Dipeptide-4  is a chemical compound, a synthetic peptide, and a molecule composed of cysteine and glycine. 

Peptides are substances consisting of two or more amino acids linked together by a linear chain. Synthetic peptides can be generated as copies of protein fragments by incorporating non-proteinogenic amino acids and modified so as to also increase the proteolytic stability of the molecules. Dipeptides are composed of two amino acids connected by a peptide bond.

What it is used for and where

Dipeptide-4 is a synthetic peptide found in various skincare products. This ingredient is recognized for its antioxidant and moisturizing properties, which help to keep the skin hydrated and protect it from free radical damage. It also promotes the strengthening of the skin barrier, making the skin more resistant to environmental stressors. Because of these benefits, Dipeptide-4 is frequently used in formulations for sensitive skin and anti-aging products.

Cosmetics

• Skin conditioning agent. It is the mainstay of topical skin treatment as it has the function of restoring, increasing or improving skin tolerance to external factors, including melanocyte tolerance. The most important function of the conditioning agent is to prevent skin dehydration, but the subject is rather complex and involves emollients and humectants that can be added in the formulation.

Medical

Tripeptides and dipeptides have proven useful in biomedical applications (1) and for sensitive skin (2) and have demonstrated antioxidant activity (3).

References_____________________________________________________________________

(1) Santos S, Torcato I, Castanho MA. Biomedical applications of dipeptides and tripeptides. Biopolymers. 2012;98(4):288-93. doi: 10.1002/bip.22067. PMID: 23193593.

Abstract. Peptides regulate many physiological processes, acting at some sites as endocrine or paracrine signals and at others as neurotransmitters or growth factors, for instance. These molecules represent a major evolution in medical and industrial fields, as it is becoming mandatory to design and exploit molecules that do not necessarily fit the description of classical drug classes. The list of peptides with potential biomedical applications is huge and is growing each year. These biomedical applications range from uses as drugs to flavor-active peptides as ingredients in natural health products, nutraceuticals and functional foods. Among the peptide family, dipeptides and tripeptides are very appealing for drug discovery and development because of their cost-effectiveness, possibility of oral administration, and simplicity to perform molecular structural and quantitative structure-activity studies. Our objective is to review different actual and future uses of dipeptides and tripeptides as well as the major advances and obstacles in this growing area.

(2) Resende DISP, Ferreira MS, Sousa-Lobo JM, Sousa E, Almeida IF. Usage of Synthetic Peptides in Cosmetics for Sensitive Skin. Pharmaceuticals (Basel). 2021 Jul 21;14(8):702. doi: 10.3390/ph14080702. 

 Abstract. Sensitive skin is characterized by symptoms of discomfort when exposed to environmental factors. Peptides are used in cosmetics for sensitive skin and stand out as active ingredients for their ability to interact with skin cells by multiple mechanisms, high potency at low dosage and the ability to penetrate the stratum corneum. This study aimed to analyze the composition of 88 facial cosmetics for sensitive skin from multinational brands regarding usage of peptides, reviewing their synthetic pathways and the scientific evidence that supports their efficacy. Peptides were found in 17% of the products analyzed, namely: acetyl dipeptide-1 cetyl ester, palmitoyl tripeptide-8, acetyl tetrapeptide-15, palmitoyl tripeptide-5, acetyl hexapeptide-49, palmitoyl tetrapeptide-7 and palmitoyl oligopeptide. Three out of seven peptides have a neurotransmitter-inhibiting mechanism of action, while another three are signal peptides. Only five peptides present evidence supporting their use in sensitive skin, with only one clinical study including volunteers having this condition. Noteworthy, the available data is mostly found in patents and supplier brochures, and not in randomized placebo-controlled studies. Peptides are useful active ingredients in cosmetics for sensitive skin. Knowing their efficacy and synthetic pathways provides meaningful insight for the development of new and more effective ingredients.

(3) Ozawa H, Miyazawa T, Burdeos GC, Miyazawa T. Biological Functions of Antioxidant Dipeptides. J Nutr Sci Vitaminol (Tokyo). 2022;68(3):162-171. doi: 10.3177/jnsv.68.162. PMID: 35768247.

Abstract. In the history of modern nutritional science, understanding antioxidants is one of the major topics. In many cases, food-derived antioxidants have π conjugate or thiol group in their molecular structures because π conjugate stabilizes radical by its delocalization and two thiol groups form a disulfide bond in its antioxidative process. In recent years, antioxidant peptides have received much attention because for their ability to scavenge free radicals, inhibition of lipid peroxidation, chelation of transition metal ions, as well as their additional nutritional value. Among them, dipeptides are attracting much interest as post-amino acids, which have residues in common with amino acids, but also have different physiological properties and functions from those of amino acids. Especially, dipeptides containing moieties of several amino acid (tryptophan, tyrosine, histidine, cysteine, and methionine) possess potent antioxidant activity. This review summarizes previous details of structural property, radical scavenging activity, and biological activity of antioxidant dipeptide. Hopefully, this review will help provide a new insight into the study of the biological functions of antioxidant dipeptides.