Crystagen

A synthetic tripeptide (Glu-Asp-Pro) from the Khavinson bioregulator family, identified as a minor component of the thymus extract Thymalin and studied in Russian preclinical work for thymic and immune effects in aging.

Also referenced as: Glu-Asp-Pro, EDP, EDP tripeptide, glutamyl-aspartyl-proline

Also appears in: Longevity

What is Crystagen?

Crystagen is a synthetic tripeptide with the sequence Glu-Asp-Pro (EDP), one of the short peptides developed by Vladimir Khavinson’s group at the Saint Petersburg Institute of Bioregulation and Gerontology and assigned to the thymus and immune system. The group reports that it was designed and synthesized from the amino acid composition of Thymalin, the bovine thymus polypeptide extract, and in 2021 it reported detecting EDP as a trace constituent of that extract. It appears in the research-peptide market as the thymic member of the Khavinson bioregulator line, alongside the dipeptide Vilon (Lys-Glu) and the registered Russian drug Thymogen (Glu-Trp; profiled here as Thymagen), from which it should be kept distinct.

How it works

The proposed mechanism follows the general Khavinson framework in which very short peptides enter the nucleus and alter transcription in the tissue they are matched to. For Glu-Asp-Pro specifically, the published and patent evidence covers:

• Thymic and lymphoid tissue growth — in organotypic spleen cultures from young and old rats, EDP (like Thymalin, Thymogen and Vilon) raised the explant growth-zone index and reduced apoptosis; the patent additionally reports a 24% increase in old-rat thymus explant growth, and both sources report stimulated proliferation of the VTEC2.H/S human thymic epithelial cell line (Khavinson et al., Biology Bulletin Reviews, 2021; US Patent 8,057,810)
• Macrophage cytokine output — the 2021 review states that peritoneal macrophages from young and old mice secreted more IL-1, IL-6 and TNF-α after exposure to EDP; the patent’s underlying experiment measured lymphocyte-activating (thymocyte comitogenic) activity of macrophage supernatants, with and without lipopolysaccharide stimulation, rather than the individual cytokines (Khavinson et al., Biology Bulletin Reviews, 2021; US Patent 8,057,810)
• Chromatin changes in aged lymphocytes — in blood lymphocytes from donors aged 75–88, the patent reports that the peptide reduced heterochromatin in chromosomes 1 and 9 and raised sister chromatid exchange frequency, which the inventors interpret as decondensation of chromatin and reactivation of age-repressed genes; the 2021 review, by contrast, states that EDP “promotes heterochromatinization” of lymphocyte chromatin in the elderly, so the group’s own accounts of the direction of the change disagree (US Patent 8,057,810; Khavinson et al., Biology Bulletin Reviews, 2021)
• B-cell activation in the aging spleen — in spleen explants from old rats, Crystagen activated the B-cell lineage but, unlike Vilon and Thymogen, did not restore cell renewal (Chervyakova et al., Advances in Gerontology, 2014)

Research status

The evidence base is small, preclinical, and comes almost entirely from one institute, much of it published in Russian-language journals or in patent filings rather than peer-reviewed articles.

• Khavinson, Zhurkovich et al. (2021) used ultra-high-performance liquid chromatography–mass spectrometry to confirm that EDP and KE are minor components of Thymalin, at 0.04 mg/g and 0.025 mg/g respectively (Molecular Medicine, Moscow, 19(3), doi 10.29296/24999490-2021-03-05; Russian-language full text)
• Voicekhovskaya et al. (2012) tested five tripeptides — T-32 (Glu-Asp-Ala), T-33 (Glu-Asp-Arg), T-34 (Glu-Asp-Gly), T-36 (Glu-Asp-Pro) and T-38 (Lys-Glu-Asp) — on organotypic skin cultures; EDP stimulated proliferation in explants from young rats, while the Lys-Glu-Asp tripeptide was the one with a marked effect in old-rat skin (Bulletin of Experimental Biology and Medicine, 152(3):357–359)
• Chervyakova et al. (2014) compared Vilon, Timogen, Crystagen and the R-1 peptide in aging rat spleen (Advances in Gerontology, 27(1):224–228; Russian-language)
• Khavinson et al. (2021) reviewed the Thymalin and short-peptide data, including a gamma-irradiation model of accelerated thymic involution in rats in which Crystagen-treated animals retained the cortex–medulla boundary and showed higher thymocyte PCNA expression (Biology Bulletin Reviews, 11(4):377–382)

Human data are limited to an open-label series described in US Patent 8,057,810 and summarized in the 2021 review: 38 patients aged 62–83 with immune decline after low-dose ionizing radiation given the peptide with standard care versus 32 on standard care alone, with “normalization” of immune indices in 82% versus 56%, a rise in CD3+ and CD4+ counts, and a CD4+/CD8+ ratio moving from 1.1 to 1.4. The patent describes the course as intramuscular injection once daily for 10 days; the review describes the same series as oral administration, and the two sources are not reconciled. There was no randomization, blinding, or clinical endpoint, and the series has not been published as a standalone peer-reviewed trial. The patent itself never uses the name Crystagen, referring only to H-Glu-Asp-Pro-OH. No trials are registered on ClinicalTrials.gov under Crystagen, Glu-Asp-Pro or EDP as of October 2026. The 2022 Italian–Russian study of Khavinson peptides in THP-1 monocytes (Avolio et al., International Journal of Molecular Sciences, 23(7):3607) tested Vilon, Thymogen, Thymalin, Epitalon and Chonluten but not Crystagen, so there is still no replication of any Crystagen finding outside the originating group.

Common dosage forms

Research vendors sell Crystagen as lyophilized powder in vials, most often 20 mg, and the Khavinson-line consumer products are oral or sublingual capsules and tablets. The patent describes a parenteral formulation; no format has been evaluated in a controlled trial.

Key considerations

• Regulatory status — not FDA approved and not in US clinical development. Thymalin (Samson-Med) and Thymogen (Cytomed) hold current drug registrations in Russia; no drug registration for Crystagen itself appears on the public record in any jurisdiction, and it circulates as a supplement-style product and research compound. The Research Market status reflects the absence of US approval or any development program aimed at approval.
• Naming confusions — Crystagen is Glu-Asp-Pro. It is not Thymogen (Glu-Trp, PubMed also spells it “Timogen”), which has its own clinical literature that does not transfer to Crystagen; not Vilon (Lys-Glu); not Thymalin (the whole extract, in which all three occur); and not Cortagen (Ala-Glu-Asp-Pro), which shares three residues but is assigned to the brain cortex. Some vendor and protocol pages mislabel Crystagen as Lys-Glu-Asp (the sequence of the vascular peptide Vesugen) or as Thr-Lys-Glu; verify the sequence on a batch certificate of analysis.
• Evidence gaps — a single research group, no randomized or blinded human study, no independent replication, and a human series that exists only in a patent and a review that disagree on the route of administration. The review’s own comparison found Crystagen less antiapoptotic than Vilon or Thymogen in aged lymphocyte cultures.
• Safety signals — the patent reports no acute toxicity in mice at more than 5,000 times the proposed dose and no chronic toxicity at 100–1,000 times, but the increase in sister chromatid exchange in elderly lymphocytes, presented there as a positive effect, is a readout conventionally used as a genotoxicity marker, and no standard genotoxicity or pharmacovigilance data have been published.
• Mechanistic plausibility — the peptide–DNA gene-regulation model applied to Crystagen is the same one proposed for the whole Khavinson family and is not widely accepted outside that literature.