AICAR (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside, also called acadesine or AICA riboside) is a cell-permeable nucleoside that laboratories use as a pharmacological activator of AMP-activated protein kinase (AMPK), the enzyme that acts as the cell's primary energy sensor. It works indirectly: once inside a cell it is phosphorylated to ZMP, an AMP mimetic that binds the AMPK γ-subunit and switches the kinase on. Despite frequently being catalogued alongside research peptides, AICAR is not a peptide — it is a small purine nucleoside with the molecular formula C9H14N4O5, a molecular weight of 258.23 g/mol, and CAS number 2627-69-2. This article reviews its origin, mechanism, the published experimental record through 2026, the well-documented off-target effects that complicate its interpretation, and laboratory handling.
What Is AICAR?
AICAR occupies an unusual position in metabolic research: it is both a naturally occurring metabolite and one of the most widely used chemical tools in the field. In its monophosphate form (ZMP), it is an obligate intermediate in the de novo purine biosynthesis pathway, which means every cell already makes small amounts of it. Its research career began when investigators recognised that supplying the riboside form exogenously would let them raise intracellular ZMP levels far above baseline and thereby fake a low-energy signal inside an otherwise well-fed cell.
That idea was formalised in a 1995 paper in the European Journal of Biochemistry by Corton and colleagues, whose title framed the question the field is still asking three decades later: "5-aminoimidazole-4-carboxamide ribonucleoside. A specific method for activating AMP-activated protein kinase in intact cells?" The study established AICAR as the first practical way to activate AMPK in intact cells — and, in its own title, flagged the specificity caveat that later work would confirm.
The compound has also been developed under the generic name acadesine as an investigational drug, which is why the two names appear interchangeably in the literature. Older pharmacology papers and clinical reports tend to use "acadesine"; cell-biology and exercise-physiology papers tend to use "AICAR" or "AICAr."
Is AICAR a Peptide?
No. This is a recurring point of confusion because AICAR is sold and discussed alongside research peptides, and because it is often grouped with metabolic peptides in supplier catalogs. Structurally it is a nucleoside — an imidazole carboxamide base attached to a ribose sugar — not a chain of amino acids. The practical consequences matter in the lab: AICAR does not act on a cell-surface receptor, it must be transported into the cell and enzymatically modified before it does anything, and unlike hydrophobic small-molecule probes it is readily water-soluble.
Mechanism of Action
The mechanism has three sequential steps, and each one is a place where experiments can diverge.
Uptake. AICAR enters cells through adenosine transporters. Cell types differ substantially in transporter expression, which is one reason effective concentrations vary widely between published models.
Conversion to ZMP. Inside the cell, adenosine kinase phosphorylates AICAR to AICAR monophosphate, better known as ZMP. This step is essential — AICAR itself does not activate AMPK. Blocking adenosine kinase abolishes the response.
AMPK activation. ZMP is a structural mimic of AMP and reproduces both of AMP's activating actions on AMPK: direct allosteric activation, and promotion of Thr172 phosphorylation by the upstream kinase LKB1 while protecting that site from dephosphorylation. ZMP binds site 3 on the AMPK γ-subunit. Notably, ZMP is a considerably weaker activator than AMP itself in cell-free assays; AICAR nonetheless activates AMPK efficiently in most intact cells because ZMP accumulates to millimolar intracellular concentrations, as reviewed in Experimental & Molecular Medicine in 2016.
Once activated, AMPK phosphorylates metabolic enzymes and transporters directly and promotes transcription of nuclear genes governing mitochondrial biogenesis and oxidative metabolism. The canonical downstream readout in muscle preparations is inactivation of acetyl-CoA carboxylase (ACC), which lowers malonyl-CoA and de-represses fatty acid oxidation.
Published Research Overview
The experimental literature is large and spans three decades. Four strands are most relevant to how AICAR is used as a research tool.
- Muscle energy metabolism (foundational work). Merrill and colleagues, publishing in the American Journal of Physiology in 1997 (volume 273, pages E1107–E1112), perfused rat hindlimbs with AICAR at 0.5–2.0 mM and reported activation of AMPK, inactivation of ACC, a fall in malonyl-CoA, and increases in both fatty acid oxidation and glucose uptake. This established the ACC/malonyl-CoA readout that most subsequent muscle studies use.
- The "exercise mimetic" literature. The most-cited AICAR study is Narkar et al., published in Cell in 2008 (volume 134, pages 405–415), which coined the phrase "exercise mimetics." In sedentary mice, four weeks of AICAR treatment induced metabolic genes and increased treadmill running endurance by 44%. Mechanistically, the induction of oxidative genes required PPARδ — AICAR failed to induce them in PPARδ-null muscle cells — and AICAR combined with the PPARδ agonist GW501516 synergistically activated PPARδ target genes including Ucp3, Pdk4, and Lpl.
- Aging skeletal muscle (recent work). A 2025 study in FASEB BioAdvances by Wilcox and colleagues gave old mice daily AICAR injections for one month. The authors reported that AICAR activated AMPK even in aged muscle, raised mitochondrial markers — cytochrome c by roughly 33% and citrate synthase by roughly 22% — restored expression of many genes toward youthful levels, and reduced the muscle atrogenes MAFbx and MuRF1. These changes accompanied increased quadriceps mass, greater ex vivo EDL force production, and prevention of a decline in treadmill performance over the treatment period.
- AMPK-independent effects (the major interpretive caveat). A systematic review in Cells in 2021 (volume 10, article 1095) catalogued the substantial and growing list of AICAR effects that are not mediated by AMPK, spanning metabolism, hypoxia signaling, exercise responses, nucleotide synthesis, and cancer biology. The cleanest demonstrations use genetic controls. In Blood in 2010 (volume 116, pages 3023–3032), Santidrián and colleagues showed that AICAR induced apoptosis in chronic lymphocytic leukemia cells independently of both AMPK and p53, acting instead through upregulation of the BH3-only proteins BIM and NOXA: AICAR still killed B lymphocytes from AMPKα1-knockout mice, while cells from Noxa/Bim double-knockout mice were strongly resistant.
These findings are scientific context describing behaviour in cell-culture, tissue-perfusion, and rodent systems. They do not establish or imply any application outside the laboratory.
Has AICAR Been Studied in Humans?
Yes, as the investigational drug acadesine, and the results are part of the compound's documented history rather than evidence of any research-chemical application. Acadesine was evaluated in hospital-administered intravenous studies, including a multicenter phase I/II study in patients with relapsed or refractory chronic lymphocytic leukemia published in Cancer Chemotherapy and Pharmacology in 2013, which reported a manageable and predictable safety profile in that supervised clinical setting. Acadesine has not been approved for any indication, and no administration regimen from that literature has any bearing on laboratory research use.
Separately, AICAR is prohibited in sport at all times: the World Anti-Doping Agency lists AMPK activators, naming AICAR explicitly, under the S4 "Hormone and Metabolic Modulators" class. This is relevant to anyone assessing the compound's regulatory position and reinforces that it is a research chemical only.
How Does AICAR Differ From Other Metabolic Research Compounds?
AICAR acts upstream of the transcriptional machinery by activating a kinase, which distinguishes it from most compounds it is studied alongside. SLU-PP-332, a pan-agonist of the estrogen-related receptors, binds a nuclear receptor directly and changes which metabolic genes are transcribed. PPARδ agonists likewise act at a nuclear receptor. Mitochondrially derived or mitochondria-targeted peptides such as MOTS-c and SS-31 (elamipretide) act at or within the organelle itself. Incretin-receptor peptides such as tirzepatide and GLP-3 R act on cell-surface G protein-coupled receptors and are studied in the context of appetite and glucose-regulatory signaling.
The 2008 Cell work is a useful illustration of how these tiers interact: AICAR's oxidative gene induction required PPARδ, meaning the kinase-level signal was being read out through a nuclear receptor. For experimental design, AICAR is the tool of choice when the question is about AMPK-dependent energy sensing — provided the study includes the controls needed to prove the effect is actually AMPK-dependent.
Storage & Handling
Dynamite Research Peptides supplies AICAR as a lyophilized powder (50 mg, research code YPB.250, CAS 2627-69-2). Store the powder at -20°C, protected from light and moisture. Unlike hydrophobic small-molecule probes, AICAR is water-soluble and is typically reconstituted in sterile or bacteriostatic water or aqueous buffer for in-vitro work; published cell and tissue studies commonly report working concentrations in the 0.1–2 mM range, with the appropriate concentration depending heavily on cell type and adenosine transporter expression. Prepare fresh stocks where possible, avoid repeated freeze-thaw cycles, and verify identity and purity against the Certificate of Analysis (COA) before use. Handle with appropriate personal protective equipment in a well-ventilated laboratory area.
Conclusion
AICAR is the original and still the most widely used pharmacological AMPK activator, and the depth of its literature — from the 1995 characterization through 1997 muscle-perfusion work, the 2008 exercise-mimetic study, and 2025 work in aged mouse muscle — is why it remains a standard reference tool in metabolic research. That same literature has also documented, in unusual detail, how many of its effects run through ZMP rather than AMPK, which makes it as valuable a cautionary example of chemical-probe specificity as it is a probe. Our AICAR is high-purity, third-party tested, and ships with documentation so experimental results stay reliable and reproducible.
Frequently Asked Questions
What does AICAR actually do at the molecular level?
AICAR is transported into cells by adenosine transporters and phosphorylated by adenosine kinase to ZMP, an AMP mimetic. ZMP binds site 3 on the AMPK γ-subunit and reproduces AMP's two activating effects — allosteric activation and promotion of Thr172 phosphorylation by LKB1 — switching AMPK on without any change in the cell's actual ATP:AMP ratio.
Is AICAR a peptide?
No. It is a purine nucleoside with the formula C9H14N4O5 and a molecular weight of 258.23 g/mol (CAS 2627-69-2), despite commonly being catalogued alongside research peptides. It has no amino acid backbone and does not act on a cell-surface receptor.
Why is AICAR called an "exercise mimetic"?
The term was introduced by a 2008 Cell study reporting that four weeks of AICAR treatment increased running endurance in sedentary mice by 44% and induced an oxidative gene program in muscle that partly overlaps the transcriptional response to endurance training. It describes a gene-expression pattern observed in rodent muscle, not a claim about any human application.
Is AICAR a specific AMPK activator?
No, and this is well documented. A 2021 systematic review in Cells catalogued numerous AMPK-independent effects, and genetic-control experiments — including apoptosis in AMPKα1-knockout B lymphocytes and, in a 2025 Cells paper, ZMP-dependent but AMPK-independent inhibition of insulin-stimulated glucose uptake in 3T3-L1 adipocytes — confirm that some AICAR effects bypass AMPK entirely. Studies attributing an effect to AMPK need independent confirmation.
What is the difference between AICAR and acadesine?
They are the same compound. "Acadesine" is the generic drug name used in pharmacology and clinical literature; "AICAR" or "AICAr" is the abbreviation used in cell-biology and physiology papers. "ZMP" refers to its intracellular monophosphate metabolite, which is the actual active species.
How is AICAR dissolved for laboratory work?
AICAR is water-soluble, so aqueous stocks in sterile water or buffer are standard — no organic co-solvent is required. Published in-vitro studies most often work in the 0.1–2 mM range, and the 1997 rat hindlimb-perfusion work used 0.5–2.0 mM.
What is the purity level of Dynamite Research Peptides' AICAR?
Our AICAR is typically 99%+ pure, verified by analytical testing. Detailed purity data is provided on the Certificate of Analysis (COA) available for each product.
All products are for research use only — not for human or animal consumption. Nothing in this article describes or endorses any human, therapeutic, or dietary application.