Inhibitors Of Melanogenesis Research Articles

Condensed tannins from the leave of Dimocarpus longan Lour. exhibit anti-tyrosinase, anti-melanogenesis, anti-browning, anti-α-glucosidase, and anti-glycation activities

Dimocarpus longan Lour. is a valuable industrial crop for its broad applications in food, traditional Chinese medicine, and other fields. In this paper, condensed tannins were isolated from the leave of D. longan Lour., and their structure, anti-tyrosinase, anti-melanogenesis, anti-browning, anti-α-glucosidase, and anti-glycation properties were methodically clarified. The joint application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), electrospray ionization time-of-flight mass spectrometer (ESI+ TOF MS), and high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) confirmed that the longan leave condensed tannins (LLCTs) were polymers of procyanidins (majority) and prodelphinidins. The polymers powerfully inhibit tyrosinase (TY) with a competitive mechanism. These compounds altered the microenvironment of the binding site through hydrophobic interaction and hydrogen bond, and caused conformational modification of the enzyme by changing the polypeptide framework and secondary structure, leading to a decrease in TY activity. Cell assays further suggested that LLCTs exhibited a strong inhibition against intracellular TY activity and melanin production, and caused apoptosis in B16F10 cells. Anti-browning studies demonstrated that LLCTs suppress the browning of fresh-cut apples. Furthermore, the LLCTs exhibited an impressive inhibition on both α-glucosidase and nonenzymatic glycation. Therefore, this study confirms the potential of LLCTs as new inhibitors of tyrosinase, melanogenesis, browning, α-glucosidase, and nonenzymatic glycation, which provided a theoretical basis for the potential utilization of these polymers in the cosmetics, pharmaceutical, and food industries.

Novel Hydrogenated Derivatives of Chemically Modified Curcumin CMC2.24 Are Potent Inhibitors of Melanogenesis in an In Vitro Model: Influence of Degree of Hydrogenation.

Chemically modified curcumin, CMC2.24, is a promising therapeutic that has shown efficacy in ameliorating excessive pigmentation in our previous studies. However, its inherent disadvantages of color, stability, solubility, and cytotoxicity to melanocytes and keratinocytes at concentrations > 4 µg/mL posed challenges in its use in cosmetic formulations. To overcome these limitations, chemical reduction by hydrogenation of CMC2.24 (compound 1) was developed to yield products at different time points of hydrogenation (1 h, 2 h, 4 h, and 24 h) referred to as partially (2, 3, 4) or fully hydrogenated (5) products, and the effects of the degree of hydrogenation on melanogenesis in vitro were explored. Compound 1 and products 2-5 were evaluated using mushroom tyrosinase activity assays with two substrates (L-tyrosine and L-DOPA), then cellular assays using B16F10 mouse melanoma cells, MNT-1 human melanoma cells, and physiological normal human melanocytes (HEMn-DP cells). The cytotoxicity, melanin contents, cellular tyrosinase activities, and cellular oxidative stress were evaluated. Moreover, the recovery of melanin contents in HEMn-DP cells was also studied. Our results provide novel insights into the role of the degree of hydrogenation of compound 1 on the biological effects of melanogenesis, which were dependent on cell type. To the best of our knowledge, this is the first study to show that in HEMn-DP cells, the anti-melanogenic efficacy of the yellow-colored CMC2.24 is retained as early as 1 h after its hydrogenation; this efficacy is enhanced with longer durations of hydrogenation, with a robust efficacy achieved for the 24 h hydrogenated product 5 at the lowest concentration of 4 µg/mL. A similar potency could be achieved for product 4 at higher concentrations, although interestingly, both differ only by a minor amount of dihydro-CMC2.24. Our results indicate promise for using products 4 & 5 as a skin-lightener in cosmetic formulations with the advantages of lack of color combined with a potency much greater than that of the parent compound 1 at lower concentrations and reversibility of the effects on melanocytes. This, along with the easy synthesis and scale-up of the hydrogenation method for CMC2.24 and the documented higher solubility, stability, and bioavailability of tetrahydrocurcumin, provides further impetus to incorporating these derivatives in cosmetic formulations. The results of this study can help to extend the therapeutic window of the lead compound CMC2.24 by providing options for selecting partially or fully hydrogenated derivatives for cosmetic applications where a trade-off between color and efficacy is needed. Thus, the degree of hydrogenation can be tuned for desired biological effects. Further studies are warranted to evaluate the efficacy of products 4 & 5 at suppressing pigmentation in 3D skin-tissue equivalents and in vivo models.

Advances in Pigmentation Management: A Multipronged Approach.

Key cellular players regulating human skin pigmentation include melanocytes in the epidermis that synthesize melanin, neighboring keratinocytes that receive and distribute melanin in the upper layers, and fibroblasts in the dermis that affect overlying melanocytes and keratinocytes. In addition, endocrine factors from the blood supply (endothelial cells) and inflammation-related factors play a role. Thus, new strategies for affecting pigmentation need to consider these multiple cell lines to adequately cover various causes and disease processes associated with hyperpigmentation. Pathophysiologic mechanisms and cellular pathways involved in melanogenesis were thoroughly reviewed with particular emphasis on the cellular interplay involved in the process. A complex system of interlinking and independent pathways was defined and described demonstrating differing pathways for altered pigmentary disorders - melasma associated with endothelial cell interactions; post inflammatory hyperpigmentation associated with keratinocyte inflammatory mediators (PGE2 in particular); and photodamage involving all 4 cell types. In vitro validation studies were then undertaken to define differing cell group gene expression profiles with selected peptides and other active agents. Melanocytic production of pigment was then tested with these agents to identify key potential players capable of limiting pigmentation. Hexapeptide-12 and lactoferrin (melanocytes), Hexapeptide-11 (in keratinocytes), and phosphatidylserine (endothelial cells) were identified as major inhibitors of melanogenesis based on their gene expression profiles. This was confirmed by secondary melanin production tests performed on melanocytic lines. Additional active agents were also identified as inhibitors of melanocytic production of melanin, and together, these constituents formed the basis for a novel formulation for use in pigmentary disorders. A comprehensive scientific narrative of the various facets relating to pigmentation has been presented including differing pathways affecting varied cell lines that effect pigment production. Based on this concept, actives were tested using gene expression studies as well as in vitro melanogenic model testing in different cell lines. Using this novel multi-faceted approach, we have selected and validated a series of active agents to be used in a formulation targeting the complex problem of hyperpigmentation. J Drugs Dermatol. 2022;21(11):1206-1220. doi:10.36849/JDD.7013.

Urolithin and Reduced Urolithin Derivatives as Potent Inhibitors of Tyrosinase and Melanogenesis: Importance of the 4-Substituted Resorcinol Moiety.

We previously reported (E)-β-phenyl-α,β-unsaturated carbonyl scaffold ((E)-PUSC) played an important role in showing high tyrosinase inhibitory activity and that derivatives with a 4-substituted resorcinol moiety as the β-phenyl group of the scaffold resulted in the greatest tyrosinase inhibitory activity. To examine whether the 4-substituted resorcinol moiety could impart tyrosinase inhibitory activity in the absence of the α,β-unsaturated carbonyl moiety of the (E)-PUSC scaffold, 10 urolithin derivatives were synthesized. To obtain more candidate samples, the lactone ring in synthesized urolithins was reduced to produce nine reduced urolithins. Compounds 1c (IC50 = 18.09 ± 0.25 μM), 1h (IC50 = 4.14 ± 0.10 μM), and 2a (IC50 = 15.69 ± 0.40 μM) had greater mushroom tyrosinase-inhibitory activities than kojic acid (KA) (IC50 = 48.62 ± 3.38 μM). The SAR results suggest that the 4-substituted resorcinol motif makes an important contribution to tyrosinase inhibition. To investigate whether these compounds bind to human tyrosinase, a human tyrosinase homology model was developed. Docking simulations with mushroom and human tyrosinases showed that 1c, 1h, and 2a bind to the active site of both tyrosinases with higher binding affinities than KA. Pharmacophore analyses showed that two hydroxyl groups of the 4-substituted resorcinol entity act as hydrogen bond donors in both mushroom and human tyrosinases. Kinetic analyses indicated that these compounds were all competitive inhibitors. Compound 2a inhibited cellular tyrosinase activity and melanogenesis in α-MSH plus IBMX-stimulated B16F10 melanoma cells more strongly than KA. These results suggest that 2a is a promising candidate for the treatment of skin pigment disorders, and show the 4-substituted resorcinol entity importantly contributes to tyrosinase inhibition.

Identification of novel C-2 symmetric Bis-Azo-Azamethine molecules as competitive inhibitors of mushroom tyrosinase and free radical scavengers: synthesis, kinetics, and molecular docking studies

Tyrosinase is a multi-copper enzyme found in plants, animals and microorganisms, plays a critical role in the melanogenesis and browning process critical to cosmetics and food industries. Many natural, semi-synthetic and synthetic inhibitors have been discovered. To this end, a small library of symmetrical Bis-Azo-Azamethine hybrids 5a–j was synthesized and characterized through spectroscopic and analytical data and explored for mushroom tyrosinase and free radical scavenging activity. All of the molecules 5a–j explicated better potential compared to the standard Kojic acid. On the whole, compound 5i having IC50 value 0.002 ± 0.004 µM was found to be the most potent derivative. The Kinetic studies were performed for 5i and indicating the mode of inhibition in a competitive manner. Structure Activity Relationship (SAR) analysis and docking studies were carried out. Thus compound 5i bearing bulky naphthyl groups was most potent and, The molecular docking indicated formation of two hydrogen bonds with Arg268 and one hydrophobic interaction with Glu322. The carbonyl oxygen of 5i interacts with Arg268 and form two hydrogen bonds having lengths 2.44 and 2.62 Å, respectively. In the same way, compounds 5a–j were appraised for DPPH free radical scavenging ability and five of them 5d, 5e, 5h, 5i and 5j were found to exhibit higher % scavenging potency compared with vitamin C, as the standard. Interesting compound 5i was again the most potent in the series. The current investigation points towards the role of naphthyl group in design of new inhibitors of melanogenesis and the antioxidants with improved efficacy. Communicated by Ramaswamy H. Sarma

Jeju Magma-Seawater Inhibits α-MSH-Induced Melanogenesis via CaMKKβ-AMPK Signaling Pathways in B16F10 Melanoma Cells.

Melanin protects skin from ultraviolet radiation, toxic drugs, and chemicals. Its synthesis is sophisticatedly regulated by multiple mechanisms, including transcriptional and enzymatic controls. However, uncontrolled excessive production of melanin can cause serious dermatological disorders, such as freckles, melasma, solar lentigo, and cancer. Moreover, melanogenesis disorders are also linked to neurodegenerative diseases. Therefore, there is a huge demand for safer and more potent inhibitors of melanogenesis. In the present study, we report novel inhibitory effects of Jeju magma-seawater (JMS) on melanogenesis induced by α-melanocyte stimulating hormone (α-MSH) in B16F10 melanoma cells. JMS is the abundant underground seawater found in Jeju Island, a volcanic island of Korea. Research into the physiological effects of JMS is rapidly increasing due to its high contents of various minerals that are essential to human health. However, little is known about the effects of JMS on melanogenesis. Here, we demonstrate that JMS safely and effectively inhibits α-MSH-induced melanogenesis via the CaMKKβ (calcium/calmodulin-dependent protein kinase β)-AMPK (5′ adenosine monophosphate-activated protein kinase) signaling pathway. We further demonstrate that AMPK inhibits the signaling pathways of protein kinase A and MAPKs (mitogen-activated protein kinase), which are critical for melanogenesis-related gene expression. Our results highlight the potential of JMS as a novel therapeutic agent for ameliorating skin pigmentation-related disorders.

Synthesis, computational studies and enzyme inhibitory kinetics of benzothiazole-linked thioureas as mushroom tyrosinase inhibitors

Herein, we report synthesis of a set of benzothiazole-thiourea hybrids with aromatic and aliphatic side chains (BT1 to BT9) using an elegant synthetic strategy. The newly synthesized benzothiazole-thiourea conjugates were subjected to In-vitro tyrosinase inhibition and free radical scavenging activity. Majority of the compounds indicated inhibition considerably improved than the standard; compound (Kojic acid with IC50 = 16.8320 ± 1.1600 µM) BT2 with IC50 = 1.3431 ± 0.0254 µM was found to be the best inhibitor. A non-competitive mode of inhibition of BT2 was disclosed with Ki value of 2.8 µM. In order to study enzyme-inhibitor interactions SAR analysis molecular docking was carried out. The amino groups of thiourea were involved in hydrogen bonding with Glu322 showing the bond length of 1.74 and 2.70 Å, respectively. Moreover, the coupling of π-π was displayed between benzothiazole and benzene rings of His244 and His263, respectively. The outcome of this study might help to develop new inhibitors of melanogenesis, important for cosmetic and food products. Communicated by Ramaswamy H. Sarma

Melochia corchorifolia extract inhibits melanogenesis in B16F10 mouse melanoma cells via activation of the ERK signaling.

Numerous researches have focused on discovering available inhibitors of melanogenesis from natural medicinal plants with stable efficacy and safety to resolve cutaneous hyperpigmentary problems. Melochia corchorifolia Linn. (MC) has been used as folk medicine to treat various diseases. However, the effect of MC on melanogenesis remains unknown. In this study, we investigated the effect of MC extract on melanogenesis and its underlying mechanisms in B16F10 mouse melanoma cells. B16F10 cells were treated with MC extract, and then, cell viability, melanin content, and tyrosinase activity were analyzed. The mRNA and protein expression of tyrosinase and microphthalmia-associated transcription factor (MITF) were evaluated using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting, respectively. Phosphorylated or total protein levels in MC extract-induced signaling pathways were analyzed by Western blotting. Treatment of B16F10 cells with MC extract inhibited melanin synthesis and intracellular tyrosinase activity in a dose-dependent manner with no cytotoxicity. Protein and mRNA expressions of tyrosinase and MITF were also significantly decreased by MC extract treatment. In addition, phosphorylated level of extracellular signal-regulated kinase (ERK) was obviously increased by MC extract, but AKT pathway was not activated. Inhibited ERK phosphorylation by pretreatment with a selective ERK inhibitor PD98059 significantly reversed the decreased melanin content induced by treatment with MC extract in B16F10 cells. MC extract inhibits melanogenesis in B16F10 mouse melanoma cells through suppression of MITF-tyrosinase signaling pathway by ERK activation.

Halogenated aromatic thiosemicarbazones as potent inhibitors of tyrosinase and melanogenesis.

A set of 21 halogenated thiosemicarbazones (TSCs) have been synthesized and its inhibitory properties toward activity diphenolase of mushroom tyrosinase and their ability to inhibition of melanogenesis in B16F10 murine, melanoma cell line have been investigated. The molecular docking to the active site of the enzyme has been also performed to investigate the nature of enzyme-inhibitor interactions. The obtained outcomes allowed us to perform SAR analysis. TSC 6, 12 and 21 exhibited the most potent inhibitory properties showing IC50 of 0.5, 0.9 and 0.8 µM, respectively. They revealed reversible and competitive manner of tyrosinase inhibition. According to SAR analysis, para-substituted acetophenone derivatives of thiosemicarbazones have the highest affinity to the enzyme among the investigated compounds. Melanin production in B16F10 cells was inhibited by all investigated compounds at the micromolar level. Suggested inhibition mechanism is based on the interaction between a sulfur atom of thiourea moiety of the thiosemicarbazones, and copper ions in the active site of the enzyme. These results might be useful in searching novel inhibitors of melanogenesis which could be used in the cosmetic and food industry.

Isolation of phenylpropanoid sucrose esters from the roots of Persicaria orientalis and their potential as inhibitors of melanogenesis

Cosmetically, hyperpigmentation is an important issue and the most prominent target for inhibiting hyperpigmentation is, tyrosinase, the rate-limiting enzyme in melanogenesis. Therefore, in this research, we have screened several medicinal plants collected from Bangladesh for their anti-tyrosinase activity and found that roots of Persicaria orientalis have potent inhibitory activity. Nine compounds, including five phenylpropanoid sucrose esters (1–5), were isolated from the EtOH extract of P. orientalis roots. The chemical structures were determined based on spectroscopic methods. All the tested compounds (1–5), significantly reduced extracellular melanin formation in B16 melanoma cells and inhibited tyrosinase monophenolase and diphenolase activity in a dose dependent manner. Compound 4 was twice as effective as kojic acid, when l-DOPA was used as the substrate. Compound 1 and 4 showed better inhibitory activity (>59%) on melanin synthesis at a treated concentration of 50 µM compare with arbutin (730 µM). At 6.25 µM concentration, compounds 2 and 5, inhibited extracellular melanin production by 53.1% and 40.2%, respectively. Structure-activity-relationship suggested that both the feruloyl (C-6′) and acetyl (C-2′/ C-4′) groups in sucrose moiety is essential for cytotoxicity. Our finding indicated the roots of P. orientalis is a potential source of natural compounds that could be used in dermatological and cosmetological research. To the best of our knowledge, this is the first study to report the potential melanogenesis inhibitory activity of phenylpropanoid sucrose esters.

Natural and semisynthetic oxyprenylated aromatic compounds as stimulators or inhibitors of melanogenesis

It has been very recently shown how naturally occurring oxyprenylated coumarins are effective modulators of melanogenesis. In this short communication we wish to generalize the potentialities as skin tanning or whitening agents of a wider panel of natural and semisynthetic aromatic compounds, including coumarins, cinnamic and benzoic acids, cinnamaldehydes, benzaldehyde, and anthraquinone derivatives. A total number of 43 compounds have been tested assaying their capacity to inhibit or stimulate melanin biosynthesis in cultured murine Melan A cells. The wider number of chemicals herein under investigation allowed to depict a detailed structure-activity relationship, as the following: (a) benzoic acid derivatives are slightly pigmenting agent, for which the effect is more pronounced in compounds with longer O-side chains; (b) independently from the type of substitution, cinnamic acids are able to increase melanin biosynthesis, while benzaldehydes are able to decrease it; (c) coumarins with a 3,3-dimethylallyl or shorter skeletons as substituents in position 7 are tanning agents, while coumarins with farnesyloxy groups are whitening ones; (d) double oxyprenylation in position 6 and 7 and 3,3-dimethylallyl or geranyl skeletons have slight depigmenting capacities, while farnesyl skeletons tend to marginally increase the tanning effect; (e) the presence of electron withdrawing groups (acetyl, COOH, and -Cl) and geranyl or farnesyl oxyprenylated chains respectively in positions 3 and 7 of the coumarin nucleus lead to a whitening effect, and finally (f) oxyprenylated anthraquinones have only a weak depigmenting capacity.

Structural and molecular modelling studies of antimelanogenic piper-amide TRPM1 antagonists

ABSTRACTPiper-amides exhibit diverse biological activities, including antimelanogenic effects. In our previous studies, we identified a potent piper-amide derivative that inhibited melanogenesis via the TRPM1 calcium channel. Despite its potential as a therapeutic target, the three-dimensional structure of TRPM1 is still not available. Thus, structure-guided compound design and the discovery of novel inhibitors of melanogenesis have been limited. In the present study, a series of computational methods, including homology modelling, docking, molecular dynamics simulation and field-based pharmacophore modelling, were integrated to explore the structural features of natural piper-amide-like compounds related to the TRPM1 target. These studies suggested the binding mode and provided a 3D pharmacophore model of the ligands, which can be helpful in understanding the TRPM1–ligand interactions at the molecular level and in designing potent antagonists of TRPM1.

Inhibitory properties of aromatic thiosemicarbazones on mushroom tyrosinase: Synthesis, kinetic studies, molecular docking and effectiveness in melanogenesis inhibition

The group of 19 thiosemicarbazones (TSCs) were synthesized and its inhibitory activity toward mushroom tyrosinase and ability to inhibition of melanogenesis in B16 cells were investigated. Moreover, molecular docking of these compounds to the active site of the enzyme was performed. The obtained results allowed to make the structure-activity relationship (SAR) analysis. Kinetic studies revealed that TSCs 1, 2, 11 and 18 have better inhibitory properties than kojic acid, a reference compound, with the best inhibitory constant (Ki) value of 0.38 µM for TSC 2. According to SAR analysis, the smaller and less branched molecules exhibit higher affinity to the enzyme. Melanin production in B16 cells was inhibited by all investigated compounds at micromolar level. Most of compounds studied in this work can be considered as potent inhibitors of tyrosinase and melanogenesis. They may have broad application in food preservatives and cosmetics. Combined results of molecular docking and SAR analysis can be helpful in designing novel tyrosinase inhibitors of desired properties.

Inhibitors of Melanogenesis: An Updated Review.

Melanins are pigment molecules that determine the skin, eye, and hair color of the human subject to its amount, quality, and distribution. Melanocytes synthesize melanin and provide epidermal protection from various stimuli, such as harmful ultraviolet radiation, through the complex process called melanogenesis. However, serious dermatological problems occur when there is excessive production of melanin in different parts of the human body. These include freckles, melasma, senile lentigo, pigmented acne scars, and cancer. Therefore, controlling the production of melanin is an important approach for the treatment of pigmentation related disorderes. In this Perspective, we focus on the inhibitors of melanogenesis that directly/indirectly target a key enzyme tyrosinase as well as its associated signaling pathways.

Melanogenesis Inhibitors.

Abnormally high production of melanin or melanogenesis in skin melanocytes results in hyperpigmentation disorders, such as melasma, senile lentigines or freckles. These hyperpigmentary skin disorders can significantly impact an individual's appearance, and may cause emotional and psychological distress and reduced quality of life. A large number of melanogenesis inhibitors have been developed, but most have unwanted side-effects. Further research is needed to better understand the mechanisms of hyperpigmentary skin disorders and to develop potent and safe inhibitors of melanogenesis. This review summarizes the current understanding of melanogenesis regulatory pathways, the potential involvement of the immune system, various drugs in current use, and emerging treatment strategies to suppress melanogenesis.

159 - Identification of Antimelanogenic Peptides through Positional Scanning of a Synthetic Peptide Combinatorial Library

Antimelanogenic peptides are potentially useful as cosmeceutical ingredients in skin whitening agents. The purpose of this study was to identify peptide inhibitors of cellular melanogenesis through positional scanning of a synthetic peptide combinatorial library (PS-SPCL). A synthetic hexapeptide combinatorial library consisted of 6 positional sub-libraries, namely OXXXXX, XOXXXX, XXOXXX, XXXOXX, XXXXOX, and XXXXXO, where O positions are any one of the 19 amino acids excluding cysteine, and other X positions are equimolar mixtures of the 19 amino acids. The antimelanogenic effects of peptide mixtures were evaluated in murine melanoma B16-F10 cells stimulated with α-melanocyte-stimulating hormone (α-MSH) to identify the sequence of antimelanogenic hexapeptides. PS-SPCL identified the active hexapeptide sequences as (F/I)(N/S)(D/H/N)(H/N)L(G/F)-NH 2 . Of the hexapeptide mixtures and individual hexapeptides evaluated, the strongest antimelanogenic activity was seen with hexapeptide B6 (FSHHLG-NH 2 ). Hexapeptide B6 decreased melanin content and levels of melanogenic enzymes in B16-F10 cells stimulated with α-MSH. Additionally, it decreased melanin content in human epidermal melanocytes stimulated with L-tyrosine. The present study identified novel antimelanogenic hexapeptides that might be useful for controlling skin pigmentation.

Inhibitors of melanogenesis in B16 melanoma 4A5 cells from flower buds of Lawsonia inermis (Henna).

The methanolic extract of Lawsonia inermis L. (henna) showed significant inhibitory activity toward melanogenesis in B16 melanoma 4A5 cells. Among the constituents isolated from the methanolic extract, luteolin, quercetin, and (±)-eriodictyol showed stronger inhibitory activity than the reference compound, arbutin. Several structure-activity relationships of the flavonoids were suggested, and OGlc<H=OH at the 3-position, OGlc<OH at the 4'-position, and the double bond between the 2- and 3-positions were important. The active constituents suppressed tyrosinase, tyrosinase related protein (TRP)-1, and TRP-2 mRNA expression. The suppression was considered as one of the mechanisms of action. Furthermore, the methanolic extract and several constituents, including luteoloside and spiraeoside, showed anti-plasmin activity, which is considered to play a key role in UV-stimulated melanogenesis in human skin.

The potential of minor ginsenosides isolated from the leaves of Panax ginseng as inhibitors of melanogenesis.

Three minor ginsenosides, namely, ginsenoside Rh6 (1), vina-ginsenoside R4 (2) and vina-ginsenoside R13 (3), were isolated from the leaves of hydroponic Panax ginseng. The chemical structures were determined based on spectroscopic methods, including fast atom bombardment mass spectroscopy (FAB-MS), 1D-nuclear magnetic resonance (NMR), 2D-NMR, and, infrared (IR) spectroscopy. The melanogenic inhibitory activity of compounds 1, 2 and 3 was 23.9%, 27.8% and 35.2%, respectively, at a concentration of 80 µM. Likewise, the three compounds showed inhibitory activity on body pigmentation on a zebrafish model, which is commonly used as a model for biomedical or cosmetic research. These results from in vitro and in vivo systems suggest that the three aforementioned compounds isolated from Panax ginseng may have potential as new skin whitening compounds.

Assessment of Cuscuta chinensis seeds׳ effect on melanogenesis: Comparison of water and ethanol fractions in vitro and in vivo

Ethnopharmacological relevanceCuscuta chinensis seeds have traditionally been used to treat freckles and melasma in Asia, although recent reports have revealed that Semen cuscutae is a promoter of melanogenesis. The present study aims to investigate the mechanism of this opposite effect of Semen cuscutae on melanogenesis. Materials and methodsIn accordance with traditional usage, the water fraction and the ethanol fraction from Semen cuscutae (WFSC/EFSC) were extracted to determine the herbal effects by examining the activity of mushroom tyrosinase, cellular melanin contents, tyrosinase activity assay, quantitative-reverse transcription polymerase chain reaction (qRT-PCR), and Western blot analysis for tyrosinase in B16F10 mouse melanoma cells. The melanocyte phenotypes of zebrafish larvae were observed while the in vivo melanin contents and tyrosinase activity were determined. ResultsThe activity of mushroom tyrosinase assay shown that WFSC was an uncompetitive inhibitor of mushroom tyrosinase, while EFSC indicated dose-dependent activation of the mushroom tyrosinase activity. The WFSC markedly inhibited 3-isobutyl-1-methylxanthine (IBMX)-stimulated melanin synthesis and tyrosinase activity in vitro. Howeveran accelerant role in melanin synthesis and tyosinase activity. Neither fraction had any effect on the IBMX-induced expression of tyrosinase protein or mRNA. The WFSC strongly inhibited melanin synthesis and cellular tyrosinase activity in vivo. Furthermore, with the function of WFSC at a higher concentration, a punctate melanocyte pattern appeared that was similar to the pattern induced by arbutin or Mequinol (MQ). The EFSC had no effect on the melanocytes of zebrafish larvae. It was discovered that WFSC did not show a stable inhibitory effect until it was extracted 1 month later. ConclusionsThese results suggest that the opposite effects of Cuscuta chinensis seeds were caused by the extraction methods and that time has an important role on the effect of WFSC. Both WFSC and EFSC significantly influence melanogenesis by regulating enzymatic activity of tyrosinase. In addition, the data indicate that wildtype (WT) zebrafish may be an ideal model for testing inhibitors of melanogenesis from clinically active herbs.

Biological evaluation of novel derivatives of the orange pigments from Monascus sp. as inhibitors of melanogenesis

Nitrogenous derivatives of the two orange pigments from Monascus sp. with anti-melanogenic activities were prepared using fermentation and chemical synthesis. The pigments were produced in a 5 l jar fermentor. A total of 33 derivatives were synthesized via incorporation of L-amino acids and amines into the pigments. Two derivatives with high inhibitory melanin-synthesizing activities and low cell toxicities were selected based on testing using B16F10 cells. Glutamic acid and (S)-(+)-1-amino-2-propanol derivatives showed high inhibitory activities against melanogenesis. Both the reaction and expression of tyrosinase, an important enzyme in the melanin-synthesizing pathway, were inhibited by the glutamic acid derivative in a dose-dependent manner. The (S)-(+)-1-amino-2-propanol derivative inhibited expression of tyrosinase in cells, but not the tyrosinase reaction. TRP1 and TRP2, other important proteins in melanin-synthesis, were not affected by the two derivatives.