Many proteins in the skin’s extracellular matrix (ECM) are broken down into bioactive peptides, which are shorter chains of amino acids. Their capacity for synthesis and customization makes them attractive in skin cell research. Studies have explored topical peptides for the primary objectives of controlling the production of collagen, elastin, and melanin and to potentially support the activity of broad-spectrum antibiotics.
General Overview of Topical Peptides
As suggested by research, proteolytic enzymes in the epidermis and dermis cut endogenous proteins to create bioactive peptides. ECM proteins and the peptide fragments of these proteins, such as collagen, elastin, and fibronectin, may control how skin cells work by either making more of them or stopping them from making more. Synthetic peptides have therefore been created to leverage this endogenous mechanism in order to alter cellular dynamics in the skin.
One group of skin conditions—psoriasis—has been linked to low levels of antimicrobial peptides (AMPs). Another group has been linked to high levels of these AMPs. However, the potential functions of peptides in skin are the emphasis here rather than any of the aforementioned concerns.
Findings imply that topical exposure of synthetic bioactive peptides is a viable method for delivering these molecules to skin cells. Because they are hydrophilic, oligopeptides can’t get through the stratum corneum, which is hydrophobic. Investigations purport that lipid conjugation modification may considerably improve skin permeability and localized presentation without systemic absorption.
Topical Peptides and Photoprotection
A hormone named α-MSH attaches to a melanocortin 1 receptor (MC1R) on the melanocytes’ surface and tells them to make and release more melanin. A piece of MSH called His-D-Phe-Arg-Trp has been tested in the lab and has been speculated to be a strong MCR1 agonist that may raise tyrosinase activity and, in turn, melanogenesis.
Furthermore, primary cultures of melanocytes presented with His-D-Phe-Arg-Trp suggested decreased UVR-induced apoptosis, hydrogen peroxide production, and DNA photoproduct accumulation. One of the “other functions” of bioactive peptides that is currently under investigation is hyperpigmentation of the skin, which may result from a lack of melatonin.
Topical Peptides and Photoaging
It is possible for the C-terminal part (residues 197–241) of procollagen I to stimulate cultured fibroblasts to make type I and type III collagen and fibronectin. A peptide called KTTKS (Lysine-Threonine-Lysine-Serine), which is made from the C-terminus of procollagen I, may help the extracellular matrix (ECM) form in vitro. The peptide palmitoyl-KTTKS (pal-KTTKS) was tested in a randomized, double-blind study to see if it could reverse photoaging in the skin on the face. For 12 weeks, researchers slathered either a control moisturizer or a pal-KTTKS moisturizer (3 ppm) on a skin patch on research models. Analysis of digital images suggested that topical pal-KTTKS seemed to have reduced the appearance of fine lines and wrinkles qualitatively compared to placebo without irritating the skin.
Glycine-Glutamate-Lysine-Glycine (GEKG) is another synthetic peptide that has been tested for its potential on ECM synthesis in vitro. The findings of the study implied that secretion of procollagen I and the expression of procollagen I, hyaluronic acid, and fibronectin mRNA all appeared considerably stimulated by GEKG in cultured fibroblasts.
A clinical double-blind, placebo-controlled trial with 10 research models supported these results. Biopsied buttock skin suggested enhanced skin elasticity and increased synthesis of procollagen I, hyaluronic acid, and fibronectin when topical GEKG was applied daily for eight weeks. A second study looked at how applying GEKG and pal-KTTKS to the skin on the face affected its elasticity. After eight weeks of twice-daily exposure, both peptides appeared to make skin much smoother, fuller, and more elastic compared to a control group.
Research suggests that topical peptides for sale may potentially enhance the clinical characteristics of elastin and collagen-poor skin cells.
GHK-Cu Peptide
GHK (glycyl-L-histidyl-L-lysine) is a collagen-chain fragment that is hypothesized to bind copper very strongly. The antioxidant enzyme superoxide dismutase (SOD) and the collagen-producing enzyme lysyl oxidase both need copper as a cofactor. GHK, both on its own and as a carrier peptide for copper (GHK-Cu), has been speculated in vitro experiments to affect the chemoattraction of immune cells, angiogenesis, and collagen formation, all key components of the wound-healing process (21–24).
GHK has also been hypothesized to improve wound healing. Research models of laser skin resurfacing were randomly assigned to receive either a topical regimen containing GHK-Cu or a placebo for 12 weeks. No statistically significant differences were seen between the groups in terms of quicker resolution of erythema, wrinkles, or overall skin quality, as measured by computerized image analysis and clinical examination.
References
[i] Lintner K, Peschard O. Biologically active peptides: from a laboratory bench curiosity to a functional skin care product. Int J Cosmet Sci. 2000;22(3):207-218. (PubMed)
[ii] Reddy B, Jow T, Hantash BM. Bioactive oligopeptides in dermatology: Part I. Exp Dermatol. 2012;21(8):563-568. (PubMed)
[iii] Reddy BY, Jow T, Hantash BM. Bioactive oligopeptides in dermatology: Part II. Exp Dermatol. 2012;21(8):569-575. (PubMed)
[iv] Abu Samah NH, Heard CM. Topically applied KTTKS: a review. Int J Cosmet Sci. 2011;33(6):483-490. (PubMed)
[v] Katayama K, Seyer JM, Raghow R, Kang AH. Regulation of extracellular matrix production by chemically synthesized subfragments of type I collagen carboxy propeptide. Biochemistry. 1991;30(29):7097-7104. (PubMed)
[vi] Katayama K, Armendariz-Borunda J, Raghow R, Kang AH, Seyer JM. A pentapeptide from type I procollagen promotes extracellular matrix production. J Biol Chem. 1993;268(14):9941-9944. (PubMed)
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