Search Results (93)

Background/Objectives: Oleuropein (OLP), the key bioactive in olive leaf extracts, has demonstrated various biological benefits. We previously reported on the pro-melanogenic action with increased dendricity of a patented olive leaf extract (Benolea^®) that was standardized to 16–24% OLP. In this study, purified OLP was evaluated to identify if it might be the bioactive responsible for the stimulating effects on melanocytes. Moreover, previous studies on OLP have never reported the effects on melanocyte dendricity or melanin export in the medium. Methods: Herein, the effect of OLP on melanogenesis was first evaluated using the B16F10 cell model and validated using the physiological model of normal human melanocytes from Caucasian (lightly pigmented; LP) and Asian (moderately pigmented; MP) skin. The effects of OLP on melanin export in LP and MP cells were indirectly evaluated by dendricity indices. Results: OLP lowered the intracellular melanin content in B16F10 cells by 26.36%, 24.48%, and 27.71% at 100, 150, and 200 µg/mL (all p < 0.01), respectively, with no effect on the intracellular melanin contents of LP or MP cells. OLP treatment did not influence tyrosinase activity in B16F10 cells or MP cells but significantly enhanced the activity in LP cells. The measurement of extracellular melanin showed significantly higher levels for all three cells, although the levels were considerably higher in MP cells, after the adjustment for OLP autoxidation observed in the cell-free system, which caused melanin-like brown coloration. Furthermore, OLP induced morphological alterations of extended dendrites of B16F10 cells that were retained in LP and MP cells. The quantitation of the dendricity of cells treated with OLP at 200 μg/mL revealed that the total dendrite length was increased by 35.24% (p < 0.05) in LP cells and by 58.45% (p < 0.001) in MP cells without any change in the dendrite number. Conclusions: This is the first study to demonstrate the novel finding that OLP possesses a hitherto unreported unique capacity to stimulate melanocyte dendricity, hence establishing the efficacy for use in increasing human pigmentation. Our findings show significance, with a potential application of the compound OLP for addressing human hypopigmentation disorders in clinical settings or for cosmetic uses related to sunless tanning. Full article

Lysine, butyric acid, and zinc play important roles in skin homeostasis, which involves aging, inflammation, and prevention of skin barrier disruption. This bioactivity spectrum is not replicated by any one topical compound currently in use. Our purpose in this study was to characterize a novel compound, zinc dibutyroyllysinate (ZDL), consisting of zinc with lysine and butyric acid moieties. We used RNA-seq to evaluate its effect on gene expression in a full-thickness skin model. We show that lysine alone has minimal effects on gene expression, whereas ZDL had greater transcriptional bioactivity. The effects of ZDL included an increased expression of genes promoting epidermal differentiation and retinol metabolism, along with a decreased expression of microphthalmia-associated transcription factor (MITF) and other melanogenesis genes. These effects were not replicated by an alternative salt compound (i.e., calcium dibutyroyllysinate). ZDL additionally led to a dose-dependent increase in skin fibroblast extracellular matrix proteins, including collagen I, collagen IV, and prolidase. Loss of melanin secretion was also seen in ZDL-treated melanocytes. These results provide an initial characterization of ZDL as a novel topical agent. Our findings support a rationale for the development of ZDL as a skincare ingredient, with potential applications for diverse conditions, involving melanocyte hyperactivity, pigmentation, inflammation, or aging. Full article

Background: Multiphoton tomography (MPT) is a femtosecond laser imaging technique that enables high-resolution virtual biopsies of human skin. It provides a non-invasive method for analyzing cellular metabolism, structural changes, and responses to cosmetic products, providing insights into cell–cosmetic interactions. This review explores the principles, historical development, and key applications of MPT in cosmetic research. Methods: The latest MPT device combines five modalities: (i) two-photon fluorescence: visualizes cells, elastin, and cosmetic ingredients; (ii) second harmonic generation (SHG): maps the collagen network; (iii) fluorescence lifetime imaging (FLIM): differentiates eumelanin from pheomelanin and evaluates the impact of cosmetics on cellular metabolic activity; (iv) reflectance confocal microscopy (RCM): images cell membranes and cosmetic particles; and (v) white LED imaging for dermoscopy. Results: MPT enables in-depth examination of extracellular matrix changes, cellular metabolism, and melanin production. It identifies skin responses to cosmetic products and tracks the intratissue distribution of sunscreen nanoparticles, nano- and microplastics, and other cosmetic components. Quantitative measurements, such as the elastin-to-collagen ratio, provide insights into anti-aging effects. Conclusions: MPT is a powerful in vivo imaging tool for the cosmetic industry. Its superior resolution and metabolic information facilitate the evaluation of product efficacy and support the development of personalized skincare solutions. Full article

Alpha-melanocyte stimulating hormone (α-MSH) is a hormone that stimulates the formation of melanin, which is responsible for protecting the skin from UV rays. However, excessive production of melanin causes pigmentation, leading to skin disorders, such as melasma and freckles. Using phage display technology, we screened a modified hagfish VLRB (α-MSH target binding polypeptide) library for polypeptides that recognize α-MSH. This was expressed in E. coli to produce binding proteins that specifically bind to α-MSH. In this study, we investigated the effect of α-MSH binder protein on the inhibition of melanogenesis in B16F10 cells stimulated with α-MSH and the mechanism of inhibition. The α-MSH-induced inhibition of intracellular and extracellular melanogenesis was accompanied by the downregulation of TRP1 and TRP2, and melanogenesis-related proteins, such as tyrosinase and MITF, were significantly downregulated. These results suggest that the α-MSH binder polypeptide regulates melanogenesis inhibition and its associated mechanisms. Full article

As Streptomycetes might produce melanin to survive in stressful environmental conditions, like under metal exposure, supplementing metal ions to the growth medium could be a wise strategy for boosting the production of the pigment. The aim of this study was to test, for the first time, the possibility of boosting S. nashvillensis DSM40314 melanin biosynthesis by adding to the growth medium singularly or, at the same time, different concentrations (1.0, 1.5, and 2.0 g∙L⁻¹) of CuSO₄ or/and Fe₂(SO₄)₃. A maximum melanin production of 4.0 ± 0.1 g·L⁻¹ was obtained in shake flasks with a 2.0 g∙L⁻¹ coupled addition of the two metals, while the extracellular tyrosinase activities ranged values between 5.4 and 11.6 ± 0.1 U·L⁻¹. The pigments produced in different conditions were precipitated from the broth supernatants under acidic conditions, purified, and characterized by UV-VIS, FT-IR, and NMR analyses that determined structures like eumelanin pigments. Fermentation experiments in stirred tank reactors allowed to scale up the process in more controlled conditions, further boosting the pigment production up to 4.9 ± 0.1 g·L⁻¹, with an increase of about 22.0% compared to the results obtained in shake flasks. Full article

In the current study, we aimed to evaluate the combined antimelanogenic effects of resveratrol- and protopanaxadiol (PPD)-enriched rice seed extracts (DJ526 and DJ-PPD) in melan-a cells. The treatment antioxidant capacity was evaluated using the ABTS radical scavenging method. TR_3 (70% [wight (w)/w] of DJ526 and 30% [w/w] of DJ-PPD) markedly increased the antioxidant activity at a level similar to that of DJ526 and DJ-PPD alone. The antimelanogenic activities in melan-a cells were evaluated after co-culturing of treatments at the concentration of 100 μg/mL. The in vitro melan-a cell experiment showed that treatment with the DJ526 and DJ-PPD mixture significantly reduced the cellular tyrosinase activity and melanin content; suppressed the expression of melanogenesis-related genes and proteins; decreased the number and size of melanin-containing cells; upregulated phosphorylated extracellular signal-regulated kinase 1/2 and protein kinase B expression levels; and suppressed the expression of p-p38 MAPK. These results show that DJ-PPD does not interfere with the antioxidant and antimelanogeneic activities of DJ526 but enhances the antioxidant and antimelanogeneic activities of DJ526. These findings indicate the potential of resveratrol- and PPD-enriched rice seeds as novel agents for controlling hyperpigmentation. Full article

Sorbus commixta Hedl. is a traditional medicinal plant in Korea, China, and Japan with known antioxidative, anti-inflammatory, anti-atherogenic, and anti-melanin activities. However, its anti-neuroinflammatory effects remain largely unknown. In this study, we investigated the inhibitory effects of S. commixta fruit extracts on lipopolysaccharide-stimulated pro-inflammatory factors in BV-2 microglia. We compared the anti-neuroinflammatory activity of S. commixta fruit water extract (SFW) and 70% ethanol extract using a nitric oxide assay. Our data indicated that the SFW (25–100 μg/mL) treatment significantly inhibited excessive nitric oxide production in lipopolysaccharide-stimulated BV-2 microglia compared to the 70% ethanol extract. It also attenuated the expression of inducible nitric oxide synthase, cyclooxygenase-2, and pro-inflammatory cytokines such as interleukin-6 and tumor necrosis factor α. Moreover, SFW exhibited its anti-inflammatory properties by downregulating the expression of factors involved in the extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase pathways and by suppressing nuclear factor kappa B. Caffeic acid was identified as a primary component of SFW showing anti-neuroinflammatory activity. These findings suggest that SFW may offer substantial therapeutic potential for the treatment of neurodegenerative diseases involving microglia activation. Full article

Aging is synonymous with the skin becoming increasingly thin and fragile, which is associated with a decrease in epidermal cell layers. Beyond this intrinsic aging process, the skin is continually exposed to environmental stressors such as UV radiation that accelerate aging. To fight the signs of aging, a comprehensive program was implemented in this study to evaluate the efficacy of an innovative ingredient, Willaertia lysate, through a multi-scale approach encompassing cellular and advanced 3D skin models. The results show that Willaertia lysate, initially sourced from French Alps thermal spring waters, is able to (i) promote cell migration; (ii) improve the quality and abundance of the extracellular matrix in aged skins and in young skins exposed to UV radiation to a similar level to that in unexposed young skins; (iii) decrease tyrosinase activity and melanin content; and (iv) reduce oxidative stress after UV exposure by decreasing exposome markers such as protein carbonylation and lipid peroxidation expression. This complete set of coherent results demonstrates the global protective efficacy of Willaertia lysate against the effects of photoaging. This study is the first to report the use of a protozoan lysate as a natural and biosourced postbiotic active ingredient in the fields of cosmetics and dermocosmetics. Full article

Vitiligo is a skin condition characterized by the loss of pigment, resulting in white patches on various parts of the body. It occurs when melanocytes, the cells that are responsible for producing skin pigment, are destroyed or stop functioning. This study aimed to investigate the melanogenic potential of various 4-methylcoumarin (4MC) derivatives, including 6-methoxy-4-methylcoumarin (6M-4MC), 7-methoxy-4-methylcoumarin (7M-4MC), 7-amino-4-methylcoumarin (7A-4MC), 6,7-dihydroxy-4-methylcoumarin (6,7DH-4MC), 7,8-dihydroxy-4-methylcoumarin (7,8DH-4MC), and 6,7-dimethoxy-4-methylcoumarin (6,7DM-4MC), in B16F10 melanoma cells. Our findings revealed that, while 4MC, 7A-4MC, 6,7DH-4MC, and 7,8DH-4MC did not exhibit any effect on melanin production, significant stimulation of melanogenesis was observed with 6M-4MC, 7M-4MC, and 6,7DM-4MC, with 6M-4MC demonstrating the most pronounced effect. 6M-4MC significantly stimulated melanin production and tyrosinase activity in a concentration-dependent manner in B16F10 cells. A Western blot analysis revealed that 6M-4MC increased the expression levels of microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2). Further mechanistic studies showed that 6M-4MC inhibited extracellular signal-regulated kinase (ERK) and protein kinase B (AKT), which led to the upregulation of MITF and TRP proteins and subsequent activation of melanin synthesis. Additionally, 6M-4MC activated GSK3β phosphorylation, reduced β-catenin phosphorylation, and stimulated melanogenesis via the GSK3β/β-catenin pathway. Moreover, a primary skin irritation test was conducted on the upper backs of 32 healthy female volunteers to assess the potential irritation or sensitization from 6M-4MC when applied topically at concentrations of 50 µM and 100 µM. The test results showed no adverse effects on the skin. Collectively, these findings suggest that 6M-4MC may be a promising pigmentation stimulator for use in cosmetics and in the medical treatment of hypopigmentation disorders, particularly in the treatment of skin conditions such as vitiligo. Full article

Quasipaa spinosa, commonly known as the spiny frog, is an economically valued amphibian in China prized for its tender meat and nutritional value. This species exhibits marked sexual dimorphism, most notably the prominent spiny structures on males that are pivotal for mating success and species identification. The spines of Q. spinosa exhibit strong seasonal variation, changing significantly with the reproductive cycle, which typically spans from April to October. Sexually mature males develop densely packed, irregularly arranged round papillae with black spines on their chests during the breeding season, which may then reduce or disappear afterward, while females have smooth chest skin. Despite their ecological importance, the developmental mechanisms and biological functions of these spines have been inadequately explored. This study integrates morphological, transcriptomic, and metabolomic analyses to elucidate the mechanisms underlying the seasonal variation in spine characteristics of Q. spinosa. Our results demonstrate that spine density inversely correlates with body size and that spine development is accompanied by significant changes in epidermal thickness and keratinization during the breeding season. Comparative transcriptomic analysis across different breeding stages revealed significant gene expression alterations in pathways related to extracellular matrix interactions, tyrosine metabolism, Wnt signaling, and melanogenesis. Metabolomic analysis further identified significant seasonal shifts in metabolites essential for energy metabolism and melanin synthesis, including notable increases in citric acid and β-alanine. These molecular changes are consistent with the observed morphological adaptations, suggesting a complex regulatory mechanism supporting spine development and functionality. This study provides novel insights into the molecular basis of spine morphogenesis and its seasonal dynamics in Q. spinosa, contributing valuable information for the species’ conservation and aquaculture. Full article

Melasma is a pathology with multifactorial causes that results in hyperpigmentation of sun-exposed areas, particularly facial skin. New treatments targeting the different factors regulating this condition need to be effective with and have limited adverse effects. Here, we describe a novel combination of two natural compounds (apigenin and phloretin) that has synergistic effects regulating melanogenesis in vitro. Both compounds inhibit Wnt-stimulated melanogenesis and induce autophagy in melanocytes. Apigenin induces DKK1, a Wnt pathway inhibitor, and reduces VEGF, a melanogenesis and proangiogenic factor, in fibroblasts. Moreover, apigenin induces miR-675, a melanogenesis inhibitor miRNA that is reduced in melasma skin in melanocytes. Both compounds showed senomorphic effects by regulating extracellular-matrix-related genes in senescent fibroblasts. Topical application of the compounds also showed significant melanin reduction in a reconstructed human epidermis after 7 days. Thus, the combination of apigenin and phloretin shows promising results as an effective topical treatment of skin hyperpigmentation conditions. Full article

Chalcone is a type of flavonoid compound that is widely biosynthesized in plants. Studies have shown that consuming flavonoids from fruits and vegetables or applying individual ingredients reduces the risk of skin disease. However, the effects of chalcone on melanogenesis and inflammation have not been fully investigated. The aim of this study was to evaluate the anti-melanogenic and anti-inflammatory effects of 2′-hydroxy-3,4′-dimethoxychalcone (3,4′-DMC), 2′-hydroxy-4,4′-dimethoxychalcone (4,4′-DMC), 2′-hydroxy-3′,4′-dimethoxychalcone (3′,4′-DMC), and 2′-hydroxy-4′,6′-dimethoxychalcone (4′,6′-DMC). Among the derivatives of 2′-hydroxy-4′-methoxychalcone, 4′,6′-DMC demonstrated the most potent melanogenesis-inhibitory and anti-inflammatory effects. As evidenced by various biological assays, 4′,6′-DMC showed no cytotoxicity and notably decreased the expression of tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 enzymes. Furthermore, it reduced cellular melanin content and intracellular tyrosinase activity in B16F10 melanoma cells by downregulating microphthalmia-associated transcription factor (MITF), cAMP-dependent protein kinase (PKA), cAMP response element-binding protein (CREB), p38, c-Jun N-terminal kinase (JNK), β-catenin, glycogen synthase kinase-3β (GSK3β), and protein kinase B (AKT) proteins, while upregulating extracellular signal-regulated kinase (ERK) and p-β-catenin. Additionally, treatment with 4′,6′-DMC significantly mitigated the lipopolysaccharide (LPS)-induced expression of NO, PGE₂, inflammatory cytokines, COX-2, and iNOS proteins. Overall, 4′,6′-DMC treatment notably alleviated LPS-induced damage by reducing nuclear factor kappa B (NF-κB), p38, JNK protein levels, and NF-kB/p65 nuclear translocation. Finally, the topical applicability of 4′,6′-DMC was evaluated in a preliminary human skin irritation test and no adverse effects were found. These findings suggest that 4′,6′-DMC may offer new possibilities for use as functional ingredients in cosmeceuticals and ointments. Full article

Hyperpigmentation skin disorders are marked by an abnormal accumulation or export of melanin pigment synthesized within melanocytes and pose a significant aesthetic concern. The search for novel natural compounds that exhibit pharmacological potential for treating pigmentation disorders is growing. In this study, kahweol (KW) and cafestol (CFS), two structural analogs of coffee diterpenes, were evaluated and compared for their effects on melanogenesis using B16F10 mouse melanoma cells and primary human melanocytes derived from Asian and African American skin. To the best of our knowledge, there are no reports of the effects of KW and CFS on melanogenesis yet. We first screened nontoxic concentrations of both compounds using an MTS assay after 72 h incubations and subsequently tested their effects on melanin synthesis and export. Cellular tyrosinase activity and cell-free mushroom tyrosinase activity were assayed to study the mechanisms of melanogenesis suppression. Human melanocytes from a moderately pigmented donor (HEMn-MP cells) and from a darkly pigmented donor (HEMn-DP cells) were next examined, and effects on cellular viability, melanin content, cellular tyrosinase activity, and melanin export (quantitated via dendricity) were similarly examined for both compounds. Our results show that KW and CFS did not significantly affect intracellular melanin content but suppressed extracellular melanin in B16F10 cells and dendritic parameters in human melanocytes, indicating their unique capacity to target extracellular melanogenesis and melanin export. Although KW showed a greater extracellular melanogenesis inhibitory capacity in B16F10 cells, in both primary melanocyte cells, CFS emerged as a potent inhibitor of melanin export compared to KW. Together, these results reveal novel modes of action of both compounds and indicate a promise to use CFS as a novel candidate for treating hyperpigmentation disorders of the human skin for clinical and cosmetic use. Additional research is necessary to shed light on the molecular pathways and the efficacy of melanogenesis inhibition by CFS in 3D human skin equivalents and in vivo studies. Full article

The excessive production of melanin can cause skin diseases and hyperpigmentation. In this study, resveratrol contained in Dongjin rice seed (DJ526) was increased through callus induction. The antioxidant capacity of resveratrol-enriched rice callus was evaluated using the ABTS radical scavenging method and was equivalent to that of vitamin C. DJ526 rice callus extract significantly increased antioxidant activities in a concentration-dependent manner. The anti-melanogenesis effects of DJ526 rice callus extract were also evaluated in melan-a cells. Resveratrol-enriched rice callus extract significantly (i) decreased the size and number of melanin-containing cells, (ii) suppressed the activity of cellular tyrosinase and melanin content, (iii) downregulated the expression of microphthalmia-associated transcription factor, tyrosinase, tyrosinase-related protein-1, and tyrosinase-related protein-2, (iv) increased the expression of phosphorylated extracellular signal-regulated kinase 1/2 and protein kinase B, and (v) inhibited the activation of phosphorylated p38 in melan-a cells. From the above observations, DJ526 rice callus extract showed strong antioxidant and anti-melanogenesis activity at the concentration test. These findings indicate the potential of resveratrol-enriched rice callus as a novel agent for controlling hyperpigmentation. Full article

In this study, we created a 3D Artificial Skin Platform that can be used for the treatment of pigmentation by artificially realizing the skin of pregnant women. For the stable realization of 3D artificial skin, a bilayer hydrogel composed of collagen type I and fibrin was designed and applied to the study to reduce the tension-induced contraction of collagen type I, the extracellular matrix (ECM) of artificial skin, by dynamic culture. Oxygen concentration and 17β-Estradiol (E2) concentration, which are highly related to melanin production, were selected as parameters of the pregnancy environment and applied to cell culture. Oxygen concentration, which is locally reduced in the first trimester (2.5–3%), and E2, which is upregulated in the third trimester, were applied to the cell culture process. We analyzed whether the 3D artificial skin implemented in the 3D Artificial Skin Platform could better represent the tendency of melanin expression in pregnant women than cells cultured under the same conditions in 2D. The expression levels of melanin and melanin-related genes in the 2D cell culture did not show a significant trend that was similar to the melanin expression trend in pregnant women. However, the 3D artificial skin platform showed a significant trend towards a 2-6-fold increase in melanin expression in response to low oxygen concentrations (2.5%) and E2 concentrations (17 ng/mL), which was similar to the trend in pregnant women in vivo. These results suggest that 3D artificial skin cultured on the Artificial Skin Platform has the potential to be used as a substitute for human pregnant skin in various research fields related to the treatment of pigmentation. Full article