ARA-290 (Cibinetide) vs KPV (Lys-Pro-Val)

ARA-290 (Cibinetide)

ARA-290, also called cibinetide, is an 11-residue synthetic peptide modelled on the helix B surface of erythropoietin. Erythropoietin is best known as the hormone that drives red blood cell production, but it also acts on other tissues, and ARA-290 was designed to probe that second set of actions without the effect on blood. Its N-terminal glutamine is cyclised to pyroglutamate, which is why it also appears in the literature as pyroglutamate helix B surface peptide. Most studies are in cell and rodent models of nerve injury, inflammation and metabolic disease. It has also been tested in small, early-phase human trials, including in neuropathy associated with sarcoidosis and with diabetes, and human data remain limited.

KPV (Lys-Pro-Val)

KPV is the tripeptide lysine–proline–valine, corresponding to the last three residues of alpha-melanocyte-stimulating hormone (α-MSH). It lacks the His-Phe-Arg-Trp core sequence through which α-MSH activates melanocortin receptors, so its pharmacology cannot be assumed to match that of the parent hormone. Interest in it follows reports that C-terminal fragments of α-MSH alter inflammatory signalling in cell and animal models. Published studies are mainly in cultured epithelial and immune cells and in mouse models of chemically induced colitis. The literature is small, and human data are scarce.

How ARA-290 (Cibinetide) acts

Erythropoietin acts on red-cell precursors through a homodimer of its receptor (EPOR). A different receptor, proposed to be EPOR paired with the beta-common receptor subunit (CD131), has been suggested to mediate its actions outside the blood-forming system. ARA-290 reproduces the helix B face of erythropoietin, which is thought to engage this proposed complex but not the classical homodimer, and it has been reported not to stimulate red-cell production in animal studies. Cell and rodent work has examined its influence on inflammatory cytokine signalling and apoptosis. The make-up and role of the proposed receptor remain debated.

How KPV (Lys-Pro-Val) acts

How KPV acts has not been settled. Cell studies have reported that it lowers activation of the transcription factor NF-κB and reduces expression of inflammatory cytokines in intestinal epithelial and immune cell lines. In intestinal epithelial cells, uptake through the di- and tripeptide transporter PepT1 has been reported, which would allow it to act inside the cell rather than at a surface receptor. Whether it also signals through melanocortin receptors such as MC1R is disputed, since reports differ and its sequence lacks the usual receptor-binding motif. The mechanistic work is limited and comes largely from cell and rodent models.

The records side by side

• Type: ARA-290 (Cibinetide), Synthetic undecapeptide; KPV (Lys-Pro-Val), Tripeptide (alpha-MSH fragment)
• Length: ARA-290 (Cibinetide), 11 amino acids; KPV (Lys-Pro-Val), not recorded
• Molecular weight: ARA-290 (Cibinetide), 1257.3 g/mol; KPV (Lys-Pro-Val), not recorded
• Molecular formula: ARA-290 (Cibinetide), C51H84N16O21; KPV (Lys-Pro-Val), not recorded

Reading a comparison

A comparison places two records side by side; it does not merge them. Each description above is drawn from that compound's own record, and the two were not necessarily characterised by the same methods, at the same time, or to the same level of detail. Before comparing any attribute, it is worth establishing that both records describe the substance you think they describe — names are not identifiers, and two entries sharing a name can differ in salt form, stereochemistry or the convention used to state a mass. Where a figure carries no method beside it, the comparison is between two reported numbers rather than between two measurements.