Biology of melanogenesis and the search for hypopigmenting agents

Cellular and Non-cellular Antioxidant Properties of Vitamin E-Loaded Metallic-Quercetin/Polycaprolactone Nanoparticles for the Treatment of Melanogenesis

Inhibition of melanogenesis by quercetin and vitamin E is extensively reported in the literature, independently, with limitations in antioxidant potential owing to less permeation, solubility, decreased bioavailability, and reduced stability. Thus, the aim of the present study was to synthesize a novel complex of metal ions (copper and zinc) with quercetin to enhance antioxidant properties which were confirmed by docking studies. Polycaprolactone-based nanoparticles of the synthesized complex (PCL-NPs, Q-PCL-NPs, Zn-Q-PCL-NPs, Cu-Q-PCL-NPs) were made later loaded with vitamin E which made the study more interesting in enhancing antioxidant profile. Nanoparticles were characterized for zeta size, charge, and polydispersity index, while physiochemical analysis of nanoparticles was strengthened by FTIR. Cu-Q-PCL-NPs-E showed maximum in vitro release of vitamin E, i.e., 80 ± 0.54%. Non-cellular antioxidant effect by 2,2-diphenyl-1-picrylhydrazyl was observed at 93 ± 0.23% in Cu-Q-PCL-NPs-E which was twofold as compared to Zn-Q-PCL-NPs-E. Michigan Cancer Foundation-7 (MCF-7) cancer cell lines were used to investigate the anticancer and cellular antioxidant profile of loaded and unloaded nanoparticles. Results revealed reactive oxygen species activity of 90 ± 0.32% with the addition of 89 ± 0.64% of its anticancer behavior shown by Cu-Q-PCL-NPs-E after 6 and 24h. Similarly, 80 ± 0.53% inhibition of melanocyte cells and 95 ± 0.54% increase of keratinocyte cells were also shown by Cu-Q-PCL-NPs-E that confirmed the tyrosinase enzyme inhibitory effect. Conclusively, the use of zinc and copper complex in unloaded and vitamin E-loaded nanoparticles can provide enhanced antioxidant properties with inhibition of melanin, which can be used for treating diseases of melanogenesis.

Dual Antimelanogenic Effect of Nicotinamide-Stabilized Phloretin Nanocrystals in Larval Zebrafish

Melanin is a kind of dark insoluble pigment that can cause pigmentation and free-radical clearance, inducing melasma, freckles, and chloasma, affecting the quality of life of patients. Due to poor water solubility and low safety, the absorption of poorly water-soluble drugs is limited by the hinderance of a skin barrier. Therefore, it is necessary to develop new, safe, and highly efficient drugs to improve their transdermal absorption efficiency and thus to inhibit the production of melanin. To address these issues, we developed a new nicotinamide (NIC)-stabilized phloretin nanocrystals (PHL-NCs). First, NC technology significantly increased the solubility of PHL. The in vitro release results indicated that at 6 h, the dissolution of the PHL-NIC-NCs was 101.39% ± 2.40% and of the PHL-NCs was 84.92% ± 4.30%, while that of the physical mixture of the two drugs was only 64.43% ± 0.02%. Second, NIC acted not only as a stabilizer to enlarge the storage time of PHL-NIC-NCs (improved to 10-day in vitro stability) but also as a melanin transfer inhibitor to inhibit melanin production. Finally, we verified the melanin inhibition effect of PHL-NIC-NCs evaluated by the zebrafish model. It showed that 0.38 mM/L PHL-NIC-NCs have a lower tyrosinase activity at 62.97% ± 0.52% and have less melanin at 36.57% ± 0.44%. The inhibition effect of PHL-NCs and PHL-NIC-NCs was stronger compared to the positive control arbutin. In conclusion, the combination of NIC and PHL achieves better inhibition of tyrosinase and inhibition of melanin production through synergism. This will provide a direction to the subsequent development of melanin-inhibiting drugs and the combined use of pharmaceutical agents.

Anthocyanins, Vibrant Color Pigments, and Their Role in Skin Cancer Prevention

Until today, numerous studies evaluated the topic of anthocyanins and various types of cancer, regarding the anthocyanins' preventative and inhibitory effects, underlying molecular mechanisms, and such. However, there is no targeted review available regarding the anticarcinogenic effects of dietary anthocyanins on skin cancers. If diagnosed at the early stages, the survival rate of skin cancer is quite high. Nevertheless, the metastatic form has a short prognosis. In fact, the incidence of melanoma skin cancer, the type with high mortality, has increased exponentially over the last 30 years, causing the majority of skin cancer deaths. Malignant melanoma is considered a highly destructive type of skin cancer due to its particular capacity to grow and spread faster than any other type of cancers. Plants, in general, have been used in disease treatment for a long time, and medicinal plants are commonly a part of anticancer drugs on the market. Accordingly, this work primarily aims to emphasize the most recent improvements on the anticarcinogenic effects of anthocyanins from different plant sources, with an in-depth emphasis on melanoma skin cancer. We also briefly summarized the anthocyanin chemistry, their rich dietary sources in flowers, fruits, and vegetables, as well as their associated potential health benefits. Additionally, the importance of anthocyanins in topical applications such as their use in cosmetics is also given.

Synthesis and Studies of the Inhibitory Effect of Hydroxylated Phenylpropanoids and Biphenols Derivatives on Tyrosinase and Laccase Enzymes

The impaired activity of tyrosinase and laccase can provoke serious concerns in the life cycles of mammals, insects and microorganisms. Investigation of inhibitors of these two enzymes may lead to the discovery of whitening agents, medicinal products, anti-browning substances and compounds for controlling harmful insects and bacteria. A small collection of novel reversible tyrosinase and laccase inhibitors with a phenylpropanoid and hydroxylated biphenyl core was prepared using naturally occurring compounds and their activity was measured by spectrophotometric and electrochemical assays. Biosensors based on tyrosinase and laccase enzymes were constructed and used to detect the type of protein-ligand interaction and half maximal inhibitory concentration (IC50). Most of the inhibitors showed an IC50 in a range of 20-423 nM for tyrosinase and 23-2619 nM for laccase. Due to the safety concerns of conventional tyrosinase and laccase inhibitors, the viability of the new compounds was assayed on PC12 cells, four of which showed a viability of roughly 80% at 40 µM. In silico studies on the crystal structure of laccase enzyme identified a hydroxylated biphenyl bearing a prenylated chain as the lead structure, which activated strong and effective interactions at the active site of the enzyme. These data were confirmed by in vivo experiments performed on the insect model Tenebrio molitur.

Annona squamosa L. leaves inhibit alpha-melanocyte-stimulating hormone (α-MSH) stimulated melanogenesis via p38 signaling pathway in B16F10 melanoma cells

BACKGROUND

Annona squamosa L. is a branched shrub, which is believed to be originated from the America and West Indies. Fruits of this plant are commonly known as custard apple, sugar apple, or sweetsops. A number of studies have proven a range of biological activities associated with various parts of A. squamosa.

AIMS

The main aim of the present investigation was to evaluate potential inhibitory effects of A. squamosa leaf extract (ALE) on melanogenesis and its underlying mechanisms in B16F10 murine melanoma cells.

METHODS

Inhibitory effects of A. squamosa leaf extract (ALE) on melanogenesis were primarily assessed by determining melanin contents. Effects of ALE on tyrosinase activity and the expression of proteins associated with melanogenesis were then determined. GC-MS analysis was carried out to identify the phytochemical profile of A. squamosa leaf extract.

RESULTS

Antimelanogenic effects of ALE were found to exert through the inhibition of melanocyte inducing transcription factor (MITF) and activation of p38. GC-MS analysis identified ent-kaur-16-en-19-ol, 18-oxokauran-17-yl acetate, and β-sitosterol as major phytochemicals.

CONCLUSION

To our knowledge, this is the first study on the antimelanogenic effects of A. squamosa leaves, rationalizing the use A. squamosa leaf extract as a natural depigmentation agent for the treatment of skin diseases and the development of cosmetic products with enhanced skin-lightening capabilities.

Discovery of new depigmenting compounds and their efficacy to treat hyperpigmentation: Evidence from in vitro study

Human skin pigmentation is a result of constitutive and facultative pigmentation. Facultative pigmentation is frequently stimulated by UV radiation, pharmacologic drugs, and hormones whereby leads to the development of abnormal skin hyperpigmentation. To date, many state-of-art depigmenting compounds have been studied using in vitro model to treat hyperpigmentation problems for cosmetic dermatological applications; little attention has been made to compare the effectiveness of these depigmenting compounds and their mode of actions. In this present article, new and recent depigmenting compounds, their melanogenic pathway targets, and modes of action are reviewed. This article compares the effectiveness of these new depigmenting compounds to modulate several melanogenesis-regulatory enzymes and proteins such as tyrosinase (TYR), TYR-related protein-1 (TRP1), TYR-related protein-2 (TRP2), microphthalmia-associated transcription factor (MITF), extracellular signal-regulated kinase (ERK) and N-terminal kinases (JNK) and mitogen-activated protein kinase p38 (p38 MAPK). Other evidences from in vitro assays such as inhibition on melanosomal transfer, proteasomes, nitric oxide, and inflammation-induced melanogenesis are also highlighted. This article also reviews analytical techniques in different assays performed using in vitro model as well as their advantages and limitations. This article also provides an insight on recent finding and re-examination of some protocols as well as their effectiveness and reliability in the evaluation of depigmenting compounds. Evidence and support from related patents are also incorporated in this present article to give an overview on current patented technology, latest trends, and intellectual values of some depigmenting compounds and protocols, which are rarely highlighted in the literatures.

Understanding the role of extracts from sea buckthorn seed residues in anti-melanogenesis properties on B16F10 melanoma cells

The hydroalcoholic extract of sea buckthorn (Hippophae rhamnoides L.) seed residues (HYD-SBSR) is a potential skin whitening agent. To test this material as a potential skin whitening agent, we identified and quantified the main chemical constituents of HYD-SBSR by using ultra-performance liquid chromatography coupled with quadruple time-of-flight tandem mass spectrometry (UPLC-QTOF-MS/MS) and ultra-high performance liquid chromatography coupled with triple quadruple mass spectrometry (UPLC-QQQ-MS). The anti-melanogenesis properties of HYD-SBSR on B16F10 mouse melanoma cells were analysed and the mechanism was measured on both the transcriptional and translational levels. About 24 compounds were identified. Kaempferol and its derivatives were the main compounds with a concentration of about (2796.22 ± 31.55) μg per g DW. The following order among the detected compounds was observed: quercetin and its derivatives > isorhamnetin and its derivatives > procyanidins. HYD-SBSR has a strong antioxidant activity but with a slight cytotoxic effect on B16F10 when treated with 45.45 μg mL-1 and 4.55 μg mL-1 respectively, for 48 h. HYD-SBSR has been found to significantly decrease melanin content (P < 0.01) in 24 h, 48 h, and 72 h. Additionally, strong inhibitory extracellular tyrosinase activities and decreasing intracellular tyrosinase activities were also observed (P < 0.01). HYD-SBSR shows inhibitory effects on the expression of tyrosinase (TYR) and tyrosinase-related protein 1 (TRP-1), and the secretion of TYR and TRP-1 proteins in cell lines. The protein levels of tyrosinase-related protein 2 (TRP-2) and microphthalmia-associated transcription factor (MITF) showed no significant difference. HYD-SBSR may inhibit melanin synthesis by decreasing the tyrosinase activity and down-regulating the expression of TYR and TRP-1 which were probably induced by other transcriptional factors rather than MITF.

Ethyl linoleate inhibits α-MSH-induced melanogenesis through Akt/GSK3β/β-catenin signal pathway

Ethyl linoleate is an unsaturated fatty acid used in many cosmetics for its various attributes, such as antibacterial and anti-inflammatory properties and clinically proven to be an effective anti-acne agent. In this study, we investigated the effect of ethyl linoleate on the melanogenesis and the mechanism underlying its action on melanogenesis in B16F10 murine melanoma cells. Our results revealed that ethyl linoleate significantly inhibited melanin content and intracellular tyrosinase activity in α-MSH-induced B16F10 cells, but it did not directly inhibit activity of mushroom tyrosinase. Ethyl linoleate inhibited the expression of microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase related protein 1 (TRP1) in governing melanin pigment synthesis. We observed that ethyl linoleate inhibited phosphorylation of Akt and glycogen synthase kinase 3β (GSK3β) and reduced the level of β-catenin, suggesting that ethyl linoleate inhibits melanogenesis through Akt/GSK3β/β-catenin signal pathway. Therefore, we propose that ethyl linoleate may be useful as a safe whitening agent in cosmetic and a potential therapeutic agent for reducing skin hyperpigmentation in clinics.

Effect of Purified Mushroom Tyrosinase on Melanin Content and Melanogenic Protein Expression

In mammalian melanocytes, melanosome is a highly specialized organelle where melanin is synthesized. Melanin synthesis is controlled by tyrosinase, the vital enzyme in melanogenic pathway. The present investigation is based on an effect of purified mushroom tyrosinase of Agaricus bisporus on B16F10 melanocytes for the melanin production via blocking pigment cell machinery. Using B16F10 melanocytes showed that the stimulation of melanogenesis by purified tyrosinase is due to increased tyrosinase absorption. Cellular tyrosinase activity and melanin content in B16F10 melanocytes were increased by purified tyrosinase in a dose-dependent manner. Western blot analysis revealed that cellular tyrosinase levels were enhanced after treatment with purified tyrosinase for 48 hours. Furthermore, tyrosinase induced phosphorylation of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) in a dose-dependent manner. The purified tyrosinase-mediated increase of tyrosinase activity was significantly attenuated by H89, LY294002, Ro-32-0432, and PD98059, cAMP-dependent protein kinase inhibitors. The results indicate that purified tyrosinase can be used as contestant for the treatment of vitiligous skin conditions.

Heterogeneous Pathology of Melasma and Its Clinical Implications

Melasma is a commonly acquired hypermelanosis that affects sun-exposed areas of the skin, with frequent facial involvement. Its histologic manifestations are evident in the epidermis, extracellular matrix, and dermis. In addition to epidermal pigmentation, pathologic findings of melasma include extracellular matrix abnormality, especially solar elastosis. The disrupted basement membrane has been described in melasma with variable incidences. In the dermis, an increase in vascularity and an increase in the number of mast cells were observed, indicating that dermal factors have critical roles in the pathogenesis of melasma, despite the fact that melasma is characterized by epidermal hyperpigmentation. This review discusses such histologic characteristics of melasma, with consideration to their implications for melasma treatment.

Compounds leached from quinoa seeds inhibit matrix metalloproteinase activity and intracellular reactive oxygen species

OBJECTIVE

Quinoa (Chenopodium quinoa Willd.) is a seed crop rich in bioactive compounds including phytoecdysones (especially 20-hydroxyecdysone, 20HE), polyphenols, proteins and essential fatty acids. We previously reported a method to leach and concentrate quinoa bioactives into a complex phytochemical mixture termed quinoa leachate (QL). Here, we aimed to determine the effect of QL and its chemically distinct fractions on five biochemical endpoints relevant to skin care applications: (i) cell viability, (ii) matrix metalloproteinase (MMP) mRNA expression, (iii) MMP enzymatic activity, (iv) tyrosinase enzymatic activity and (v) intracellular reactive oxygen species (ROS) production.

METHODS

Quinoa leachate was fractionated and chemically characterized using column chromatography and liquid chromatography-mass spectrometry (LC-MS). Cell viability was determined using a MTT assay in four mammalian cell lines. MMP-1 mRNA expression was assessed in human dermal fibroblasts (HDF) via qRT-PCR. The enzymatic activity of MMP-9 and tyrosinase was measured using fluorometric and colorimetric in vitro assays, respectively. Lipopolysaccharide (LPS)-induced ROS production was determined in human dermal fibroblasts by fluorescence intensity of an oxidant-sensitive probe.

RESULTS

Quinoa leachate was separated into three fractions: (i) carbohydrate-rich fraction (QL-C; 71.3% w/w of QL); (ii) phytoecdysone, polyphenol and protein-rich fraction (QL-P, 13.3% w/w of QL); (iii) oil-rich fraction (QL-O, 10.8% w/w of QL). QL did not reduce cell viability in any of the four cell lines tested. QL, QL-P and QL-O each significantly inhibited MMP-1 mRNA expression in HDF at a concentration of 5 μg mL(-1) . QL and QL-P also significantly inhibited MMP-9 enzymatic activity, whereas QL-P demonstrated significant tyrosinase enzymatic inhibition. Furthermore, QL, QL-P, QL-O and 20HE significantly inhibited intracellular ROS production.

CONCLUSION

This study is the first to demonstrate the MMP, tyrosinase and ROS inhibiting properties of multiple different phytochemical components derived from quinoa seeds. Our work indicates that quinoa phytochemicals may play a role in the treatment and prevention of skin ageing through a multiplicity of effects.

Application of FTIR microspectroscopy for characterization of biomolecular changes in human melanoma cells treated by sesamol and kojic acid

BACKGROUND

Hyperpigmentation is aesthetic undesirable. Sesamol and the standard antimelanogenic agent (kojic acid) were shown to hinder melanogenesis by blocking tyrosinase and reducing melanin content.

OBJECTIVE

The FTIR microspectroscopy was used in an attempt to find a novel method to define biological alternation in a melanogenesis inhibition of sesamol and kojic acid.

METHODS

Tyrosinase inhibition and melanin content of sesamol and kojic acid were evaluated. The FTIR microspectroscopy was adopted to define the vibrational characteristic involved with the melanogenesis in the untreated SK-MEL2 cells vs. the sesamol- and kojic-treated SK-MEL2 cells.

RESULTS

Sesamol and kojic acid inhibited mushroom tyrosinase at IC₅₀ of 0.33 μg/ml and 6.1±0.4 μg/ml, respectively. Moreover, 30 μg/ml sesamol inhibited 23.55±8.25% cellular tyrosinase activity in human SK-MEL2 cells, while 600 μg/ml kojic acid inhibited 33.9±1.4% cellular tyrosinase activity in the same cells. In the SK-MEL2-treated with two inhibitors, the FTIR spectra assigned to the lipid and nucleic acid bands were significantly depleted with the secondary protein structure shifted to a more β-pleated secondary protein one.

CONCLUSION

Both sesamol and kojic acid display a similar pattern of antimelanogenesis activity albeit to a different degree. The mechanism of their whitening effect may be via the alteration of (a) the enzyme conformation disallowing the ordinary enzyme-substrate interaction and maybe (b) the integrity of the lipid-containing melanosome. Our results support the alternative use of FTIR microspectroscopy as a simple and reagent-free method for characterization of biomolecular changes in human melanoma cells.

Recent biotechnological progress in enzymatic synthesis of glycosides

Glycosylation is one of the most important post-modification processes of small molecules and enables the parent molecule to have increased solubility, stability, and bioactivity. Enzyme-based glycosylation has achieved significant progress due to advances in protein engineering, DNA recombinant techniques, exploitation of biosynthetic gene clusters of natural products, and computer-based modeling programs. Our report summarizes glycosylation data that have been published within the past five years to provide an overall review of current progress. We also present the future trends and perspectives for glycosylation.