Glutathione as a depigmenting agent: an overview

Peptide and peptidomimetic tyrosinase inhibitors

Melanin, which is produced by melanocytes and spread over keratinocytes, is responsible for human skin browning. There are several processes involved in melanogenesis, mostly prompted by enzymatic activities. Tyrosinase (TYR), a copper containing metalloenzyme, is considered the main actor in melanin production, as it catalyzes two crucial steps that modify tyrosine residues in dopaquinone. For this reason, TYR inhibition has been exploited as a possible mechanism of modulation of hyper melanogenesis. There are various types of molecules used to block TYR activity, principally used as skin whitening agents in cosmetic products, e.g., tretinoin, hydroquinone, azelaic acid, kojic acid, arbutin and peptides. Peptides are highly valued for their versatile nature, making them promising candidates for various functions. Their specificity often leads to excellent safety, tolerability, and efficacy in humans, which can be considered their primary advantage over traditional small molecules. There are several examples of tyrosinase inhibitor peptides (TIPs) operating as possible hypo-pigmenting agents, which can be classified according to their origin: natural, hybrid or synthetically produced. Moreover, the possibility of variating their backbones, introducing non-canonical amino acids or modifying one or more peptide bond(s), to obtain peptidomimetic molecules, is an added value to avoid or delay proteolytic activity, while the possibility of conjugation with other bioactive peptides or organic moieties can bring other specific activity leading to dual-functional peptides.

Glutathione-mediated redox regulation in Cryptococcus neoformans impacts virulence

The fungal pathogen Cryptococcus neoformans is well adapted to its host environment. It has several defence mechanisms to evade oxidative and nitrosative agents released by phagocytic host cells during infection. Among them, melanin production is linked to both fungal virulence and defence against harmful free radicals that facilitate host innate immunity. How C. neoformans manipulates its redox environment to facilitate melanin formation and virulence is unclear. Here we show that the antioxidant glutathione is inextricably linked to redox-active processes that facilitate melanin and titan cell production, as well as survival in macrophages and virulence in a murine model of cryptococcosis. Comparative metabolomics revealed that disruption of glutathione biosynthesis leads to accumulation of reducing and acidic compounds in the extracellular environment of mutant cells. Overall, these findings highlight the importance of redox homeostasis and metabolic compensation in pathogen adaptation to the host environment and suggest new avenues for antifungal drug development.

Cyclo(l-Pro-l-Tyr) Isolated from the Human Skin Commensal Corynebacterium tuberculostearicum Inhibits Tyrosinase

Melanin is produced by melanocytes to protect human skin from harmful ultraviolet radiation. During skin cell renewal, melanin and dead skin cells are disposed of. However, prolonged exposure to ultraviolet rays or aging can disturb this cycle, leading to skin hyperpigmentation due to melanin accumulation. Tyrosinase is a crucial enzyme involved in melanin biosynthesis. Although various compounds, including tyrosine inhibitors, that counteract melanin accumulation have been reported, some, such as hydroquinone, are toxic and can cause vitiligo. Meanwhile, the skin is the largest organ and the outermost layer of the immune system, containing a diverse range of bacteria that produce low-toxicity compounds. In the current study, we aim to identify metabolites produced by skin microbiota that inhibit tyrosinase. Specifically, mushroom tyrosinase served as the study model. Following commensal skin bacteria screening, Corynebacterium tuberculostearicum was found to inhibit tyrosinase activity. The active compound was cyclo(l-Pro-l-Tyr); commercially available cyclo(l-Pro-l-Tyr) also exhibited inhibitory activity. Docking simulations suggested that cyclo(l-Pro-l-Tyr) binds to the substrate-binding site of mushroom tyrosinase, obstructing the substrate pocket and preventing its activity. Hence, cyclo(l-Pro-l-Tyr) might have potential applications as a cosmetic agent and food additive.

Multiplicative Effects of Essential Oils and Other Active Components on Skin Tissue and Skin Cancers

Naturally derived essential oils and their active components are known to possess various properties, ranging from anti-oxidant, anti-inflammatory, anti-bacterial, anti-fungal, and anti-cancer activities. Numerous types of essential oils and active components have been discovered, and their permissive roles have been addressed in various fields. In this comprehensive review, we focused on the roles of essential oils and active components in skin diseases and cancers as discovered over the past three decades. In particular, we opted to highlight the effectiveness of essential oils and their active components in developing strategies against various skin diseases and skin cancers and to describe the effects of the identified essential-oil-derived major components from physiological and pathological perspectives. Overall, this review provides a basis for the development of novel therapies for skin diseases and cancers, especially melanoma.

Development and quality assessment of glutathione tripeptide loaded niosome containing carbopol emulgels as nanocosmeceutical formulations

This study focuses on the preparation, physicopharmaceutical and mechanical characterization of reduced glutathione tripeptide loaded niosome containing emulgels as a novel nanocosmeceutical product. Prepared emulgel formulations were mainly composed of oily phase containing different lipids such as glycerine dibehenate, cetyl alcohol, cetearyl alcohol, etc., and aqueous phase containing Carbopol934® as gelling agent. Niosomal lipidic vesicles prepared from Span 60 and cholesterol were subsequently incorporated into optimum emulgel formulations. The pH, viscosity, and textural/mechanical properties of emulgels were examined before and after the incorporation of niosomes. The viscoelasticity and morphological characterization were performed on the final formulation before the packed formulation's microbiological stability test. The hardness and compressibility results ensured easy removal of the emulgel from the container. Due to the carboxyl groups of Carbopol934®, moderate adhesiveness with good cohesiveness was achieved. The rheological characteristics of the emulgels were estimated by oscillatory testing and the data fitted with the Herschel-Bulkley model. Thus, the viscoelastic properties and shear-thinning flow of emulgels were demonstrated. The final formulation was microbiologically stable, and pathogens or skin-irritating allergens were not detected. An anti-aging cosmeceutical preparation containing glutathione tripeptide loaded lipid-based niosome dispersion, suitable for topical use due to its textural and viscosity properties, was successfully produced.

Dermatological Management of Aged Skin

The subject of the work concerns the dermatological management of patients mainly with aged skin. The purpose of the work was to present the basic techniques and preparations which are performed by dermatologists in the treatment of aged skin. There are dermatological treatments related to the treatment of skin diseases and cosmetic treatments which are mainly related to skin care. In this work, the method of literature research was applied. On the basis of books and journal articles on dermatological and cosmetic procedures for aged skin, an analysis of treatment types was made. Then, the results of this analysis were presented in the paper under discussion. The paper presents information on the skin and its properties. The structure and functions of the skin, aging processes and characteristics of aged skin were discussed. Then, the possibilities of reducing the visible signs of skin aging through the use of invasive and non-invasive dermatological and cosmetological treatments were given, and the most important components of preparations used supportively in combating skin aging processes were discussed.

An anticancer Ti(IV) complex increases mitochondrial reactive oxygen species levels in relation with hypoxia and endoplasmic-reticulum stress: A distinct non DNA-related mechanism

PhenolaTi is a promising Ti(IV) anticancer complex, with high stability and cytotoxicity, without notable toxic side-effects. Its cellular mechanism was proposed to relate to ER stress. Herein, we investigated the downstream effects of this mode of action in two cancer cell lines: ovarian carcinoma A2780 and cervical adenocarcinoma HeLa. First, although Ti(IV) is a non-redox metal, the formation of mitochondrial reactive oxygen species (ROS) was detected with live-cell imaging. Then, we inspected the effect of the mitochondrial ROS on cytotoxicity, using two methods: (a) addition of compounds that either elevate or reduce the mitochondrial glutathione concentration, thus affecting the oxidative state of the cells; and (b) scavenging mitochondrial ROS. Unlike the results observed for cisplatin, neither method influenced the cytotoxicity of phenolaTi, implying that ROS formation was a mere side effect of its activity. Additionally, live cell imaging displayed the hypoxia induced by phenolaTi, which can be associated with ROS formation. Overall, the results support the notion that ER-stress is the main cellular mechanism of phenolaTi, leading to hypoxia and mitochondrial ROS. The distinct mechanism of phenolaTi, which is different from that of cisplatin, combined with its stability and favorable anticancer properties, altogether make it a strong chemotherapeutic drug candidate.

Non-ergodic fragmentation upon collision-induced activation of cysteine-water cluster cations

Cysteine-water cluster cations Cys(H2O)3,6+ and Cys(H2O)3,6H+ are assembled in He droplets and probed by tandem mass spectrometry with collision-induced activation. Benchmark experimental data for this biologically important system are complemented with theory to elucidate the details of the collision-induced activation process. Experimental energy thresholds for successive release of water are compared to water dissociation energies from DFT calculations showing that clusters do not only fragment exclusively by sequential emission of single water molecules but also by the release of small water clusters. Release of clustered water is observed also in the ADMP (atom centered density matrix propagation) molecular dynamics model of small Cys(H2O)3+ and Cys(H2O)3H+ clusters. For large clusters Cys(H2O)6+ and Cys(H2O)6H+ the less computationally demanding statistical Microcanonical Metropolis Monte-Carlo method (M3C) is used to model the experimental fragmentation patterns. We are able to detail the energy redistribution in clusters upon collision activation. In the present case, about two thirds of the collision energy redistribute via an ergodic process, while the remaining one third is transferred into a non-ergodic channel leading to ejection of a single water molecule from the cluster. In contrast to molecular fragmentation, which can be well described by statistical models, modelling of collision-induced activation of weakly bound clusters requires inclusion of non-ergodic processes.

Natural products in cosmetics

The global cosmetics market reached US$500 billion in 2017 and is expected to exceed US$800 billion by 2023, at around a 7% annual growth rate. The cosmetics industry is emerging as one of the fastest-growing industries of the past decade. Data shows that the Chinese cosmetics market was US$60 billion in 2021. It is expected to be the world's number one consumer cosmetics market by 2050, with a size of approximately US$450 billion. The influence of social media and the internet has raised awareness of the risks associated with the usage of many chemicals in cosmetics and the health benefits of natural products derived from plants and other natural resources. As a result, the cosmetic industry is now paying more attention to natural products. The present review focus on the possible applications of natural products from various biological sources in skin care cosmetics, including topical care products, fragrances, moisturizers, UV protective, and anti-wrinkle products. In addition, the mechanisms of targets for evaluation of active ingredients in cosmetics and the possible benefits of these bioactive compounds in rejuvenation and health, and their potential role in cosmetics are also discussed.

The potential impact of melanosomal pH and metabolism on melanoma

Melanin is synthesized in melanocytes and is transferred into keratinocytes to block the effects of ultraviolet (UV) radiation and is important for preventing skin cancers including melanoma. However, it is known that after melanomagenesis and melanoma invasion or metastases, melanin synthesis still occurs. Since melanoma cells are no longer involved in the sun tanning process, it is unclear why melanocytes would maintain melanin synthesis after melanomagenesis has occurred. Aside from blocking UV-induced DNA mutation, melanin may provide other metabolic functions that could benefit melanoma. In addition, studies have suggested that there may be a selective advantage to melanin synthesis in melanoma; however, mechanisms regulating melanin synthesis outside the epidermis or hair follicle is unknown. We will discuss how melanosomal pH controls melanin synthesis in melanocytes and how melanosomal pH control of melanin synthesis might function in melanoma. We will also discuss potential reasons why melanin synthesis might be beneficial for melanoma cellular metabolism and provide a rationale for why melanin synthesis is not limited to benign melanocytes.

Augmented Glutathione Absorption from Oral Mucosa and its Effect on Skin Pigmentation: A Clinical Review

Treatment of dark skin with glutathione has become popular due to its depigmenting properties and low toxicity. Glutathione has been used topically, orally and parenterally in the management of dark skin. There are no clear published guidelines for management of skin pigmentation despite some clinical trials of shorter duration and small sample sizes. We examined published scientific and patient data to generate guidance for the clinician for managing hyperpigmentation using glutathione by orobuccal route. Various aspects of glutathione bioavailability were examined when administered by oral routes. Absorption of glutathione from the gastrointestinal tract is poor. Some trials have favored administering high oral doses to achieve therapeutic effect. General consensus remains against treatment of hyperpigmentation with glutathione by the oral route. Clinical and experimental evidence supporting significant glutathione absorption from orobuccal mucosa was examined. The latter is superior to the oral route since glutathione passes directly into systemic circulation resulting in a much higher rate of absorption compared to that achieved by oral intake. High blood levels thus achieved have therapeutic value. Treatment of hyperpigmentation with glutathione by the orobuccal route using hydroxypropyl cellulose (HPC) film was reviewed to formulate clinical guidance from published data. A future randomized, double-blind, placebo-controlled trial should study treatment of hyperpigmentation with glutathione using oral dispersible HPC film, with longer-term follow-up and larger sample size. This paper will hopefully offer broad guidance for the clinician on use of glutathione for hyperpigmentation management, until outcomes of larger, longer duration trials become available.

Regulation of Tyrosinase Enzyme Activity by Glutathione Peroxidase Mimics

Hydrogen peroxide plays a crucial role in the melanogenesis process by regulating the activity of the key melanin-forming enzyme tyrosinase, responsible for the browning of fruits, vegetables, and seafood. Therefore, a molecule with dual activities, both efficient tyrosinase inhibition and strong hydrogen peroxide degrading ability, may act as a promising antibrowning agent. Herein, we report highly efficient selone-based mushroom tyrosinase inhibitors 2 and 3 with remarkable glutathione peroxidase (GPx) enzyme-like activity. The presence of benzimidazole moiety enhances the tyrosinase inhibition efficiency of selone 2 (IC₅₀ = 0.4 μM) by almost 600 times higher than imidazole-based selone 1 (IC₅₀ = 238 μM). Interestingly, the addition of another aromatic ring to the benzimidazole moiety has led to the development of an efficient lipid-soluble tyrosinase inhibitor 3 (IC₅₀ = 2.4 μM). The selenium center and the -NH group of 2 and 3 are extremely crucial to exhibit high GPx-like activity and tyrosinase inhibition potency. The hydrophobic moiety of the inhibitors (2 and 3) further assists them in tightly binding at the active site of the enzyme and facilitates the C═Se group to strongly coordinate with the copper ions. Inhibitor 2 exhibited excellent antibrowning and polyphenol oxidase inhibition properties in banana and apple juice extracts.

Deletion C-terminal thioesterase abolishes melanin biosynthesis, affects metabolism and reduces the pathogenesis of Fonsecaea monophora

Dematiaceous Fonsecaea monophora is one of the major pathogens of chromoblastomycosis. It has been well established that melanization is catalyzed by the type I polyketide synthase (PKS) in F. monophora. Multidomain protein Type I PKS is encoded by six genes, in which the last enzyme thioesterase (TE) catalyzes the cyclization and releases polyketide. Two PKS genes AYO21_03016 (pks1) and AYO21_10638 have been found in F. monophora and both PKS loci have the same gene arrangement but the TE domain in AYO21_10638 is truncated at 3’- end. TE may be the key enzyme to maintain the function of pks1. To test this hypothesis, we constructed a 3’-end 500 bp deletion mutant of AYO21_03016 (Δpks1-TE-C500) and its complemented strain. We profiled metabolome of this mutant and analyzed the consequences of impaired metabolism in this mutant by fungal growth in vitro and by pathogenesis in vivo. Compared with wild-type strain, we found that the mutant repressed pks1 expression and other 5 genes expression levels were reduced by more than 50%, perhaps leading to a corresponding melanin loss. The mutant also reduced sporulation and delayed germination, became vulnerable to various environmental stresses and was less resistance to macrophage or neutrophil killings in vitro, and less virulence in mice footpad model. Metabolomic analysis indicated that many metabolites were remarkably affected in Δpks1-TE-C500, in particular, an increased nicotinamide and antioxidant glutathione. In conclusion, we confirmed the crucial role of C-terminal TE in maintaining fully function of pks1 in F. monophora. Deletion of TE negatively impacts on the synthesis of melanin and metabolites that eventually affect growth and virulence of F. monophora. Any potential inhibitor of TE then could be a novel antifungal target for drug development.

F. monophora is a fungal pathogen that causes chromoblastomycosis. Melanin of F. monophora was synthesized through PKS in which TE is the last enzyme to catalyze the cyclization and release polyketide. Few studies have investigated the effect of TE on the metabolism and pathogenesis of F. monophora. In this study, TE deletion leads to albino phenotype, decreases the expression of other domains of the pks1, and reduces biosynthesis of metabolites. The Δpks1-TE-C500 strain exhibits a changed morphogenesis and becomes less resistant to various environmental stresses. In vitro study, the Δpks1-TE-C500 strain is avirulent and less resistant to macrophages and neutrophils. In conclusion, we demonstrate that the 500 bp C-terminal of TE is essential for the function of pks1, perhaps through its effects on melanin and metabolites to regulate the growth and virulence of F. monophora. Data from this study could inspire an exploration in development of clinical therapy for CBM.

Metabolic Basis and Clinical Evidence for Skin Lightening Effects of Thiol Compounds

Melanin pigment is a major factor in determining the color of the skin, and its abnormal increase or decrease can cause serious pigmentation disorders. The melanin pigment of the skin is divided into light pheomelanin and dark eumelanin, and a big difference between them is whether they contain sulfur. Melanin synthesis starts from a common reaction in which tyrosine or dihydroxyphenylalanine (DOPA) is oxidized by tyrosinase (TYR) to produce dopaquinone (DQ). DQ is spontaneously converted to leukodopachrome and then oxidized to dopachrome, which enters the eumelanin synthesis pathway. When DQ reacts with cysteine, cysteinyl dopa is generated, which is oxidized to cysteinyl DQ and enters the pheomelanin synthesis pathway. Therefore, thiol compounds can influence the relative synthesis of eumelanin and pheomelanin. In addition, thiol compounds can inhibit enzymatic activity by binding to copper ions at the active site of TYR, and act as an antioxidant scavenging reactive oxygen species and free radicals or as a modulator of redox balance, thereby inhibiting overall melanin synthesis. This review will cover the metabolic aspects of thiol compounds, the role of thiol compounds in melanin synthesis, comparison of the antimelanogenic effects of various thiol compounds, and clinical trials on the skin lightening efficacy of thiol compounds. We hope that this review will help identify the advantages and disadvantages of various thiol compounds as modulators of skin pigmentation and contribute to the development of safer and more effective strategies for the treatment of pigmentation disorders.

Shedding a New Light on Skin Aging, Iron- and Redox-Homeostasis and Emerging Natural Antioxidants

Reactive oxygen species (ROS) are necessary for normal cell signaling and the antimicrobial defense of the skin. However excess production of ROS can disrupt the cellular redox balance and overwhelm the cellular antioxidant (AO) capacity, leading to oxidative stress. In the skin, oxidative stress plays a key role in driving both extrinsic and intrinsic aging. Sunlight exposure has also been a major contributor to extrinsic photoaging of the skin as its oxidising components disrupt both redox- and iron-homeostasis, promoting oxidative damage to skin cells and tissue constituents. Upon oxidative insults, the interplay between excess accumulation of ROS and redox-active labile iron (LI) and its detrimental consequences to the skin are often overlooked. In this review we have revisited the oxidative mechanisms underlying skin damage and aging by focussing on the concerted action of ROS and redox-active LI in the initiation and progression of intrinsic and extrinsic skin aging processes. Based on these, we propose to redefine the selection criteria for skin antiaging and photoprotective ingredients to include natural antioxidants (AOs) exhibiting robust redox-balancing and/or iron-chelating properties. This would promote the concept of natural-based or bio-inspired bifunctional anti-aging and photoprotective ingredients for skincare and sunscreen formulations with both AO and iron-chelating properties.

The critical role of glutathione redox homeostasis towards oxidation in ermanin-induced melanogenesis

Vitiligo is a depigmented disease featured as diagnosis simplicity and cure difficulty. Its occurrence and development are associated with a variety of factors, including oxidative stress, heredity and immunity, etc. Existing drugs for the treatment of vitiligo are to reduce the death of melanocytes and induce pigment accumulation as the main treatment strategy. Ermanin, a member of the flavonoids, is extracted from bee glue which is wildly used to treat vitiligo in traditional Chinese medicine. Therefore, this article discusses the relationship between melanogenesis and glutathione redox homeostasis by ermanin via biochemical and free radical approaches in vivo and in vitro. In this study, we found that ermanin effectively increased the melanin content at the in vivo model (zebrafish). Moreover, the melanin levels at the in vitro models (B16F10 cells and primary melanocytes) were also increased significantly accompanied with a shift of glutathione redox homeostasis towards oxidation. Ermanin also significantly enhanced the activity of tyrosinase. Meanwhile, ermanin increased the expression levels of TYR, TRP-1, and DCT genes, while ROS accumulation and glutathione depletion mediated the accumulation of pigments caused by ermanin, which increased the production of pigments and regulated the expression mRNA levels of TYR and DCT genes. From the perspective of pigment production regulation pathways, western blot showed that the pigment accumulation caused by ermanin was closely related to the CREB-MITF pathways, it activated CREB, TYR, TRP-1, and DCT proteins. The use of CREB specific inhibitor 666-15 and MITF inhibitor ML329 confirmed that the pigment accumulation caused by ermanin was positively correlated with CREB and MITF proteins. Our findings revealed the potential mechanisms by which ermanin promoted the production of melanin through activated CREB-MITF signaling pathway and glutathione redox homeostasis towards oxidation function as a signal are beneficial to melanin production and will help develop novel therapeutic approaches for vitiligo.

A Review of Oral Therapies for the Treatment of Skin Hyperpigmentation

This review article examines evidence supporting the use of oral therapies in treating idiopathic, actinic, and metabolically induced skin hyperpigmentation. A thorough review of the literature regarding oral treatments for hyperpigmentation was systematically conducted through PubMed. Keywords used in the primary search include "Hyperpigmentation," "Melanosis" or "Melasma," "Lightening," "Oral," and "Therapeutics." The search was limited to the English language, and no timeframe restrictions were implemented. Numerous orally administered therapies have been proposed for the treatment of skin hyperpigmentation. There is an abundant body of literature demonstrating the efficacy of orally administered tranexamic acid, glutathione, isotretinoin, and proanthocyanidin. It is reasonable to expect that the most effective oral therapies will address known underlying causes of hyperpigmentation such as thyroid disease, diabetes, and hormonal imbalance. Improvement due to oral therapy of otherwise unresponsive skin hyperpigmentation or hyperpigmentation of unknown cause is less predictable. This review is limited by the strength of evidence contained within the available studies. Clinical studies investigating the treatments discussed within this article are limited in number, at times lack blinding in the study design, and are based on small sample sizes. Based on existing research, the most promising oral remedies for hyperpigmentation appear to be tranexamic acid, glutathione, isotretinoin, and proanthocyanidin. Additional studies to better establish safety and efficacy are necessary.

Chrysopogon zizanioides-a review on its pharmacognosy, chemical composition and pharmacological activities

Vetiver is a traditional plant with versatile applications in medicine, aroma, commerce, environmental-protection, and agriculture. This review was designed to compile all the latest information on phytochemistry, pharmacology, and traditional uses of C. zizanioides. All the information related to this plant was gathered from several authentic sites, using keywords like Chrysopogon zizanioides, Vetiveria zizanioides, Khus, and Khas-Khas. The included resources were journaled articles, book chapters, books, Ayurvedic Pharmacopoeias, and Ayurvedic Formulary of India, from science direct, PubMed, research gate etc. All the necessary, relevant, authentic, and updated information were tried to inculcate in the manuscript. The literature was collected via online sites like Pub med, Scopus, and Science direct as well. During compilation, it observed that many traditional utilities of vetiver got their authentication when tested using different disease-based pharmacological models taking various extracts of roots, leaves, and root oil as test samples. However, systematic studies for isolation of active constituents and establishing their mechanism of action are still required to be validated. On the other hand, the development of novel and robust techniques needed for oil extraction can further enhance the exploration of biological utilities faster. Moreover, the cultivators and harvesters must address carefully to prevent the linked drawback of soil erosion.

Identification of L-Cysteinamide as a Potent Inhibitor of Tyrosinase-Mediated Dopachrome Formation and Eumelanin Synthesis

The purpose of this study is to identify amino acid derivatives with potent anti-eumelanogenic activity. First, we compared the effects of twenty different amidated amino acids on tyrosinase (TYR)-mediated dopachrome formation in vitro and melanin content in dark-pigmented human melanoma MNT-1 cells. The results showed that only L-cysteinamide inhibited TYR-mediated dopachrome formation in vitro and reduced the melanin content of cells. Next, the antimelanogenic effect of L-cysteinamide was compared to those of other thiol compounds (L-cysteine, N-acetyl L-cysteine, glutathione, L-cysteine ethyl ester, N-acetyl L-cysteinamide, and cysteamine) and positive controls with known antimelanogenic effects (kojic acid and β-arbutin). The results showed the unique properties of L-cysteinamide, which effectively reduces melanin content without causing cytotoxicity. L-Cysteinamide did not affect the mRNA and protein levels of TYR, tyrosinase-related protein 1, and dopachrome tautomerase in MNT-1 cells. L-Cysteinamide exhibited similar properties in normal human epidermal melanocytes (HEMs). Experiments using mushroom TYR suggest that L-cysteinamide at certain concentrations can inhibit eumelanin synthesis through a dual mechanism by inhibiting TYR-catalyzed dopaquinone synthesis and by diverting the synthesized dopaquinone to the formation of DOPA-cysteinamide conjugates rather than dopachrome. Finally, L-cysteinamide was shown to increase pheomelanin content while decreasing eumelanin and total melanin contents in MNT-1 cells. This study suggests that L-cysteinamide has an optimal structure that can effectively and safely inhibit eumelanin synthesis in MNT-1 cells and HEMs, and will be useful in controlling skin hyperpigmentation.

Determination of Phenolic Content, Antioxidant Activity, and Tyrosinase Inhibitory Effects of Functional Cosmetic Creams Available on the Thailand Market

Recently, the global trend toward the use of natural extracts and antioxidant agents in the cosmetic cream industry to produce whitening effects has been increasing. This has also been a persistent trend in Thailand. In this study, samples of commercial cosmetic creams on the Thai market were assessed for a functional evaluation of their antioxidant activity, tyrosinase inhibitory effects, and phenolic contents. Samples were extracted using hot water and sonication extraction method to obtain the functional cream extracts. Total phenolic contents in all samples were within the range of 0.46-47.92 mg GAE/30 g cream. Antioxidant activities of the cream extracts were within the range of 3.61-43.98 mg Trolox equivalent/30 g cream, while tyrosinase inhibition activities were within the range of 2.58-97.94% of inhibition. With regard to the relationship between the total phenolic content and the antioxidant activity of the cosmetic creams, Pearson's correlation coefficient revealed a moderately positive relationship with an r value of 0.6108. Furthermore, the relationship between the antioxidant activity and the tyrosinase inhibitory activity of the cosmetic creams was highly positive with an r value of 0.7238. Overall, this study demonstrated that the total phenolic contents in the functional cosmetic creams could play a role in antioxidant activity and anti-tyrosinase activities. The findings indicate how the whitening and antioxidant effects of cosmetic creams could be maintained after the products have been formulated, as this concern can affect the consumer's decision when purchasing cosmetic products.

Characterization of polyphosphate kinases for the synthesis of GSH with ATP regeneration from AMP

Polyphosphate kinase (PPK) is important for industrial processes involving ATP regeneration. While a variety of methods have been reported for regenerating ATP from ADP, few have explored enzyme catalyzed ATP regeneration from cheaper and stable AMP. In this work, PPKs from different sources were expressed and their catalytic activity were tested at different reaction temperatures, reaction pH and with different polyphosphate (polyP_n) types. The ATP regeneration system for glutathione (GSH) synthesis was established using a single PPK capable of phosphorylating AMP to synthesize ATP from AMP and short chain polyP_n. GSH yield was obtained using adenosine mono-, di- and triphosphates, which confirmed the flexibility of our constructed ATP regeneration system coupled with GSH synthesis via bifunctional GSH synthase. Finally, optimization of the GSH synthesis yielded conversion value above 80 %. Overall, these results illustrate that PPK is suitable for a broader range of substrates than previously expected, and has great untapped potential for applications involving ATP regeneration.

Combination of topical and oral glutathione as a skin-whitening agent: a double-blind randomized controlled clinical trial

BACKGROUND

The antimelanogenesis effect of topical and oral glutathione has been shown in several in vitro and clinical studies. However, whether combination of topical and oral glutathione is superior to topical or oral monotherapy is unknown. This study aimed to compare the skin-whitening effect of topical and oral glutathione combination therapy against topical and oral monotherapy.

METHODS

This double-blind randomized controlled study was done on 46 participants who were divided into two equal groups. Each group received oral placebo and oral glutathione, respectively. All participants were also instructed to apply topical placebo and glutathione to each facial side, respectively. Colorimeter examination was done biweekly using mexameter and chromameter for 8 weeks. One-way ANOVA test was used to compare the results of all groups.

RESULTS

The combination group showed significantly lower melanin index (MI) and L* score to placebo (P < 0.05). The mean MI and L* score of the combination group were the highest of all groups. Statistical significance of difference in L* score was reached when the combination group was compared to the oral placebo and topical glutathione group (P < 0.05).

CONCLUSION

This study showed that topical and oral glutathione were effective skin-lightening agents. Furthermore, combination of topical and oral glutathione might be superior to monotherapy.

The effects of the oral supplementation of L-Cystine associated with reduced L-Glutathione-GSH on human skin pigmentation: a randomized, double-blinded, benchmark- and placebo-controlled clinical trial

BACKGROUND

Glutathione has become a potential skin-lightening ingredient after the discovery of its anti-melanogenic properties. Various mechanisms of action have been considered to explain this property, one of them being the skewing of the melanin synthesis pathway toward the production of lighter pheomelanin instead of darker eumelanin, consequently producing a lightening effect.

AIMS

To evaluate the skin lightening and anti-dark spot effects of oral supplementation with L-Cystine associated with L-Glutathione as compared to placebo and benchmark.

METHODS

Effects of this L-Cystine-L-Glutathione oral combination were investigated in a 12-week randomized, double-blind, parallel-group, benchmark- and placebo-controlled trial involving 124 Asian female subjects. Women were randomly allocated into 4 equal groups (500 mg L-Cystine and 250 mg L-Glutathione, 250 mg reduced L-Glutathione, 500 mg L-Cystine, or a placebo, daily). Skin color was measured at baseline, after 6 and 12 weeks by spectrophotometry. Size and color of facial dark spots were determined from digital photographs.

RESULTS

A significant skin lightening was observed after 12 weeks of oral supplementation with L-Cystine associated with L-Glutathione. This combination also induced a significant reduction in the size of facial dark spots after 6 and 12 weeks. It is noteworthy that the observed effects were not only significantly better than those obtained with placebo, but also with L-Cystine alone or L-Glutathione alone.

CONCLUSION

The daily oral administration of 500 mg L-Cystine and 250 mg L-Glutathione during 12 weeks was a safe treatment to effectively lighten the skin and reduce the size of facial dark spots of Asian women.

Challenges for cysteamine stabilization, quantification, and biological effects improvement

The aminothiol cysteamine, derived from coenzyme A degradation in mammalian cells, presents several biological applications. However, the bitter taste and sickening odor, chemical instability, hygroscopicity, and poor pharmacokinetic profile of cysteamine limit its efficacy. The use of encapsulation systems is a good methodology to overcome these undesirable properties and improve the pharmacokinetic behavior of cysteamine. Besides, the conjugation of cysteamine to the surface of nanoparticles is generally proposed to improve the intra-oral delivery of cyclodextrin-drug inclusion complexes, as well as to enhance the colorimetric detection of compounds by a gold nanoparticle aggregation method. On the other hand, the detection and quantification of cysteamine is a challenging mission due to the lack of a chromophore in its structure and its susceptibility to oxidation before or during the analysis. Derivatization agents are therefore applied for the quantification of this molecule. To our knowledge, the derivatization techniques and the encapsulation systems used for cysteamine delivery were not reviewed previously. Thus, this review aims to compile all the data on these methods as well as to provide an overview of the various biological applications of cysteamine focusing on its skin application.

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.

Evaluation of hypopigmentation in embryonic zebrafish induced by emerging disinfection byproduct, 3, 5-di-I-tyrosylalanine

Halogenated dipeptides, 3, 5-di-I-tyrosylalanine (DIYA), have been identified as novel disinfection byproducts (DBPs), following chloramination of authentic water. However, little is known about their toxicity. Zebrafish embryos were used to assess the toxicity of novel iodinated DBPs (I-DBPs). Although DIYA did not exhibit high acute toxicity to embryonic zebrafish (LC₅₀ > 2 mM), it significantly inhibited pigmentation of melanophores and xanthophores on head, trunk and tail at 500 μM as determined by photographic analysis. Whereas N-phenylthiourea (PTU) as a pigment inhibitor did not inhibit development of yellow pigments. Colorimetric detection of melanin further confirmed these results. Quantitative real time polymerase chain reaction (qRT-PCR) measurements indicated that genes (dct, slc24a5, tyr, tyrp1a, tyrp1b, silva) associated with the melanogenesis pathway were dramatically down-regulated following exposure to 500 μM DIYA. In addition, enzymatic activity of tyrosinase (TYR) decreased, also demonstrating that the underlying mechanism of hypopigmentation was attributed to the disruption of melanogenesis pathway. Transcription levels of xanthophore genes (gch2, bnc2, csf1a, csf1b, pax7a and pax7b) were also monitored by qRT-PCR assay. DIYA exposure up-regulated expression of gch2 and bnc2, but not csf1 and pax7. Tested DIYA analogues, brominated tyrosine was unlikely to inhibit pigmentation, indicating that the iodine substitution and dipeptides structure are of important structural feature for the inhibition of pigmentation. In this study, we observed that DIYA inhibited melanogenesis related genes, which might contribute to pigmentation defects. Moreover, as an emerging I-DBPs, the developmental toxicity of aromatic dipeptides should be further studied.

"The unfair drive to be fair": Psychosocial aspects and implications of the use of skin lightening agents

The quest to be fair is not a concept of the new world. For centuries untold, having a lighter skin tone has been considered as a trait of beauty and supremacy. Society implicates fairness as a factor for getting a prospective life partner. Media portrays fair skin tone as a predecessor for success. These subtle influences affect young minds and drive them towards wanting fair skin. Physicians observe that it is one of the most common forms of body dysmorphic disorder. This article aims to highlight the psychosocial factors that mold this mentality and the possible ill effects it can have on a person, both psychologically as well as physically.

Inhibition of melanogenesis by sodium 2-mercaptoethanesulfonate

Sodium 2-mercaptoethanesulfonate (mesna) is a protective agent that is widely used in medicine because of its antioxidant effects. Recently, reactive oxygen species (ROS) were shown to increase pigmentation. Thus, ROS scavengers and inhibitors of ROS production may suppress melanogenesis. Forkhead box-O3a (FoxO3a) is an antimelanogenic factor that mediates ROS-induced skin pigmentation. In this study, we aimed to investigate the whitening effect of mesna and the signaling mechanism mediating this effect. Human melanoma (MNT-1) cells were used in this study. mRNA and protein expression were measured by real-time quantitative PCR and Western blotting analysis to track changes in FoxO3a-related signals induced by mesna. An immunofluorescence assay was performed to determine the nuclear translocation of FoxO3a. When MNT-1 melanoma cells were treated with mesna, melanin production and secretion decreased. These effects were accompanied by increases in FoxO3a activation and nuclear translocation, resulting in downregulation of four master genes of melanogenesis: MITF, TYR, TRP1, and TRP2. We found that mesna, an antioxidant and radical scavenger, suppresses melanin production and may therefore be a useful agent for the clinical treatment of hyperpigmentation disorders.

Odorless Glutathione Microneedle Patches for Skin Whitening

Glutathione is a natural anti-aging substance that prevents the oxidation of protein thiols from reactive oxygen species. In the pharmaceutical industry, reduced glutathione (GSH) has been widely used for skin whitening due to its ability to inhibit tyrosinase. However, its poor permeability and foul odor limit its use in skin applications. Herein, we report a GSH-loaded dissolving microneedle (MN) patch prepared with hyaluronic acid (HA) that enables enhanced permeation across the skin and reduces the foul odor of GSH. HA was selected to prepare odorless GSH solutions and used for MN fabrications as a carrier of GSH. GSH-loaded MN (GSH-MN) arrays prepared from MN-forming solution containing up to 10% GSH showed good pattern uniformity and appropriate mechanical properties for insertion into the skin. The GSH-MNs with a loading capacity of 17.4% dissolve within 10 min following insertion into porcine skin and release the loaded GSH without being oxidized. This new approach combines functional biopolymers to reduce the characteristic GSH odor and advanced transdermal delivery based on MN technology to enhance skin permeation without pain. We believe this technique could expand the application of GSH in many cosmeceutical fields.

Efficacy of mesotherapy with tranexamic acid and ascorbic acid with and without glutathione in treatment of melasma: A split face comparative trial

INTRODUCTION

Melasma is a prevalent annoying skin hyperpigmentation disorder that commonly involves reproductive-aged females. Variety of treatments with controversial results has been recommended. The aim of the current study was to evaluate combination therapy of tranexamic acid (TA) and vitamin C with and without glutathione with mesotherapy technique for treatment of melasma.

METHODS AND MATERIALS

This is a randomized clinical trial study conducted on 30 patients referred to Dermatology Clinics. Patients were examined under wood lamp in order of melasma type (epidermal, dermal, or mixed) determination. Then, patients underwent melasma therapy using Cocktail A (TA 4 mg/mL; vitamin C 3% and glutathione 2%) on their right half of the face and Cocktail B (TA 4 mg/mL and vitamin C 3%) on their left half of the face, with mesotherapy technique. This procedure was done for six times with 2-week intervals. Patients' modified Melasma Area and Severity Scoring (mMASI) was assessed at initiation and end of the study.

RESULTS

According to mMASI score changes 12 weeks after intervention, both cocktails had significant efficacy in reduction of mMASI score in each side. Mean of mMASI in left side had decrease of 1.82 ± 0.88 (P-value < 0.001) and in right side had decrease of 3.046 ± 1.25 (P-value < 0.001) from base line. Comparison between two groups 12 weeks after treatment showed significantly more reduction (1.28 ± 0.64) of mMASI score with cocktail A than B (P-value < 0.001). Erythema, edema, and ecchymosis was not significantly different among two cocktails (P-value > 0.05).

CONCLUSION

Use of combination mesotherapy in treatment of melasma was accompanied with appropriate outcomes regardless of type of agents but treatment with glutathione containing cocktail A presented superior results compared with cocktail of TA and vitamin C but not glutathione.

Oral supplementation of L-glutathione prevents ultraviolet B-induced melanogenesis and oxidative stress in BALB/c mice

Dietary antioxidant supplements such as L-glutathione have gained considerable attention in dermatology and cosmeceutical fields. L-glutathione possesses antiaging, antimelanogenic, antioxidant, and anticancer properties. This study aimed to investigate the inhibitory effects of L-glutathione on melanogenesis activity and oxidative stress in ultraviolet B (UVB)-irradiated BALB/c mice. Eighteen female BALB/c mice were randomly divided into 3 groups: a control group (n=6), a group without UVB irradiation and L-glutathione administration; a UVB irradiated group (n=6), a group irradiated with a UVB dose of 250 mJ/cm² for 3 min; and a treatment group (n=6), a group irradiated with UVB and treated with 100 mg/kg of L-glutathione by oral gavage. Treatment was given for 14 days, and UVB irradiation was given on days 9, 11, and 13. Oral L-glutathione significantly (P<0.05) reduced lipid peroxidation and elevated superoxide dismutase activity the and glutathione level. L-glutathione also inhibited melanin content and tyrosinase activity significantly (P<0.05) as compared with the UVB-irradiated group. Histopathological examination also showed that L-glutathione reduced the deposition of melanin pigment in the basal layer of the epidermis as compared with that in UVB-irradiated mice. All in all, the present study demonstrated that L-glutathione has the potential to be developed as a photoprotection agent against UVB-induced oxidative stress and melanogenesis.

Glutathione as a photo-stabilizer of avobenzone: an evaluation under glass-filtered sunlight using UV-spectroscopy

Avobenzone is the most widely used UVA filter in sunscreen lotion and it is prone to degradation in the presence of sunlight/UV radiation. To overcome the photo-instability of avobenzone, various photostabilizers have been used as additives, including antioxidants such as vitamin C, vitamin E, and ubiquinone. In the present study, the well known antioxidant, glutathione, was evaluated for protecting avobenzone from photodegradation in the presence of glass-filtered sunlight. The features of glutathione as a skin whitener and a radical scavenger in cells have prompted the assessment of the photostabilzing activity of glutathione on avobenzone. Glutathione significantly attenuated the glass-filtered sunlight-induced degradation of avobenzone at equimolar or higher ratios of glutathione and avobenzone. Mutational studies have been undertaken to investigate the role of the thiol group and the isopeptide bond of glutathione on its photoprotection activity towards avobenzone. The thiol group of glutathione plays a vital role in exhibiting the photoprotection activity, which was further supported by the studies on photodegradation of avobonzone in the presence of β-mercaptoethanol. The dual role of glutathione as a skin whitening agent and a photostabilizer of avobenzone may be useful for the development of multipurpose cosmetic lotions.

Phytocosmeceutical formulation development, characterization and its in-vivo investigations

Several plants found rich in flavonoid, polyphenols, and antioxidants reported antiaging, oppose inflammation and carcinogenic properties but have rarely been applied in dermatology. The present study was an active attempt to formulate a stable phytocosmetic emulsion system loaded with 2% pre-concentrated Prosopis cineraria bark extract, aiming to revive facial skin properties. In order to obtain potent therapeutic activities, we first prepared extracts of stem, leaves, and bark and screen them on basis of phenolic, flavonoids contents and antioxidant, antibacterial, lipoxygenase and tyrosinase inhibition activities. Furthermore, cytocompatibility of the extract was also determined prior starting in vivo investigations. Then the in vivo performance of 2% bark extract loaded emulsion formulation was determined by using non-invasive probe cutometer and elastometer with comparison to base formulation. The preliminary experiment showed that bark extract has a significant amount of phenolic and flavonoid compounds with eminent antioxidant potential. Furthermore, indicated an efficient antibacterial, lipoxygenase, and tyrosinase enzyme inhibition activities. Importantly, the bark extract did not induce any toxicity or apoptosis, when incubated with HaCat cells. Moreover, the in vivo results showed the formulation (size 3 μm) decreased the skin melanin, erythema and sebum contents up to 2.1-,2.7-and 79%, while increased the skin hydration and elasticity up to 2-folds and 22% as compared to the base, respectively. Owing to enhanced therapeutic effects the phytocosmetic formulation proved to be a potential skin whitening, moisturizer, anti-acne, anti-wrinkle, anti-aging therapy and could actively induce skin rejuvenation and resurfacing.

The role of systemic treatments for skin lightening

BACKGROUND

Pigmentation of the skin occurs as a result of increased melanin production or deposition due to various reasons including age, hormonal imbalances, endocrine disease, inflammation, and/or exposure to damaging radiation, resulting in dermatologic conditions such as lentigines, melasma, or postinflammatory hyperpigmentation. Although numerous topical therapies exist for skin lightening, they are limited by efficacy and pigmentation recurrence after treatment cessation. New research into systemic therapies for hyperpigmentation has been promising.

OBJECTIVE

To summarize the current literature for systemic skin lightening therapies.

METHODS

A review of the literature surrounding systemic skin lightening therapies was completed using PubMed (US National Library of Medicine).

RESULTS

Multiple systemic therapies for skin lightening exist including oral carotenoids, glutathione, melatonin, Polypodium leucotomos hydrophilic extract, procyanidin, and tranexamic acid. Preliminary data for the treatment of hyperpigmentation are promising, and currently, these oral treatments appear safe. It is not suggested to use intravenous glutathione for skin lightening due to the increased risk of adverse events.

CONCLUSION

With the patient population seeking effective systemic treatments for skin pigmentation, it is important for dermatologists to understand the properties, the efficacy, and the adverse events profile of each compound, thus ensuring proper use by patients, and that patients are appropriately counseled regarding treatment expectation and safety.

Glutathione for skin lightening: a regnant myth or evidence-based verity?

The recent hype surrounding the antimelanogenic properties of glutathione has resulted in physicians frequently administering it as a “wonder” drug for skin lightening and treatment of hyperpigmentation, especially in ethnic populations with darker skin tones. This phenomenon has seen a recent surge owing to aggressive marketing and capitalization of pharma-cosmeceutical companies. However, the unbridled and prodigal use of it, especially as a parenteral formulation, seems unjustified, given the lacunae in our knowledge about its antimelanogenic potential, limited clinical evidence favoring its role in skin lightening, and the statutory ban/advisory issued by certain federal agencies. Even though parenteral glutathione is approved only for severe liver disorders and for prevention of chemotherapy associated neurotoxicity, the lack of statutory laws governing the use of systemic glutathione in most countries has contributed to its unchecked use for skin lightening. The current clinical evidence of intravenous glutathione for skin lightening is limited to a single study with a dubious study design and apparently flawed analysis of results, casting doubt on the drug’s efficacy and reported adverse effects. Two studies evaluating oral/sublingual administration and one trial involving the use of topical glutathione reported good safety profile and appreciable but reversible results on skin tone. In this article, we shall review and discuss the current status of glutathione as a skin lightening agent and address the sundry unanswered queries regarding the dosage, duration of use and longevity of accrued effects based on clinical evidence and recent insights into its antimelanogenic mechanism.

Melaleuca quinquenervia essential oil inhibits α-melanocyte-stimulating hormone-induced melanin production and oxidative stress in B16 melanoma cells

BACKGROUND

Essential oils are odorous, volatile products of plant secondary metabolism, which are found in many leaves and stems. They show important biological activities, which account for the development of aromatherapy used in complementary and alternative medicine. The essential oil extracted from Melaleuca quinquenervia (Cav.) S.T. Blake (paperbark) (MQ-EO) has various functional properties.

PURPOSE

The aim of this study is to investigate the chemical composition of MQ-EO by using gas chromatography-mass spectrometry (GC-MS) and evaluate its tyrosinase inhibitory activity.

METHODS

Gas chromatography-mass spectrometry (GC-MS)-based metabolomics was used to identify 18 components in MQ-EO. The main components identified were 1,8-cineole (21.60%), α-pinene (15.93%), viridiflorol (14.55%), and α-terpineol (13.73%). B16 melanoma cells were treated with α-melanocyte-stimulating hormone (α-MSH) in the presence of various concentrations of MQ-EO or its major compounds. Cell viability was accessed by MTT assay and cellular tyrosinase activity and melanin content were determined by using spectrophotographic methods. The antioxidant mechanism of MQ-EO in α-MSH stimulated B16 cells was also investigated.

RESULTS

In α-melanocyte-stimulating hormone (α-MSH)-stimulated murine B16 melanoma cells, MQ-EO, 1,8-cineole, α-pinene, and α-terpineol significantly reduced melanin content and tyrosinase activity. Moreover, MQ-EO, 1,8-cineole, α-pinene, and α-terpineol decreased malondialdehyde (MDA) levels. In addition, restored glutathione (GSH) levels, glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase activities were increased in α-MSH-stimulated B16 cells. MQ-EO not only decreased apoptosis but also reduced DNA damage in α-MSH stimulated B16 cells. These results showed that MQ-EO and its main components, 1,8-cineole, α-pinene, and α-terpineol, possessed potent anti-tyrosinase and anti-melanogenic activities besides the antioxidant properties.

CONCLUSIONS

The active functional components of MQ-EO were found to be 1,8-cineole, α-pinene, and α-terpineol. Consequently, the results of present study suggest that MQ-EO is non-cytotoxic and can be used as a skin-whitening agent, both medically and cosmetically.

Glutathione and its antiaging and antimelanogenic effects

Background

Previous studies showed that supplementation of reduced form of glutathione (GSH, 500 mg/d) has a skin-lightening efficacy in humans. This study was designed to evaluate the influences of both GSH and oxidized form (GSSG), at doses lower than 500 mg/d, on improving skin properties.

Patients and methods

A randomized, double-blind, placebo-controlled, parallel, three-arm study was conducted. Healthy female subjects were equally randomized into three groups and took GSH (250 mg/d), GSSG (250 mg/d), or placebo orally for 12 weeks. At each visit at baseline and for 12 weeks, skin features including melanin index, wrinkles, and other relevant biophysical properties were measured. Blood samples were collected for safety monitoring.

Results

In generalized estimating equation analyses, melanin index and ultraviolet spots of all sites including face and arm when given GSH and GSSG tended to be lower than placebo. At some sites evaluated, subjects who received GSH showed a significant reduction in wrinkles compared with those taking placebo. A tendency toward increased skin elasticity was observed in GSH and GSSG compared with placebo. There were no serious adverse effects throughout the study.

Conclusion

We showed that oral glutathione, 250 mg/d, in both reduced and oxidized forms effectively influences skin properties. Overall, glutathione in both forms are well tolerated.

Modifying effects of carboxyl group on the interaction of recombinant S100A8/A9 complex with tyrosinase

Tyrosinase is a determinant enzyme for modulating melanin production as its abnormal activity can result in an increased amount of melanin. Reduction of tyrosinase activity has been targeted for preventing and healing hyperpigmentation of skin, such as melanoma and age related spots. The aim of this systematic study is to investigate whether recombinant S100A8/A9 and its modified form reduce the activity of mushroom tyrosinase (MT) through changing its structure. Recombinant His-Tagged S100A8 and S100A9 are expressed in Escherichia coli BL21 (DE3) and modified using Woodward's reagent K which is a carboxyl group modifier. The structures of S100A8/A9 and its modified form are studied using fluorescence and circular dichroism spectroscopy, and the activity of MT is measured using UV-visible spectrophotometry in the presence of its substrate, L-3,4-dihydroxyphenylalanine (L-DOPA). The results show a lower stability of the modified protein when compared with its unmodified form. The interaction of S100A8/A9 with MT changes the structure and successfully reduces the activity of mushroom tyrosinase. Recombinant S100A8/A9 complex decreases MT activity which can control malignant melanoma, the most dangerous type of skin cancer.

The Glutathione Derivative, GSH Monoethyl Ester, May Effectively Whiten Skin but GSH Does Not

Glutathione in its reduced form (GSH) is an antioxidant and also is involved in pheomelanin formation. Thus, it has been long believed that GSH has a skin whitening effect. However, its actual or direct effect is unproven. We evaluated the anti-melanogenic effects of GSH and its derivatives in vitro. We examined change of melanogenesis and its related proteins by GSH itself and its derivatives, including GSH monoethyl ester (GSH-MEE), GSH diethyl ester (GSH-DEE) and GSH monoisopropyl ester (GSH-MIPE) in Melan-A cells, Mel-Ab cells, and B16F10 cells. GSH and GSH-MEE did not display cytotoxic activity, but GSH-MIPE and GSH-DEE did. Intriguingly, GSH itself had no inhibitory effect on melanin production or intracellular tyrosinase activity. Rather, it was GSH-MEE and GSH-MIPE that profoundly reduced the amount of melanin and intracellular tyrosinase activity. Thus, GSH-MEE was selected as a suitable candidate skin-whitening agent and it did not alter melanogenesis-associated proteins such as microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2, but it did increase the amount of suggested pheomelanin and suggested pheomelanin/eumelanin ratio. GSH-MEE was effective for anti-melanogenesis, whereas GSH itself was not. GSH-MEE could be developed as a safe and efficient agent for the treatment of hyperpigmentation skin disorders.

Using tyrosinase as a monophenol monooxygenase: A combined strategy for effective inhibition of melanin formation

Tyrosinase is a binuclear copper-containing metalloprotein that leads the fast and regio-selective o-hydroxylation of monophenols to o-diphenols. However, the subsequent second oxidation to produce o-quinones, i.e., melanin precursors, from the o-diphenols has restricted its use to the production of functional o-diphenol derivatives. Herein, we present a combined strategy for the effective inhibition of melanin formation in tyrosinase reaction, which allows the use of tyrosinase as a monophenol monooxygenase. The o-diphenolic products were protected from being oxidized in the tyrosinase reaction by borate ions and L-ascorbic acid (LAA). Borate-o-diphenol complexes were favorable formed at high pH and consequentially protected the o-diphenolic products from the catecholase activity of tyrosinase. LAA not only directly reduced the byproduct, o-quinones, into o-diphenols but also assisted the completion of the tyrosinase reaction cycle by removing a hydroxyl group attached to the copper metal cluster at the active site of the met-form tyrosinase. The regio-selective o-hydroxylation of 7,4'-dihydroxyisoflavone (daidzein) to produce 7,3',4'-trihydroxyisoflavone (3'-ODI) was successfully carried out by whole E. coli cell biotransformation with heterologously expressed tyrosinase from Bacillus megaterium. The yield of this o-hydroxylation of 5 mM daidzein in one-pot 400 mL reaction was ca. 100% in 90 min and the productivity was 16.3 mg 3'-ODI · L(-1)  ·  h(-1)  ·  DCW mg(-1), which is considerably higher than that of other monooxygenases. The method effectively abolished melanin synthesis, so that the o-diphenolic product remained stable without enzyme inactivation. Other monophenolic phytochemicals such as resveratrol and genistein could be subjected to the same strategy. After 1 h, 1 mM of genistein and resveratrol were both converted to orobol and piceatannol, respectively, with ca. 95% conversion yield. These results support the strong potential of tyrosinase as a monooxygenase for regio-selective o-hydroxylation of various monophenolic compounds.

An open-label, single-arm trial of the safety and efficacy of a novel preparation of glutathione as a skin-lightening agent in Filipino women

BACKGROUND

Glutathione (GSH) is a naturally occurring thiol that has been reported to cause skin lightening in a manner for which several mechanisms have been proposed. Highest plasma concentrations are achieved with IV administration but are accompanied by greater levels of risk. Oral administration has been less successful in elevating plasma GSH levels.

OBJECTIVES

The use of a lozenge containing GSH was investigated in order to evaluate the buccal mucosa as a route for GSH administration. Substances that are absorbed through the buccal route go directly into the systemic circulation, effectively bypassing the gastrointestinal tract.

METHODS

Thirty Filipino females with Fitzpatrick skin types IV or V received a glutathione-containing lozenge daily for eight weeks.

RESULTS

Findings showed a significant decrease in melanin indices from baseline to endpoint that became evident in as little as two weeks. There were no serious adverse events, and laboratory examination findings remained normal.

CONCLUSIONS

The authors conclude that the lozenge containing glutathione was safe and effective in lightening the skin of Filipino women.

Skin-whitening and skin-condition-improving effects of topical oxidized glutathione: a double-blind and placebo-controlled clinical trial in healthy women

Purpose

Glutathione is a tripeptide consisting of cysteine, glycine, and glutamate and functions as a major antioxidant. It is synthesized endogenously in humans. Glutathione protects thiol protein groups from oxidation and is involved in cellular detoxification for maintenance of the cell environment. Reduced glutathione (GSH) has a skin-whitening effect in humans through its tyrosinase inhibitory activity, but in the case of oxidized glutathione (GSSG) this effect is unclear. We examined the skin-whitening and skin-condition effects of topical GSSG in healthy women.

Subjects and methods

The subjects were 30 healthy adult women aged 30 to 50 years. The study design was a randomized, double-blind, matched-pair, placebo-controlled clinical trial. Subjects applied GSSG 2% (weight/weight [w/w]) lotion to one side of the face and a placebo lotion to the other side twice daily for 10 weeks. We objectively measured changes in melanin index values, moisture content of the stratum corneum, smoothness, wrinkle formation, and elasticity of the skin. The principal investigator and each subject also used subjective scores to investigate skin whitening, wrinkle reduction, and smoothness. Analysis of variance was used to evaluate differences between groups.

Results

The skin melanin index was significantly lower with GSSG treatment than with placebo from the early weeks after the start of the trial through to the end of the study period (at 10 weeks, P<0.001). In addition, in the latter half of the study period GSSG-treated sites had significant increases in moisture content of the stratum corneum, suppression of wrinkle formation, and improvement in skin smoothness. There were no marked adverse effects from GSSG application.

Conclusion

Topical GSSG is safe and effectively whitens the skin and improves skin condition in healthy women.

Determination of melanin types and relative concentrations: an observational study using a non-invasive inverse skin reflectance analysis

OBJECTIVE

Melanin is a major skin colour pigment that is made up of eumelanin (the dark brown-black colour) and pheomelanin (the light red-yellow colour) pigments. Skin-whitening products typically contain depigmentation agents that reduce the level of pigmentation by changing the pheomelanin-eumelanin production. Similarly, in skin pigment treatment of skin disorders, the melanin production is managed accordingly. To assess and improve treatment efficacy, it is important to have a measurement tool that is capable of determining the melanin types objectively. So far, the efficacy assessment is subjective. In this study, an inverse skin reflectance pigmentation analysis system that determines eumelanin and pheomelanin content is developed and evaluated in an observational study involving 36 participants with skin photo type IV.

METHODS

The reflectance spectra of the left forearms of participants were analysed by the pigmentation analysis system to determine their skin parameters--pheomelanin and eumelanin concentrations, melanosome volume fraction, and epidermal thickness. The determined skin parameters are then inputted into the realistic skin model (RSM) of the Advanced Systems Analyses Program (asap®) to generate the ground truth reflectance spectra for the given skin parameters to validate the system.

RESULTS

The developed pigmentation analysis system is found to be accurate with a spectral error of 0.0163 ± 0.009 between measured reflectance and the reflectance output of the analysis system and RSM. The regression analysis shows a strong linear relationship (R(2) = 0.994) indicating good precision. The relative concentrations of pheomelanin (38.23 ± 15.04) and eumelanin (1.68 ± 0.91) analysed by the system gives a ratio of pheomelanin to eumelanin of 0.048 ± 0.029; this value is consistent with previously reported figure of 0.049.

CONCLUSION

The proposed pigmentation analysis system is able to determine melanin types and their relative concentrations. It has the potential to assess the efficacy of the skin-whitening and pigmentation treatments objectively in a non-invasive manner.

'Skin Trade': Genealogy of Anti-ageing 'Whiteness Therapy' in Colonial Medicine

This article investigates the extent to which the emerging trend of do-it-yourself anti-ageing skin-whitening products represents a re-articulation of Western colonial concerns with environmental pollution and racial degeneracy into concern with gendered vulnerability. This emerging market is a multibillion dollar industry anchored in the USA, but expanding globally. Do-it-yourself anti-ageing skin-whitening products purport to address the needs of those looking to fight the visible signs of ageing, often promising to remove hyper-pigmented age spots from women’s skin, and replace it with ageless skin, free from pigmentation. In order to contextualize the investigation of do-it-yourself anti-ageing skin-whitening practice and discourse, this article draws from the literature in colonial commodity culture, colonial tropical medicine, the contemporary anti-ageing discourse, and advertisements for anti-ageing skin-whitening products. First, it argues that the framing of the biomedicalization of ageing as a pigmentation problem caused by deteriorating environmental conditions and unhealthy lifestyle draws tacitly from European colonial concerns with the European body’s susceptibility to tropical diseases, pigmentation disorders, and racial degeneration. Second, the article argues that the rise of do-it-yourself anti-ageing skin-whitening commodities that promise to whiten, brighten, and purify the ageing skin of women and frames the visible signs of ageing in terms of pigmentation pathology.

Effect of Vetiveria zizanioides essential oil on melanogenesis in melanoma cells: downregulation of tyrosinase expression and suppression of oxidative stress

The major objective of this study was to estimate the hypopigmentation function of the essential oil from Vetiveria zizanioides (VZ-EO). Our results indicated that VZ-EO exhibits potent lipid peroxidation inhibitory activity to moderate the bleaching of β-carotene and to maintain the cellular glutathione (GSH) levels. VZ-EO can markedly decrease melanin production and tyrosinase activity in α-melanin-stimulating-hormone- (α-MSH-) stimulated B16 cells. The effect of VZ-EO on melanogenesis is achieved by the suppression of cellular tyrosinase expression. The results demonstrated that the activity of VZ-EO on melanogenesis might be the result of its potent antioxidative ability, which was reflected in the decreased cellular oxidant and malondialdehyde (MDA) levels and the recovered activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) in α-MSH-stimulated B16 cells. The most abundant compound in VZ-EO is cedr-8-en-13-ol (12.4%), which has a strong capability to inhibit lipid peroxidation. Therefore, VZ-EO has the potential to become an ingredient in future hypopigmentation drugs, foods, and cosmetics.

An integral topical gel for cellulite reduction: results from a double-blind, randomized, placebo-controlled evaluation of efficacy

BACKGROUND

Cellulite is a serious cosmetic concern for most of the 90% of women affected by it.

OBJECTIVE

To assess the clinical efficacy of a complex integral anti-cellulite gel.

METHODS

This double-blind, randomized, placebo-controlled study involved 44 healthy women, aged 25-55 years. Subjects had a normal to slightly overweight body mass index and presented slight to moderate cellulite on their thighs, buttocks, and/or hips at baseline. Subjects were randomly assigned to either the treated or placebo group and accordingly applied the active product or placebo on their hips, stomach, buttocks, and thighs, twice daily for 3 months. Skin tonicity, orange-peel aspect, and stubborn cellulite were assessed at day 0, 28, 56, and 84. A self-evaluation questionnaire was completed by all volunteers.

RESULTS

At the end of the study, an average of 81% of the subjects applying the active product presented improvement in their cellulite condition versus 32% for the placebo group (all descriptors and sites combined). At day 84, skin tonicity, orange-peel appearance, and stubborn cellulite were improved in a significant manner (P<0.05) over placebo, on all studied areas. Skin tonicity improved on average by +41% for buttocks, +35% for hips, and +31% for thighs. Orange peel appearance was reduced on average by -25% for buttocks, -22% for hips, and -22% for thighs. Stubborn cellulite was reduced on average by -19% for buttocks, -24% for hips, and -22% for thighs. Circumference measurements decreased in a significant manner (P<0.05) over placebo, for the abdomen (average value of -1.1 cm) and thighs (average value of -0.8 cm). The product was well tolerated and perceived by the volunteers themselves as better performing than placebo on all criteria.

CONCLUSION

All results validate the efficacy of the present integral formulation to significantly reduce signs of cellulite and reshape the silhouette.