Decrease In Melanin Content Research Articles

Effect of fluoroquinolones on melanogenesis in normal human melanocytes HEMn-DP: a comparative in vitro study

Purpose: Fluoroquinolones are one of the most commonly prescribed classes of antibiotics. However, their use is often connected with high risk of phototoxic reactions that lead to various skin or eye disorders. The aim of this study was to examine the effect of ciprofloxacin, lomefloxacin, moxifloxacin and fluoroquinolone derivatives with different phototoxic potential, on the viability and melanogenesis in melanocytes.Materials and methods: Normal human epidermal melanocytes, dark pigmented (HEMn-DP) were used as an in vitro model system. The effect of the tested antibiotics on cell viability and melanization in pigmented cells was investigated using a spectrophotometric method. The WST-1 assay was used to detect the cytotoxic effect of antibiotics.Results: Ciprofloxacin, lomefloxacin and moxifloxacin induced the concentration-dependent loss in melanocytes viability. The values of EC50 for the tested fluoroquinolone derivatives were found to be 2.0 mM for ciprofloxacin, 0.51 mM for lomefloxacin and 0.27 mM for moxifloxacin. The exposure of cells to different concentrations of the analyzed drugs resulted in decrease in melanin content and tyrosinase activity. The highest decrease was observed for lomefloxacin which may explain its high phototoxic potential in vivo. The role of melanin in the mechanism of the toxicity of fluoroquinolones was discussed and the obtained results were compared with the previously obtained data concerning light-pigmented melanocytes (HEMa-LP).Conclusions: The results obtained in vitro suggest that the phototoxic potential of fluoroquinolones in vivo depends on specific drug–melanin interaction, the ability of drugs to affect melanogenesis as well as on the degree of melanocytes pigmentation.

Efficacy and possible mechanisms of topical tranexamic acid in melasma.

Tranexamic acid (TA) has been suggested as an effective treatment for melasma. To investigate the effects and mechanism of action of topical TA in the treatment of melasma. In this study, 23 participants with melasma applied a 2% TA formulation to the whole face for 12 weeks. Clinical effects were evaluated using the modified Melasma Area and Severity Index (mMASI) and a chromameter. Skin biopsies were obtained from 10 participants to evaluate pigmentation, vascularity and the expression levels of possible paracrine factors contributing to the effect of TA. Most of the participants had mild melasma, with mMASI of < 5. The mMASI scores significantly improved in 22 of 23 participants after application. The L* values were increased and the a* values were decreased in both lesional and perilesional normal skin. Fontana-Masson staining showed a significant decrease in melanin content in the epidermis. The number of CD31-positive vessels and the expression of the vascular endothelial growth factor both tended to decrease. Endothelin (ET)-1 was found to be downregulated with TA. Topical TA is effective for melasma. This immunohistochemical study found that suppression of ET-1 could be one of the mechanisms of action of TA on melasma.

Ultrastructural changes in the melanocytes of aging human choroid

Retinal pigment epithelial cells as well as choroidal melanocytes (CM) possess melanin granules. The former show clear, age-related changes (formation of lipofuscin granules with a concomitant decrease in melanin content); however, data on changes in the CM with aging are fairly limited. We examined CM in human macular and mid-peripheral areas by light- and transmission electron microscopy in 50–94 year-old donor eyes (N=12). Unlike in the choroid of lower ages, the melanocytes from aging choroid (>75 years) showed partial fusion of about 8–15 melanosomes, forming rosettes-like structures. Besides, there was evidence of emptiness in cytoplasm caused by the loss of melanosomes in aged CM, as was confirmed by quantification in macular part of choroid. In advanced aged eyes (85–94-year-old), the CM possessed many lipid droplets as well as irregular lipofuscin granules, the latter had a tendency to fuse with melanosomes, as happens in aged retinal pigment epithelium. Macrophages in their cytoplasm contained abundant irregular as well as clumped melanosomes of variable size, suggesting that damaged granules/melanocytes are cleared by these phagocytes. These obvious changes in the CM are likely to make the choroid prone to damage by visible light.

짚신나물(Agrimonia pilosa) 추출물의 생리활성

In this study, we investigated the applicability of functional materials by examining various physiological activities with an extract from the Agrimonia pilosa root. The A. pilosa extract showed low cytotoxicity against murine melanoma B16F10 cells. With little or no cytotoxicity at various concentrations, the A. pilosa extract showed high levels of DPPH radical scavenging activity (ID50, 20.70 mg/L) and anti-microbial activity against Bacillus subtilis, Escherichia coli, and Candida albicans. In particular, it had a high level of anti-microbial activities against Gram-positive bacteria. These results suggest that the A. pilosa extract can be used as a natural preservative. It also showed inhibition of tyrosinase activity (ID50, 90.18 mg/L), as does kojic acid (ID50, 89.13 mg/L), and especially, a higher decrease in melanin content (ID50, 62.5 mg/L) than the arbutin level (ID50, 100.7 mg/L) as a positive control. These findings suggest that the A. pilosa extract inhibits melanin synthesis by suppressing the intracellular tyrosinase expression. These results indicate that the A. pilosa extract may be an effective material for functional cosmetics, such as skin whitening materials.

Evaluation of 70% glycolic peels versus 15% trichloroacetic peels for the treatment of photodamaged facial skin in aging women.

Chronic solar irradiation results in both morphological and functional changes in affected skin. Superficial peels have been shown to improve all symptoms of photodamaged skin. This study was designed to compare the efficacy and tolerability of glycolic acid (GA, 70%) with trichloroacetic acid (TCA, 15%) for the treatment of photoaging. Twenty female patients affected by photodamage were treated with graded concentrations of 70% GA and 15% TCA peel. Each patient was submitted to 5 sessions of these peels, with an interval of 14 days between each session. Four clinical parameters of surface evaluation of the living skin (hydration, elasticity, melanin, and erythema) were measured. The records were made before each treatment and 3 months after the last application. The statistical significance in each group of patients was observed with elasticity and hydration. Decrease in melanin content in the skin occurred significantly after the application of a series of treatments with GA. Increase in severity of erythema showed statistical significance after the treatment with TCA. Superficial peels, such as 70% GA and 15% TCA, proved to be an effective treatment modality for photodamaged facial skin. Both acids contribute to improvement of the photodamaged skin's parameters. Glycolic acid increases skin's hydration faster.

Activation of MITF by Argan Oil Leads to the Inhibition of the Tyrosinase and Dopachrome Tautomerase Expressions in B16 Murine Melanoma Cells

Argan (Argania spinosa L.) oil has been used for centuries in Morocco as cosmetic oil to maintain a fair complexion and to cure skin pimples and chicken pox pustules scars. Although it is popular, the scientific basis for its effect on the skin has not yet been established. Here, the melanogenesis regulatory effect of argan oil was evaluated using B16 murine melanoma cells. Results of melanin assay using B16 cells treated with different concentrations of argan oil showed a dose-dependent decrease in melanin content. Western blot results showed that the expression levels of tyrosinase (TYR), tyrosinase-related protein 1 (TRP1), and dopachrome tautomerase (DCT) proteins were decreased. In addition, there was an increase in the activation of MITF and ERK1/2. Real-time PCR results revealed a downregulation of Tyr, Trp1, Dct, and Mitf mRNA expressions. Argan oil treatment causes MITF phosphorylation which subsequently inhibited the transcription of melanogenic enzymes, TYR and DCT. The inhibitory effect of argan oil on melanin biosynthesis may be attributed to tocopherols as well as the synergistic effect of its components. The results of this study provide the scientific basis for the traditionally established benefits of argan oil and present its therapeutic potential against hyperpigmentation disorders.

Inhibitory effects of autolysate of Leuconostoc mesenteroides isolated from kimoto on melanogenesis

We investigated the inhibitory effects of the autolysate of Leuconostoc mesenteroides, a lactic acid bacterium isolated from sake mash, on melanogenesis in B16F0 murine melanoma cells and a human skin model. The autolysate: induced a decrease in melanin content in B16F0 murine melanoma cells and a 17%, 36%, 41% and 58% decrease in the human skin model by the application of 0.125, 1.25, 6.25, and 12.5mg/tissue in total; decreased tyrosinase activity to 71%, 46% and 29% of control in B16F0 cells with 0.1, 0.2 and 0.4mg/ml-medium respectively, but did not inhibit tyrosinase activity under cell-free conditions; decreased amount of tyrosinase in a dose-dependent manner from 74% with 0.1mg/ml to 33% with 0.4mg/ml; and decreased amount of tyrosinase mRNA to 80-90% with 0.2-0.4mg/ml-medium. As the decrease in tyrosinase mRNA levels could not fully account for the reduction in protein, we suggest that the autolysate had post-transcriptional effects rather than transcription inhibition. Our results indicate that the autolysate of L.mesenteroides has potential therapeutic use as an effective anti-melanogenic agent.

A skin lightening, sun protector and antioxidant agent: origa'light®

Today's, there is an amazing increase in the demand for skin lightening products. We have developed a new natural extract inhibiting melanin production: an oregano leaf extract, Origa'light®. This extract has a significant and dose-dependent lightening activity. It shows a strong inhibition of melanogenesis by a decrease of melanin content (-13%) and tyrosinase activity (-14%) in B16 murine melanocytes*. Moreover, with a SPF of 7.14 and a proved photostability, it has interesting photoprotective properties. It has also strong antioxidant activities against DPPH and superoxide anion radicals (IC50=16.0µg/mL and 7.4µg/mL). Thus, Origa'light® is an excellent cosmetics multi-active ingredient: skin lightening, sun protector and antioxidant.

Melanogenesis inhibitory effect of dehydroevodiamine isolated from fruits of Evodia rutaecarpa

Dehydroevodiamine, an alkaloid, was isolated from the fruit of Evodia rutaecarpa and melanin production, and tyrosinase inhibition in B16F10 melanoma cells treated with the isolated dehydroevodiamine was investigated. The compound decreased melanin synthesis significantly without promoting cytotoxicity. The IC50 value of dehydro- evodiamine for melanogenesis and cell viability were 59.8 µM and 90.0 µM, respectively. The L-dopa oxidase activity of mushroom tyrosinase was reduced after dehydroevodiamine treatment by about 22.4% at a concentration of 33.2 µM. However, there was no effect on cellular tyrosinase activity. These results indicate that the observed decrease in melanin content after treatment with dehydroevodiamine was attributed to the direct inhibition of tyrosinase activity, rather than the suppression of tyrosinase gene expression. Dehydroevodiamine may be a promising new agent for use in cosmeceutical application.

Dermoscopy of White Fibrous Papulosis of the Neck

W HITE FIBROUS PAPULOSIS OF THE NECK (WFPN), which was first described by Shimizu et al in 1985, clinically presents as asymptomatic white papules, measuring 2 to 3 mm in diameter, on the neck of elderly persons. The lesions are round to oval, clearly marginated, and unrelated to hair follicles. The lesions shown in Figures 1, 2, 3, and 4 were located on the neck of a 58-year-old Japanese man (Figures 1 and 2) and a 68-year old Japanese man (Figures 3 and 4). Dermoscopy of both lesions revealed clearly circumscribed, homogeneous, white areas, including dotted or short, thin vessels, without follicular involvement. Peripheral pigmentation can be seen but fails to form a pigment network (Figures 1 and 2). The diagnosis of WFPN was confirmed histopathologically in both cases (Figure 5 and Figure 6 [hematoxylin-eosin, original magnification 100]). The histopathologic characteristics of WFPN include relatively well-circumscribed areas consisting of thickened collagen bundles in the papillary to middle dermis, without vascular proliferation, and a decrease of melanin content in the epidermis. These histopathologic features are consistent with the white, nodular, dermoscopic appearance. The differential diagnosis includes dermatofibroma, which is less well circumscribed and has a peripheral delicate pigment network. Furthermore, dermatofibromas have been noted to be erythematous (31.5%) and include dotted vessels (30.6%). Ten patterns of dermatofibroma have been described, but none matches our cases of WFPN. The differential diagnosis of WFPN may also include sebaceous hyperplasia and molluscum contagiosum, which are both distinguishable because of the presence of crown vessels. The dermoscopic features of WFPN may be unique and include homogeneous, white, wellcircumscribed lesions punctuated with dotted or short, thin vessels.

Eating thyself toward the dark side?

Eating thyself toward the dark side?

Delta-Tocotrienol Causes Decrease of Melanin Content in Mouse Melanoma Cells

We examined the effect of δ-tocotrienol on melanin content in mouse melanoma B16 cells. Melanin content was significantly reduced in cells treated with 50 and 100 μM δ-tocotrienol, but not 10 μM δ-tocotrienol. The activity and amount of tyrosinase also significantly decreased in cells treated with 10, 50, and 100 μM δ-tocotrienol. Furthermore, the mRNA level of tyrosinase as measured using realtime PCR was significantly decreased compared to controls in cells treated with 100 μM δ-tocotrienol, but not 10 or 50 μM δ-tocotrienol. These results indicated that at first δ-tocotrienol caused tyrosinase degradation, and then caused a further decrease in the tyrosinase protein level via both tyrosinase degradation and a decrease in the mRNA level of tyrosinase. We conclude that the decrease of melanin content in the cells by δ-tocotrienol was the result of the decrease of the protein level of tyrosinase (tyrosinase degradation is more important than the decrease of mRNA).

Childhood malnutrition is associated with a reduction in the total melanin content of scalp hair

Childhood malnutrition is known to be associated with visible lightening of hair colour (hypochromotrichia). Nevertheless, no systematic investigations have been carried out to determine the biochemical basis of this change. We used an HPLC method to measure melanins in the scalp hair of thirteen Jamaican children, diagnosed as having primary malnutrition, during various stages of their treatment and after recovery. During treatment for malnutrition, a progressive decrease in total melanin content along the hair shaft from tip to root (root:tip ratio: 0.62 (sd 0.31)) was observed. This ratio was significantly different (P = 0.003) from the ratio observed among children sampled several months after discharge from hospital (0.93 (sd 0.23)) and among normal control children (0.97 (sd 0.12)). Thus, it appears that a decrease in melanin content is associated with periods of malnutrition. The low root:tip ratio during malnutrition presumably arises because the tips reflect prior hair growth during 'normal' nutrition and the roots reflect hair growth during malnutrition; a return of the root:tip ratio to that seen among controls reflects 'recovery' from malnutrition. It is possible that reduced intake or availability of tyrosine, a key substrate in melanin synthesis, may play a role in the reduction of hair melanin content during periods of malnutrition. The precise mechanisms by which melanin content is reduced, and the role of aromatic amino acid availability in hair colour change and other features of childhood malnutrition remain to be explored.

RALGA (Diacnéal®) Decreases Melanin Content in a Human Skin Model

Background: Retinaldehyde and glycolic acid RALGA (Diacnéal^®) are both effective in the topical treatment of acne. A decrease in the postinflammatory pigmentation has been observed after application of Diacnéal during 3 months. Aim: To verify the effect of this association on pigmentation using an original model of surviving human skin. Methods: Human skin explants were maintained alive in organ culture for 14 days. Diacnéal^® was applied every day. Pigmentation of skin, depending on the transfer of melanosomes from melanocytes to keratinocytes, was visualized histologically by Fontana-Masson staining. The number of melanocytes was determined after the DOPA reaction. Results: A decrease in melanin content was shown after application of Diacnéal. The number of melanocytes was not modified. Conclusion: These results suggest that RALGA (Diacnéal^®) may be of interest to prevent the postinflammatory pigmentation of acne.

Down-regulation of Melanogenesis by Phospholipase D2 through Ubiquitin Proteasome-mediated Degradation of Tyrosinase

The involvement of phospholipase D (PLD) in the regulation of melanogenesis was examined. Treatment of B16 mouse melanoma cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) resulted in the activation of PLD and a decrease in melanin content. 1-Butanol, but not 2-butanol, completely blocked the TPA-induced inhibition of melanogenesis, suggesting the involvement of PLD in this event. Reverse transcription-PCR and immunoblot analyses revealed the existence of both PLD isozymes, PLD1 and PLD2, in B16 cells. When PLD1 or PLD2 was introduced into those cells by an adenoviral gene-transfer technique, both PLD1 and PLD2 were activated by TPA. When PLD1 and PLD2 were overexpressed, PLD2 potently caused a decrease in melanin content, whereas the effect of PLD1 expression on melanin content was minimal. Over-expression of PLD2 itself did not affect protein kinase C activity, as assessed by the intracellular distribution and levels of expression of each isoform expressed in B16 cells. The effects of TPA on the down-regulation of basal or alpha-melanocyte-stimulating hormone-enhanced melanogenesis were almost completely blocked by expressing a lipase activity-negative mutant, LN-PLD2, but not by LN-PLD1. Further, the PLD2-induced decrease in melanin content was accompanied by a decrease in the amount and activity of tyrosinase, a key enzyme in melanogenesis, whereas the mRNA level of tyrosinase was unchanged by the over-expression of PLD2. Moreover, treatment with proteasome inhibitors completely blocked the PLD2-induced down-regulation of melanogenesis. Taken together, the present results indicate that the TPA-induced down-regulation of melanogenesis is mediated by PLD2 but not by PLD1 through the ubiquitin proteasome-mediated degradation of tyrosinase. This suggests that PLD2 may play an important role in regulating pigmentation in vivo.

Regulation of Melanogenesis through Phosphatidylinositol 3-Kinase-Akt Pathway in Human G361 Melanoma Cells

The involvement of the phosphatidylinositol 3-kinase pathway in the regulation of melanogenesis was examined using human G361 melanoma cells. In the cells treated with wortmannin, a potent inhibitor of phosphatidylinositol 3-kinase, the melanin content increased concomitant with the elevated protein level of tyrosinase, a key enzyme in melanogenesis. Northern blot analysis revealed that the mRNA level of tyrosinase increased transiently on treatment of the cells with the phosphatidylinositol 3-kinase inhibitor. When the cells were infected with the adenovirus vector encoding the mutant adapter subunit of phosphatidylinositol 3-kinase, which acts as a dominant negative of phosphatidylinositol 3-kinase, both the melanin content and the expression of tyrosinase increased. In cells infected with the adenovirus vector encoding the constitutively active mutant of the lipid kinase, a decrease in melanin content as well as reduced expression of tyrosinase was observed. In cells expressing the constitutively active mutant of the serine-threonine protein kinase Akt, one of the downstream targets of phosphatidylinositol 3-kinase, the melanin content decreased as in the cells overproducing the constitutively active mutant of phosphatidylinositol 3-kinase. These results indicate that phosphatidylinositol 3-kinase regulates melanogenesis by modulating the expression of tyrosinase, and that activation of Akt is sufficient for suppression of melanin production in G361 melanoma cells.

An Experimental Study on Depigmenting Activity of 4‐(p‐Hydroxyphenyl)‐2‐Butanone in C57 Black Mice

An Experimental Study on Depigmenting Activity of 4‐(p‐Hydroxyphenyl)‐2‐Butanone in C57 Black Mice: Depigmenting Activity of HPB in Black Mice: Yoshiharu Fukuda, et al. Department of Public Health, Kumamoto University School of Medicine—The authors previously reported three cases of occupational leukoderma in workers engaged in a 4‐(p‐hydroxyphenyl)‐2‐butanone (HPB, Raspberry Ketone) manufacturing process. These cases suggested that HPB might be a chemical causing the leukoderma and it had depigmenting activity. The purpose of this study is to evaluate the depigmenting activity of HPB by using laboratory animals. HPB, its two crude products and monomethyl ether of hydroquinone as the positive control were topically applied to the dorsal surface of C57 black mice. Depigmentation was shown in black mice to which HPB and its crude products were topically applied but the effect produced by these chemicals was weaker than that seen with monomethyl ether of hydroquinone. Though evidence of a reduction in melanocytes and pigmentation was not documented in the microscopic analysis, spectrophotometric assay showed a decrease in melanin content in the hair of mice to which HPB and the crude product had been applied. The results indicated a depigmenting activity of HPB and supported the conclusion that the leukoderma which we reported in a companion paper was induced by exposure to HPB and/or its crude products. Nevertheless, the potential of this depigmenting activity is so weak that the development of leukoderma due to these chemicals may be limited to those who are occupationally exposed.

Sub-lethal effects of exposing the human melanoma cell line SKmel-23 to 532 nm laser light.

The human melanoma cell line SKmel-23 has been used to investigate the sub-lethal damage that can occur as a result of exposing melanin containing cells to light (532 nm) from a frequency doubled Q-switched (Nd:YAG) laser. A dose response curve was obtained, which indicates that at energy levels of 0.6 J/cm2 and below no effect on either the viability or growth rate of the cell line was observed. Above this, cells rapidly died and at an energy level of 2.0 J/cm2, only approximately 15% of cells survived. This contrasts with the effects on the G361 melanoma line, which contains far less melanosomes, as an LD50 for this cell line was approximately 5.5 J/cm2. Exposing SKmel-23 cells to 0.4 J/cm2 of 532 nm light results in a diminution of the number of melanosomes within cells as well as a marked decrease in melanin content, as determined by spectrophotometric assay and electron microscopy. Using the reverse transcriptase polymerase chain reaction technique, the reduction in melanin content of the cells was accompanied by a selective decrease in mRNA coding for tyrosinase, the first enzyme in the biosynthetic pathway for melanin. No decrease in the mRNA coding for the GAPDH protein was observed. Our finding has implications for understanding the control processes that regulate the melanin content of cells and suggests that the model described can be used to further investigate changes that may occur in cells as a result of their exposure to sub-lethal levels of laser light.

Effect of ethylenebis (dithiocarbamic acid)disodium salt(nabam)and ethylenebis(dithiocarbamato)manganese(maneb) on Xenopus laevis development.

AbstractThe fungicides ethylenebis [dithiocarbamic acid] (nabam) and ethylenebis [dithiocarbamato] manganese (maneb) were dissolved in a modified Holtfreter's solution at concentrations of 0.1–5 ppm. Thirty to 60 yolk‐plug Xenopus laevis embryos were placed for 1–10 days in 200 ml of different concentrations of the fungicide solution. Treated and control (Holtfreter's only) embryos were fixed in Bouin's fluid or formalin for light microscopy, and in glutaraldehyde‐formaldehyde for electron microscopy. Gross morphological and histological observations were made. The first changes observed in experimental embryos was a slight growth retardation and a transient absence or reduction in melanogenesis in the eye and on the rest of the body. The tail was shortened and the notochord had a distinct waviness. Animals in higher concentrations were unable to swim as well as controls. Histological examination, both light and electron microscopic, showed a general decrease in melanin content of the melanosomes in the pigmented retina. The notochord was increased in diameter; in sagittal sections the foldings were obvious. These results indicate that minute doses of these commonly used fungicides are harmful to the normal development of amphibian embryos.