Hormone, anabolic & androgen-receptor research compounds
YK-11
Also known as YK11
A steroidal partial androgen-receptor agonist reported to raise follistatin expression in muscle cells — sold illicitly as a "myostatin inhibitor".
In 60 seconds
Cell and animal research only; first identified in a seized black-market product; prohibited in sport. No human safety data at all; its steroidal structure means androgen-class risks cannot be excluded.
- Identified YK11 as a partial agonist of the androgen receptor in an androgen-responsive reporter system.
- In C2C12 myoblasts, YK11 induced myogenic differentiation via increased follistatin expression.
- After YK11 was found in a seized black-market product, its metabolites were characterised for doping control.
Mechanism
Despite being marketed as a SARM, YK-11 is a steroid (a 19-norpregnadiene derivative). In C2C12 myoblasts it acted as a partial AR agonist and induced myogenic differentiation through increased follistatin, which neutralises myostatin.
Research status
Cell and animal research only; first identified in a seized black-market product; prohibited in sport.
Key studies
Identified YK11 as a partial agonist of the androgen receptor in an androgen-responsive reporter system.
(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 · PMID 21372378
In C2C12 myoblasts, YK11 induced myogenic differentiation via increased follistatin expression.
Selective androgen receptor modulator, YK11, regulates myogenic differentiation of C2C12 myoblasts by follistatin expression — Biol Pharm Bull, 2013 · PMID 23995658
After YK11 was found in a seized black-market product, its metabolites were characterised for doping control.
Studies on the in vivo metabolism of the SARM YK11: Identification and characterization of metabolites potentially useful for doping controls — Drug Test Anal, 2018 · PMID 30379415
YK11 increased osteoblastic proliferation and differentiation in MC3T3-E1 cells.
Selective Androgen Receptor Modulator, YK11, Up-Regulates Osteoblastic Proliferation and Differentiation in MC3T3-E1 Cells — Biol Pharm Bull, 2018 · PMID 29491216
Safety signals in the literature
No human safety data at all; its steroidal structure means androgen-class risks cannot be excluded.
Legal status (South Africa)
Androgens and anabolic steroids are scheduled substances in South Africa (prescription-only under the Medicines and Related Substances Act) and are prohibited in sport. SARM-class compounds are unapproved for human use anywhere. Educational content only — no use guidance.
Questions
What is YK-11?
A steroidal partial androgen-receptor agonist reported to raise follistatin expression in muscle cells — sold illicitly as a "myostatin inhibitor". Despite being marketed as a SARM, YK-11 is a steroid (a 19-norpregnadiene derivative). In C2C12 myoblasts it acted as a partial AR agonist and induced myogenic differentiation through increased follistatin, which neutralises myostatin.
What is the research status of YK-11?
Cell and animal research only; first identified in a seized black-market product; prohibited in sport.
What safety signals are reported for YK-11?
No human safety data at all; its steroidal structure means androgen-class risks cannot be excluded.
Does Living Water Labs stock YK-11?
Not at present. YK-11 is profiled here for reference, with citations to the published literature. Androgens and anabolic steroids are scheduled substances in South Africa (prescription-only under the Medicines and Related Substances Act) and are prohibited in sport. SARM-class compounds are unapproved for human use anywhere. Educational content only — no use guidance.
More in Hormone & anabolic
Research reference only. This page summarises published literature; it is not medical advice and contains no guidance on human use. Products supplied by Living Water Labs are for laboratory research only.