LGD-4033 / YK-11 Solution Overview
This research solution contains two distinct synthetic androgen receptor ligands supplied in combination: LGD-4033 (Ligandrol; VK-5211), a nonsteroidal selective androgen receptor modulator (SARM) originally developed by Ligand Pharmaceuticals, and YK-11, a synthetic steroidal compound structurally derived from the 19-norpregnadiene scaffold. The two compounds represent contrasting chemical classes — one a fluorinated phenylpyrrolidine nonsteroidal AR ligand, the other a modified steroidal scaffold — and are sometimes referenced together in published analytical and structure-activity literature comparing steroidal versus nonsteroidal androgen receptor modulators.
This combination solution is supplied strictly for laboratory and analytical research purposes. Neither compound is approved for human or veterinary use.
Compound Identification
LGD-4033 (Ligandrol)
- Chemical Name: 4-[(2R)-2-[(1R)-2,2,2-Trifluoro-1-hydroxyethyl]pyrrolidin-1-yl]-2-(trifluoromethyl)benzonitrile
- Synonyms: LGD4033; Ligandrol; VK-5211
- CAS Number: 1165910-22-4
- Molecular Formula: C₁₄H₁₂F₆N₂O
- Molecular Weight: 338.25 g/mol
- PubChem CID: 44137686
- UNII: 1EJT54415A
- Structural class: Nonsteroidal phenylpyrrolidine
YK-11
- Chemical Name: Methyl (17α,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylate
- Synonyms: YK11; Myostine
- CAS Number: 1370003-76-1
- Molecular Formula: C₂₅H₃₄O₆
- Molecular Weight: 430.54 g/mol
- UNII: Z9748J6B0R
- Structural class: Steroidal — 19-norpregnadiene derivative; structurally related to dihydrotestosterone (DHT)
Mechanism of Action (Research Context)
The two compounds in this solution represent mechanistically distinct AR ligand classes:
- LGD-4033 binds the androgen receptor ligand-binding domain with high affinity (reported K_i ≈ 1 nM) and acts as a tissue-differential AR ligand, with full-agonist transcriptional activity in cell models representative of muscle and bone tissue and reduced (partial agonist) activity in prostate-derived reporter models.
- YK-11 acts as a gene-selective partial agonist of the androgen receptor. Published in vitro work (Kanno et al., 2011) reported that YK-11 does not induce the N/C-terminal interaction required for full AR transactivation, producing a distinct transcriptional profile relative to DHT and other steroidal androgens. The original work and subsequent reports also describe in vitro effects on follistatin expression in C2C12 myoblast cultures, though the broader myostatin-pathway findings have not been independently replicated across multiple research groups and remain an active area of investigation.
The two compounds together are referenced in some analytical chemistry contexts as examples of structurally divergent AR ligands within the broader SARM analyte panel.
Physical and Chemical Properties
- Appearance: Clear, light-colored solution
- Solvent system: Organic carrier; not aqueous
- Stability: Stable under controlled storage conditions when protected from light
- Storage: Room Temperature (Away From Light)
Research Focus Areas
This combination solution may be referenced in laboratory research involving:
- Comparative AR ligand pharmacology — steroidal versus nonsteroidal scaffolds
- Analytical method development and chromatographic separation of mixed SARM analyte panels (relevant to anti-doping analytical chemistry literature)
- Structure-activity relationship (SAR) analysis across distinct AR ligand chemical classes
- In vitro receptor binding and transactivation studies referencing multiple AR ligand chemotypes
- Forensic toxicology and metabolite identification research
Research Background & Regulatory Context
Both LGD-4033 and YK-11 are included on the World Anti-Doping Agency (WADA) Prohibited List under the anabolic agents category. LGD-4033 has been the subject of FDA public consumer advisories specifically naming Ligandrol in the context of unapproved bodybuilding supplements. YK-11 has been documented in analytical literature as a novel designer-drug analyte requiring inclusion in SARM screening panels. This published regulatory and analytical record is part of the scientific literature on both compounds and reinforces that this product is supplied strictly as a research reagent for laboratory and analytical use, not for therapeutic, performance, dietary supplement, or any other consumer application.
Storage & Handling
- Store refrigerated at 2–8 °C; do not freeze
- Protect from light
- Keep vial tightly sealed after each use
- Discard if solution appears cloudy or discolored
- Record opening date on container label
- Use appropriate laboratory handling procedures and PPE
Research Use Disclaimer
This product is intended strictly for laboratory research use only (RUO). Not for human consumption, clinical use, veterinary use, therapeutic application, dietary supplement use, or diagnostic purposes. All handling and use must comply with applicable federal, state, and local laws and institutional laboratory safety standards.
| CAS Number | 1165910-22-4/1370003-76-1 |
| Other Names | LGD4033, LGD 4033, Ligandrol, UNII-1EJT54415Am, VK-5211, 1EJT54415A, SCHEMBL221159, CHEMBL5170587/YK11, YK 11, Z9748J6B0R, Z9748J6B0R, UNII-Z9748J6B0R, EX-A727, DTXSID301107018, VEC00376 |
| IUPAC Name | 4-[(2R)-2-[(1R)-2,2,2-trifluoro-1-hydroxyethyl]pyrrolidin-1-yl]-2-(trifluoromethyl)benzonitrile/methyl (2E)-2-[(8R,9S,10R,13S,14S,17S)-2′-methoxy-2′,13-dimethyl-3-oxospiro[1,2,6,7,8,9,10,11,12,14,15,16-dodecahydrocyclopenta[a]phenanthrene-17,5′-1,3-dioxolane]-4′-ylidene]acetate |
| Molecular Formula | C₁₄H₁₂F₆N₂O/C₂₅H₃₄O₆ |
| Molecular Weight | 338.25/430.5 |
| Aliquot Concentration And Solution | 50mg/50mg Per ml/ MCT Oil, Benzyl Benzoate, Ethyl Oleate, Benzyl Alcohol |
