YK-11 A steroidal partial AR agonist whose myostatin lore outruns the human evidence

01 Names and chemical character

YK-11 is a synthetic steroidal molecule ((17α,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester) characterised as a partial AR agonist that activates AR without inducing the N/C interaction typical of full agonists (PMID 21372378). It is often marketed as a SARM; mechanistically it is an edge case relative to nonsteroidal arylpropionamides. It is not enobosarm, not ligandrol, and not Cardarine.

A dedicated PubMed retry after an earlier HTTP 429 returned twenty recent hits spanning cell pharmacology, osteogenesis, hippocampal toxicology, and doping detection — still a small literature.

02 Myogenic differentiation and follistatin — cell tier

Kanno et al. (2013) reported that YK-11 regulates myogenic differentiation of C2C12 myoblasts with induction of myogenic regulatory factors and follistatin expression more marked than DHT in that system (PMID 23995658). Later work extended osteoblastic proliferation/differentiation signals in MC3T3-E1 cells (PMID 29491216) and BMSC osteogenesis / cranial-defect repair models in animals (PMID 39660819). These are cell and animal findings. Community claims that YK-11 is a human myostatin inhibitor are an extrapolation and are labelled contested in this series.

03 Gene-selective AR signalling

Differential DNA-binding and cofactor recruitment have been proposed as determinants of YK-11-dependent gene activation patterns versus DHT (PMID 36030969). Docking and mutational studies suggest steric effects at the C17 region alter helix packing. That mechanistic nuance explains gene selectivity hypotheses; it does not validate grey-market physique use.

04 Hippocampal oxidative-stress signals (animal)

Recent rat studies report hippocampal oxidative stress, mitochondrial dysfunction, and neurochemical alterations with YK-11, including work that models co-exposure with exercise (PMID 37468001; 38521455). These are animal toxicology / neurochemistry signals. They are not human cognitive outcome trials, but they complicate marketing that presents YK-11 as a low-risk “myostatin blocker.”

05 Anti-doping detection

Mass-spectrometric characterisation, in-vivo metabolism, equine hair/urine methods, and adverse analytical findings (PMID 28440570; 30379415; 37946705; 36519889 among harvest hits) show that YK-11 is in the doping-control stream. Detection is not efficacy.

06 Regulatory status

YK-11 is not FDA-approved. As a SARM-marketed / AR-modulating agent it falls under the WADA S1 problem set for athletes. FDA consumer warnings on SARM body-building products apply to the retail context in which YK-11 is sold.

07 Absences

No therapeutic human RCT. No approved indication. Myostatin / follistatin human claims remain unproven at harvest. Product identity on grey-market bottles is unverified by default.

08 Harvest literature map

Deep-harvest strata for YK-11: (1) Kanno partial-agonist and C2C12/follistatin cell papers; (2) osteoblast/BMSC animal extension; (3) rat hippocampal oxidative stress; (4) doping detection. A PubMed 429 on first pass was cleared on retry (20 ids). Computational docking papers in 2025–26 hits are hypothesis-generating. YouTube and ChemicalBook myostatin marketing pages were excluded from the confirmed claim set.

How this document was assembled

Commissioned 5 August 2026 in the Adjacent Compounds / SARMs group and rewritten the same day after a deep research-API harvest (Tavily, Exa, PubMed E-utilities, ClinicalTrials.gov API v2, Camoufox for selected primary pages). Artefacts live under projects/adjacent_compounds_research_2026/deep_harvest/. HOUSE_STYLE governs presentation. PubMed-indexed references are NCBI-resolved.

Evidence handling

Study type is named in the reporting sentence. Animal and in-vitro results are not phrased as human outcomes. Sponsor press is secondary until peer-reviewed full text is admitted. Consumer case reports are grey-market exposure literature unless product analytics accompany the report. Cardarine is never called a SARM.

References

1. Dahleh MMM, Bortolotto VC, Guerra GP, Boeira SP, Prigol M. YK11 induces oxidative stress and mitochondrial dysfunction in hippocampus: The interplay between a selective androgen receptor modulator (SARM) and exercise. J Steroid Biochem Mol Biol. 2023;233:106364.
   PMID 37468001 · doi:10.1016/j.jsbmb.2023.106364
2. Dahleh MMM, Bortolotto VC, Boeira SP, Segat HJ, Guerra GP, Prigol M. From gains to gaps? How Selective Androgen Receptor Modulator (SARM) YK11 impact hippocampal function: In silico, in vivo, and ex vivo perspectives. Chem Biol Interact. 2024;394:110971.
   PMID 38521455 · doi:10.1016/j.cbi.2024.110971
3. Kanno Y, Hikosaka R, Zhang SY, Inoue Y, Nakahama T, Kato K, et al.. (17α,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester (YK11) is a partial agonist of the androgen receptor. Biol Pharm Bull. 2011;34(3):318-23.
   PMID 21372378 · doi:10.1248/bpb.34.318
4. Kanno Y, Ota R, Someya K, Kusakabe T, Kato K, Inouye Y. Selective androgen receptor modulator, YK11, regulates myogenic differentiation of C2C12 myoblasts by follistatin expression. Biol Pharm Bull. 2013;36(9):1460-5.
   PMID 23995658 · doi:10.1248/bpb.b13-00231
5. Kanno Y, Saito N, Saito R, Kosuge T, Shizu R, Yatsu T, et al.. Differential DNA-binding and cofactor recruitment are possible determinants of the synthetic steroid YK11-dependent gene expression by androgen receptor in breast cancer MDA-MB 453 cells. Exp Cell Res. 2022;419(2):113333.
   PMID 36030969 · doi:10.1016/j.yexcr.2022.113333
6. Piper T, Dib J, Putz M, Fusshöller G, Pop V, Lagojda A, et al.. Studies on the in vivo metabolism of the SARM YK11: Identification and characterization of metabolites potentially useful for doping controls. Drug Test Anal. 2018;10(11-12):1646-1656.
   PMID 30379415 · doi:10.1002/dta.2527
7. Sobolevsky T, Kucherova Y, Ahrens B. Detection of selective androgen receptor modulator YK-11 in a doping control sample. Drug Test Anal. 2024;16(6):655-660.
   PMID 37946705 · doi:10.1002/dta.3604
8. Thevis M, Piper T, Dib J, Lagojda A, Kühne D, Packschies L, et al.. Mass spectrometric characterization of the selective androgen receptor modulator (SARM) YK-11 for doping control purposes. Rapid Commun Mass Spectrom. 2017;31(14):1175-1183.
   PMID 28440570 · doi:10.1002/rcm.7886
9. Wang R, Zhong Y, Du Q, Zhao C, Wang Y, Pan J. YK11 promotes osteogenic differentiation of BMSCs and repair of bone defects. J Mol Endocrinol. 2025;74(2).
   PMID 39660819 · doi:10.1530/JME-24-0073
10. Yatsu T, Kusakabe T, Kato K, Inouye Y, Nemoto K, Kanno Y. Selective Androgen Receptor Modulator, YK11, Up-Regulates Osteoblastic Proliferation and Differentiation in MC3T3-E1 Cells. Biol Pharm Bull. 2018;41(3):394-398.
    PMID 29491216 · doi:10.1248/bpb.b17-00748
11. U.S. Food and Drug Administration. Consumer updates and warning letters on body-building products containing SARMs. Regulatory context.
    https://www.fda.gov/
12. World Anti-Doping Agency. Prohibited List — S1 Anabolic Agents (selective androgen receptor modulators).
    https://www.wada-ama.org/
13. NIDDK LiverTox. Selective Androgen Receptor Modulators (SARMs). NCBI Bookshelf NBK619971.
    https://www.ncbi.nlm.nih.gov/books/NBK619971/
14. ClinicalTrials.gov. Protocol inventory via API v2; not peer-reviewed results.
    https://clinicaltrials.gov/
15. PubChem compound summary pages used for identity cross-checks.
    https://pubchem.ncbi.nlm.nih.gov/