It is a peptide , which is a short chain of amino acids (the building blocks of proteins)
For context, the GHK-Cu copper peptide another compound with a strong preclinical profile faces similar evidence constraints

Ingredients: Water, Centella Asiatica Extract (22.7%), Glycerin, Cetyl Ethylhexanoate, Butylene Glycol, Polyglyceryl-3 Methylglucose Distearate, Niacinamide (20,000ppm), Stearic Acid, Sodium Polyacryloyldimethyl Taurate, Silica, Sodium Hyaluronate, Glyceryl Stearate, Beeswax, Butyrospermum Parkii (Shea) Butter, Macadamia Ternifolia Seed Oil, Hydrogenated Polydecene, Betaine, Glutathione (1,000ppm), Trehalose, Adenosine, Citric Acid, Trideceth-10, Disodium EDTA, Sodium Citrate, Caprylic/Capric Triglyceride, Hydrogenated Lecithin, Cholesterol, Xanthan Gum, Nelumbo Nucifera Extract, Artemisia Annua Extract, Oryza Sativa (Rice) Extract, Saccharomyces Ferment, Solanum Melongena (Eggplant) Fruit Extract, Melaleuca Alternifolia (Tea Tree) Leaf Extract, Hydrolyzed Collagen, Squalane, Beta-Glucan, Dipropylene Glycol, Hippophae Rhamnoides Fruit Extract, Madecassic Acid, Asiaticoside, Asiatic Acid, Propanediol, Hydroxyacetophenone, 1,2-Hexanediol, Ethylhexylglycerin, Dipotassium Glycyrrhizate
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However, after 3 and 5 min the GSH signal decreased without the presence of different peaks