data + articles · 2 listed
newest 2018spec sheet11 rows
MEPB is an experimental small molecule that acts on the androgen receptor at a site distinct from its usual hormone-binding pocket. Chemically it is a benzimidazole, with the full name 1-[2-(4-methylphenoxy)ethyl]-2-[(2-phenoxyethyl)sulfanyl]-1H-benzimidazole. It was identified in research on spinal and bulbar muscular atrophy, a motor neuron disease driven by toxic androgen receptor activity, and it remains a laboratory research compound with no approved use.
- No verified benefits are documented in the public literature
- Compound identity could not be confirmed
- No peer-reviewed pharmacology located
- No established human data
- Not evaluated for use outside the laboratory
Overview
MEPB is a small-molecule modulator of the androgen receptor and, structurally, a benzimidazole; its systematic name is 1-[2-(4-methylphenoxy)ethyl]-2-[(2-phenoxyethyl)sulfanyl]-1H-benzimidazole and it is catalogued under CAS number 331948-99-3. It is neither a hormone nor a steroid. What sets it apart from ordinary androgen drugs is where it acts: instead of the receptor's ligand-binding pocket, it engages an allosteric surface known as the binding-function-3 (BF3) site, which in turn governs the activation-function-2 (AF-2) region where the receptor recruits its coregulator proteins [2].
The compound emerged from drug-discovery work aimed at these allosteric surfaces of the androgen receptor. In a 2018 study, investigators screened a set of AF-2 modulators for the ability to rescue toxicity in a fruit fly model of spinal and bulbar muscular atrophy (SBMA), a motor neuron disease caused by a toxic gain of function of an androgen receptor carrying an expanded polyglutamine tract. MEPB emerged as one of the two strongest candidates [1].
In that research MEPB improved survival, locomotor function, and neuromuscular junction integrity in the fly model, and pharmacokinetic testing in mice showed favorable distribution and retention in muscle, brain, and spinal cord. In a mouse model of SBMA it produced a dose-dependent rescue of body weight, motor performance, and grip strength and reduced neuronal and testicular loss, supporting selective AF-2 modulation as an androgen-sparing strategy for the disease [1].
MEPB is a preclinical research compound. It has not been tested in humans, is not an approved drug, and is handled as a laboratory reagent available from chemical suppliers. Its identity should not be confused with unrelated substances that happen to share a similar abbreviation.
Mechanism
Rather than binding the 's hormone pocket, MEPB engages an surface called the binding-function-3 (BF3) site, which sits next to and controls the activation-function-2 (AF-2) region that the receptor uses to recruit coregulator proteins. By occupying this surface it shifts the balance of coregulator binding toward corepressors and dampens the receptor's transcriptional output [1][2]. In spinal and bulbar muscular atrophy, where an with an expanded polyglutamine tract becomes toxic in a way that depends on AF-2 coregulator binding, this selective modulation blunts the harmful gain-of-function activity while sparing much of normal androgen signaling, which is why MEPB was able to rescue degeneration in fly and mouse models of the disease [1].
receptor fingerprint
Not characterized in public literatureUnknown
Unconfirmed identityUnknown
Safetyrisks and cautions, not medical advice
Everything known about MEPB comes from fruit flies and mice, so its risk profile in people is undefined; there is no human dose, no tolerability record and no toxicology in the public literature. The mouse study was a rescue experiment rather than a safety study, though it did report dose-dependent gains in body weight, grip strength and rotarod performance, and it specifically noted that testicular atrophy was reduced rather than caused, which is the selling point of modulating the receptor instead of blocking it outright. Nothing here supports use outside a laboratory.
Subjective profileweighing the evidence above
There is not enough here to judge, and that is the judgement. Its identity could not even be confirmed, no peer-reviewed pharmacology was located, and there is no human data whatsoever; treat any claim made about it as unsupported.
Resources
This entry is here for reference.
Research
- 1.Selective modulation of the androgen receptor AF2 domain rescues degeneration in spinal bulbar muscular atrophy
- 2.Drug-Discovery Pipeline for Novel Inhibitors of the Androgen Receptor
2 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
What is MEPB?
We could not confidently identify it in the scientific literature. The abbreviation does not clearly map to a documented compound.
Is there safety data?
No reliable safety, toxicology or pharmacology data could be found.
Why so little information?
It appears to be a novel or obscure research chemical, and without a confirmed chemical structure we cannot responsibly characterize it.
Should I use it?
There is no basis to consider an unidentified, uncharacterized research chemical safe or effective.
Limitations of the evidence
- No human safety data
Adverse effects
- Not evaluated for use outside the laboratory
Notes and cautions
- Preclinical research compound only