Usage of Synthetic Peptides in Cosmetics for Sensitive Skin

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.

Keywords: chemical synthesis; cosmetics; peptides; sensitive skin.

Figure 1

Structures of peptides found at INCI lists from cosmetic products for sensitive skin.

Figure 2

Flow chart of selected articles according to four different parts of the search process: identification, screening, eligibility, and inclusion.

Scheme 1

Synthesis of acetyl dipeptide-1 cetyl ester. PTSA: p-toluenesulfonic acid; TEA: triethylamine; NHS: N-hydroxysuccinimide; THF: tetrahydrofuran; DCC: N,N’-dicyclohexylcarbodiimide; rt: room temperature; h: hours. Adapted from [23].

Scheme 2

Solid-phase synthesis of palmitoyl tripeptide-8. HBTU: N,N,N′,N′-tetramethyl-O-(1H-benzotriazol-1-yl)uronium hexafluorophosphate; DMF: N,N-dimethylformamide; NMP: N-methyl-2-pyrrolidone; TIS: triisopropylsilane; TFA: trifluoroacetic acid. Adapted from [37].

Scheme 3

Solid-phase synthesis of acetyl tetrapeptide-15. HOBt: hydroxybenzotriazole; DIC: N,N′-diisopropylcarbodiimide; DMAP: 4-(dimethylamino)pyridine; DIPEA: N,N-diisopropylethylamine. Reproduced from reference with permission from the Centre National de la Recherche Scientifique (CNRS) and the Royal Society of Chemistry [46].

Scheme 4

Liquid-phase synthesis of palmitoyl tripeptide-5. EDC: 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. Adapted from [50].

Scheme 5

Liquid-phase synthesis of palmitoyl tripeptide-5. Adapted from [51].

Scheme 6

Solid-phase synthesis of palmitoyl tetrapeptide-7. Adapted from [63].

Scheme 7

Liquid-phase synthesis of palmitoyl tripeptide-1. NHS: N-Hydroxysuccinimide. Adapted from [73].

Scheme 8

Liquid-phase synthesis of palmitoyl tripeptide-1. HOBt: hydroxybenzotriazole; DIPEA: N,N-diisopropylethylamine; N-methylmorpholine; DIC: N,N′-diisopropylcarbodiimide; EDC: 1-ethyl-3-carbodiimide hydrochloride. Adapted from [72].

Scheme 9

Synthesis of palmitoyl hexapeptide-12. Adapted from [74].