ARA-290 is eleven residues long and was not designed from an organ extract or a hormone fragment in the usual way. Brines and colleagues reported in 2008 that they had traced the solvent-exposed surface of one helix of erythropoietin, helix B, and made a linear peptide with that sequence. The peptide they described was QEQLERALNSS; ARA-290 is that sequence with the N-terminal glutamine cyclised to pyroglutamate, which is how it is sold here as a 10 mg lyophilized vial with a certificate for the lot. Its generic name is cibinetide.
This post covers the molecule, the certificate line by line, the arithmetic that connects the two, and the compound's regulatory status, which is different from the two approved molecules written up this week, melanotan-1 and SS-31.
What is the sequence?
pGlu-Glu-Gln-Leu-Glu-Arg-Ala-Leu-Asn-Ser-Ser. In single letters, with the first residue cyclised: pE-E-Q-L-E-R-A-L-N-S-S.
| Feature | Residues | Consequence |
|---|---|---|
| Pyroglutamate N-terminus | position 1 | No free N-terminal amine; stable to aminopeptidases; the cyclisation removes 17 daltons of ammonia from the linear mass |
| Three glutamates against one arginine | 2, 3 is glutamine, 5, 6 | Net charge about minus two at neutral pH; anionic and very soluble |
| Asparagine followed by serine | 9 and 10 | The one slow degradation site, by deamidation; faster at alkaline pH |
| No cysteine, methionine, tryptophan, tyrosine or phenylalanine | No oxidation or light problem; no absorbance at 280 nm, so purity at 214 nm and no A280 quantification | |
| Two leucines | 4 and 8 | Modest hydrophobicity; enough to retain on a column, not enough to aggregate |
What does lot ARA2901-0803 report?
COA7616, issued by Bioviridian Inc. on 17 August 2026. Five tests.
| Test | Method | Result | What it establishes |
|---|---|---|---|
| Identity | LC-MS/MS | 1257.1 observed | The pyroglutamate peptide, not the linear glutamine form; fragment ladder consistent with the sequence |
| Purity | RP-HPLC, 214 nm | 99.72% | Main peak at 9.75 minutes is 99.72% of the UV-absorbing area |
| Content | Gravimetric against label | 10.86 mg | Nine percent over the 10 mg label |
| Endotoxin | LAL | < 0.05 EU/mL | Below the reporting limit |
| Heavy metals | ICP | < 0.01 ppm | Below the reporting limit |
How does 1257.1 confirm the pyroglutamate?
By an arithmetic anyone can repeat. The linear peptide QEQLERALNSS has an average mass of about 1274.4: the eleven residue masses summed, minus ten waters for the ten peptide bonds. Cyclising the N-terminal glutamine to pyroglutamate releases one ammonia, 17.0, giving 1257.4. The certificate observed 1257.1, within the method's reporting. Had the lot been the linear glutamine form, the mass would have been 17 higher. The sequence post has the residue masses for doing this with any sequence, and the LC-MS post explains what tandem MS adds.
The retention time of 9.75 minutes is longer than the composition alone would suggest, because the pyroglutamate removes a charge and the two leucines add hydrophobicity. It is a well-retained peak, and the area-percent post explains why that makes the purity figure discriminating.
How many micromoles is 10 mg?
The label's 10 mg at 1257.1 g/mol is 7.95 micromoles; the measured content, 10.86 mg, is 8.64. The published cell work used nanomolar to low micromolar concentrations, so one vial is thousands of wells. The concentration table and the molarity post have the arithmetic. At the listed price of $82 the vial is about $10 per micromole.
How is it handled?
- Solubility. Immediate in water or buffer; an anionic peptide with no hydrophobic core.
- Degradation. No oxidation routes. The asparagine-serine pair can deamidate slowly; keep stocks cold and near neutral, as the reconstituted shelf-life post recommends.
- pH. The peptide's own solution is acidic; buffer the working stock per the pH and buffer post.
- Adsorption. Low for an anionic peptide of this size; standard tubes are fine above micromolar.
- Storage. Lyophilized at minus 20 °C; solutions aliquoted and frozen.
- Diluent. Water or buffer; reconstitution solution only for a preserved multi-entry stock, per the diluent post.
What is its regulatory status?
Cibinetide is investigational. It has been studied in registered clinical trials by its developer and holds orphan designations, which are a regulatory status short of approval. It is not an approved medicine in the United States or elsewhere as of 2 October 2026. That is a different position from the approved molecules in the catalogue, and the product page states it in those terms rather than borrowing language from the trials. The vial sold here is the research reagent, for laboratory research use only and not for human or animal use; the research-use post explains the designation.
Frequently asked questions
Is ARA-290 a fragment of erythropoietin?
Not a contiguous one. It is a linear peptide whose sequence follows the solvent-exposed surface of erythropoietin's helix B, as Brines and colleagues described in 2008. It has none of erythropoietin's erythropoietic activity, which was the point of the design.
Why does the certificate mass not match the linear sequence's mass?
Because the N-terminal glutamine is cyclised to pyroglutamate, which removes 17 daltons. The certificate's 1257.1 is the pyroglutamate form; the linear form would be 1274.
Can it be quantified by A280?
No. There is no tyrosine, tryptophan or phenylalanine. Use the content figure and mass; the A280 post covers which peptides suit the method.
Is cibinetide an approved drug?
No. It is investigational, with registered trials and orphan designations, and no marketing approval anywhere as of the date of this post.
What is ARA-290 sold for?
Laboratory research. Every product on this site is for in-vitro research use only and not for human or animal use.
References
- Brines M, Patel NSA, Villa P, et al. Nonerythropoietic, tissue-protective peptides derived from the tertiary structure of erythropoietin. Proceedings of the National Academy of Sciences 2008;105(31):10925-10930. doi.org/10.1073/pnas.0805594105
- PubChem, National Library of Medicine. Cibinetide, CID 91810664, C51H84N16O21, CAS 1208243-50-8. Read 2 October 2026. pubchem.ncbi.nlm.nih.gov/compound/91810664
- Bioviridian Inc. Certificate of analysis COA7616, lot ARA2901-0803, issued 17 August 2026. Verification code on the certificate. bioviridians.com/coa-search.html
Every product mentioned is sold for laboratory research use only and is not for human or animal use. Nothing on this page describes or recommends use of the material sold here in humans or animals.
