Epitalon (Epithalon, AEDG) vs Glutathione (GSH)

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.

Glutathione (GSH)

Glutathione is a tripeptide of glutamate, cysteine and glycine in which glutamate is linked through its side-chain (gamma) carboxyl group. It is made inside cells by two ATP-dependent enzymes, glutamate–cysteine ligase and glutathione synthetase, and is one of the most abundant small thiols in animal cells. It occurs in a reduced form (GSH) and an oxidised disulfide form (GSSG), and the ratio between them is widely used as a measure of cellular redox state. Its biochemistry inside the cell is well mapped. Studies that supply glutathione from outside, in animals or people, are harder to interpret because extracellular glutathione is readily broken down, and human findings in that area are inconsistent.

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.

How Glutathione (GSH) acts

The reactive part of glutathione is the thiol of its cysteine residue. Glutathione peroxidases use it to reduce hydrogen peroxide and lipid hydroperoxides, in the process oxidising two molecules of GSH to GSSG; glutathione reductase then regenerates GSH using NADPH. Glutathione S-transferases attach it to electrophilic compounds, the first step in a conjugation pathway that handles many drugs and foreign chemicals. It also forms mixed disulfides with cysteine residues in proteins, a modification studied as a form of redox signalling. Because the gamma-glutamyl bond resists most peptidases, breakdown begins with gamma-glutamyl transpeptidase on the outer surface of cells.

The records side by side

• Type: Epitalon (Epithalon, AEDG), Tetrapeptide; Glutathione (GSH), Tripeptide
• Length: Epitalon (Epithalon, AEDG), 4 amino acids; Glutathione (GSH), 3 amino acids
• Molecular weight: Epitalon (Epithalon, AEDG), 390.35 g/mol; Glutathione (GSH), 307.33 g/mol
• Molecular formula: Epitalon (Epithalon, AEDG), C14H22N4O9; Glutathione (GSH), C10H17N3O6S

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.