sh-Octapeptide-4 is a chemical compound, molecular platform and synthetic protein, identical to a portion of the protein Enkephalin and capable of providing bioactivity, composed of 8 amino acids linked together including:  glycine, histidine, leucine, lysine, phenylalanine, and tyrosine.

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 name describes the structure of the molecule:

• sh - This abbreviation typically stands for "signal peptide" or "synthetic human" suggesting that the peptide is engineered to mimic human biological activities or is designed for specific signaling functions in cosmetic or medical applications.
• Octapeptide  indicates that the molecule is composed of 8 amino acids linked together.
• 4 - The numeral represents a specific sequence or variant of the octapeptide, indicating its unique identification or the particular modification in its sequence compared to other similar peptides.

What it is used for and where

sh-Octapeptide-4 is widely used in cosmetic formulations for its diverse functional capabilities. It acts as an anti-seborrheic agent, controlling and reducing excessive sebum production, which is particularly beneficial for oily or acne-prone skin. As an antioxidant, it protects the skin from free radical damage, delaying aging signs. Its chelating function helps to neutralize heavy metals present in the skin, improving health and resilience. Additionally, its reducing ability contributes to protecting the skin structure. sh-Octapeptide-4 is also effective in strengthening the skin barrier, protecting the skin from harmful environmental factors. It is ideal for products aimed at caring for sensitive, acne-prone, or pollution and environmental stress-exposed skin.

Cosmetics - INCI Functions

• Anti-sebum.  Controls and reduces emissions from the sebaceous glands, which are responsible for greasy, enlarged pores in the skin, where it occurs, particularly on the forehead, cheeks, nose and hair. Adjuvant in the treatment of acne.
• Antioxidant agent. Ingredient that counteracts oxidative stress and prevents cell damage. Free radicals, pathological inflammatory processes, reactive nitrogen species and reactive oxygen species are responsible for the ageing process and many diseases caused by oxidation.
• Chelating agent. It has the function of preventing unstable reactions and improving the bioavailability of chemical components within a product, and removes calcium and magnesium cations that can cause cloudiness in clear liquids.
• Reducing agent. Ingredient that facilitates permanent hair waving by adjusting the pH to an optimal level.
• Skin protectant. It creates a protective barrier on the skin to defend it from harmful substances, irritants, allergens, pathogens that can cause various inflammatory conditions. These products can also improve the natural skin barrier and in most cases more than one is needed to achieve an effective result.

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

• Preparation of solid phase. An appropriate resin is selected as the solid support, which is functionalized with the C-terminal amino acid of the decapeptide.
• Peptide synthesis. Using solid-phase peptide synthesis, amino acids are sequentially added, starting from the C-terminus and proceeding to the N-terminus. Each addition involves deprotecting the terminal amino group followed by coupling of the next amino acid.
• Deprotection. After each amino acid coupling, the protective group is removed and the resin is washed to eliminate unreacted reagents and byproducts.
• Cleavage. Once the peptide chain synthesis is complete, the peptide is cleaved from the resin using a mixture of trifluoroacetic acid (TFA) and other scavenger agents, which help remove side-chain protective groups.
• Purification. The crude peptide is purified using chromatography techniques such as ion-exchange or reverse-phase chromatography to isolate the desired decapeptide.
• Lyophilization. Finally, the decapeptide is lyophilized to remove the solvent and convert it into a powder for more stable storage and distribution.
• Quality control. The purified decapeptide undergoes various tests, including purity determination via HPLC and molecular weight verification via mass spectrometry.

References_____________________________________________________________________

(1) Myšková A, Sýkora D, Kuneš J, Maletínská L. Lipidization as a tool toward peptide therapeutics. Drug Deliv. 2023 Dec;30(1):2284685. doi: 10.1080/10717544.2023.2284685. 

Abstract. Peptides, as potential therapeutics continue to gain importance in the search for active substances for the treatment of numerous human diseases, some of which are, to this day, incurable. As potential therapeutic drugs, peptides have many favorable chemical and pharmacological properties, starting with their great diversity, through their high affinity for binding to all sort of natural receptors, and ending with the various pathways of their breakdown, which produces nothing but amino acids that are nontoxic to the body. Despite these and other advantages, however, they also have their pitfalls. One of these disadvantages is the very low stability of natural peptides. They have a short half-life and tend to be cleared from the organism very quickly. Their instability in the gastrointestinal tract, makes it impossible to administer peptidic drugs orally. To achieve the best pharmacologic effect, it is desirable to look for ways of modifying peptides that enable the use of these substances as pharmaceuticals. There are many ways to modify peptides. Herein we summarize the approaches that are currently in use, including lipidization, PEGylation, glycosylation and others, focusing on lipidization. We describe how individual types of lipidization are achieved and describe their advantages and drawbacks. Peptide modifications are performed with the goal of reaching a longer half-life, reducing immunogenicity and improving bioavailability. In the case of neuropeptides, lipidization aids their activity in the central nervous system after the peripheral administration. At the end of our review, we summarize all lipidized peptide-based drugs that are currently on the market.

(2) Nguyen HLT, Trujillo-Paez JV, Umehara Y, Yue H, Peng G, Kiatsurayanon C, Chieosilapatham P, Song P, Okumura K, Ogawa H, Ikeda S, Niyonsaba F. Role of Antimicrobial Peptides in Skin Barrier Repair in Individuals with Atopic Dermatitis. Int J Mol Sci. 2020 Oct 14;21(20):7607. doi: 10.3390/ijms21207607.

Abstract. Atopic dermatitis (AD) is a common chronic inflammatory skin disease that exhibits a complex interplay of skin barrier disruption and immune dysregulation. Patients with AD are susceptible to cutaneous infections that may progress to complications, including staphylococcal septicemia. Although most studies have focused on filaggrin mutations, the physical barrier and antimicrobial barrier also play critical roles in the pathogenesis of AD. Within the physical barrier, the stratum corneum and tight junctions play the most important roles. The tight junction barrier is involved in the pathogenesis of AD, as structural and functional defects in tight junctions not only disrupt the physical barrier but also contribute to immunological impairments. Furthermore, antimicrobial peptides, such as LL-37, human b-defensins, and S100A7, improve tight junction barrier function. Recent studies elucidating the pathogenesis of AD have led to the development of barrier repair therapy for skin barrier defects in patients with this disease. This review analyzes the association between skin barrier disruption in patients with AD and antimicrobial peptides to determine the effect of these peptides on skin barrier repair and to consider employing antimicrobial peptides in barrier repair strategies as an additional approach for AD management.

(3) Stephanopoulos N. Peptide-Oligonucleotide Hybrid Molecules for Bioactive Nanomaterials. Bioconjug Chem. 2019 Jul 17;30(7):1915-1922. doi: 10.1021/acs.bioconjchem.9b00259. Epub 2019 May 28. PMID: 31082220.

Abstract. Peptides and oligonucleotides are two of the most interesting molecular platforms for making bioactive materials. Peptides provide bioactivity that can mimic that of proteins, whereas oligonucleotides like DNA can be used as scaffolds to immobilize other molecules with nanoscale precision. In this Topical Review, we discuss covalent conjugates of peptides and DNA for creating bioactive materials that can interface with cells. In particular, we focus on two areas. The first is multivalent presentation of peptides on a DNA scaffold, both linear assemblies and more complex nanostructures. The second is the reversible tuning of the extracellular environment-like ligand presentation, stiffness, and hierarchical morphology-in peptide-DNA biomaterials. These examples highlight the potential for creating highly potent materials with benefits not possible with either molecule alone, and we outline a number of future directions and applications for peptide-DNA conjugates.