What is MK-2866 (Ostarine)?

MK-2866 (known chemically as Ostarine, Enobosarm, GTx-024, or S-22) is an investigational nonsteroidal Selective Androgen Receptor Modulator (SARM) belonging to the aryl-propionamide chemical class. Originally developed by GTx, Inc. to combat sarcopenia, MK-2866 binds the ligand-binding domain of androgen receptors with high affinity (K_i = 3.8 nM). Because its nonsteroidal backbone escapes enzymatic conversion by 5α-reductase into dihydrotestosterone (DHT) and aromatase into estrogen, MK-2866 functions as a foundational baseline reference for tissue-selective anabolic signaling.

Batch-verified for high analytical purity at Modern Aminos, MK-2866 is supplied in three versatile laboratory formats:

30ML aqueous liquid solution in an Amber vial with 1mL precision dropper
60-unit dry-fill oral capsules
10ML MCT-based oil solution vial.

Researchers evaluating myocyte differentiation, receptor binding kinetics, and nitrogen retention dynamics utilize MK-2866 alongside related nonsteroidal SARMs on the site, such as LGD-4033, RAD-140, S4, and RAD-150.

Chemical and Molecular Data

Compound Name	MK-2866 (Ostarine)
Quantity / Formats Offered	30ML Liquid Dropper \| 60-Unit Dry-Fill Capsules \| 10ML MCT Oil Vial
Synonyms / Alt Names	Ostarine, Enobosarm, GTx-024, S-22, MK2866
CAS Number	841205-47-8
Chemical Formula	C₁₉H₁₄F₃N₃O₃
Molecular Weight	389.33 g/mol
IUPAC Name	(2S)-3-(4-cyanophenoxy)-N-[4-cyano-3-(trifluoromethyl)phenyl]-2-hydroxy-2-methylpropanamide
InChIKey	JNGVJMBLXIUVRD-SFHVURJKSA-N
SMILES Code	`CC(C(=O)NC1=CC(=C(C=C1)C#N)C(F)(F)F)(COC2=CC=C(C=C2)C#N)O`

What are the Mechanisms of Action?

The biochemical pathways and cellular targets of MK-2866 in laboratory research include:

Selective Androgen Receptor (AR) Agonism: Research demonstrates that MK-2866 acts as a potent, full or partial agonist at the androgen receptor (K_i = 3.8 nM). Upon binding, it recruits tissue-specific transcriptional coactivators in skeletal muscle and bone tissue, promoting anabolic gene expression without stimulating androgenic pathways in secondary tissues.
Myogenic Differentiation & ERK1/2 Kinase Activation: In skeletal muscle cell culture models (C2C12 and L6), MK-2866 stimulates extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. This signaling cascade upregulates essential myogenic transcription factors—including MyoD, myogenin, and myosin heavy chain (MyH)—accelerating muscle cell proliferation and differentiation.
Nonsteroidal Metabolism & Enzymatic Resistance: Unlike endogenously produced testosterone, MK-2866’s aryl-propionamide core cannot be converted by 5α-reductase into DHT or by aromatase into 17β-estradiol. This isolates its experimental activity strictly to primary androgen receptor pathways in target cell models.

What do Preclinical & Academic Studies Show for MK-2866?

When evaluating research efficacy and published scientific literature for MK-2866 (Ostarine):

Myogenic Differentiation & Muscle Cell Viability (PMC): Comprehensive in vitro studies cataloged in PMC (PMC9031805) demonstrate that MK-2866 directly increases cell viability, C2C12/L6 proliferation, and expression of myogenin and MyH via androgen receptor activation.
Phase II Clinical Trial & Lean Mass Homeostasis (PMC): Double-blind placebo-controlled research archived in PMC (PMC3177038) evaluates MK-2866’s tissue-selective anabolic activity, confirming dose-dependent increases in total lean body mass and physical function markers.
Chemical Profiling & Identification (PubChem): Official structural characterization archived on PubChem verifies the molecular weight (389.33 g/mol), trifluoromethyl-cyanophenyl structure, and HPLC retention profile of CAS 841205-47-8.

How does MK-2866 compare to other compounds?

To evaluate receptor binding kinetics, tissue selectivity, and anabolic signaling pathways, researchers compare MK-2866 against alternative nonsteroidal SARMs available at Modern Aminos:

Compound / Reference	Chemical Class	Core Mechanism of Action	Research Focus & Profile
MK-2866 (Ostarine)	Aryl-Propionamide Nonsteroidal SARM	Selective AR agonism (K_i = 3.8 nM) driving MyoD and myogenin myogenic transcription	Gold-standard baseline reference for tissue-selective anabolic signaling, myocyte differentiation, and muscle wasting research
LGD-4033 (Ligandrol)	Pyrrolidinyl-Benzonitrile SARM	Binds the androgen receptor with sub-nanomolar affinity (K_i = 1 nM)	Evaluates high-potency anabolic muscle building and bone mineral density responses in cell models
RAD-140 (Testolone)	Substituted Benzimidazole SARM	Tissue-selective AR agonism featuring neuroprotective crosstalk in neuronal cell cultures	Focuses on heavy anabolic signaling in muscle and androgenic neuroprotective pathways in central tissue models
S4 (Andarine)	Aryl-Propionamide First-Generation SARM	Partial AR agonist (K_i = 4 nM) targeting skeletal muscle and prostate tissue selectivity	Pioneer reference compound evaluated for partial agonism, lean mass retention, and vascular lipid clearance

Frequently Asked Questions (FAQs)

1. Is Modern Aminos a reliable place to buy MK-2866 (Ostarine)?

Yes, Modern Aminos is a trusted supplier of high-purity research chemicals and nonsteroidal SARM reference standards. Every batch of MK-2866 undergoes strict third-party analytical testing (including HPLC and Mass Spectrometry) to verify minimum 98%+ purity, correct molecular weight (389.33 g/mol), and complete absence of unreacted synthetic precursors or heavy metals.

2. What is the primary molecular target and class of MK-2866?

MK-2866 is an aryl-propionamide nonsteroidal selective androgen receptor modulator (SARM). It targets the ligand-binding domain of human androgen receptors with high affinity (K_i = 3.8 nM), selective for muscle and bone tissue models.

3. How does MK-2866 induce myogenesis in muscle cell lines?

In C2C12 and L6 skeletal muscle cell lines, MK-2866 activates ERK1/2 kinase signaling through androgen receptor binding. This upregulates the myogenic transcription factors MyoD, myogenin, and myosin heavy chain (MyH), driving muscle cell proliferation and differentiation.

4. Does MK-2866 undergo aromatization or 5α-reduction?

No. MK-2866 possesses a nonsteroidal chemical backbone that cannot be converted into dihydrotestosterone (DHT) by 5α-reductase, nor into estrogen by aromatase. This isolates its experimental activity strictly to the androgen receptor without secondary steroidal metabolite formation.

5. What available formats does Modern Aminos offer for MK-2866 research?

Modern Aminos provides MK-2866 in three standardized formats: a 30ML aqueous liquid solution with 1mL dropper, 60-unit dry-fill solid oral capsules, and a 10ML MCT-based oil solution vial. All three formats deliver consistent active material purity for in vitro screening protocols.

6. How does MK-2866 compare to LGD-4033 in androgen receptor kinetics?

Both compounds are potent nonsteroidal SARMs. LGD-4033 belongs to the pyrrolidinyl-benzonitrile class and exhibits higher binding affinity (K_i = 1 nM), whereas MK-2866 (K_i = 3.8 nM) belongs to the aryl-propionamide class and represents the most widely cited baseline reference in muscle wasting literature.

7. Why is MK-2866 widely used as a benchmark reference in SARM research?

Due to its extensive preclinical and Phase I/II clinical trial documentation, MK-2866 serves as the primary benchmark compound for validating androgen receptor assay selectivity, competitive ligand displacement, and anabolic vs. androgenic gene expression profiling.

8. What are the proper storage and handling parameters for MK-2866?

Liquid dropper bottles, capsule containers, and MCT solution vials should be stored tightly sealed in a cool, dry environment (15°C to 25°C) away from direct light, heat, and moisture. Liquid formulations do not require an external reconstitution solution prior to laboratory testing.

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SARMs

AC-262

MK-2866 (Ostarine)

S23 10MG

S4

YK-11