AHK-Cu (Copper Tripeptide-3) vs Epitalon (Epithalon, AEDG)

AHK-Cu (Copper Tripeptide-3)

AHK-Cu is a copper(II) complex of the synthetic tripeptide alanyl-histidyl-lysine, a close relative of the naturally occurring GHK-Cu. The two differ only in the first residue: alanine here, glycine in GHK. GHK is found in human plasma and has a long history in the literature as a copper-binding peptide; AHK is a synthetic variant with the histidine in the same position. Published work on AHK-Cu is small and mostly in vitro, using cultured human dermal papilla cells and fibroblasts, and isolated hair follicles kept alive in organ culture. Controlled human studies are scarce, and much of the wider discussion of the compound borrows from GHK-Cu rather than from data on AHK-Cu itself.

Epitalon (Epithalon, AEDG)

Epitalon, also spelled epithalon, is the synthetic tetrapeptide Ala-Glu-Asp-Gly, modelled on epithalamin, a peptide extract of bovine pineal gland. It came out of a Russian research programme on short regulatory peptides, and nearly all of the published work comes from that programme and its collaborators. The studies include cultured human cells, rodents and fruit flies, together with some human studies reported mostly in Russian-language journals. The topics are ageing biology, telomere maintenance and pineal function. Independent replication outside that group is limited, and the human data are sparse and come almost entirely from the same source.

How AHK-Cu (Copper Tripeptide-3) acts

In GHK-Cu, the copper ion is held by the N-terminal amine, the deprotonated amide nitrogen between the first two residues and a nitrogen of the histidine imidazole ring. AHK is thought to bind copper in the same way, since its histidine sits in the same position. Copper-peptide complexes of this kind have been studied as carriers that deliver copper, a cofactor for enzymes such as lysyl oxidase and superoxide dismutase, to cells. In cultured human dermal papilla cells, AHK-Cu has been reported to affect cell proliferation and markers of apoptosis, including the balance of Bcl-2 and Bax. Which receptors or transporters mediate these observations has not been established.

How Epitalon (Epithalon, AEDG) acts

No receptor for Epitalon has been identified, and most mechanistic proposals come from the same research school. Cell-culture studies from that group have reported induction of telomerase activity and telomere elongation in human somatic cells, which normally express little telomerase. Other papers propose that short peptides of this kind enter the nucleus and bind DNA or histones, altering the expression of particular genes; this idea has not been widely tested elsewhere. Animal studies have examined melatonin secretion by the pineal gland and circadian markers. The overall picture rests on a narrow base of laboratories.

The records side by side

• Type: AHK-Cu (Copper Tripeptide-3), Copper tripeptide complex; Epitalon (Epithalon, AEDG), Tetrapeptide
• Length: AHK-Cu (Copper Tripeptide-3), 3 amino acids; Epitalon (Epithalon, AEDG), 4 amino acids
• Molecular weight: AHK-Cu (Copper Tripeptide-3), 451.39 g/mol; Epitalon (Epithalon, AEDG), 390.35 g/mol
• Molecular formula: AHK-Cu (Copper Tripeptide-3), C15H24ClCuN6O4-; Epitalon (Epithalon, AEDG), C14H22N4O9

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.