al. Bull Exp Biol Med. 2011;150(4):495-9. PMID 22268052.

Lys-Glu-Asp-Gly was synthesized on the basis of the amino acid composition of anterior pituitary peptide complexes. In hypophysectomized chickens and old hens given the peptide for 40 days, it raised thyrotropic hormone and thyroid hormone concentrations and restored thyroid structure (PMID 19024016, PMID 22268052, PMID 21809626), restored thymus structure (PMID 23658898), and normalized immune and hemostatic parameters (PMID 20731122). The effects were smaller in old hens. The abstracts give no dose, no route, and no gonadal, luteinizing hormone, follicle-stimulating hormone, or testosterone endpoint.

Participants / model
Hypophysectomized young chickens, mature chickens, and old hens or birds
Treatment
Administration for 40 days; route and dose not stated in the abstracts
Follow-up
40 days
Study design
Preclinical bird studies of the pituitary-thyroid axis, thymus and immunity
Funding
not stated in the source

The in vivo work on this sequence is about the pituitary-thyroid axis and the immune system, not the testis.

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2011 HeLa cells: cell uptake and DNA binding

Cell study

Fedoreyeva LI et al. Biochemistry (Mosc). 2011;76(11):1210-9. PMID 22117547.

Fluorescein-labeled testagen, epithalon, and pinealon entered the cytoplasm, nucleus, and nucleolus of HeLa cells, and the abstract reports that testagen binds preferentially to CAG-containing oligonucleotide sequences in a test tube. This is a mechanism-level cell result in a cervical cancer line.

Participants / model
HeLa cells; synthetic oligonucleotides
Treatment
Labeled peptide in culture medium and in vitro mixtures
Follow-up
not stated in the source
Study design
Cell uptake and in vitro DNA-binding study
Funding
not stated in the source

Cell uptake only. It measures no hormone and no reproductive endpoint.

Read the original source
PubMed: 2 records, no testosterone measure, no clinical trial

PubMed search record

PubMed searches run 10 October 2026: testagen; (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen); (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) with clinical trial or randomized controlled trial publication types; KEDG under its sequence names. ClinicalTrials.gov and DailyMed queries, run the same day.

A PubMed search for testagen returned 2 records: the HeLa study and a 2025 chemistry paper in which the peptide was tested as a copper corrosion inhibitor in salt solution (about 86% inhibition efficiency, no biological measurement). A search for (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) AND (testosterone OR testis OR testicular OR Leydig OR spermatogenesis OR hypogonadism OR androgen) returned 0 records. A search for (testagen OR "Lys-Glu-Asp-Gly" OR KEDG) with clinical trial or randomized controlled trial publication types returned 0 records. A search for KEDG under its sequence names returned 13 records: the 5 hypophysectomized bird papers, 4 general Khavinson peptide papers (including the HeLa study and the histone-binding paper), the 2025 corrosion paper, and 3 unrelated records. ClinicalTrials.gov returned 1 record for Testagen (the testosterone lotion) and none for a KEDG tetrapeptide. In the records reviewed there is no testosterone, luteinizing hormone, follicle-stimulating hormone, or sperm measure after the peptide in any animal or person, no study with hCG, gonadorelin, or enclomiphene, no human dose, and no human safety data.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Search run on 10 October 2026
Study design
Dated literature and registry search
Funding
not stated in the source

An absence finding as of 10 October 2026, not proof that no unpublished work exists.

Read the original source

Why is Testagen in D tier?

D fits a compound with a defined sequence and chicken papers that never touch the gonadal axis. The group's male reproductive label rests on references that are not about reproduction, no study measured testosterone or tested it with hCG, gonadorelin or enclomiphene, and a registered topical testosterone product shares the name.