Chicken Egg White-Advancing from Food to Skin Health Therapy: Optimization of Hydrolysis Condition and Identification of Tyrosinase Inhibitor Peptides

Egg white hydrolysate peptides act as antimicrobial and anti-inflammatory agents for acne

A simple method to generate antibacterial peptides by alkaline hydrolysis of hen egg whites is reported. The method reproducibly generates short peptides with molecular weight of less than 14.4 kDa that exhibit low to no cytotoxicity on RAW 264.7 macrophage cells, but do inhibit the bacterial growth of Cutibacterium acnes (C. acnes), Staphylococcus aureus (S. aureus) and antibiotic-resistant S. aureus (MRSA), while also reducing nitric oxide production from heat-killed C. acnes-treated RAW 264.7 cells. Peptidomics revealed at least thirty peptides within the complex mixture, of which eight were evaluated individually. Three peptides (PK8, EE9 and RP8) were potent anti-inflammation and antibacterial agents, but notably the complex egg white hydrolysate (EWH) was more effective than the individual peptides. Electron microscopy suggests the antibacterial mechanism of both the hydrolysate and the selected peptides is through disruption of the cell membrane of C. acnes. These findings suggest that EWH and EWH-derived peptides are promising candidates for infection and inflammation treatment, particularly in managing acne and combating antibiotic-resistant bacteria like MRSA.

Isolation, identification, and preparation of tyrosinase inhibitory peptides from Pinctada martensii meat

Recently, natural tyrosinase inhibitors have gained attention in clinical cosmetology research. In this study, the enzymatic hydrolysis of Pinctada martensii meat by protease from Bacillus licheniformis, 401 peptides with tyrosinase inhibitory were identified after isolated by ultrafiltration and Sephadex G-15 from the fraction F4. The peptide effects on the tyrosinase activity and structure were evaluated using molecular docking. Three synthetic peptides classified as W1 (WDRPKDDGGSPIK), W2 (DRGYPPVMF), and W3 (SGGGGGGGLGSGGSIRSSY), which had the lowest binding energies were selected for in vitro synthesis and biological activity investigation. The W3 peptide (5 mg/mL) had the highest tyrosinase activity, SPF, DPPH, and ABTS clearance values, and total antioxidant capacity. W3 did not affect the survival rate of mouse melanoma B16-F10 cells (1.0-5.0 mg/mL) but decreased the melanin content. Hence, W3 could be suitable for multifunctional tyrosinase inhibition and provides a novel method to use marine organisms as natural tyrosinase inhibitor sources.

Investigation of the optimal production conditions for egg white hydrolysates and physicochemical characteristics

This study aimed to investigate the potential of egg white protein hydrolysate (EWH) as a functional food by identifying the optimum production conditions for EWH with response surface methodology (the results of the sensory evaluation were considered as an essential quality indicator). At the same time, its physicochemical and biological activity was also evaluated. The optimal economic production conditions were selected: substrate concentration of 12.5%, enzyme content of 7.5%, and hydrolysis time at 100 min. The degree of hydrolysis (DH %) was 13.51%. In addition, to the better acceptance of the evaluation, it also helps to reduce the production cost of the protein hydrolysate, which is beneficial to future processing and applications. The antioxidant capacity experiments showed that EWH has good antioxidant activity, which presents a dose-dependent relationship. Hence, this study provides a theoretical basis for future research and application of EWH for processing applications, including dietary supplementation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05708-0.

Rapid screening of novel tyrosinase inhibitory peptides from a pearl shell meat hydrolysate by molecular docking and the anti-melanin mechanism

Pearls are an edible and medicinal resource with whitening activity and nutritional value in China. In the previous study, we found that the pearl shell meat hydrolysate showed dual activities of antioxidation and tyrosinase inhibition, which were similar to the activities of pearls. In this research, a pearl shell meat hydrolysate was isolated, identified and screened by molecular docking, and three peptides FLF, SPSSS and WLL with high tyrosinase inhibitory activities were obtained. The results indicated that FLF, SPSSS and WLL could effectively inhibit tyrosinase activities and the inhibition rates (1.0 mg mL^-1) were 54.32%, 65.26% and 57.50%, respectively. The results of a zebrafish whitening experiment showed that the tyrosinase activities of zebrafish treated with FLF, SPSSS and WLL decreased by 75.41%, 62.87% and 64.99% (p < 0.05), respectively, and the melanin content decreased by 37.34%, 38.52% and 40.39% (p < 0.05), respectively. In a B16F10 cell whitening experiment, compared with a control group, FLF, SPSSS and WLL also showed a significant whitening effect, the tyrosinase activities decreased by 84.08%, 79.08% and 77.45% (p < 0.05), respectively, and the melanin content decreased by 42.23%, 34.37% and 34.02% (p < 0.05), respectively. Moreover, the active peptides could act on three signal pathways including Wnt/β-catenin, MAPK and MC1R/α-MSH and significantly downregulated the expressions of the signaling factors WNT4, MITF, β-catenin, ERK, JNK, TRP1 and TRP2 (p < 0.05). The results demonstrated that the whitening active peptides were edible natural antioxidants, tyrosinase inhibitors and skin anti-melanin agents, which could be added to functional foods as food ingredients.

Microwave-assisted extraction of polysaccharide from Cinnamomum cassia with anti-hyperpigmentation properties: Optimization and characterization studies

The anti-hyperpigmentation effect and tyrosinase inhibitory mechanism of cinnamon polysaccharides have not been reported. The current study focused on the extraction of polysaccharides from Cinnamomum cassia bark using microwave-assisted approach and optimization of the extraction process (i.e., microwave power, irradiation time and buffer-to-sample ratio) by Box-Behnken design to obtain a high yield of polysaccharides with high sun protection factor (SPF), anti-hyperpigmentation and antioxidant activities. The extracted pectic-polysaccharides had low molecular weight and degree of esterification. The optimal extraction process had polysaccharides characterized by (a) monophenolase inhibitory activity = 97.5 %; (b) diphenolase inhibitory activity = 99.4 %; (c) ferric reducing antioxidant power = 4.4 mM; (d) SPF = 6.1; (e) yield = 13.7 %. The SPF, tyrosinase inhibitory and antioxidant activities were primarily contributed by the polysaccharides. In conclusion, the polysaccharides from C. cassia could be an alternative therapeutic source for skin hyperpigmentation treatment.

Effect of Chicken Egg White-Derived Peptide and Hydrolysates on Abnormal Skin Pigmentation during Wound Recovery

Abnormal skin pigmentation commonly occurs during the wound healing process due to the overproduction of melanin. Chicken egg white (CEW) has long been used to improve skin health. Previous published works had found CEW proteins house bioactive peptides that inhibit tyrosinase, the key enzyme of melanogenesis. The current study aimed to evaluate the anti-pigmentation potential and mechanism of the CEW-derived peptide (GYSLGNWVCAAK) and hydrolysates (CEWH_mono and CEWH_di), using a cell-based model. All of these peptide and hydrolysates inhibited intracellular tyrosinase activity and melanin level up to 45.39 ± 1.31 and 70.01 ± 1.00%, respectively. GYSLGNWVCAAK and CEWH_di reduced intracellular cAMP levels by 13.38 ± 3.65 and 14.55 ± 2.82%, respectively; however, CEWH_mono did not affect cAMP level. Moreover, the hydrolysates downregulated the mRNA expression of melanogenesis-related genes, such as Mitf, Tyr, Trp-1 and Trp-2, but GYSLGNWVCAAK only suppressed Tyr gene expression. Downregulation of the genes may lower the catalytic activities and/or affect the structural stability of TYR, TRP-1 and TRP-2; thus, impeding melanogenesis to cause an anti-pigmentation effect in the cell. Outcomes from the current study could serve as the starting point to understand the underlying complex, multifaceted melanogenesis regulatory mechanism at the cellular level.

Tyrosinase inhibitory effects of the peptides from fish scale with the metal copper ions chelating ability

Tyrosinase inhibitors have important applications in the cosmetics, medical and food industries due to they can effectively inhibit the synthesis of melanin. In this study, tilapia scale polypeptides were used as raw materials, and high-purity polypeptides with metal copper ions chelating ability were obtained by enzymatic hydrolysis, column chromatography, and EDTA elution. In vitro cell model analysis showed that the fish squamous peptides could strongly inhibit the activity of tyrosinase. When the sample concentration was 5 mg·mL^-1, its inhibition rate of tyrosinase reached to 59.73%, which had a better inhibition of enzyme activity compared with the positive control of the same concentration. The comprehensive results showed that the fish scale polypeptide with metal copper ions chelating ability could be a strong tyrosinase inhibitor, and might be used to prevent food browning in food-related fields, and could also be used for skin whitening in the fields of medicine and cosmetics.

The Hypopigmentation Mechanism of Tyrosinase Inhibitory Peptides Derived from Food Proteins: An Overview

Skin hyperpigmentation resulting from excessive tyrosinase expression has long been a problem for beauty lovers, which has not yet been completely solved. Although researchers are working on finding effective tyrosinase inhibitors, most of them are restricted, due to cell mutation and cytotoxicity. Therefore, functional foods are developing rapidly for their good biocompatibility. Food-derived peptides have been proven to display excellent anti-tyrosinase activity, and the mechanisms involved mainly include inhibition of oxidation, occupation of tyrosinase’s bioactive site and regulation of related gene expression. For anti-oxidation, peptides can interrupt the oxidative reactions catalyzed by tyrosinase or activate an enzyme system, including SOD, CAT, and GSH-Px to scavenge free radicals that stimulate tyrosinase. In addition, researchers predict that peptides probably occupy the site of the substrate by chelating with copper ions or combining with surrounding amino acid residues, ultimately inhibiting the catalytic activity of tyrosinase. More importantly, peptides reduce the tyrosinase expression content, primarily through the cAMP/PKA/CREB pathway, with PI3K/AKT/GSK3β, MEK/ERK/MITF and p38 MAPK/CREB/MITF as side pathways. The objective of this overview is to recap three main mechanisms for peptides to inhibit tyrosinase and the emerging bioinformatic technologies used in developing new inhibitors.

Recent advances in the design and discovery of synthetic tyrosinase inhibitors

Tyrosinase is a copper-containing metalloenzyme that is responsible for the rate-limiting catalytic step in the melanin biosynthesis and enzymatic browning. As a promising target, tyrosinase inhibitors can be used as skin whitening agents and food preservatives, thus having broad potential in the fields of food, cosmetics, agriculture and medicine. From 2015 to 2020, numerous synthetic inhibitors of tyrosinase have been developed to overcome the challenges of low efficacy and side effects. This review summarizes the enzyme structure and biological functions of tyrosinase and demonstrates the recent advances of synthetic tyrosinase inhibitors from the perspective of medicinal chemistry, providing a better understanding of the catalytic mechanisms and more effective tyrosinase inhibitors.

Egg white peptides ameliorate dextran sulfate sodium-induced acute colitis symptoms by inhibiting the production of pro-inflammatory cytokines and modulation of gut microbiota composition

Egg white peptides (EWPs) can be effectively used to alleviate and treat inflammatory diseases due to their anti-oxidation, anti-inflammation, and microbiota regulation capabilities. A dextran sodium sulfate (DSS)-induced colitis model was used to clarify the regulatory effects of EWPs on colitis. Forty-three peptide sequences were identified from EWPs using LC-MS/MS. The results demonstrated that EWPs decreased the levels of pro-inflammatory cytokines and the extent of crypt damage in a dose-dependent manner. 16S rRNA gene sequencing results indicated that 200 mg/kg EWPs significantly increased the relative abundance of beneficial bacteria Lactobacillus and Candidatus_Saccharimonas, and reduced the relative abundance of pathogenic bacteria Ruminiclostridium and Akkermansia. In addition, the degree of correlation between pro-inflammatory cytokines and microbiota was as follows: interleukin (IL)-1β > IL-8 > IL-6 > tumor necrosis factor-α To summarize, EWPs contributed to the alleviation of colitis symptoms and the intestinal injury through anti-inflammatory effects, repair of intestinal mucosa, and modulation of gut microbiota.

Naturally occurring and synthetic peptides: Efficient tyrosinase inhibitors

Tyrosinase is a copper-containing enzyme involved in the biosynthesis of melanin pigment, which is the most important photo protective agent against skin photo carcinogenesis. Excess production of melanin causes hyperpigmentation leading to undesired browning in human skin, fruits, and vegetable as well as plant-derived foods. Moreover, the role of tyrosinase in the onset and progression of various diseases such as cancers, Alzheimer's, and Parkinson diseases has been well documented in the literature. In this respect, tyrosinase inhibitors have been in the center of attention particularly as the efficient skin whitening agents. Among a wide range of compounds possessing anti-tyrosinase activity, peptides both natural and synthetic derivatives have attracted attention due to high potency and safety.

Multifunctional Tyrosinase Inhibitor Peptides with Copper Chelating, UV-Absorption and Antioxidant Activities: Kinetic and Docking Studies

Nature-derived tyrosinase inhibitors are of great industrial interest. Three monophenolase inhibitor peptides (MIPs) and three diphenolase inhibitor peptides (DIPs) from a previous study were investigated for their in vitro tyrosinase inhibitory effects, mode of inhibition, copper-chelating activity, sun protection factor (SPF) and antioxidant activities. DIP1 was found to be the most potent tyrosinase inhibitor (IC₅₀ = 3.04 ± 0.39 mM), which could be due to the binding interactions between its aromatic amino acid residues (Y2 and D7) with tyrosinase hotspots (H85, V248, H258, H263, F264, R268, V283 and E322) and its ability to chelate copper ion within the substrate-binding pocket. The conjugated planar rings of tyrosine and tryptophan may interact with histidine within the active site to provide stability upon enzyme-peptide binding. This postulation was later confirmed as the Lineweaver-Burk analysis had identified DIP1 as a competitive inhibitor and DIP1 also showed 36.27 ± 1.17% of copper chelating activity. In addition, DIP1 provided the highest SPF value (11.9 ± 0.04) as well as ferric reducing antioxidant power (FRAP) (5.09 ± 0.13 mM FeSO₄), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) (11.34 ± 0.90%) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (29.14 ± 1.36%) free radical scavenging activities compared to other peptides. These results demonstrated that DIP1 could be a multifunctional anti-tyrosinase agent with pharmaceutical and cosmeceutical applications.