Hypopigmenting Effect Research Articles

Natural products with skin - Whitening effects

UV radiation is widely considered as a major cause of skin pigmentation. Upon exposure to UV radiation, the melanocytes increase the production of intracellular nitric oxide, which triggers signal transduction cascades to initiate melanogenesis by tyrosinase. UV radiation also influences melanogenesis through a paracrine regulation process involving the keratinocytes. Although a number of hypopigmenting products have been developed, those from natural sources are preferred and will predominate in the cosmetics market. More active compounds such as phenols, flavonoids, coumarins and other derivatives have been identified from natural sources. This article summarized natural skin whitening products involving tyrosinase blockers like phenols and polyphenols, and non-tyrosinase blockers like α-MSH, melanosome transferase and cytokine inhibitors. In addition, the skin-whitening effects and the mechanisms of these natural products were also reviewed. Most of the compounds achieve the hypopigmenting effect by inhibiting tyrosinase; however, some interesting compounds blocking the upstream regulation points of melanogenesis are extraordinarily promising for developing novel whitening agents.

Hypopigmenting Effects of Brown Algae-Derived Phytochemicals: A Review on Molecular Mechanisms.

There is a rapid increase in the demand for natural hypopigmenting agents from marine sources for cosmeceutical and pharmaceutical applications. Currently, marine macroalgae are considered as a safe and effective source of diverse bioactive compounds. Many research groups are exploring marine macroalgae to discover and characterize novel compounds for cosmeceutical, nutraceutical, and pharmaceutical applications. Many types of bioactive secondary metabolites from marine algae, including phlorotannins, sulfated polysaccharides, carotenoids, and meroterpenoids, have already been documented for their potential applications in the pharmaceutical industry. Among these metabolites, phlorotannins from brown algae have been widely screened for their pharmaceutical and hypopigmenting effects. Unfortunately, the majority of these articles did not have detailed investigations on molecular targets, which is critical to fulfilling the criteria for their cosmeceutical and pharmaceutical use. Very recently, a few meroterpenoids have been discovered from Sargassum sp., with the examination of their anti-melanogenic properties and mechanisms. Despite the scarcity of in vivo and clinical investigations of molecular mechanistic events of marine algae-derived hypopigmenting agents, identifying the therapeutic targets and their validation in humans has been a major challenge for future studies. In this review, we focused on available data representing molecular mechanisms underlying hypopigmenting properties of potential marine brown alga-derived compounds.

Erratum to: Hypo-pigmenting effect of sesquiterpenes from Inula britannica in B16 melanoma cells

Erratum to: Hypo-pigmenting effect of sesquiterpenes from Inula britannica in B16 melanoma cells

IL-17 and TNF Synergistically Modulate Cytokine Expression while Suppressing Melanogenesis: Potential Relevance to Psoriasis

Inflammation-associated pigmentation changes are extremely common, but the etiology behind this clinical observation remains elusive. Particularly, it is unclear how the myriad of cytokines known to be involved in inflammatory skin processes affect epidermal melanocytes. We sought to determine how IL-17 and TNF influence normal human melanocytes, as these two cytokines have been implicated in various skin diseases. IL-17 and TNF jointly stimulated broad inductions of cytokines , including melanoma mitogens CXCL1 and IL-8. Moreover, IL-17 and TNF synergistically inhibited pigmentation-related signaling and melanin production, and induced keratinocytes production of β-defensin 3, an antagonist for melanocortin-receptor 1. When analyzing psoriasis lesions that are known to over express IL-17 and TNF, we observed an increase in melanocyte number and a simultaneous decrease in pigmentation signaling. Furthermore, therapeutic neutralization of TNF and IL-17 with mAbs results in a rapid recovery of pigment gene expression in psoriasis lesions. These results demonstrate that IL-17 and TNF can impact both the growth and pigment production of melanocytes, which may contribute to the pigmentation changes associated with psoriasis. These findings may allow the development of novel therapeutics for pigmentary disorders and bring new insights into the immune milieu surrounding melanocytes and related neoplasms.

PP2A and DUSP6 are involved in sphingosylphosphorylcholine-induced hypopigmentation

Activation of extracellular signal-related kinase (ERK) is involved in decreased melanogenesis by sphingosylphosphorylcholine (SPC). In the present study, we confirmed that SPC activated ERK and that a specific inhibitor of the ERK pathway (PD98059) recovered SPC-induced hypopigmentation. Moreover, we found that SPC significantly reduces protein phosphatase 2A (PP2A) activity in Mel-Ab cells, and that PP2A activator treatment abrogated SPC-induced hypopigmentation. We determined that α-melanocyte-stimulating hormone (α-MSH) increased the expression of dual-specificity phosphatase 6 (DUSP6), an ERK phosphatase, in a time-dependent manner. In contrast, SPC decreased the level of DUSP6 in Mel-Ab cells. Furthermore, inhibiting DUSP6 increased ERK activation and subsequently augmented the SPC-induced hypopigmenting effects. Taken together, our data suggest that SPC-induced phosphatase inhibition is also responsible for the hypopigmentary effects.

Comparison of the antimelanogenic effects of p-coumaric acid and its methyl ester and their skin permeabilities

p-Coumaric acid (PCA) inhibits human tyrosinase (TYR) activity and melanin synthesis in human epidermal melanocytes. The purpose of the current study was to examine the potential of PCA and its hydrophobic derivative, methyl p-coumarate (MPC), as hypopigmenting agents for topical use. PCA and MPC were comparatively tested against in vitro human TYR enzyme activity and cellular melanin synthesis in human epidermal melanocytes. Permeation studies were undertaken using an artificial lipophilic membrane and an excised porcine skin. In vivo hypopigmenting efficacy was assessed on the skin of melanin-possessing hairless mice exposed to UVB. Although PCA was a stronger inhibitor than MPC against TYR activity in vitro, the former inhibited cellular melanin synthesis less effectively than the latter. A non-cell based permeability assay indicated that PCA was practically impermeable through the lipophilic barrier while MPC was highly permeable. In contrast, an ex vivo skin permeation study demonstrated that topically applied PCA in the form of a cream can diffuse into the aqueous medium underneath the skin. No MPC was released from a MPC cream but PCA was released instead as a bio-converted product. Topical application of PCA cream attenuated the UVB-induced erythema formation and pigmentation in mice models, more effectively compared with MPC cream. PCA may be useful as an active ingredient for topical applications for a hypopigmenting effect. MPC has potential as a hypopigmenting agent but requires rather invasive methods for its delivery to the target cells.

Inhibition of melanogenesis by the extract from Agaricus blazei without affecting iNOS gene expression

Tyrosinase is a key enzyme in melanin synthesis. Owing to enlargement of availability of edible types of mushrooms in food medicines, we investigated effects of Agaricus blazei (ABE) on tyrosinase activity using l-tyrosine and l-3, 4-dihydroxyphenylalanine (l-DOPA) as the substrate in normal human epidermal melanocytes (NHEM). ABE inhibited tyrosinase activity similar to arbutin and Vitamin C as two whitening agents in a dose dependent manner. In agreement with this, treatment of the cells with ABE (3–100 μg/ml) reduced melanin content up to 57% of the control in NHEM. In addition, production of nitric oxide (NO) which has the ability of inducing tyrosinase activity in melanocytes was also suppressed by ABE treatment. Furthermore, ABE inhibited NO production in lipopolysaccharides (LPS)-stimulated RAW264.7 macrophages, in a dose dependent manner but without affecting iNOS mRNA expression indicated by reverse transcription-PCR (RT-PCR) technique. These findings suggest that ABE inhibits melanin production via partial inhibition of tyrosinase activity and NO production. This hypopigmenting effect of water soluble Agaricus blazei extract could be useful for the treatment of some skin disorders.

Efficacy and safety of liposome‐encapsulated 4‐n‐butylresorcinol 0.1% cream for the treatment of melasma: A randomized controlled split‐face trial

Melasma is an acquired pigmentary disorder that most commonly occurs in women of child-bearing age. Melasma is therapeutically challenging, and most commercially available hypopigmenting agents include tyrosinase inhibitors, which regulate the rate-limiting step of melanogenesis. 4-n-Butylresorcinol has received considerable attention as a novel hypopigmenting agent in the last 15 years because it has an inhibitory effect against tyrosinase and tyrosinase-related protein-1. However, the hypopigmenting effect of 4-n-butylresorcinol in human subjects has only been shown in a few studies. Liposome encapsulation is known to improve stabilization and enhance penetration of the product. Therefore, this study was conducted to evaluate the hypopigmenting efficacy and safety of liposome-encapsulated 4-n-butylresorcinol 0.1% cream in patients with melasma. This was a randomized, double-blind, vehicle-controlled and split-face comparison study. Twenty-three patients with a clinical diagnosis of melasma were included. 4-n-Butylresorcinol 0.1% cream or vehicle was applied to each side of the face twice daily for 8 weeks. Clinical and photographic evaluations, Mexameter measurements and assessment of patient satisfaction and side-effects were performed at baseline, 4 and 8 weeks. All subjects completed the study. Mexameter measurements demonstrated that the melanin index of the 4-n-butylresorcinol-treated side showed a significant decrease when compared with the vehicle-treated side after 8 weeks (P = 0.043). No adverse reactions were observed throughout the study. Subjectively, 4-n-butylresorcinol was considered to be efficacious in more than 60% of the patients after 8 weeks of treatment. In conclusion, liposome-encapsulated 4-n-butylresorcinol 0.1% cream was well tolerated and showed significant higher efficacy than vehicle alone for the treatment of melasma.

Sphingosylphosphorylcholine inhibits melanin synthesis via pertussis toxin-sensitive MITF degradation

Sphingolipids act as structural components in cell membranes, and form lipid intermediates that have functional roles as signalling molecules in various cellular processes. Our previous findings have suggested that sphingolipid metabolites are deeply involved in the regulation of melanogenic processes. In this study we aimed to examine sphingosylphosphorylcholine-mediated signalling pathways related to melanogenesis. We determined the hypopigmenting effects and the related signalling pathways of sphingosylphosphorylcholine in Mel-Ab cells. In particular, we analysed the involvement of the G-protein-coupled receptor in sphingosylphosphorylcholine-induced MITF degradation. Western blotting revealed that sphingosylphosphorylcholine induced the activation of extracellular signal-regulated kinase (ERK), as well as Akt. Moreover, the specific Akt pathway inhibitor LY294002 blocked the hypopigmenting effect of sphingosylphosphorylcholine and abrogated the sphingosylphosphorylcholine-mediated down-regulation of microphthalmia-associated transcription factor (MITF), showing that the Akt pathway is involved in sphingosylphosphorylcholine-mediated melanin inhibition. Treatment with the proteasome inhibitor MG132 blocked the decrease in MITF by sphingosylphosphorylcholine, but sphingosylphosphorylcholine did not decrease the level of MITF mRNA, indicating that the reduction in the level of MITF results from MITF degradation. Furthermore, pre-incubation of Mel-Ab cells with pertussis toxin completely abolished the hypopigmenting effects and the activation of ERK and Akt by sphingosylphosphorylcholine, suggesting that the effects of sphingosylphosphorylcholine are mainly dependent on the G-protein-coupled receptor). Together, these results suggest that sphingosylphosphorylcholine reduces melanin synthesis via pertussis toxin-sensitive ERK and Akt activation, and subsequent MITF degradation.

Effects of vitamin C vs. multivitamin on melanogenesis: comparative study in vitro and in vivo

Vitamin C has been used for the treatment of hyperpigmented diseases. However, there is no study available on hypopigmenting effect of multivitamin. To investigate the inhibitory effects of multivitamin and vitamin C on melanogenesis. We assessed the effect of multivitamin and vitamin C on cell viability, melanogenesis, and mushroom tyrosinase. The antioxidant activity of multivitamin and vitamin C was measured. We performed the Western blot analysis to study the effect of multivitamin and vitamin C on the expression of tyrosinase, microphthalmia-associated transcription factor (MITF), extracellular signal-regulated kinase (ERK), and Akt/protein kinase B. In a clinical trial, 20 melasma patients were treated with split face iontophoresis using either multivitamin or vitamin C. We evaluated the hypopigmenting effects of multivitamin and vitamin C through colorimetric measurement. Both vitamin C and multivitamin inhibited melanogenesis with low cytotoxicity. Multivitamin reduced melanin contents greater than vitamin C. However, the effects of vitamin C are greater than those of multivitamin on mushroom tyrosinase inhibition and antioxidation. In the Western blot, the reduced tyrosinase expression and MITF level were observed only in multivitamin-treated group, and not in vitamin C-treated group. No changes of ERK and Akt activation were observed in both multivitamin and vitamin C-treated groups. After 12 weeks of treatment with iontophoresis, both multivitamin and vitamin C were effective for melasma. Multivitamin has shown more anti-melanogenic effect than vitamin C via the downregulation of MITF.

The Efficacy and Safety of 4-n-butylresorcinol 0.1% Cream for the Treatment of Melasma: A Randomized Controlled Split-face Trial

Melasma is a common acquired symmetrical hypermelanosis that occurs on sun-exposed areas, and it is frequently observed among women. Various treatment modalities have been tried, but none are completely satisfactory. 4-n-butylresorcinol, which is a resorcinol derivative that has an inhibitory effect on both tyrosinase and tyrosinase-related protein-1, was introduced in 1995 and it has received increasing attention as a new hypopigmenting agent. However, the hypopigmenting effect of 4-n-butylresorcinol in human subjects has only been shown in a few studies. The aim of this study was to investigate the hypopigmenting efficacy and safety of 4-n-butylresorcinol 0.1% cream for the treatment of melasma. Twenty patients with melasma were enrolled to this randomized, double-blind, vehicle-controlled, split-face comparative study. The patients were instructed to apply 4-n-butylresorcinol 0.1% cream or vehicle to each side of the face twice daily for 8 weeks. Mexameter measurements were performed along with photography at baseline, 4 weeks and 8 weeks. Adverse events were observed and recorded throughout the study. All the patients completed the study. Mexameter measurements demonstrated that the melanin index of the treated side showed a significant decrease when compared with that of the vehicle-treated side after 4 weeks (p=0.006) and after 8 weeks (p<0.0005). All the adverse reactions were mild and transient. 4-n-butylresorcinol 0.1% cream showed rapid efficacy and it was well tolerated when used for the treatment of melasma.

Combination of Amino Acids Reduces Pigmentation in B16F0 Melanoma Cells

Amino acids, the building blocks of proteins, play significant roles in numerous physiological events in mammals. As the effects of amino acids on melanogenesis have yet to be demonstrated, the present study was conducted to identify whether amino acids, in particular alanine, glycine, isoleucine and leucine, influence melanogenesis in B16F0 melanoma cells. Glycine and L-isoleucine, but not D-isoleucine, reduced melanogenesis in a concentration-dependent manner without any morphological changes in B16F0 melanoma cells. L-Alanine and L-leucine, but not D-alanine and D-leucine, also reduced melanogenesis without any morphological changes in B16F0 melanoma cells. However these amino acids did not show a concentration-dependency. Combination of L-alanine and the other amino acids, particularly 4 amino acids combination, had an additive effect on the inhibition of melanogenesis compared with single treatment of L-alanine. None of the amino acids affected the activity of tyrosinase, a key enzyme in melanogenesis. These results suggest that L-alanine, glycine, L-isoleucine and L-leucine, but not the D-form amino acids, have a hypopigmenting effect in B16F0 melanoma cells, and that these effects are not due to the inhibition of tyrosinase activity. Combination of these 4 amino acids had the additive effect on hypopigmentation that was as similar as that of kojic acid.

Glycine Inhibits Melanogenesis in Vitro and Causes Hypopigmentation in Vivo

The simplest amino acid, glycine, is important in protein composition and plays a significant role in numerous physiological events in mammals. Despite the inhibitory effect of glycine on spontaneous melanogenesis in B16F0 melanoma cells, the details of the underlying mechanisms remain unknown. The present study was conducted to investigate the further effects and the mechanisms of inhibitory effect of glycine on melanogenesis using B16F0 melanoma cells and hair follicle melanogenesis in C57BL/6J mice. Treatment with glycine (1-16 mM) for 72 h inhibited alpha-melanocyte stimulating hormone (alpha-MSH)-induced melanogenesis in a concentration-dependent manner without any effects on cell proliferation in B16F0 melanoma cells. Treatment with kojic acid (2.5 mM) for 72 h also inhibited alpha-MSH-induced melanogenesis in B16F0 melanoma cells. The highest dose of glycine inhibited the alpha-MSH-induced increment of tyrosinase protein levels in B16F0 melanoma cells. In hair follicle melanogenesis in C57BL/6J mice, treatment with glycine (1250 or 2500 mg/kg, i.p.) for 5 d prevented the decrement of L* and C* values and inhibited the increment of tyrosinase protein levels and melanin content within the skin. Treatment with hydroquinone (100 mg/kg, i.p.) for 5 d had a similar hypopigmenting effect to that of high dose glycine. These results suggest that glycine has an inhibitory effect on melanogenesis that is mediated by down-regulation of tyrosinase protein levels, leading to a hypopigmenting effect in C57BL/6J mice.

Transforming growth factor-$beta;1 decreases melanin synthesis via delayed extracellular signal-regulated kinase activation

Transforming growth factor-β1 (TGF-β1) plays a pivotal role in cell proliferation, differentiation, and apoptosis. In this study, we investigated the effects of TGF-β1 on melanogenesis using a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Our results show that TGF-β1 significantly inhibits melanin synthesis in a concentration-dependent manner and that it reduces the activity of tyrosinase, the rate-limiting melanogenic enzyme. We also found that TGF-β1 reduces microphthalmia-associated transcription factor (MITF) promoter activity and decreased MITF, tyrosinase, tyrosinase-related protein-1 (TRP-1), and TRP-2 protein production. In addition, TGF-β1 was found to induce a delay in the activation of extracellular signal-regulated kinase (ERK) at 6 h, whereas many growth factors activate ERK transiently in minutes. Moreover, the specific ERK pathway inhibitor, PD98059 blocked the hypopigmenting effects induced by TGF-β1. PD98059 was also found to abrogate the TGF-β1-mediated down-regulation of MITF, tyrosinase, TRP-1, and TRP-2 production. These results suggest that the ERK pathway may be involved in the melanogenic signaling cascade, and that delayed ERK activation by TGF-β1 contributes to reduced melanin synthesis via MITF down-regulation.

The mechanism of hypopigmenting effect by sphingosine-1-phosphate.

The mechanism of hypopigmenting effect by sphingosine-1-phosphate.

(−)-Epigallocatechin-3-gallate and hinokitiol reduce melanin synthesisvia decreased MITF production

In this study, the effects of (-)-epigallocatechin-3-gallate (EGCG) and/or hinokitiol (beta-thujaplicin) on melanogenesis were investigated. Our results showed that both EGCG and hinokitiol significantly inhibited melanin synthesis in a concentration-dependent manner, and that their hypopigmenting effects were stronger than that of kojic acid, which is known to inhibit melanin formation in melanocytes and melanoma cells. Interestingly, EGCG did not show any additive hypopigmenting effect in combination with kojic acid, though EGCG did show a synergistic effect in combination with hinokitiol. Several reports indicate that the activation of extracellular signal-regulated kinase (ERK) induces microphthalmia-associated transcription factor (MITF) degradation. Accordingly, the effects of EGCG and hinokitiol on the ERK signaling pathway were examined. EGCG and hinokitiol induced neither ERK activation nor MITF degradation. On the other hand, both EGCG and hinokitiol reduced the protein levels of MITF and of tyrosinase, the rate limiting melanogenic enzyme, whereas kojic acid had no effect. In addition, hinokitiol strongly downregulated the activity of tyrosinase, whereas EGCG or kojic acid had only a little effect. These results show that both EGCG and hinokitiol reduce MITF production, and suggest that reduced tyrosinase activity by hinokitiol explains their synergistic effect on melanogenesis.

Transforming growth factor-β1 decreases melanin synthesis via delayed extracellular signal-regulated kinase activation

Transforming growth factor-β1 (TGF-β1) plays a pivotal role in cell proliferation, differentiation, and apoptosis. In this study, we investigated the effects of TGF-β1 on melanogenesis using a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Our results show that TGF-β1 significantly inhibits melanin synthesis in a concentration-dependent manner and that it reduces the activity of tyrosinase, the rate-limiting melanogenic enzyme. We also found that TGF-β1 reduces microphthalmia-associated transcription factor (MITF) promoter activity and decreased MITF, tyrosinase, tyrosinase-related protein-1 (TRP-1), and TRP-2 protein production. In addition, TGF-β1 was found to induce a delay in the activation of extracellular signal-regulated kinase (ERK) at 6 h, whereas many growth factors activate ERK transiently in minutes. Moreover, the specific ERK pathway inhibitor, PD98059 blocked the hypopigmenting effects induced by TGF-β1. PD98059 was also found to abrogate the TGF-β1-mediated down-regulation of MITF, tyrosinase, TRP-1, and TRP-2 production. These results suggest that the ERK pathway may be involved in the melanogenic signaling cascade, and that delayed ERK activation by TGF-β1 contributes to reduced melanin synthesis via MITF down-regulation.

Assessment of Topical Hypopigmenting Agents on Solar Lentigines of Asian Women

Background: So-called darkened age spots encompass distinct pathological processes. The efficacy of topical depigmenting agents is difficult to objectivate. Objective: To assess the hypopigmenting effect of three cosmetic formulations using objective biometrological methods. Methods: 50 women of South-East Asian ancestry were enrolled in this pilot study. They had solar lentigines according to dermoscopic criteria. The lesions were treated by topical hypopigmenting formulations. Products were applied twice daily for 2 or 3 months. Assessments at 1-month intervals were made using narrow-band reflectance spectrophotometry, image analysis of video-recorded ultraviolet light reflection and photodensitometry- and image-analysis-assisted corneomelametry. Results: A 20% azelaic acid formulation and another one containing 5% ascorbyl glucosamine, 1% kojic acid and α-hydroxyacid esters appeared inefficacious on solar lentigines. A stabilized soy extract showed a better although modest lightening effect when assessed by corneomelametry. The subclinical or faint mottled skin revealed by ultraviolet light examination better responded (p < 0.05) to treatments. Conclusion: Focal epidermal hyperpigmentation is better controlled by topical whitening agents when the increase in melanin content reflects a modest functional hyperactivity of melanocytes.

Transforming growth factor β1 mediates hypopigmentation of B16 mouse melanoma cells by inhibition of melanin formation and melanosome maturation

Transforming growth factor-β1 (TGFβ1) downregulates tyrosinase in B16 melanoma cells by decreasing gene expression and the intracellular half-life of the enzyme, but does not block tyrosinase stimulation by α-melanocyte stimulating hormone (αMSH). In the presence of both agents, the enzymatic activity is intermediate between the one of cells treated with either agent alone. Here we show that TGFβ1 equally inhibits the melanogenic activities of melan-a melanocytes and B16 melanoma cells, thus validating the B16 model. In both cell types, TGFβ1 (10 −10 M, 48 h) inhibited to comparable levels tyrosine hydroxylation and melanin formation from L-tyrosine. Thus, the inhibitory effect is exerted mainly at the rate limiting step of the pathway. By means of quantitative image analysis techniques, we also studied the effects of TGFβ1 and αMSH on melanosome number, volume density and maturation degree. αMSH (10 −7 M, 48 h) increased 7-fold melanosome volume density, whereas TGFβ1 by itself had no significant effect. However, melanosomal volume density was intermediate in cells treated with both agents, as compared to control or αMSH-treated cells. Moreover, TGFβ1 blocked the αMSH-elicited increase in the number of melanosomes. Control and αMSH-treated melanocytes contained more stage I+II premelanosomes and stage IV, fully melanized organelles than partially melanized stage III melanosomes. TGFβ1 increased the percentage of stage III melanosomes. This trend was even more marked in cells treated with αMSH and TGFβ1. The accumulation of incompletely melanized melanosomes is consistent with the inhibition of melanin formation activity by TGFβ1 and with its hypopigmenting effect.