Antioxidant and Anti-Melanogenic Effect of the Novel Synthetic Hexapeptide (SFKLRY-NH2)

Tyrosinase inhibitory peptides: Structure-activity relationship study on peptide chemical properties, terminal preferences and intracellular regulation of melanogenesis signaling pathways

BACKGROUND

Bioactive peptides have gained attention as potential alternatives to chemical-based skin lightening agents. Based on literature search, the reported articles focused mainly on the sources and preparation methods of tyrosinase inhibitory peptides and there is lacking information regarding the structure-activity relationship (SAR) between peptide property and tyrosinase inhibition. It was hypothesized that peptide properties such as hydrophobicity/hydrophilicity and the amino acid type and position/arrangement at the terminal positions could affect peptide mode of binding hence result in various degrees of tyrosinase inhibition.

METHODS

In this study, the sequences of 128 tyrosinase inhibitory peptides were collected from peer-reviewed articles. The hydrophobicity/hydrophilicity property and the amino acid profile of peptides at the N- and C-terminals were analyzed using bioinformatics tools. Molecular docking analysis was employed to further elucidate the roles of reactive amino acids in tyrosinase-peptide binding interactions. The peptide-regulated intracellular melanogenesis pathways were also compiled and discussed.

RESULTS

It was found that hydrophobic and/or polar neutral properties may facilitate or stabilize peptide binding with tyrosinase. Moreover, short peptides featuring a cysteine and tyrosine at the N- and C- terminal ultimate positions tend to bind to the active site of tyrosinase whereas positively charged amino acid such as arginine at the N-terminal does not favor peptide binding to tyrosinase.

CONCLUSIONS

These findings provide detailed explanation on how peptide/amino acid structures are related and what function they play in tyrosinase inhibition. It could also inspire researchers to account for tyrosinase-peptide SAR and the underlying anti-melanogenesis mechanisms in formulating peptide-based treatments or strategies against skin hyperpigmentation.

Up- or Downregulation of Melanin Synthesis Using Amino Acids, Peptides, and Their Analogs

Harmonious synthesis and distribution of melanin in the skin contribute to the expression of beauty and the maintenance of health. When skin pigmentary disorders occur because of internal or external factors or, when there is a need to artificially increase or reduce the pigmentation level of the skin for aesthetic or therapeutic purposes, various pharmacological therapies are applied but the results are not always satisfactory. Studies have been conducted to improve the efficacy and safety of these treatment strategies. In this review, we present the latest studies regarding peptides and related compounds that may be useful in artificially increasing or reducing skin melanin levels. Certain analogs of α-melanocyte stimulating hormone (MSH) and oligopeptides with the sequences derived from the hormone were shown to promote melanin synthesis in cells and in vivo models. Various amino acids, peptides, their analogs, and their hybrid compounds with other chemical moieties were shown to inhibit tyrosinase (TYR) catalytic activity or downregulate TYR gene expression. Certain peptides were shown to inhibit melanosome biogenesis or induce autophagy, leading to decreased pigmentation. In vivo and clinical evidence are available for some compounds, including [Nle⁴-_D-Phe⁷]-α-MSH, glutathione disulfide, and glycinamide hydrochloride. For many other compounds, additional studies are required to verify their efficacy and safety in vivo and in clinical trials. The accumulating information regarding pro- and antimelanogenic activity of peptides and related compounds will lead to the development of novel drugs for the treatment of skin pigmentary disorders.

Identification of small peptides and glycinamide that inhibit melanin synthesis using a positional scanning synthetic peptide combinatorial library

BACKGROUND

Antimelanogenic peptides are potentially useful to treat hyperpigmentation, but many peptides have limited application because of high cost and/or low activity.

OBJECTIVES

To identify small and potent peptide inhibitors of cellular melanin synthesis that are useful for cosmetic and medical applications.

METHODS

A positional scanning synthetic tetrapeptide combinatorial library was used for screening of potentially active peptides. Antimelanogenic activities of the peptide pools and individual peptides were evaluated in B16-F10 melanoma cells and human epidermal melanocytes treated with alpha-melanocyte-stimulating hormone (α-MSH).

RESULTS

Predicted active tetrapeptide sequences were R-(F/L)-(C/W)-(G/R)-NH₂ . Of the individual tetrapeptides tested, D3 (RFWG-NH₂ ) and D5 (RLWG-NH₂ ) exhibited high antimelanogenic activities. Tetrapeptide D9 (FRWG-NH₂ ) with a sequence identical to that of a portion of α-MSH also showed antimelanogenic activity. Of the tripeptides tested, E5 (FWG-NH₂ ), E6 (LWG-NH₂ ) and E7 (RWG-NH₂ ) were relatively more active. Dipeptide F1 (WG-NH₂ ) and monopeptide G1 (G-NH₂ , glycinamide) retained activity, but G2 (Ac-G-NH₂ ) and G3 (glycine) did not. The antimelanogenic activities of peptides D3, E5, F1 and G1 were verified in α-MSH-stimulated human epidermal melanocytes. Commercially available G-NH₂ ·HCl suppressed the phosphorylation levels of cAMP-responsive element binding protein, protein levels of microphthalmia-associated transcription factor and tyrosinase, l-tyrosine hydroxylase activity of tyrosinase, and the melanin levels in stimulated cells.

CONCLUSIONS

Small peptides, including glycinamide and tryptophanyl glycinamide, are potent antimelanogenic agents with potential value for the treatment of skin hyperpigmentation.

Isolation and Identification of Tyrosinase-Inhibitory and Copper-Chelating Peptides from Hydrolyzed Rice-Bran-Derived Albumin

Rice-bran albumin (RBAlb), which shows higher tyrosinase-inhibitory activity than other protein fractions, was hydrolyzed with papain to improve the bioactivity. The obtained RBAlb hydrolysate (RBAlbH) was separated into 11 peptide fractions by RP-HPLC. Tyrosinase inhibition and copper chelation activities decreased with increasing retention times of the peptide fractions. RBAlbH fraction 1, which exhibited the greatest activity, contained 13 peptides whose sequences were determined by using LC-MS/MS. Most of the peptide sequences contained features of previously reported tyrosinase-inhibitory and metal-chelating peptides, especially peptide SSEYYGGEGSSSEQGYYGEG. RBAlbH fraction 1 showed more effective tyrosinase inhibition (IC50 = 1.31 mg/mL) than citric acid (IC50 = 9.38 mg/mL), but it was less effective than ascorbic acid (IC50 = 0.03 mg/mL, P ≤ 0.05). It showed copper-chelating activity (IC50 = 0.62 mg/mL) stronger than that of EDTA (IC50 = 1.06 mg/mL, P ≤ 0.05). These results suggest that RBAlbH has potential as a natural tyrosinase inhibitor and copper chelator for application in the food and cosmetic industries.

The Latest Advance in Hair Regeneration Therapy Using Proteins Secreted by Adipose-Derived Stem Cells

Introduction:

Adipose-derived stem cells (ADSCs) that can be harvested from fat cells are one of the latest breakthroughs in the aesthetic field. In addition, basic studies have reported that ADSC conditioned medium (ADSC-CM) promotes skin and hair regeneration. We validate our novel approach, known as hair regenerative therapy, for hair growth treatment using ADSC-CM.

Materials and Methods:

ADSCs were cultured and expanded in hypoxic culture conditions, and ADSC-CM was collected. ADSC-CM includes various cytokines and growth factors that influence hair regrowth, to which we added buflomedyl, cysteine, coenzyme Q10, and vitamins. Protein solution from ADSC-CM was applied 4 to 6 times every 3 to 5 weeks by mesotherapy techniques such as nappage and papule injections. Satisfactory results of hair regenerative therapy in 12 women and 13 men were determined with a visual analog scale.

Results:

All patients experienced increased hair growth from the treatments with ADSC-CM. Four treatment sessions performed within 3 to 4 months provided especially good results. Scores on the visual analog scale increased with treatment frequency. Statistical significance was determined by Friedman's 2-way analysis of variance (P < .01) and Wilcoxon's signed rank test (P < .01).

Discussion:

ADSCs secrete cytokines, such as keratinocyte growth factor, vascular endotheliatl growth factor, platelet-derived growth factor, hepatocyte growth factor. Those cytokines and growth factor are very important for hair growth. Our new therapy with ADSC-CM does not require specialized facilities, such as a cell-processing center, and can be a valuable treatment.