Skin-whitening Agent Research Articles

The Role of Glutathione as a Bleaching Agent in Whitening Skin: A Review

Objective: To review and compare the efficacy of glutathione formulations as skin-whitening agents in adults participating in several clinical studies. Methods: Using a MEDLINE search with the time frame specified up to March 2020 , seven clinical studies involving GSH use for lightening the skin were recognized and assessed for significance and validity. Results: Four controlled clinical trials (GSH capsules: 60 healthy volunteers; 250 mg oral GSH capsules:60; 2% glutathione lotion: 30s healthy volunteers; GSH as wash:74 healthy volunteers) and a case series(GSH lozenges: 30 patients) showed a significant reduction in melanin index. A case series (GSH soap: 15 patients) revealed a skin-lightening effect based on photography. Only one placebo-controlled study on IV GSH (1200 mg) in 60 healthy volunteers demonstrated a poor effect of glutathione as a whitening agent. Conclusion: The literature search revealed that glutathione is not useful enough as a skin-whitening agent, as it is only effective on some parts of the skin and did not present any long-lasting effect. Although the safety profile of topical and oral glutathione seemed to be good, long-term research studies employing better study design are required in order to evaluate the efficacy of this antioxidant.

Discovery and identification of potential anti-melanogenic active constituents of Bletilla striata by zebrafish model and molecular docking

BackgroundBletilla striata is the main medicine of many skin whitening classic formulas in traditional Chinese medicine (TCM) and is widely used in cosmetic industry recently. However, its active ingredients are still unclear and its fibrous roots are not used effectively. The aim of the present study is to discover and identify its potential anti-melanogenic active constituents by zebrafish model and molecular docking.MethodsThe antioxidant activities were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2′-azino-bis-(3-ethylbenthiazoline-6-sulphonic acid) (ABTS) radical scavenging activity and ferric reducing antioxidant power (FRAP) assay. The anti-melanogenic activity was assessed by tyrosinase inhibitory activity in vitro and melanin inhibitory in zebrafish. The chemical profiles were performed by ultra-high-performance liquid chromatography combined with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS). Meanwhile, the potential anti-melanogenic active constituents were temporary identified by molecular docking.ResultsThe 95% ethanol extract of B. striata fibrous roots (EFB) possessed the strongest DPPH, ABTS, FRAP and tyrosinase inhibitory activities, with IC50 5.94 mg/L, 11.69 mg/L, 6.92 mmol FeSO4/g, and 58.92 mg/L, respectively. In addition, EFB and 95% ethanol extract of B. striata tuber (ETB) significantly reduced the melanin synthesis of zebrafish embryos in a dose-dependent manner. 39 chemical compositions, including 24 stilbenoids were tentatively identified from EFB and ETB. Molecular docking indicated that there were 83 (including 60 stilbenoids) and 85 (including 70 stilbenoids) compounds exhibited stronger binding affinities toward tyrosinase and adenylate cyclase.ConclusionThe present findings supported the rationale for the use of EFB and ETB as natural skin-whitening agents in pharmaceutical and cosmetic industries.

The Misuse of Clobetasol Propionate 0.05% Based Products as Skin Lightening Agents Among Sudanese Women

The Misuse of Clobetasol Propionate 0.05% Based Products as Skin Lightening Agents Among Sudanese Women

Preparation of low molecular weight Enteromorpha prolifera polysaccharide and its antioxidant and tyrosinase inhibitory activities

Enteromorpha prolifera polysaccharide (EP) is a water-soluble sulfated polysaccharide with many types of biological activities. In this study, the crude polysaccharide was extracted from Enteromorpha prolifera and degraded by different physical, chemical, and biological methods. The results showed that the enzymatic degradation products displayed the best tyrosinase inhibitory activity. The optimal enzymatic degradation conditions were as follows: 30 °C, pH 5.5, 750 U/mL enzyme dosage for 2 h. The enzymatic hydrolysates were then divided into six EP fractions (EPFs) by an ultrafiltration membrane. The in vitro tyrosinase inhibitory activity of these fractions showed that the smaller the molecular weight of EPF, the better the inhibitory effect on tyrosinase. The antioxidant and tyrosinase inhibitory effect of the most effective EPF, a molecular weight below 5 kDa, (EPF5), was further confirmed on B16 cells. A kinetic study of tyrosinase inhibitory activity revealed that EPF5 is a competitive-uncompetitive mixed-type inhibitor of tyrosinase. These findings suggested that EPF5 has significant potential as a skin-whitening agent in cosmetics as well as an antibrowning agent in the food and agriculture industries.

Tremella fuciformis Inhibits Melanogenesis in B16F10 Cells and Promotes Migration of Human Fibroblasts and Keratinocytes.

Natural skin whiteners have been investigated for centuries. The development of preparations that safely achieve whitening of hyper-pigmented skin lesions is a challenge for the cosmetics industry. Furthermore, promoting rapid wound healing and minimizing inflammation in injured skin are key to prevent from abnormal pigmentation in scar tissue. Natural products, including the fungus Tremella fuciformis (TF), are attracting attention as potential sources of lead compounds for these applications. We investigated the in vitro effects of TF on melanogenesis in murine B16F10 cells. Melanin and tyrosinase levels were measured after treatment with TF. Wound healing in human keratinocytes (HaCaT) and fibroblasts (Detroit 551) was also determined via cell migration assay prior to TF exposure. TF significantly decreased melanin content and tyrosinase expression in a concentration-dependent manner in B16F10 cells. Furthermore, TF promoted wound healing in human HaCaT keratinocytes and Detroit 551 fibroblasts. TF proved effectively on inhibiting melanogenesis and promoting wound healing in vitro, demonstrating its potential as a novel skin-whitening agent. However, further clinical studies of safety and efficacy are required.

Determination of hydroquinone and benzoquinone in pharmaceutical formulations: critical considerations on quantitative analysis of easily oxidized compounds.

Hydroquinone is a skin-lightening agent used as an active ingredient in topical dermatological formulations prescribed for treating cutaneous diseases caused by hyperpigmentation. Despite being widely used, some toxicological aspects have been associated with these products, mainly due to overdosage and long-term use combined with the easy oxidation of hydroquinone. In this work, an investigative study has been done to gather enough data for selecting a quantitative analytical method for quality control purposes that considers the ease of oxidation not only within the product but also during the experimental procedures. After studying the influence of pH, reversibility, sampling, and standard solution preparation on the redox reaction between hydroquinone and benzoquinone by using spectroscopic, electrophoretic, and electroanalytical measurements, a reliable, fast, and selective chronoamperometric method was achieved. The optimized method was used for the analysis of samples, previously diluted in Britton-Robinson (BR) buffer (pH 5.5) and methanol (1 : 9, v/v), by applying a potential fixed at 0.4 V. A glassy-carbon working electrode, lab-made Ag/AgCl(sat) and platinum wire as a reference electrode and auxiliary electrodes, respectively, and BR buffer (pH 5.5) as supporting electrolyte were the additional experimental conditions used. Analytical performance parameters were verified to confirm the applicability of the new method (LOD 4.22 μmol L-1 and LOQ 14.1 μmol L-1; recovery mean value of 100% with 0.22% RSD). A gel topical formulation containing 4% (w/w) hydroquinone was analyzed through the developed method for determination of dosage and oxidation traces, and a content of 3.53 ± 0.095% (w/w) was found with no indications of degradation.

Skin-lightening practices in India

Skin lightening involves various practices to bleach the skin or to reduce the normal skin tone. The practice of skin-lightening spans several continents throughout the centuries and cultures primarily aimed at improving the quality of life. The main aim of skin lightening in medieval times was to increase the sign of femininity and thereby its benefits. In India, skin lightening is preferred as a mark of class, caste, and richness. Dermatologists are faced with many problems dealing with requests to make skin fairer, while in the west, there is a problem dealing with skin conditions in skin of color. Many skin-lightening agents are sold as over-the-counter products and are popularized or advertised through magazines, social media, and celebrity influences. These products are self-prescribed and used rampantly despite the side effects. There is a strong equation between caste, social class, marital prospects, and occupational status based on skin color. Multinational skin-lightening cosmetic brands have a lucrative market. The most widely used topical agent in skin lightening is hydroquinone, while other non-hydroquinone agents are also frequently used. In general, combining skin-lightening agents have increased efficacy. Systemic agents such as glutathione, tranexamic acid, Vitamin C, and other miscellaneous agents are also popular. Several procedures ranging from chemical peels to lights and lasers are increasingly practiced for more effective skin lightening. In India, all skin-whitening creams can be bought without a prescription as OTC products. These products are not considered pharmaceutical products and are not subject to testing and regulations. In addition, the injudicious use of intravenous glutathione by unqualified personnel poses a threat to the lay public. In our role as dermatologists, we should develop a holistic approach in counseling and treating those patients on a quest for skin lightening.

Skin lightening: causes and complications.

Skin bleaching, also known as skin lightening, is the deliberate lightening of an individual's skin tone without medical supervision. The causes are complex, multifactorial and often intertwined, although the unifying themes centre around a belief that lighter skin denotes an individual of higher status, socioeconomic background or physical beauty, than their darker-skinned counterpart. Skin lightening is achieved using agents that block the production of melanin and often contain drugs such as hydroquinone, superpotent topical steroids or mercury. These drugs can cause serious local and systemic complication. Skin-lightening compounds are illegal in most countries throughout the world; however the industry is worth billions of dollars annually, and the agents can be easily obtained by individuals seeking to lighten their skin. Dermatologists are in a unique position to identify those at risk of using skin-bleaching agents, manage complications and give advice on the physiological variation in pigmentation and how to avoid using skin-lightening agents to treat dermatological conditions. To manage the belief that lighter skin is better, societal level change is required to ensure that people of all skin tones are represented in the media.

Childhood effects of prenatal and postnatal exposure to mercurial skin lightening agents. Literature Review

Children's exposure to mercurial skin lightening agents at any time during their development, from intra-uterine to early developmental life, can lead to severe detrimental health effects. This is because these skin lightening agents contain inorganic mercury as their active ingredient at varying concentrations that exceed acceptable levels. Mercury does not confer any physiological benefit to the human body, and as such, it has only been linked to numerous adverse effects on users and may pose a possible health risk for children born to, living with, and in contact with skin bleaching agent users. Although studies have shown that inorganic mercury exposure may be detrimental to children, there is a paucity of data, to the best of our knowledge, on reviews exploring specifically the possible routes of exposure to and effects of mercurial skin lightening agents on children. Since prevention is the only key to reducing mercury poisoning and toxicity, this study aims to extensively review the literature on prenatal and postnatal exposure to mercury in children from cosmetic skin lightening agents and discuss possible detrimental effects.

The Inhibitory Effect of Curcumin Derivative J147 on Melanogenesis and Melanosome Transport by Facilitating ERK-Mediated MITF Degradation.

The therapeutic use of curcumin and chemically modified curcumin (CMC) for suppressing melanogenesis and tyrosinase activity have been recognized. J147 is a modified version of curcumin with superior bioavailability and stability. However, there is no report about the effects of J147 on pigmentation in vitro and in vivo. In our studies, we investigated the hypopigmentary effects of J147 treatment on melanocytes and explored the underlying mechanism. The present studies suggested that J147 suppressed both basal and α-MSH-induced melanogenesis, as well as decreased melanocyte dendricity extension and melanosome transport. J147 played these roles mainly by activating the extracellular signal-regulated protein kinase (ERK) pathway. Once activated, it resulted in MITF degradation and further down-regulated the expression of tyrosinase, TRP-1, TRP-2, Myosin Va, Rab27a and Cdc42, ultimately inhibited melanin synthesis and melanosome transport. Furthermore, the hypopigmentary effects of J147 were demonstrated in vivo in a zebrafish model and UVB-induced hyperpigmentation model in brown guinea pigs. Our findings also suggested that J147 exhibited no cytotoxicity in vitro and in vivo. Taken together, these data confirmed that J147 may prove quite useful as a safer natural skin-whitening agent.

Characterization of Phenethyl Cinnamamide Compounds from Hemp Seed and Determination of Their Melanogenesis Inhibitory Activity.

Hyperpigmentation is induced by the overactivation of tyrosinase, which is a rate-limiting enzyme in melanogenesis. The defatted extract of hemp (Cannabis sativa L.) seed is known to have inhibitory effects on melanogenesis; however, effective compounds in the extract have not been identified yet. In this study, three phenethyl cinnamamides present in hemp seed extract were prepared by purification and chemical synthesis and were assessed for their inhibitory effect on melanogenesis in B16F10 melanoma cells. A comparison of the anti-melanogenesis and anti-tyrosinase activity of hemp seed solvent fractions revealed that the ethyl acetate fraction possessed the greatest potential for suppressing melanogenesis in melanoma cells by decreasing tyrosinase activity. We tentatively identified 26 compounds in the ethyl acetate fraction by comparing spectroscopic data with the literature. Three phenethyl cinnamamides such as N-trans-caffeoyltyramine, N-trans-coumaroyltyramine, and N-trans-feruloyltyramine present abundantly in the ethyl acetate fraction were prepared and their anti-melanogenesis and anti-tyrosinase activities in melanoma cells were evaluated. We found that N-trans-caffeoyltyramine and N-trans-feruloyltyramine inhibited alpha melanocyte stimulating hormone (α-MSH)-induced melanogenesis without cytotoxicity, while N-trans-coumaroyltyramine inhibited melanogenesis with cytotoxicity. IC50 values of N-trans-caffeoyltyramine, N-trans-feruloyltyramine, and N-trans-coumaroyltyramine for inhibition of α-MSH-mediated tyrosinase activation were 0.8, 20.2, and 6.3 μM, respectively. Overall, N-trans-caffeoyltyramine possessed the strongest anti-melanogenesis activity among the three phenethyl cinnamamides evaluated. The inhibitory effect of N-trans-caffeoyltyramine was verified by determining the melanin content and tyrosinase activity in melanoma after treating the cells with synthetic compounds. Thus, N-trans-caffeoyltyramine isolated from hemp seed extract could be useful in cosmetics as a skin-whitening agent.

Camellia japonica Essential Oil Inhibits α-MSH-Induced Melanin Production and Tyrosinase Activity in B16F10 Melanoma Cells.

Essential oils are aromatic oils extracted from the leaves, stems, peels, petals, and roots of aromatic plants grown in nature or grown in organic methods and have various medical effects as natural substances. The essential oil extracted from Camellia japonica seeds exhibits various functional properties; however, its tyrosinase inhibitory activity has not been investigated extensively. This study is performed to investigate the chemical composition and tyrosinase inhibitory activity of Camellia japonica seed essential oil (CJS-EO). Hexamethylcyclotrisiloxane (42.36%) and octamethylcyclotetrasiloxane (23.28%) are the two primary components of CJS-EO, as identified via gas chromatography-mass spectrometry. The inhibitory activities of CJS-EO and positive control arbutin are further evaluated against mushroom tyrosinase. The results show that CJS-EO and arbutin inhibit tyrosinase activity. Moreover, CJS-EO significantly inhibits melanogenesis in the α-melanocyte-stimulating hormone-treated group, and a significant amount of melanin is suppressed. To ascertain the cause of the CJS-EO tyrosinase inhibitory effect and melanin reduction effect, genetic and protein analyses are performed. Based on our results, we tentatively conclude that CJS-EO can inhibit melanocytes from harmful factors such as tyrosinase-related protein. These results demonstrate that CJS-EO possesses potent antityrosinase activity and may be a good skin-whitening agent.

Evaluating the Efficacy of Lotion Containing Black Rice Bran (Oryza sativa L. indica) Extract as Skin Brightening Agent: A Clinical Trial

Background: Ultraviolet exposure is an extrinsic factor to initiate melanogenesis, the process of melanin formation in the skin. Nowadays, natural ingredients tend to be more prevalent in cosmetic formulations due to consumers’ concern about synthetic ingredients and the risks they may represent for human health. Rice bran, the outer layer of a rice grain, can be utilized as a skin-lightening agent. Objectives: This study aimed to determine the efficacy of a lotion containing black rice bran (Oryza sativa L. indica) ethanolic extract as a skin lightening agent. Methods: The black rice bran ethanolic extract was formulated into oil in water (o/w) lotion. In this study, 34 women applied the lotion at one side of the forearm and base placebo lotion as control at the other side of forearm. The results were tested with a paired t-test by GraphPad Prism 8.3.0 software. Results: There was a significant decrease in the melanin index and erythema index in the forearm with a lotion containing black rice bran extract (P-value < 0.0001). Conclusions: The lotion containing 10% black rice bran extract was effective as a skin lightener because it effectively reduced skin melanin production when applied topically.

Salicylic acid in ginseng root alleviates skin hyperpigmentation disorders by inhibiting melanogenesis and melanosome transport

Abnormal melanogenesis and melanosome transport can cause skin pigmentation disorders that are often treated using ginseng-based formulation. We previously found that phenolic acid compounds in ginseng root could inhibit melanin production and as a skin-whitening agents. However, mechanisms of action underlying effects of ginseng phenolic acid monomers on melanogenesis remain unclear. This study was conducted to investigate effects of salicylic acid, a main ginseng root phenolic acid component, on melanogenesis and melanosome functions in melanocytes of zebrafish and other species. Salicylic acid exhibited no cytotoxicity and reduced melanin levels and tyrosinase activity in B16F10 murine melanoma cells and normal human epidermal melanocytes regardless of prior cell stimulation with α-melanocyte stimulating hormone. Additionally, salicylic acid treatment reduced expression of melanogenic enzymes tyrosinase, tyrosinase-related protein 1 and tyrosinase-related protein 2, while reducing expression of their master transcriptional regulator, microphthalmia-associated transcription factor. Moreover, reduced phosphorylation of cAMP response-element binding protein was observed due to reduced cAMP levels resulting from salicylic acid inhibition of upstream signal regulators (adenylyl cyclase and protein kinase A). Furthermore, salicylic acid treatment suppressed expression of transport complex-associated proteins melanophilin and myosin Va in two UVB-treated melanocytic cell lines, suppressed phagocytosis of fluorescent microspheres by UVB-stimulated human keratinocytes (HaCaT), inhibited protease-activated receptor 2 activation by reducing both Ca2+ release and activation of phosphoinositide 3 kinase/AKT and mitogen-activated protein kinases and induced anti-melanogenic effects in zebrafish. Collectively, these results indicate that salicylic acid within ginseng root can inhibit melanocyte melanogenesis and melanin transport, while also suppressing keratinocyte phagocytic function.

A Comparative Study on Photo-Protective and Anti-Melanogenic Properties of Different Kadsura coccinea Extracts.

Kadsura coccinea (KC), a beneficial plant for human health, has been used for centuries in China, Thailand, and Korea in folk medicine and food. There is evidence supporting the biological effects of highly bioactive ingredients in KC such as lignans, triterpenoids, flavonoids, phenolic acids, steroids, and amino acids. In this study, we aimed to explore the effects, functions, and mechanisms of the extracts from KC root (KCR), stem (KCS), leaf (KCL), and fruit (KCF) in UVA and UVB-irradiated keratinocytes and α-melanocyte stimulating hormone (α-MSH)-stimulated melanocytes. First, the total polyphenol and flavonoid contents of KCR, KCS, KCL, and KCF and their radical scavenging activities were investigated. These parameters were found to be in the following order: KCL > KCR > KCS > KCF. UVA and UVB-irradiated keratinocytes were treated with KCR, KCS, KCL, and KCF, and keratinocyte viability, LDH release, intracellular ROS production, and apoptosis were examined. Our results demonstrated that KC extracts improved keratinocyte viability and reduced LDH release, intracellular ROS production, and apoptosis in the presence UVA and UVB irradiation. The overall photoprotective activity of the KC extracts was confirmed in the following order: KCL > KCR > KCS > KCF. Moreover, KC extracts significantly decreased the intracellular melanin content and tyrosinase activity in α-MSH-stimulated melanocytes. Mechanistically, KC extracts reduced the protein and mRNA expression levels of tyrosinase, tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2) in α-MSH-stimulated melanocytes. In addition, these extracts markedly downregulated myophthalmosis-related transcription factor expression and cAMP-related binding protein phosphorylation, which is upstream of the regulation of Tyrosinase, TRP-1, and TRP-2. The overall anti-melanogenic activity of the KC extracts was established in the following order. KCL > KCR > KCS > KCF. Overall, the KC extracts exert photoprotective and anti-melanogenic effects, providing a basis for developing potential skin-whitening and photoprotective agents.

Evaluation of Anti-Melanogenesis Activity of Enriched Pueraria lobata Stem Extracts and Characterization of Its Phytochemical Components Using HPLC-PDA-ESI-MS/MS.

The root of Pueraria lobata (Willd.) is a widely used herbal medicine worldwide, whereas the stem of the plant is discarded or used as feed for livestock. To reuse and exploit the stem of P. lobata as a resource, we investigated its potential as a skin-whitening agent. We found that the developed, enriched P. lobata stem (PLS) extract significantly inhibited melanin production in the 3-isobutyl-1-methylxanthine-induced B16/F10 cells at a concentration of 50 μg/mL. To further confirm the mechanism of the antimelanogenic effect of the enriched PLS extracts, we examined the mRNA expression of tyrosinase, which was suppressed by the extracts. To standardize and implement effective quality control of the enriched PLS extracts, its major chemical constituents were identified by high-performance liquid chromatography–photodiode array–electrospray ionization–mass spectrometry. In total, 12 constituents were identified. In silico analysis showed that the main constituents, puerarin and daidzin, had excellent binding affinities for human tyrosinase. Collectively, our results suggest that the PLS extracts could be used as anti-pigmentation agents.

The anti-melanogenic effects of 3-O-ethyl ascorbic acid via Nrf2-mediated α-MSH inhibition in UVA-irradiated keratinocytes and autophagy induction in melanocytes

3-O-ethyl ascorbic acid (EAA) is an ether-derivative of ascorbic acid, known to inhibit tyrosinase activity, and is widely used in skincare formulations. Nevertheless, the molecular mechanisms underlying the EAA's effects are poorly understood. Here, the anti-melanogenic activity of EAA was demonstrated through Nrf2-mediated α-MSH inhibition in UVA-irradiated keratinocytes (HaCaT) and autophagy induction and inhibition of α-MSH-stimulated melanogenesis in melanocytes (B16F10). EAA pretreatment increased the HaCaT cell viability but suppressed ROS-mediated p53/POMC/α-MSH pathways in UVA-irradiated cells. Further, the conditioned medium from EAA-pretreated and UVA-irradiated HaCaT cells suppressed the MITF-CREB-tyrosinase pathways leading to the inhibition of melanin synthesis in B16F10 cells. EAA treatment increased nuclear Nrf2 translocation via the p38, PKC, and ROS pathways leading to HO-1, γ-GCLC, and NQO-1 antioxidant expression in HaCaT cells. However, Nrf2 silencing reduced the EAA-mediated anti-melanogenic activity, evidenced by impaired antioxidant gene expression and uncontrolled ROS (H202) generation following UVA irradiation. In B16F10 cells, EAA-induced autophagy was shown by enhanced LC3-II levels, AVO formation, Beclin-1 upregulation, and activation of p62/SQSTM1. Further, EAA-induced anti-melanogenic activity was substantially decreased in autophagy inhibitor (3-MA) pretreated or LC3 knockdown B16F10 cells. Notably, transmission electron microscopy data showed increased melanosome-engulfing autophagosomes in EAA-treated B16F10 cells. Moreover, EAA also down-regulated MC1R, TRP-1/-2, tyrosinase expressions, and melanin synthesis by suppressing the cAMP-CREB-mediated MITF expression in B16F10 cells stimulated with α-MSH. In vivo studies on the zebrafish model further confirmed that EAA inhibited tyrosinase expression/activity and endogenous pigmentation. In conclusion, 3-O-ethyl ascorbic acid is an effective skin-whitening agent and could be used as a topical agent for cosmetic purposes.

Differential diagnosis and management of hyperpigmentation.

There is an increasing recognition of ethnic dermatology to reflect the increase in skin of colour (SOC) populations in the UK. Hyperpigmentary disorder is one of the commonest skin concerns in SOC but there has been limited training available in this field of dermatology. Variations in skin colour are genetically determined by the amount of melanin content, the eumelanin/pheomelanin ratio and the size of melanosomes, but is also influenced by other factors such as hormones and extrinsic factors such as ultraviolet radiation. Hyperpigmentation is a broad term to describe increased pigmentation in the skin, and making a correct diagnosis is an important first step in the successful management of hyperpigmentary disorders. A systematic approach based on the disease pathogenesis (e.g. reactive vs. nonreactive, increased melanin vs. increased number of cells or epidermal vs. dermal pigmentation) aided by a detailed history and clinical examination is the best way to diagnose a hyperpigmentary disorder. Based on its pathogenesis, management can be planned. For epidermal hyperpigmentation caused by increased melanin, topical skin-lightening agents targeting inhibition of tyrosinase or melanosome transfer and promotion of keratinocyte turnover can be used. Hydroquinone-containing cream is the gold-standard treatment for epidermal hyperpigmentation. Alternative treatments include laser toning or chemical peels. However, increased dermal pigmentation is more challenging to target with topical treatments. If hyperpigmentation is due to increased numbers of melanocytes or keratinocytes, high-fluence laser is the most appropriate treatment method.

The in vitro and in vivo depigmenting activity of pterostilbene through induction of autophagy in melanocytes and inhibition of UVA-irradiated α-MSH in keratinocytes via Nrf2-mediated antioxidant pathways

Pterostilbene (Pt) is a natural polyphenol found in blueberries and several grape varieties. Pt's pharmacological importance was well documented. Nevertheless, the depigmenting effects are not demonstrated. We evaluated the Pt's depigmenting effects through autophagy induction in B16F10 cells and inhibition of UVA (3 J/cm2)-irradiated α-MSH in keratinocyte HaCaT cells via Nrf2-mediated antioxidant pathways. Pt (2.5–5μM) attenuated ROS production and downregulated the POMC/α-MSH pathway in HaCaT cells. The conditioned medium-derived from UVA-irradiated HaCaT pretreated with Pt suppressed melanogenesis in B16F10 through MITF-CREB-tyrosinase pathway downregulation. Interestingly, Pt-induced HaCaT autophagy was revealed by enhanced LC3-II accumulation, p62/SQSTM1 activation, and AVO formation. Pt significantly decreased melanosome gp100 but increased LC3-II levels in HaCaT cells exposed to B16F10-derived melanin. Pt activated and facilitated the Nrf2 antioxidant pathway in HaCaT cells leading to increased HO-1, γ-GCLC, and NQO-1 antioxidant protein expression. ERK, AMPK, and ROS pathways mediate the Nrf2 activation. However, Nrf2 knockdown suppressed Pt's antioxidant ability leading to uncontrolled ROS and α-MSH levels after UVA-irradiation suggested the essentiality of the Nrf2 pathway. Moreover, in α-MSH-stimulated B16F10 cells, Pt (10–30 μM) downregulated the MC1R, MITF, tyrosinase, TRP-1/-2, and melanin expression. Further, Pt showed potent anti-melanogenic effects through autophagy induction mechanism in B16F10 cells, verified by increased LC3-II/p62 levels, AVO formation, and Beclin-1/Bcl-2 ratio, decreased ATG4B levels and PI3K/AKT/mTOR pathway. Transmission electron microscopy provided direct evidence by showing autophagosomes engulfing melanosomes following Pt treatment in α-MSH-stimulated B16F10 cells. Moreover, Pt-induced anti-melanogenic activity through the downregulation of CREB-MITF pathway-mediated TRP-1/-2, tyrosinase expressions, melanosome formation, and melanin synthesis was substantially reversed due to 3-MA (autophagy inhibitor) pretreatment or LC3 silencing in B16F10 cells. In vivo results also confirmed that Pt-inhibited tyrosinase expression/activity and endogenous pigmentation in the zebrafish model. Therefore, pterostilbene is a potent skin-whitening and antioxidant agent and could be used in skin-whitening formulations as a topical applicant.

Citral-Containing Essential Oils as Potential Tyrosinase Inhibitors: A Bio-Guided Fractionation Approach.

Excessive melanin production causes serious dermatological conditions as well as minor aesthetic problems (i.e., freckles and solar lentigo). The downregulation of tyrosinase is a widespread approach for the treatment of such disorders, and plant extracts have often proven to be valuable sources of tyrosinase inhibitors. Citral (a mixture of neral and geranial) is an important fragrance ingredient that has shown anti-tyrosinase potential. It is highly concentrated in the essential oils (EOs) of Cymbopogon schoenanthus (L.) Spreng., Litsea cubeba (Lour.) Pers., Melissa officinalis L., and Verbena officinalis L. However, only L. cubeba EO has been investigated for use as a potential skin-whitening agent. This work evaluates the in vitro tyrosinase inhibitory activity of these EOs and studies, using bio-assay oriented fractionation, whether their differing chemical compositions influence the overall EO inhibitory activities via possible synergistic, additive, and/or competitive interactions between EOs components. The inhibitory activity of C. schoenanthus EO and that of M. officinalis EOs, with negligible (+)-citronellal amounts, were in-line with their citral content. On the other hand, L. cubeba and V. officinalis EOs inhibited tyrosinase to considerably greater extents as they contained β-myrcene, which contributed to the overall EO activities. Similar observations were made for M. officinalis EO, which bears high (+)-citronellal content which increased citral activity.