Pentapeptide-42 is a chemical compound, a class of biomolecules in abbreviated form, a synthetic protein composed of five amino acids linked together: arginine, leucine, proline, and serine.

The name describes the structure of the molecule:

• Pentapeptide  indicates that the molecule is composed of five amino acids linked together.
• 42 - The numeral represents a specific sequence or variant of the pentapeptide, indicating its unique identification or the particular modification in its sequence compared to other similar peptides.

What it is used for and where

Pentapeptide-42 is used in cosmetic formulations for its barrier-enhancing and moisturizing properties. This peptide helps to strengthen the skin's barrier, increasing the skin’s ability to retain moisture and protecting it from environmental stresses. It is particularly effective in products for caring for sensitive and dry skin, such as moisturizing creams, soothing lotions, and restorative treatments.

Cosmetics - INCI Functions

• 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.

Synthetic peptides can be generated as copies of protein fragments by incorporating non-proteinogenic amino acids and modifications to enhance the proteolytic stability of the molecules. Peptides are used in the development of therapeutic drugs (1) for their antimicrobial activity (2), and their bioactive interest (3).

The industrial production process of peptides can be divided into several key phases.

• Peptide Synthesis. This phase involves the chemical or biotechnological synthesis of the desired peptides. Chemical synthesis involves building the peptide one step at a time, using protection and deprotection of functional groups to control the reactivity of the amino acid residues. Biotechnological synthesis, on the other hand, may involve the use of microorganisms or cultured cells to produce peptides through gene expression.
• Isolation and Purification. After synthesis, peptides need to be isolated and purified from contaminants and reaction intermediates. This can be done using separation techniques such as chromatography.
• Characterization. Once purified, peptides need to be characterized to determine their identity, purity, and biological activity. This can be done using analytical techniques such as mass spectrometry and chromatography.
• Formulation and Stability. Finally, peptides can be formulated into pharmaceutical or cosmetic preparations and tested for their stability and safety.

References_____________________________________________________________________

(1) Yuan Y. Mechanisms Inspired Targeting Peptides. Adv Exp Med Biol. 2020;1248:531-546. doi: 10.1007/978-981-15-3266-5_21. 

Abstract. Peptides, as a large group of molecules, are composed of amino acid residues and can be divided into linear or cyclic peptides according to the structure. Over 13,000 molecules of natural peptides have been found and many of them have been well studied. In artificial peptide libraries, the number of peptide diversity could be up to 1 × 1013. Peptides have more complex structures and higher affinity to target proteins comparing with small molecular compounds. Recently, the development of targeting cancer immune checkpoint (CIP) inhibitors is having a very important role in tumor therapy. Peptides targeting ligands or receptors in CIP have been designed based on three-dimensional structures of target proteins or directly selected by random peptide libraries in biological display systems. Most of these targeting peptides work as inhibitors of protein-protein interaction and improve CD8+ cytotoxic T-lymphocyte (CTL) activation in the tumor microenvironment, for example, PKHB1, Ar5Y4 and TPP1. Peptides could be designed to regulate CIP protein degradation in vivo, such as PD-LYSO and PD-PALM. Besides its use in developing therapeutic drugs for targeting CIP, targeting peptides could be used in drug's targeted delivery and diagnosis in tumor immune therapy.

(2) Bin Hafeez A, Jiang X, Bergen PJ, Zhu Y. Antimicrobial Peptides: An Update on Classifications and Databases. Int J Mol Sci. 2021 Oct 28;22(21):11691. doi: 10.3390/ijms222111691. 

Abstract. Antimicrobial peptides (AMPs) are distributed across all kingdoms of life and are an indispensable component of host defenses. They consist of predominantly short cationic peptides with a wide variety of structures and targets. Given the ever-emerging resistance of various pathogens to existing antimicrobial therapies, AMPs have recently attracted extensive interest as potential therapeutic agents. As the discovery of new AMPs has increased, many databases specializing in AMPs have been developed to collect both fundamental and pharmacological information. In this review, we summarize the sources, structures, modes of action, and classifications of AMPs. Additionally, we examine current AMP databases, compare valuable computational tools used to predict antimicrobial activity and mechanisms of action, and highlight new machine learning approaches that can be employed to improve AMP activity to combat global antimicrobial resistance.

(3) O'Connor J, Garcia-Vaquero M, Meaney S, Tiwari BK. Bioactive Peptides from Algae: Traditional and Novel Generation Strategies, Structure-Function Relationships, and Bioinformatics as Predictive Tools for Bioactivity. Mar Drugs. 2022 May 10;20(5):317. doi: 10.3390/md20050317. 

Abstract. Over the last decade, algae have been explored as alternative and sustainable protein sources for a balanced diet and more recently, as a potential source of algal-derived bioactive peptides with potential health benefits. This review will focus on the emerging processes for the generation and isolation of bioactive peptides or cryptides from algae, including: (1) pre-treatments of algae for the extraction of protein by physical and biochemical methods; and (2) methods for the generation of bioactive including enzymatic hydrolysis and other emerging methods. To date, the main biological properties of the peptides identified from algae, including anti-hypertensive, antioxidant and anti-proliferative/cytotoxic effects (for this review, anti-proliferative/cytotoxic will be referred to by the term anti-cancer), assayed in vitro and/or in vivo, will also be summarized emphasizing the structure-function relationship and mechanism of action of these peptides. Moreover, the use of in silico methods, such as quantitative structural activity relationships (QSAR) and molecular docking for the identification of specific peptides of bioactive interest from hydrolysates will be described in detail together with the main challenges and opportunities to exploit algae as a source of bioactive peptides.