Paolo Giacomoni, PhD, Insight Analysis Consulting01.16.23
Digestion is one of the steps to transform food in energy. Ancient Greeks called digestion pepsis (peyiV). Digestion is performed by an enzyme that modern biochemists have called, without much imagination, pepsin. The result of the work of pepsin is a mixture of digested proteins called, again without much imagination, peptones. Proteins are polymers of amino-acids and pepsin breaks the chemical bond that keeps them together.
This bond is formed between the amino group of an amino-acid and the carboxyl group of the neighboring one. This bond has been called, as usual without much imagination, peptide bond, and the molecules made up of amino-acids are called, in short, peptides. According to how many amino-acids they contain, they are called poly-peptides when they contain many amino-acids (polu in Greek is the prefix to mean many, as in polygon), or oligo-peptides when they only contain just a few (oligoV in Greek means a small number, as in oligarch). And di-peptides, tri-peptides and tetra-peptides contain two, three and four, amino acids, respectively.
Peptides play a role in reducing the appearance of wrinkles.
Many biochemical processes are regulated by peptides. Many hormones are peptides: Oxytocin, insulin and epidermal growth factor are just a few examples of peptides involved in phenomena as diverse as childbirth, sugar metabolism and epidermal differentiation. Glutathione is a tripeptide that acts as a powerful antioxidant. The tripeptide KWK (lysine-tryptophane-lysine) recognizes the sites in DNA where adenine or guanine have been removed1 and helped in the understanding of the mechanism of DNA repair.
All the proteins are peptides with defined biological roles, such as tyrosinase, involved in the synthesis of melanin or collagen I, a provider of skin elasticity.
Biochemical reactions are often triggered by a “signaling molecule.” What is the signal telling fibroblasts to synthetize new collagen in a wound? When cultured fibroblasts are added with hydrolyzed proteins, they respond by increasing their rate of growth. The higher the molecular weight, the larger the synthesis of the messenger RNA for collagen I and, presumably, of collagen I itself.2 Similar experiments were performed using peptides from hydrolyzed elastin3 to check their effect on cellular growth.
An oligopeptide with a short, defined sequence might be easier to be produced industrially and might have a more defined activity.4 A remarkable result was obtained by the team of Jean Krutmann in Düsseldorf, Germany: a tetrapeptide with the sequence GEKG (glycin, glutamic acid, lysine, glycin) was shown to induce collagen production in human dermal fibroblasts in vitro as well as in vivo in a double-blind, randomized, placebo-controlled study enrolling 10 volunteers.
The authors also reported: “The effect of GEKG on facial wrinkles was studied in 30 volunteers using state of the art fringe projection, which allows determination of surface roughness in three-dimensions. Here, only GEKG but not the placebo was able to significantly decrease skin roughness as a measure for wrinkles.”5
Other experiments were performed using peptides linked to other molecules. Huang and co-workers observed that irradiation with red light from a LED increases the synthesis of collagen I. When the irradiation is followed by incubation with the tri-peptide Copper-GHK (Cu-Glycine-Histidine-Lysine) the fibroblasts produce even more Collagen I, as well as basic-FGF (fibroblast growth factor) and procollagen type I C-peptide.6
Bae and coworkers7 observed that the topical application of the tripeptide Palm-RGD; i.e., palmitoyl arginine-glycin-aspartic acid, decreases global photodamage and skin roughness and increases skin elasticity and dermal density. Cultured human dermal fibroblasts (HDF) treated with Palm-RGD increase the production of type I procollagen. Furthermore, Palm-RGD suppressed the synthesis of matrix metalloproteinase 1 (MMP-1) in HDF and I would like to point out that, if this were true in vivo, Palm-RGD could be an interesting tool in preventing skin sagging by protecting against collagen degradation.
Somebody will point out that Collagen I is unique insofar as it contains large amounts hydroxyproline. Well, the fact is that hydroxyproline is the result of a biochemical modification driven by vitamin C, occurring *after that collagen I has been synthetized. Free hydroxyproline resulting from collagen I hydrolysis will not be incorporated into any newly synthetized protein, let alone collagen I! Molecular biologists know that there is no triplet in messenger RNA that codes for hydroxyproline.
The cutaneous effects of the ingestion of collagen hydrolysate are not jaw-dropping. A randomized, double-blind, placebo-controlled clinical trial was performed to explore the effects of the ingestion of two collagen hydrolysates, composed of different amounts of the bioactive dipeptides Pro-Hyp and Hyp-Gly. Improvement in skin conditions, such as skin moisture, elasticity, wrinkles, and roughness, were compared with a placebo group at baseline, and 4 and 8 weeks after the start of the trial. Collagen hydrolysate with a higher content of bioactive collagen peptides showed significant improvement than the collagen hydrolysate with a lower content of bioactive collagen peptides in facial skin moisture, elasticity, wrinkles and roughness, compared with the placebo group.8 That is to say that drinking collagen hydrolysate for eight weeks results in skin moisturization that can be obtained in minutes upon topical application of a classical moisturizer.
Inducing the synthesis of collagen I in skin is one possible action that can help restore some of the mechanical properties of the skin lost with age. The injection of hyaluronic acid or collagen beads in the dermis is sensed by the fibroblasts as a wound-provoked remodeling, to which they respond with new collagen synthesis. The topical application of peptides or of derivatives of peptides, is believed to be a promising way to improve thin, sagging skin.
References
Paolo Giacomoni, PhD
Insight Analysis Consulting
paologiac@gmail.com
516-769-6904
Paolo Giacomoni acts as an independent consultant to the skin care industry. He served as Executive Director of Research at Estée Lauder and was Head of the Department of Biology with L’Oréal. He has built a record of achievements through research on DNA damage and metabolic impairment induced by UV radiation as well as on the positive effects of vitamins and antioxidants. He has authored more than 100 peer-reviewed publications and has more than 20 patents. He is presently Head of R&D with L.RAPHAEL—The science of beauty—Geneva, Switzerland .
This bond is formed between the amino group of an amino-acid and the carboxyl group of the neighboring one. This bond has been called, as usual without much imagination, peptide bond, and the molecules made up of amino-acids are called, in short, peptides. According to how many amino-acids they contain, they are called poly-peptides when they contain many amino-acids (polu in Greek is the prefix to mean many, as in polygon), or oligo-peptides when they only contain just a few (oligoV in Greek means a small number, as in oligarch). And di-peptides, tri-peptides and tetra-peptides contain two, three and four, amino acids, respectively.
What Role for Peptides?
Peptides play a role in reducing the appearance of wrinkles.
All the proteins are peptides with defined biological roles, such as tyrosinase, involved in the synthesis of melanin or collagen I, a provider of skin elasticity.
Biochemical reactions are often triggered by a “signaling molecule.” What is the signal telling fibroblasts to synthetize new collagen in a wound? When cultured fibroblasts are added with hydrolyzed proteins, they respond by increasing their rate of growth. The higher the molecular weight, the larger the synthesis of the messenger RNA for collagen I and, presumably, of collagen I itself.2 Similar experiments were performed using peptides from hydrolyzed elastin3 to check their effect on cellular growth.
An oligopeptide with a short, defined sequence might be easier to be produced industrially and might have a more defined activity.4 A remarkable result was obtained by the team of Jean Krutmann in Düsseldorf, Germany: a tetrapeptide with the sequence GEKG (glycin, glutamic acid, lysine, glycin) was shown to induce collagen production in human dermal fibroblasts in vitro as well as in vivo in a double-blind, randomized, placebo-controlled study enrolling 10 volunteers.
The authors also reported: “The effect of GEKG on facial wrinkles was studied in 30 volunteers using state of the art fringe projection, which allows determination of surface roughness in three-dimensions. Here, only GEKG but not the placebo was able to significantly decrease skin roughness as a measure for wrinkles.”5
Other experiments were performed using peptides linked to other molecules. Huang and co-workers observed that irradiation with red light from a LED increases the synthesis of collagen I. When the irradiation is followed by incubation with the tri-peptide Copper-GHK (Cu-Glycine-Histidine-Lysine) the fibroblasts produce even more Collagen I, as well as basic-FGF (fibroblast growth factor) and procollagen type I C-peptide.6
Bae and coworkers7 observed that the topical application of the tripeptide Palm-RGD; i.e., palmitoyl arginine-glycin-aspartic acid, decreases global photodamage and skin roughness and increases skin elasticity and dermal density. Cultured human dermal fibroblasts (HDF) treated with Palm-RGD increase the production of type I procollagen. Furthermore, Palm-RGD suppressed the synthesis of matrix metalloproteinase 1 (MMP-1) in HDF and I would like to point out that, if this were true in vivo, Palm-RGD could be an interesting tool in preventing skin sagging by protecting against collagen degradation.
Alternative Administration Routes
In recent years, it has become quite fashionable to drink hydrolyzed collagen in an effort to stimulate collagen synthesis. Hydrolyzed collagen is a mixture of amino-acids and some random oligopeptides. Upon drinking, these amino-acids will be distributed to all body cells and will be used to synthetize each and every one of the several thousand enzymes and proteins produced by the human body.Somebody will point out that Collagen I is unique insofar as it contains large amounts hydroxyproline. Well, the fact is that hydroxyproline is the result of a biochemical modification driven by vitamin C, occurring *after that collagen I has been synthetized. Free hydroxyproline resulting from collagen I hydrolysis will not be incorporated into any newly synthetized protein, let alone collagen I! Molecular biologists know that there is no triplet in messenger RNA that codes for hydroxyproline.
The cutaneous effects of the ingestion of collagen hydrolysate are not jaw-dropping. A randomized, double-blind, placebo-controlled clinical trial was performed to explore the effects of the ingestion of two collagen hydrolysates, composed of different amounts of the bioactive dipeptides Pro-Hyp and Hyp-Gly. Improvement in skin conditions, such as skin moisture, elasticity, wrinkles, and roughness, were compared with a placebo group at baseline, and 4 and 8 weeks after the start of the trial. Collagen hydrolysate with a higher content of bioactive collagen peptides showed significant improvement than the collagen hydrolysate with a lower content of bioactive collagen peptides in facial skin moisture, elasticity, wrinkles and roughness, compared with the placebo group.8 That is to say that drinking collagen hydrolysate for eight weeks results in skin moisturization that can be obtained in minutes upon topical application of a classical moisturizer.
Conclusion
It is believed that skin collagen content decreases in men and women with aging. This is due to a misunderstanding of a paper by Shuster and coworkers9 reporting that the content of hydroxyproline in human skin decreases with aging. Many scientists concluded that, since hydroxyproline decreases, collagen I decreases too. Several authors (Ali M, Ruiz-Torres A (1977) Aktuelle Geront 7: 263-266; Miyahara T, Shiozawa S, Murai A(1978) J.Gerontol 33: 498-503 and Schmiegelow P, Nuessgen A et al (1986) Z. Gerontol19: 179-189 reported that these findings could not be reproduced and that the content of hydroxyproline does not change with age. It was also pointed out that the loss of mechanical properties of the skin is due to the disorganization of the elastic fibers and to the loss of water retention.Inducing the synthesis of collagen I in skin is one possible action that can help restore some of the mechanical properties of the skin lost with age. The injection of hyaluronic acid or collagen beads in the dermis is sensed by the fibroblasts as a wound-provoked remodeling, to which they respond with new collagen synthesis. The topical application of peptides or of derivatives of peptides, is believed to be a promising way to improve thin, sagging skin.
References
- Behmoaras T, Toulme JJ, Helene C. Specific recognition of apurinic sites in DNA by a tryptophan-containing peptide. Proc Natl Acad Sci U S A. 1981 Feb;78(2):926-30. doi: 10.1073/pnas.78.2.926. PMID: 6940157; PMCID: PMC319917.
- Sanchez A, Blanco M, Correa B, Perez-Martin RI, Sotelo CG. Effect of Fish Collagen Hydrolysates on Type I Collagen mRNA Levels of Human Dermal Fibroblast Culture. Mar Drugs. 2018 Apr 26;16(5):144. doi: 10.3390/md16050144. PMID: 29701725; PMCID: PMC5983275.
- Kamoun A, Landeau JM, Godeau G, Wallach J, Duchesnay A, Pellat B, Hornebeck W. Growth stimulation of human skin fibroblasts by elastin-derived peptides. Cell Adhes Commun. 1995 Nov;3(4):273-81. doi: 10.3109/15419069509081013. PMID: 8821030.
- Guglielmi DA, Martinelli AM, Rissi NC, Cilli EM, Soares CP, Chiavacci LA. Synthesis of the Peptide Ac-Wahx-KTTKS and Evaluation of the Ability to Induce In Vitro Collagen Synthesis. Protein Pept Lett. 2016;23(6):544-7. doi: 10.2174/0929866523666160331144315.
- Farwick M, Grether-Beck S, Marini A, Maczkiewitz U, Lange J, Köhler T, Lersch P, Falla T, Felsner I, Brenden H, Jaenicke T, Franke S, Krutmann J. Bioactive tetrapeptide GEKG boosts extracellular matrix formation: in vitro and in vivo molecular and clinical proof. Exp Dermatol. 2011 Jul;20(7):602-4. doi: 10.1111/j.1600-0625.2011.01307.x. PMID: 21692860.
- Huang PJ, Huang YC, Su MF, Yang TY, Huang JR, Jiang CP. In vitro observations on the influence of copper peptide aids for the LED photoirradiation of fibroblast collagen synthesis. Photomed Laser Surg. 2007 Jun;25(3):183-90. doi: 10.1089/pho.2007.2062. PMID: 1760385
- Bae JS, Kim JM, Kim JY, Choi CH, Kim JY, Moon WK, Lee MS, Moon SH, Lim JH, Park SJ, Lee JS, Song H, Kim BJ, Park YJ, Seo JS. Topical application of palmitoyl-RGD reduces human facial wrinkle formation in Korean women. Arch Dermatol Res. 2017 Oct;309(8):665-671. doi: 10.1007/s00403-017-1763-y. Epub 2017 Jul 27. PMID: 28752204.
- Inoue N, Sugihara F, Wang X. Ingestion of bioactive collagen hydrolysates enhance facial skin moisture and elasticity and reduce facial ageing signs in a randomised double-blind placebo-controlled clinical study. J Sci Food Agric. 2016 Sep;96(12):4077-81. doi: 10.1002/jsfa.7606. Epub 2016 Feb 10. PMID: 26840887.
- Shuster S, Black MM, McVitie E (1975) Skin Collagen, measured as hydroxy-proline content, decreases with age in men and women. Brit J Dermatol 93: 639-643
Paolo Giacomoni, PhD
Insight Analysis Consulting
paologiac@gmail.com
516-769-6904
Paolo Giacomoni acts as an independent consultant to the skin care industry. He served as Executive Director of Research at Estée Lauder and was Head of the Department of Biology with L’Oréal. He has built a record of achievements through research on DNA damage and metabolic impairment induced by UV radiation as well as on the positive effects of vitamins and antioxidants. He has authored more than 100 peer-reviewed publications and has more than 20 patents. He is presently Head of R&D with L.RAPHAEL—The science of beauty—Geneva, Switzerland .
