Aicar Explained: What It Is and What the Name Actually Refers To

For laboratory research use only. Not for human or veterinary use.

Aicar is the most commonly mislabelled compound in the research catalogue, and the mislabelling is not carelessness — it is baked into the name. “AICAR” is used in the published literature for two different molecules that differ by a phosphate group, eighty atomic mass units, and whether they can cross a cell membrane at all. This guide sets out which is which, why it matters when you read a certificate, and what the compound does.

Two molecules, one abbreviation

The difference is one phosphate group, and it is the difference between a compound that enters cells and one that does not. Phosphate groups carry charge; charged molecules do not cross lipid membranes unaided. The nucleotide form cannot get in. The nucleoside form can.

What every supplier sells as Aicar is acadesine, the nucleoside — molar mass 258.23, CAS 2627-69-2. If you see 338 on a certificate, that is not what was ordered.

How it works

The mechanism is unusually elegant, and understanding it explains why the naming confusion exists in the first place.

Acadesine is an analogue of adenosine, close enough in shape that it enters cells through the same nucleoside transporters. Once inside, adenosine kinase phosphorylates it — converting it to the nucleotide form, ZMP. The compound that could not get in is therefore manufactured on the inside, from the one that could.

ZMP structurally resembles AMP, adenosine monophosphate. AMP is the cell's low-fuel signal: when ATP is consumed, AMP accumulates, and rising AMP allosterically activates AMP-activated protein kinase (AMPK), the enzyme that switches cellular metabolism from storage to consumption.

ZMP occupies the same regulatory site. AMPK responds as though AMP had risen — but no ATP has been spent and the real nucleotide ratios are unchanged. The compound does not deplete cellular energy; it mimics the signal that energy has been depleted.

That is what makes it a research tool rather than a curiosity. It lets AMPK activation be studied as a variable in its own right, separated from the energy stress that would normally cause it.

It is also a natural metabolite

Worth stating plainly, because it is often missed: AICA ribonucleotide is not a foreign molecule. It is a genuine intermediate in de novo purine biosynthesis — the pathway by which cells build purine bases from scratch — sitting on the route to inosine monophosphate.

So the compound is not introducing a novel chemical entity to the cell. It is raising the concentration of something the cell already makes, at a point where that molecule happens to resemble a regulatory signal.

Where it came from

Acadesine was developed in the 1980s, investigated for cardiac protection during surgery rather than for anything metabolic. The proposed mechanism involved nitric oxide and ATP-sensitive potassium channels.

It was licensed to Schering-Plough in 2007 and entered the RED-CABG Phase III trial in May 2009. The trial was terminated in late 2010 following an interim futility analysis, which concluded it had a low probability of meeting its primary efficacy endpoint. It has never been approved for clinical use anywhere.

The reason anyone outside cardiology has heard of it is separate. In 2008, research in mice reported metabolic effects that drew attention well beyond the laboratory.

Anti-doping status — read this before ordering

Following that 2008 research, the World Anti-Doping Agency added acadesine to its Prohibited List from 2009, under Class S4, metabolic modulators. It was subsequently reported as detected in cycling.

The practical consequence: anyone subject to anti-doping testing should not handle this compound, and any laboratory whose work involves tested populations should regard its presence as a controlled matter. This is a straightforward fact about the compound and it belongs on a supplier's page rather than being left for the customer to discover afterwards.

What to check on the certificate

• Mass spectrometry: 258.23, not 338.21. This is the single most important check and it is specific to this compound. The 80 g/mol separation between nucleoside and nucleotide is unmistakable on a mass spectrum. A certificate reporting the higher mass has not characterised the material that was ordered.
• HPLC purity, with the method named. Reported as measured on that batch. A figure without a method behind it is a number, not a result.
• Water content. Acadesine is hygroscopic. Mass measured on a damp sample is not mass of compound, and a batch stored badly before testing will read light on assay.
• Appearance. White to off-white crystalline powder. Discolouration is a reason to ask questions before use.

Pioneer publishes the certificate for each tested batch in full, with its verification key, in the COA library. The guides on reading a COA and what a purity figure means go through each of these.

Handling — it is not a peptide

Most of what we supply is peptide, and peptide handling rules do not transfer here. Acadesine is a small-molecule nucleoside: a single ribose-linked heterocycle, not a chain of amino acids. It has no secondary structure to lose, which means it is not denatured by agitation and does not carry the shear sensitivity that makes peptide handling fussy.

What it is sensitive to is moisture. Keep it sealed, dry and cold, and let a cold vial reach room temperature before opening — condensation on cold powder is the realistic failure mode for a hygroscopic compound. It is water-soluble, which simplifies preparation relative to compounds requiring an organic co-solvent.

The storage guide covers general conditions, and the equipment guide covers transfer.

What Pioneer supplies

Aicar is stocked as acadesine. A batch certificate is not currently published for this compound; contact us for the documentation available on the batch in stock. It ships from the UK with same-day dispatch on orders before 2pm.

Quality comes first

With a compound whose own name refers to two different molecules, documentation is not a formality — it is the only way to know which one is in the vial. Where Pioneer holds an independent laboratory certificate for a batch, it is published in full with its verification key in the COA library. Ask us what documentation exists for the batch in stock before ordering rather than after.

Pioneer Research Peptides — UK supplier of research peptides for laboratory use. Independently tested by batch, certificates published with verification keys at the COA library.

For laboratory research use only — not for human consumption. 18+.