Reduction In Melanin Research Articles

The G-protein alpha subunit AaGA1 positively regulates vegetative growth, appressorium-like formation, and pathogenicity in Alternaria alternata.

The Gα subunit is a major component of heterotrimeric G proteins, which play a crucial role in the development and pathogenicity of several model fungi. However, its detailed function in the causal agent of pear black spot (Alternaria alternata) is unclear. Our aim was to understand the characteristics and functions of AaGA1 in A. alternata. AaGA1 was cloned from A. alternata in this study, which encodes 353 amino acids and has a "G-alpha" domain. Mutant ΔAaGA1 resulted in reduced vegetative growth, conidiation, and spore germination. Especially, mutant ΔAaGA1 produced only fewer conidia on the V8A medium, and spore formation-related genes AbaA, BrlA, and WetA were significantly downregulated. More tolerance against cell wall-inhibiting agents was observed after the deletion of AaGA1. Moreover, AaGA1 deletion led to a significant reduction in melanin and toxin production. Interestingly, deletion of AaGA1 resulted in defective appressorium-like formations, complete loss of the ability to penetrate cellophane, and decreased infection on non-wound inoculated tobacco leaves. Cell wall-degrading enzyme-related genes PME, CL, Cut2, and LC were significantly downregulated in mutant ΔAaGA1 mutant, significantly reducing virulence on wound-inoculated pear fruits. The G protein alpha subunit AaGA1 is indispensable for fungal development, appressorium-like formations, and pathogenicity in A. alternata.

The pigmentation interference of bisphenol F and bisphenol A

Bisphenol A (BPA) and bisphenol F (BPF) are widely distributed in the environment and daily consumptions, leading to exposure toward human and environmental animals. The potential risk of bisphenol analogs on pigment and skin health is not well documented. In this study, we found that 0.05 mg/L BPF (tolerated daily intake (TDI) value of BPA) affected the particle size and color density of zebrafish melanin. While BPA caused less depigmentation effect toward zebrafish with effective concentration of 5.0 mg/L. The downregulation of melanin synthases induced by BPF is associated with the reduction in melanin. Molecular dynamics indicated that both BPF and BPA could act as ligands of zebrafish and human Tyr family proteins; however, these compounds have completely different energetics and spatial steric effects, potentially explaining their varying depigmentation effects. Additionally, an in vitro assay using A375 melanoma cells demonstrated that the inhibitory effect of BPF on human melanin production was primarily attributed to Tyr inhibition. These findings provide an important basis for understanding the molecular mechanisms of BPF and BPA in melanin inhibition, and the results reflect the skin pigmentation interference risk of these compounds, which are ubiquitous in everyday personal products.

702 Malassezin: A proof of concept study documenting the efficacy of a novel microbiome-based ingredient for facial hyperpigmentation

Malassezin is a natural indole compound produced by the fungus Malassezia furfur which causes Tinea Versicolor characterized by patches of hypo and/or hyperpigmentation. Our preliminary in-vitro and ex-vivo experiments documented the ability of Malassezin to decrease skin pigmentation. The objective of this randomized, double blind, controlled study was to investigate the skin lightening effects of novel formulations of Malassezin for facial hyperpigmentation. This 22-week study enrolled subjects with melasma(n=8) and dyschromia(n=12) caused by photodamage. Subjects had mild, moderate, or severe hyperpigmentation. They were randomized to 1 of 4 groups including vehicle, 0.1%, 0.5%, and 1.0%. Subjects were evaluated at baseline, 2, 4, 8, 14, 18 and 22 weeks. Twenty subjects were enrolled and 16 completed the study. As early as 2 weeks, colorimetry assessments (Mexameter MX18) showed improvement. The 1.0% formulation group showed a significant percent reduction in the melanin index compared to vehicle for involved skin (2.93% vs 0.27% respectively). At 14 weeks, clinical assessments and photography using the Visia-CR (Canfield Scientific) showed that there was a decrease in facial hyperpigmentation in 69% of subjects. The lightening effects were sustained during the 8-week regression period from week 14 to week 22. Histopathological assessments( Fontana Masson staining) showed a reduction in melanin. There were no clinically significant adverse events observed during the study. This proof of concept study documents the very novel efficacy and safety of malassezin for skin lightening.

Effect of Q-switched Nd-YAG laser on the clinical, pigmentary, and immunological markers in patients with lichen planus pigmentosus: A pilot study.

The persistent discoloration in lichen planus pigmentosus (LPP) is secondary to persistent melanophages in the superficial dermis in these patients. We evaluated the effect of Q-switched Nd-YAG laser on the clinical, pigmentary, and immunological markers in patients with LPP. Nine females with a clinical diagnosis of LPP were included in the study. After six sessions of laser with toning protocol, performed over a representative area of 5 × 5 cm2 at 2-weekly intervals, the mean clinical improvement as per the physician assessment was 25.7% (10-40%). There was no significant reduction in melanin and erythema index. On expression analysis using quantitative-polymerase chain reaction, the reduction in tyrosinase (p = 0.03) was statistically significant, though, the reduction in other pigment and immunological markers was not significant. The immunohistochemistry quantification data of corresponding proteins also did not show any significant difference. Post inflammatory hypopigmentation was noted in one patient. Q-switched Nd-YAG laser toning protocol resulted in modest clinical and histological improvement in patients of LPP.

Origanum essential oils reduce the level of melanin in B16-F1 melanocytes.

Hyperpigmentation disorders are considered signs of skin aging and are aesthetically unpleasant. Most active ingredients used against hyperpigmentation disorders predominantly target tyrosinase activity. To study the effect of two Origanum essential oils on the melanogenic activity of B16-F1 murine melanocytes. The main component of these oils, carvacrol, was also investigated and a model for anti-melanogenic activity is proposed. B16-F1 melanocytes were exposed to different concentrations of essential oils and carvacrol. The level of tyrosinase and melanin was determined using spectrophotometric measurements. Essential oils of Origanum syriacum and Origanum ehrenbergii led to a significant 14% and 17% reduction in melanin level at 40μgmL-1, respectively. However, neither demonstrated a significant effect on the level of intracellular tyrosinase. The same effects were found for carvacrol which led to a 30% reduction in melanin at 45μgmL-1. Our results indicate that the oils studied are anti-melanogenic. We propose a mechanism, similar to that for hydroquinone, whereby carvacrol functions as a competitive inhibitor of tyrosinase, thus inhibiting oxidation of tyrosine and causing a deregulation of melanogenesis.

795 Acetyl-arctigenin (Ac-ATG), a novel and safe skin lightening molecule

There is high demand to identify novel skin lightening actives that are effective and safe. Previously, it has been shown that arctigenin (ATG) found in A. lappa, inhibits melanogenesis. To explore this chemotype further and identify more potent skin lightening actives, several ATG derivatives were synthesized including acetyl-arctigenin (Ac-ATG). Utilizing murine melanoma cells, ATG and Ac-ATG both reduce melanin content, with Ac-ATG demonstrating increased potency. However, when measuring tyrosinase inhibition capacity, both ATG and Ac-ATG showed modest inhibitory activity (20-25%), while kojic acid (KA) reached almost 100% inhibition. Endothelin-1 (ET-1) is a key mediator for melanocytes in UVB induce pigmentation and melanosome transfer. Our results show both ATG and Ac-ATG inhibit ET-1 in human epidermal keratinocytes. We thus sought to evaluate the anti-melanogenesis activity of Ac-ATG and ATG when applied topically (MelanoDerm™). Results show that after 2 weeks, both 0.1% ATG and 0.1% Ac-ATG significantly reduce melanin production by 56% and 72% respectively. Moreover, 1% Ac-ATG results in an 84% inhibition of melanin, which is significantly greater than 2% KA (62% inhibition). Interestingly, when 0.1% Ac-ATG was combined with 2% KA, we observed an additive effect resulting in 96% reduction in melanin. Moreover, this effect is not observed when 0.1% ATG and 2% KA are combined (62% inhibition). Additional studies need to be performed to elucidate Ac-ATG’s mechanism of action. Lastly, safety assessment for Ac-ATG including, in vitro sensitization, skin and eye irritation, Ames test, phototoxicity and HRIPT have been performed and in all instances, Ac-ATG was found to be safe. Thus, Ac-ATG is a novel, safe depigmentation compound and our results suggest that it can be utilized as both a stand-alone skin lightning ingredient and/or in combination with other depigmentation compounds that function through different mechanisms.

Intraretinal Correlates of Reticular Pseudodrusen Revealed by Autofluorescence and En Face OCT.

PurposeWe sought to determine whether information revealed from the reflectance, autofluorescence, and absorption properties of RPE cells situated posterior to reticular pseudodrusen (RPD) could provide insight into the origins and structure of RPD.MethodsRPD were studied qualitatively by near-infrared fundus autofluorescence (NIR-AF), short-wavelength fundus autofluorescence (SW-AF), and infrared reflectance (IR-R) images, and the presentation was compared to horizontal and en face spectral domain optical coherence tomographic (SD-OCT) images. Images were acquired from 23 patients (39 eyes) diagnosed with RPD (mean age 80.7 ± 7.1 [SD]; 16 female; 4 Hispanics, 19 non-Hispanic whites).ResultsIn SW-AF, NIR-AF, and IR-R images, fundus RPD were recognized as interlacing networks of small scale variations in IR-R and fluorescence (SW-AF, NIR-AF) intensities. Darkened foci of RPD colocalized in SW-AF and NIR-AF images, and in SD-OCT images corresponded to disturbances of the interdigitation (IZ) and ellipsoid (EZ) zones and to more pronounced hyperreflective lesions traversing photoreceptor-attributable bands in SD-OCT images. Qualitative assessment of the outer nuclear layer (ONL) revealed thinning as RPD extended radially from the outer to inner retina. In en face OCT, hyperreflective areas in the EZ band correlated topographically with hyporeflective foci at the level of the RPE.ConclusionsThe hyperreflective lesions corresponding to RPD in SD-OCT scans are likely indicative of degenerating photoreceptor cells. The darkened foci at positions of RPD in NIR-AF and en face OCT images indicate changes in the RPE monolayer with the reduced NIR-AF and en face OCT signal suggesting a reduction in melanin that could be accounted for by RPE thinning.

RNAi-mediated down-regulation of a melanin polyketide synthase (pks1) gene in the fungus Slafractonia leguminicola.

The fungus Slafractonia leguminicola, the causal agent of blackpatch disease of legumes produces two mycotoxins slaframine and swainsonine, causing slobbers' symptoms and locoism of grazing animals, respectively. The genetics of this important fungus is poorly understood. This work aimed to develop a genetic transformation system and evaluate the efficacy of RNA interference (RNAi) in S. leguminicola. In this study, S. leguminicola was transformed using a PEG-mediated method with a fungal construct that carries a hygromycin resistance cassette. To assess the use of RNAi, a silencing construct pSilentPKS1-AS was constructed which includes inverted repeat transgenes of the polyketide synthase gene (pks1) that is involved in melanin biosynthesis. Transformation of S. leguminicola with the IRT pks1 vector decreased pks1 transcripts levels 82-92% in knockdown mutants when compared with the wild type and was accompanied with a reduction in melanin and swainsonine production. These results demonstrate that RNAi can be a useful tool for studying gene function in S. leguminicola.

Anti-aging activities of <i>Pyrus pyrifolia</i> var culta plant callus extract

Purpose: To investigate the anti-aging properties of callus extract from Pyrus pyrifolia var. culta with skin regeneration and lightening activities.Methods: Callus extract of P. pyrifolia var. culta was produced on Murashige and Skoog (MS) medium supplemented with picloram, followed by extraction of the callus biomass in phosphate-buffered saline. The anti-oxidant activity of the extract was assessed using the DPPH free radical-scavenging assay. Inhibition of skin pigmentation by callus extract was evaluated by measuring the melanogenesis of melanoma cells. The skin-regenerating efficacy of the extract was evaluated in terms of its ability to promote procollagen synthesis and fibroblast cell proliferation.Results: The callus extract, at 10 mg/mL, exhibited 78.7 % free radical-scavenging activity, equivalent to that exhibited by 500 μM ascorbic acid. The 1 mg/mL extract solution afforded a 1.4-fold greater reduction in melanocyte melanin than did a 1 mg/mL arbutin solution. Fibroblast cells treated with 5 mg/mL callus extract exhibited 127 % higher levels of proliferation and 2.0-fold higher levels of procollagen type I C-peptide synthesis, respectively, compared with the untreated controls.Conclusion: These findings suggest that the callus extract of P. pyrifolia var. culta may be useful as a source of anti-aging cosmetic components with skin lightening and regenerating activities.Keywords: P. pyrifolia var. culta, Anti-aging, Callus extract, Skin lightening, Anti-tyrosinase activity, Melanogenesis, Wound recovery, Procollagen type I C-peptide synthesis

Melanin reduction by peroxidase activity in lysosome-related organelle extracts from hen egg whites, HeLa cells, and Saccharomyces cerevisiae

Although melanin plays a biological role in the protection of underlying tissues from harmful ultraviolet radiations, yet large amounts of melanin in light-skinned individuals can make them susceptible to skin cancer. In this study, lysosome-related organelles extracts (LOE) from hen egg whites, HeLa cells, and Saccharomyces cerevisiae have been used to lower melanin color intensity. The results show 80% reduction in melanin upon daily treatment with 100 μg LOE for a period of 19 days. Additionally, the treatment with S. cerevisiae LOE showed the best melanin color reduction, which is consistent with the level of peroxidase activity. The treatment of LOE from S. cerevisiae with NH4Cl decreases melanin reduction activity and peroxidase activity compare to LOE from normal S. cerevisiae. Meanwhile, in contrast, the treatment with H2O2 showed a completely contrary pattern. The above results thus indicate that LOEs can be promising agents for use in cosmeceutical skin lightening as well as for the treatment of hyper pigmentation disorders.

An abnormality in glucocorticoid receptor expression differentiates steroid responders from nonresponders in keloid disease.

SummaryBackgroundGlucocorticoids (GCs) are first‐line treatment for keloid disease (KD) but are limited by high incidence of resistance, recurrence and undesirable side‐effects. Identifying patient responsiveness early could guide therapy.MethodsNineteen patients with KD were recruited at week 0 (before treatment) and received intralesional steroids. At weeks 0, 2 and 4, noninvasive imaging and biopsies were performed. Responsiveness was determined by clinical response and a significant reduction in vascular perfusion following steroid treatment, using full‐field laser perfusion imaging (FLPI). Responsiveness was also evaluated using (i) spectrophotometric intracutaneous analysis to quantify changes in collagen and melanin and (ii) histology to identify changes in epidermal thickness and glycosaminoglycan (GAG) expression. Biopsies were used to quantify changes in glucocorticoid receptor (GR) expression using quantitative reverse transcriptase polymerase chain reaction, immunoblotting and immunohistochemistry.ResultsAt week 2, the FLPI was used to separate patients into steroid responsive (n = 12) and nonresponsive groups (n = 7). All patients demonstrated a significant decrease in GAG at week 2 (P < 0·05). At week 4, responsive patients exhibited significant reduction in melanin, GAG, epidermal thickness (all P < 0·05) and a continued reduction in perfusion (P < 0·001) compared with nonresponders. Steroid‐responsive patients had increased GR expression at baseline and showed autoregulation of GR compared with nonresponders, who showed no change in GR transcription or protein.ConclusionsThis is the first demonstration that keloid response to steroids can be measured objectively using noninvasive imaging. FLPI is a potentially reliable tool to stratify KD responsiveness. Altered GR expression may be the mechanism gating therapeutic response.

Effects of vivo morpholino knockdown of lateral hypothalamus orexin/hypocretin on renewal of alcohol seeking.

Two experiments used vivo morpholinos to assess the role of orexin/hypocretin in ABA renewal of extinguished alcohol seeking. Rats were trained to respond for alcoholic beer in a distinctive context, A, and then extinguished in a second distinctive context, B. When rats were tested in the extinction context, ABB, responding was low but when they were tested in the training context, ABA, responding was significantly higher. Microinjection of an orexin/hypocretin antisense vivo morpholino into LH significantly reduced orexin/hypocretin protein expression but had no effect on the ABA renewal of alcohol seeking (Experiment 1). Microinjection of a higher dose of the antisense vivo morpholino into LH also significantly reduced orexin/hypocretin protein expression but this was not selective and yielded significant reduction in melanin -concentrating hormone (MCH) protein expression. This non-selective knockdown did significantly reduce ABA renewal as well as reduce the reacquisition of alcohol seeking. Taken together, these findings show an important role for LH in the ABA renewal of alcohol seeking but that orexin/hypocretin is not necessary for this renewal.

Isabelline Coloration in American Red Squirrels (Tamiasciurus hudsonicus) from the Yukon

Aberrations in coat color are common in Scuiridae. However, various workers have concluded that coat color aberrations in American Red Squirrels (Tamiasciurus hudsonicus) are apparently rare (Banfield 1974; Obbard 1987; Steele 1998; Yahner 2003; S Boutin, University of Alberta, pers. comm.), presumably because coat color is adaptive (Wauters and others 2004; Caro 2005). Regardless, genetic mutations occur. Benton (1958) and Mengel and Jenkinson (1971) reported melanistic Red Squirrels, and Wood (1965) reported albinistic individuals. Several records of unusual color variants, that are neither albinistic nor melanistic, have also been reported, although these also appear to be rare. For example, Svihla (1931) and Layne (1954), reported individuals that were piebald (leucistic), and a similarly-colored individual was photographed in 2010 in Edmonton, Alberta, Canada (S Boutin, University of Alberta, pers. comm.). Banfield (1974) noted that in socalled partial albinos ‘‘the general tone may be pale grey, or perhaps only the tail will be white’’. Dapson (1963) reported a coat color variation that was also unique, in that ‘‘(t)he dorsum and sides are dirty white, due to the underfur, which is dark gray, tipped with faint rufous’’. The eyes and vibrissae in Dapson’s specimen were normal color. Here, we report an observation of unusual coloration in an American Red Squirrel. On 23 August 2011, we received information and photographs from local residents about an unusually colored Red Squirrel seen in a residential neighborhood in Whitehorse, Yukon, Canada (UTM: Zone 8V, 497272E, 6731229N, WGS 84). We set 3 Tomahawk live-traps (model 201, Tomahawk, Wisconsin, USA), baited with apples and peanut butter, in the area, and on 24 August we captured an unusually colored Red Squirrel. We examined its coloration, determined its sex and age-class, weighed it with a spring scale (Pesola AG, Baar, Switzerland), photographed and, then released it. The Red Squirrel was a juvenile female (mass 5 140 g). Coloration of her sides, dorsum, tail, head, legs, and feet was pale or sandy, with rufous tips on the guard hairs (Fig. 1). The ventral surface was white, the typical coloration of Red Squirrels, and the eyes were also typical, not pink, as in truly albinistic individuals. The vibrissae, however, were white, not black, as typically seen (Fig. 1). The white eye rings were faintly discernible. Lateral lines or a dark dorsal median band were not evident. Overall, the coat color of the Red Squirrel appeared faded or ‘‘washed out’’ (Fig. 1). The Red Squirrel we observed was not albinistic, as it was not completely white and the eyes were of typical coloration. There was no evidence of a complete (albinistic) or partial (leucistic) lack of melanin. The propensity to incorrectly categorize all white (or light colored), or partially white, birds as albinistic was pointed out by van Grouw (2006). Jones (1920) noted the same for mammals. Based on our review of color variants, we consider the Red Squirrel we observed to be of Isabelline coloration. This coloration is not a partially albinistic variant, rather it is a type of pigment dilution whereby there is a substantial but not complete reduction in melanin caused by genetic mutation (van Grouw 2006). Isabelline dilution is marked by a uniform reduction in melanin. The result of this genetic mutation is an individual that looks ‘‘washed out’’. Everitt and Miskelly (2003) review the offcolor origin of the term Isabelline. The term Isabelline is commonly applied to individual birds that have faded plumage (for example, Everitt and Miskelly 2003; van Grouw 2006); to the best of our knowledge, it is rarely applied to mammals that have diluted pelage, where ‘‘partial albino’’ is often incorrectly used (Jones 1920). The term Isabelline is also applied to

A Histological Examination for Skin Atrophy After 6 Months of Treatment With Fluocinolone Acetonide 0.01%, Hydroquinone 4%, and Tretinoin 0.05% Cream

Melasma is a common disorder affecting a significant percentage of the population, particularly those with skin of color. Therapy with hydroquinone, a depigmenting agent, as a single agent or in combination with other agents has been used with variable success. A triple-combination (TC) cream combining hydroquinone 4% with tretinoin 0.05% and fluocinolone acetonide 0.01% was developed for the treatment of melasma. We studied the use of TC cream for 24 weeks and had tissue samples for all time points in 62 patients with moderate to severe melasma. The atrophogenic potential of TC cream was evaluated through serial histopathologic examination of skin biopsies. No statistically significant histopathologic signs of atrophy of the epidermis or dermis were noted at any time point throughout the study. There was a marked reduction in epidermal melanin in treated subjects; however, we did not observe any significant difference in baseline and treated samples in the amount of perivascular inflammatory infiltrate, dermal mucin, keratinocyte and melanocyte atypia, or mast cells, consistent with findings of previous studies where topical retinoids were used. An increase in the mean number of blood vessels per square millimeter of tissue was observed in 2 study cohorts between baseline and week 24. These results suggest that the risk of skin atrophy with 24-week use of TC cream for the treatment of melasma is very low.

Effect of low levels of dietary tyrosine on the hair colour of cats.

Experiments were conducted to investigate the basis for the change in hair colour of black cats to reddish-brown. Black cats were given purified diets based on gelatin, casein plus lactalbumin, or crystalline amino acids as protein sources. Diets that caused the colour of hair to change to reddish-brown were associated with a reduction in melanin in hair (observed by direct microscopic examination), a decreased total melanin concentration and low concentrations of tyrosine in plasma. Reddish hair coat was induced in black kittens born to queens given a tyrosine-deficient diet during pregnancy. Black hair colour was maintained or restored by diets containing a high concentration of tyrosine or phenylalanine. Current dietary recommendations for dietary tyrosine and phenylalanine for cats are below those required to support maximal melanin synthesis in black cats. The requirement appears to be greater than a combination of 4.5 g tyrosine plus 12 g phenylalanine/kg diet but less than 24 g phenylalanine alone/kg diet.

Impaired visual thresholds in hypopigmented animals

Ocular hypopigmentation is associated with neurological defects in structure and function. This paper investigates the absolute visual thresholds in dark-adapted hypopigmented animals compared to their normally pigmented controls. Here we asked (1) whether the threshold elevation found in hypopigmented animals is a general consequence of the reduction in melanin content; (2) if so, which melanin components in the eye are likely to influence visual thresholds; and (3) whether similar threshold defects can be detected in orders other than rodents. By single-unit recordings from the superior colliculus, we compared incremental thresholds of normal black mice of the C57BL/6J strain to hypopigmented mutants: beige (bg/bg), pale ear (ep/ep), and albino (c2J/c2J) mice, three mutants in which melanin pigment throughout the body is affected; and Steel (Sl/Sld) and dominant-spotting/W-mice (W/Wv), two mutants with normal pigmentation in the retinal pigment epithelium (RPE) but without any melanin in the choroid or the rest of the body. We found that all mutants had elevated thresholds that varied with the reduction in melanin. The albinos were 25 times less sensitive than black mice, pale ear mice 20 times, beige mice 11 times, and Steel and W-mice 5 times. The mean thresholds of dark-adapted black mice were 0.008 cd/m2. Recordings from rabbits showed a similar impairment of visual sensitivity; incremental thresholds were elevated 40 times in New Zealand-White albino rabbits (0.0008 cd/m2) compared to Dutch-Belted pigmented controls (0.00002 cd/m2).(ABSTRACT TRUNCATED AT 250 WORDS)

The land birds of Aldabra

The land birds of Aldabra