Mannosylerythritol lipids inhibit melanogenesis via suppressing ERK-CREB-MiTF-tyrosinase signalling in normal human melanocytes and a three-dimensional human skin equivalent

Potential anti-aging applications of microbial-derived surfactantsin cosmetic formulations

The skin aging process is a complex interaction of genetic, epigenetic, and environmental factors, such as chemical pollution and UV radiation. There is growing evidence that biosurfactants, especially those of microbial origin, have distinct age-supportive effects through different mechanisms, such as stimulation of fibroblast growth, high antioxidant capacities, and favorable anti-inflammatory properties. With a growing financial contribution of more than 15 m€per year, microbial surfactants (MSs) display unique biological effects on the skin including improved cell mobility, better nutrient access, and facilitated cellular growth under harsh conditions. Their biodegradable nature, unusual surface activity, good safety profile and tolerance to high temperature and pH variations widen their potential spectrum in biomedical and pharmaceutical applications. MSs typically have lower critical micelle concentration (CMC) levels than chemical surfactants enhancing their effectiveness. As natural surfactants, MSs are considered possible "green" alternatives to synthetic surfactants with better biodegradability, sustainability, and beneficial functional properties. This review therefore aims to explore the potential impacts of MSs as anti-aging ingredients.

Designed Mannosylerythritol Lipid Analogues Exhibiting Both Selective Cytotoxicity Against Human Skin Cancer Cells and Recovery Effects on Damaged Skin Cells

Mannosylerythritol lipids (MELs) are a class of amphipathic molecules bearing a hydrophilic 4-O-β-D-mannopyranosyl-D-erythritol skeleton. Here, we designed and synthesized four kinds of MEL analogues R-MEL-A ([2R,3S]-erythritol type), S-mannosylthreitol lipid (MTL)-A ([2S,3S]-threitol type), R-MTL-A ([2R,3R]-threitol type), and α-S-MEL-A ([2S,3R]-erythritol type) using our previously reported boron-mediated aglycon delivery (BMAD) method and a neighboring group assisted glycosylation method. The selective cytotoxicity of the target compounds against cancer cells was evaluated, with R-MTL-A showing the highest selective cytotoxicity against human skin squamous carcinoma HSC-5 cells. Our findings suggest that R-MTL-A induces necrosis-like cell death against HSC-5 cells by decreasing cell membrane fluidity. R-MTL-A also exhibits an efficient recovery effect on damaged skin cells, indicating that R-MTL-A has potential as a lead compound for new cosmeceuticals with both cancer cell-selective toxicity and recovery effects on damaged skin cells.

Petanin Potentiated JNK Phosphorylation to Negatively Regulate the ERK/CREB/MITF Signaling Pathway for Anti-Melanogenesis in Zebrafish

Petanin, an acylated anthocyanin from the Solanaceae family, shows potential in tyrosinase inhibitory activity and anti-melanogenic effects; however, its mechanism remains unclear. Therefore, to investigate the underlying mechanism of petanin's anti-melanogenic effects, the enzyme activity, protein expression and mRNA transcription of melanogenic and related signaling pathways in zebrafish using network pharmacology, molecular docking and molecular dynamics simulation were combined for analysis. The results showed that petanin could inhibit tyrosinase activity and melanogenesis, change the distribution and arrangement of melanocytes and the structure of melanosomes, reduce the activities of catalase (CAT) and peroxidase (POD) and enhance the activity of glutathione reductase (GR). It also up-regulated JNK phosphorylation, inhibited ERK/RSK phosphorylation and down-regulated CREB/MITF-related protein expression and mRNA transcription. These results were consistent with the predictions provided through network pharmacology and molecular docking. Thus, petanin could inhibit the activity of tyrosinase and the expression of tyrosinase by inhibiting and negatively regulating the tyrosinase-related signaling pathway ERK/CREB/MITF through p-JNK. In conclusion, petanin is a good tyrosinase inhibitor and anti-melanin natural compound with significant market prospects in melanogenesis-related diseases and skin whitening cosmetics.

Promising Application, Efficient Production, and Genetic Basis of Mannosylerythritol Lipids

Mannosylerythritol lipids (MELs) are a class of glycolipids that have been receiving increasing attention in recent years due to their diverse biological activities. MELs are produced by certain fungi and display a range of bioactivities, making them attractive candidates for various applications in medicine, agriculture, and biotechnology. Despite their remarkable qualities, industrial-scale production of MELs remains a challenge for fungal strains. Excellent fungal strains and fermentation processes are essential for the efficient production of MELs, so efforts have been made to improve the fermentation yield by screening high-yielding strains, optimizing fermentation conditions, and improving product purification processes. The availability of the genome sequence is pivotal for elucidating the genetic basis of fungal MEL biosynthesis. This review aims to shed light on the applications of MELs and provide insights into the genetic basis for efficient MEL production. Additionally, this review offers new perspectives on optimizing MEL production, contributing to the advancement of sustainable biosurfactant technologies.

2,4,6-Triphenyl-1-hexene, an Anti-Melanogenic Compound from Marine-Derived Bacillus sp. APmarine135

Although melanin protects against ultraviolet radiation, its overproduction causes freckles and senile lentigines. Recently, various biological effects of metabolites derived from marine microorganisms have been highlighted due to their potential for biological and pharmacological applications. In this study, we discovered the anti-melanogenic effect of Bacillus sp. APmarine135 and verified the skin-whitening effect. Fractions of APmarine135 showed the melanin synthesis inhibition effect in B16 melanoma cells, and 2,4,6-triphenyl-1-hexene was identified as an active compound. The melanogenic capacity of 2,4,6-triphenyl-1-hexene (1) was investigated by assessing the intracellular melanin content in B16 cells. Treatment with 5 ppm of 2,4,6-triphenyl-1-hexene (1) for 72 h suppressed the α-melanocyte-stimulating hormone (α-MSH)-induced intracellular melanin increase to the same level as in the untreated control group. Additionally, 2,4,6-triphenyl-1-hexene (1) treatment suppressed the activity of tyrosinase, the rate-limiting enzyme for melanogenesis. Moreover, 2,4,6-triphenyl-1-hexene (1) treatment downregulated tyrosinase, Tyrp-1, and Tyrp-2 expression by inhibiting the microphthalmia-associated transcription factor (MITF). Furthermore, 2,4,6-triphenyl-1-hexene (1) treatment decreased the melanin content in the three-dimensional (3D) human-pigmented epidermis model MelanoDerm and exerted skin-whitening effects. Mechanistically, 2,4,6-triphenyl-1-hexene (1) exerted anti-melanogenic effects by suppressing tyrosinase, Tyrp-1, and Tyrp-2 expression and activities via inhibition of the MITF. Collectively, these findings suggest that 2,4,6-triphenyl-1-hexene (1) is a promising anti-melanogenic agent in the cosmetic industry.

Rhamnolipids: A biosurfactant for the development of lipid-based nanosystems for food applications

Biosurfactants (surfactants synthesized by microorganisms) are produced by microorganisms and are suitable for use in different areas. Among biosurfactants, rhamnolipids are the most studied and popular, attracting scientists, and industries' interest. Due to their unique characteristics, the rhamnolipids have been used as synthetic surfactants' alternatives and explored in food applications. Besides the production challenges that need to be tackled to guarantee efficient production and low cost, their properties need to be adjusted to the final application, where the pH instability needs to be considered. Moreover, regulatory approval is needed to start being used in commercial applications. One characteristic of interest is their capacity to form oil-in-water nanosystems. Some of the most explored have been nanoemulsions, solid-lipid nanoparticles and nanostructured lipid carriers. This review presents an overview of the main properties of rhamnolipids, asserts the potential and efficiency of rhamnolipids to replace the synthetic surfactants in the development of nanosystems, and describes the rhamnolipids-based nanosystems used in food applications. It also discusses the main characteristics and methodologies used for their characterization and in the end, some of the main challenges are highlighted.

Statistical Optimization of Biosurfactant Production from Aspergillus niger SA1 Fermentation Process and Mathematical Modeling

In this study, we sought to investigate the production and optimization of biosurfactants by soil fungi isolated from petroleum oil-contaminated soil in Saudi Arabia. Forty-four fungal isolates were isolated from ten petroleum oil-contaminated soil samples. All isolates were identified using the internal transcribed spacer (ITS) region, and biosurfactant screening showed that thirty-nine of the isolates were positive. Aspergillus niger SA1 was the highest biosurfactant producer, demonstrating surface tension, drop collapsing, oil displacement, and an emulsification index (E24) of 35.8 mN/m, 0.55 cm, 6.7 cm, and 70%, respectively. This isolate was therefore selected for biosurfactant optimization using the Fit Group model. The biosurfactant yield was increased 1.22 times higher than in the nonoptimized medium (8.02 g/l) under conditions of pH 6, temperature 35°C, waste frying oil (5.5 g), agitation rate of 200 rpm, and an incubation period of 7 days. Model significance and fitness analysis had an RMSE score of 0.852 and a p-value of 0.0016. The biosurfactant activities were surface tension (35.8 mN/m), drop collapsing (0.7 cm), oil displacement (4.5 cm), and E24 (65.0%). The time course of biosurfactant production was a growth-associated phase. The main outputs of the mathematical model for biomass yield were Yx/s (1.18), and μmax (0.0306) for biosurfactant yield was Yp/s (1.87) and Yp/x (2.51); for waste frying oil consumption the So was 55 g/l, and Ke was 2.56. To verify the model's accuracy, percentage errors between biomass and biosurfactant yields were determined by experimental work and calculated using model equations. The average error of biomass yield was 2.68%, and the average error percentage of biosurfactant yield was 3.39%.

MiR-585-5p impedes gastric cancer proliferation and metastasis by orchestrating the interactions among CREB1, MAPK1 and MITF

Background

Gastric cancer (GC) is one of the most malignant and lethal cancers worldwide. Multiple microRNAs (miRNAs) have been identified as key regulators in the progression of GC. However, the underlying pathogenesis that miRNAs govern GC malignancy remains uncertain. Here, we identified a novel miR-585-5p as a key regulator in GC development.

Methods

The expression of miR-585-5p in the context of GC tissue was detected by in situ hybridization for GC tissue microarray and assessed by H-scoring. The gain- and loss-of-function analyses comprised of Cell Counting Kit-8 assay and Transwell invasion and migration assay. The expression of downstream microphthalmia-associated transcription factor (MITF), cyclic AMP-responsive element-binding protein 1 (CREB1) and mitogen-activated protein kinase 1 (MAPK1) were examined by Immunohistochemistry, quantitative real-time PCR and western blot. The direct regulation between miR-585-5p and MITF/CREB1/MAPK1 were predicted by bioinformatic analysis and screened by luciferase reporter assay. The direct transcriptional activation of CREB1 on MITF was verified by luciferase reporter assay, chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assays (EMSAs). The interaction between MAPK1 and MITF was confirmed by co-immunoprecipitation (Co-IP) and immunofluorescent double-labelled staining.

Results

MiR-585-5p is progressively downregulated in GC tissues and low miR-585-5p levels were strongly associated with poor clinical outcomes. Further gain- and loss-of-function analyses showed that miR-585-5p possesses strong anti-proliferative and anti-metastatic capacities in GC. Follow-up studies indicated that miR-585-5p targets the downstream molecules CREB1 and MAPK1 to regulate the transcriptional and post-translational regulation of MITF, respectively, thus controlling its expression and cancer-promoting activity. MiR-585-5p directly and negatively regulates MITF together with CREB1 and MAPK1. According to bioinformatic analysis, promotor reporter gene assays, ChIP and EMSAs, CREB1 binds to the promotor region to enhance transcriptional expression of MITF. Co-IP and immunofluorescent double-labelled staining confirmed interaction between MAPK1 and MITF. Protein immunoprecipitation revealed that MAPK1 enhances MITF activity via phosphorylation (Ser73). MiR-585-5p can not only inhibit MITF expression directly, but also hinder MITF expression and pro-cancerous activity in a CREB1-/MAPK1-dependent manner indirectly.

Conclusions

In conclusion, this study uncovered miR-585-5p impedes gastric cancer proliferation and metastasis by orchestrating the interactions among CREB1, MAPK1 and MITF.

Mannosylerythritol lipids: production, downstream processing, and potential applications

Mannosylerythritol lipids (MELs) are biosurfactants produced by various fungal species. Depending on the degree of acetylation and further chemical modifications, these glycolipids can show remarkable biological properties, including the increase of water retention in the stratum corneum suppression of melanogenic enzymes tyrosinase-1 and -2, reversion of UV-A radiation-induced aquaporin-3 suppression, skin whitening, and anti-aging effects. These applications of MELs require high purity, which is usually reached by liquid-liquid extraction followed by chromatography, obtaining ≥95% purity. This worked aimed to critically discuss the current state of the art and trends on the production of MELs, including post-production treatment as enzymatic conversion. In addition, their application as skincare or pharmaceutical agents and agricultural biostimulants.

Diarylpropionitrile inhibits melanogenesis via protein kinase A/cAMP-response element-binding protein/microphthalmia-associated transcription factor signaling pathway in α-MSH-stimulated B16F10 melanoma cells

Diarylpropionitrile (DPN), a selective agonist for estrogen receptor β (ERβ), has been reported to regulate various hormonal responses through activation of ERβ in tissues including the mammary gland and brain. However, the effect of DPN on melanogenesis independent of ERβ has not been studied. The aim of this study is to examine the possibility of anti-melanogenic effect of DPN and its underlying mechanism. Melanin contents and cellular tyrosinase activity assay indicated that DPN inhibited melanin biosynthesis in alpha-melanocyte stimulating hormone-stimulated B16F10 melanoma cell line. However, DPN had no direct influence on in vitro tyrosinase catalytic activity. On the other hand, 17β-estradiol had no effect on inhibition of melanogenesis, suggesting that the DPN-mediated suppression of melanin production was not related with estrogen signaling pathway. Immunoblotting analysis showed that DPN down-regulated the expression of microphthalmia-associated transcription factor (MITF), a central transcription factor of melanogenesis and its down-stream genes including tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2. Also, DPN attenuated the phosphorylation of protein kinase A (PKA) and cAMP-response element-binding protein (CREB). Additionally, DPN suppressed the melanin synthesis in UVB-irradiated HaCaT conditioned media culture system suggesting that DPN has potential as an anti-melanogenic activity in physiological conditions. Collectively, our data show that DPN inhibits melanogenesis via down-regulation of PKA/CREB/MITF signaling pathway.

Phase Behaviour, Functionality, and Physicochemical Characteristics of Glycolipid Surfactants of Microbial Origin

Growing demand for biosurfactants as environmentally friendly counterparts of chemically derived surfactants enhances the extensive search for surface-active compounds of biological (microbial) origin. The understanding of the physicochemical properties of biosurfactants such as surface tension reduction, dispersion, emulsifying, foaming or micelle formation is essential for the successful application of biosurfactants in many branches of industry. Glycolipids, which belong to the class of low molecular weight surfactants are currently gaining a lot of interest for industrial applications. For this reason, we focus mainly on this class of biosurfactants with particular emphasis on rhamnolipids and sophorolipids, the most studied of the glycolipids.

Production of mannosylerythritol lipids: biosynthesis, multi-omics approaches, and commercial exploitation

Compilation of resources regarding MEL biosynthesis, key production parameters; available omics resources and current commercial applications, for smut fungi known to produce MELs.

Self-Assembling Properties and Recovery Effects on Damaged Skin Cells of Chemically Synthesized Mannosylerythritol Lipids

Mannosylerythritol lipids (MELs), which are one of the representative sugar-based biosurfactants (BSs) produced by microorganisms, have attracted much attention in various fields in the sustainable development goals (SDGs) era. However, they are inseparable mixtures with respect to the chain length of the fatty acids. In this study, self-assembling properties and structure-activity relationship (SAR) studies of recovery effects on damaged skin cells using chemically synthesized MELs were investigated. It was revealed, for the first time, that synthetic and homogeneous MELs exhibited significant self-assembling properties to form droplets or giant vesicles. In addition, a small difference in the length of the fatty acid chains of the MELs significantly affected their recovery effects on the damaged skin cells. MELs with medium or longer length alkyl chains exhibited much higher recovery effects than that of C18-ceramide NP.

Pseudoalteromone A, a Ubiquinone Derivative from Marine Pseudoalteromonas spp., Suppresses Melanogenesis

An ubiquinone derivative, pseudoalteromone A (1), has been isolated from two marine-derived Pseudoalteromonas spp., APmarine002 and ROA-050, and its anti-melanogenesis activity was investigated. The anti-melanogenic capacity of pseudoalteromone A was demonstrated by assessing the intracellular and extracellular melanin content and cellular tyrosinase activity in the B16 cell line, Melan-a mouse melanocyte cell line, and MNT-1 human malignant melanoma cell line. Treatment with pseudoalteromone A (40 μg/mL) for 72 h reduced α-melanocyte-stimulating hormone (α-MSH)-induced intracellular melanin production by up to 44.68% in B16 cells and 38.24% in MNT-1 cells. Notably, pseudoalteromone A induced a concentration-dependent reduction in cellular tyrosinase activity in B16 cell, and Western blot analyses showed that this inhibitory activity was associated with a significant decrease in protein levels of tyrosinase and tyrosinase-related protein 1 (Tyrp-1), suggesting that pseudoalteromone A exerts its anti-melanogenesis activity through effects on melanogenic genes. We further evaluated the skin-whitening effect of pseudoalteromone A in the three-dimensional (3D) pigmented-epidermis model, MelanoDerm, and visualized the 3D distribution of melanin by two-photon excited fluorescence imaging in this human skin equivalent. Collectively, our findings suggest that pseudoalteromone A inhibits tyrosinase activity and expression and that this accounts for its anti-melanogenic effects in melanocytes.

Apoptosis Induction in Murine Melanoma (B16F10) Cells by Mannosylerythritol Lipids-B; a Glycolipid Biosurfactant with Antitumoral Activities

Mannosylerythritol lipids have drawn attention to cosmetic and pharmaceutical industries due to their non-toxicity and excellent biological interactions with human skin, particularly with the deepest epidermal layer. Lamellar liquid crystal structure, formed by MEL-B, is an interesting feature due to its similarity to the stratum corneum molecular arrangement and cell signaling events involved in the deregulation of the cancerous cell membrane. Thus, this work aimed to evaluate the cytotoxicity of commercial mannosylerythritol lipids-B in murine melanoma, fibroblast, and human erythrocytes cells. Cytotoxic effect was more pronounced on the tumor cells from 20 µg/mL, reducing cell viability by 65%, whereas fibroblast and human erythrocytes cells were more resistant to glycolipid treatment. Fluorescence microscopy and flow cytometer proved that mannosylerythritol lipids-B is an apoptosis inducer in tumor cells related to reactive oxygen species generation.

Fungal biosurfactants, from nature to biotechnological product: bioprospection, production and potential applications

Biosurfactants are in demand by the global market as natural commodities that can be added to commercial products or use in environmental applications. These biomolecules reduce the surface/interfacial tension between fluid phases and exhibit superior stability to chemical surfactants under different physico-chemical conditions. Biotechnological production of biosurfactants is still emerging. Fungi are promising producers of these molecules with unique chemical structures, such as sophorolipids, mannosylerythritol lipids, cellobiose lipids, xylolipids, polyol lipids and hydrophobins. In this review, we aimed to contextualize concepts related to fungal biosurfactant production and its application in industry and the environment. Concepts related to the thermodynamic and physico-chemical properties of biosurfactants are presented, which allows detailed analysis of their structural and application. Promising niches for isolating biosurfactant-producing fungi are presented, as well as screening methodologies are discussed. Finally, strategies related to process parameters and variables, simultaneous production, process optimization through statistical and genetic tools, downstream processing and some aspects of commercial products formulations are presented.

Biological activity of mannosylerythritol lipids on the mammalian cells

Mannosylerythritol lipids (MEL) are glycolipids mainly produced by pseudo-yeasts. These molecules present remarkable biological activities widely explored in many fields, including medicine, pharmaceuticals, and cosmetics. This review presents the main biological activity of MEL on the HL60, K562, B16, PC12, and skin cells. There is strong evidence that MEL changes the levels of glycosphingolipids of HL-60 lineage, which induce differentiation into granulocytic cells. Regarding B16 cells, MEL can trigger both apoptosis (10 μM) and cell differentiation (5 μM), in which the MEL concentration is related to each metabolic pathway. MEL can also trigger differentiation in PC12 cells due to the increase in the GalCer content. In this specific case, the effects are transient, and the differentiated cells are unstable and tend to apoptosis. MEL-B can particularly maintain skin hydration and moisture due to their self-assembled structures that resemble the tissue cells. Moreover, MEL-B repair aquaporin expression in the HaCaT keratinocytes damaged with UVA irradiation, whereas MEL-C suppresses the expression of COX-2 protein in fibroblasts, indicating that these glycolipids activate the cellular antioxidant mechanism. Recent findings denoted the anti-melanogenic activity of MEL since they suppress tyrosinase enzyme at mRNA levels in B16 and NHMs cells. MEL act effectively on mammalian cells; however, there is no clear pattern of their metabolic effects. Also, gene expression levels seem to be related to two main factors: chemical structure and concentration. However, the specific signaling cascades that are induced by MEL remain inconclusive. Thus, further investigations are vital to understanding these mechanisms clearly. KEY POINTS: • The four MEL homologs promote different biological responses in mammalian cells. • MEL modifies the pattern of glycosphingolipids in the plasma membrane of tumor cells. • Activation/deactivation of phosphorylation of serine/threonine kinase proteins.

Tyrosinase-Targeting Gallacetophenone Inhibits Melanogenesis in Melanocytes and Human Skin-Equivalents

Demands for safe depigmentation compounds are constantly increasing in the pharmaceutical and cosmetic industry, since the numerous relevant compounds reported to date have shown undesirable side effects or low anti-melanogenic effects. In this study, we reported three novel inhibitors of tyrosinase, which is the key enzyme in melanogenesis, identified using docking-based high throughput virtual screening of an in-house natural compound library followed by mushroom tyrosinase inhibition assay. Of the three compounds, gallacetophenone showed high anti-melanogenic effect in both human epidermal melanocytes and a 3D human skin model, MelanoDerm. The inhibitory effect of gallacetophenone on tyrosinase was elucidated by computational molecular modeling at the atomic level. Binding of gallacetophenone to the active site of tyrosinase was found to be stabilized by hydrophobic interactions with His367, Ile368, and Val377; hydrogen bonding with Ser380 and a water molecule bridging the copper ions. Thus, our results strongly suggested gallacetophenone as an anti-melanogenic ingredient that inhibits tyrosinase.

Glucose Exerts an Anti-Melanogenic Effect by Indirect Inactivation of Tyrosinase in Melanocytes and a Human Skin Equivalent

Sugars are ubiquitous in organisms and well-known cosmetic ingredients for moisturizing skin with minimal side-effects. Glucose, a simple sugar used as an energy source by living cells, is often used in skin care products. Several reports have demonstrated that sugar and sugar-related compounds have anti-melanogenic effects on melanocytes. However, the underlying molecular mechanism by which glucose inhibits melanin synthesis is unknown, even though glucose is used as a whitening as well as moisturizing ingredient in cosmetics. Herein, we found that glucose significantly reduced the melanin content of α-melanocyte-stimulating hormone (MSH)-stimulated B16 cells and darkly pigmented normal human melanocytes with no signs of cytotoxicity. Furthermore, topical treatment of glucose clearly demonstrated its whitening efficacy through photography, Fontana-Masson (F&M) staining, and multi-photon microscopy in a pigmented 3D human skin model, MelanoDerm. However, glucose did not alter the gene expression or protein levels of major melanogenic proteins in melanocytes. While glucose potently decreased intracellular tyrosinase activity in melanocytes, it did not reduce mushroom tyrosinase activity in a cell-free experimental system. However, glucose was metabolized into lactic acid, which can powerfully suppress tyrosinase activity. Thus, we concluded that glucose indirectly inhibits tyrosinase activity through conversion into lactic acid, explaining its anti-melanogenic effects in melanocytes.

Effect of serum from healthy individuals on the growth of melanocytes in vitro following moxibustion at the "Jiudianfeng" point

Objective

To investigate the effects of serum from healthy individuals obtained following moxibustion at the “Jiudianfeng” point on melanocytes in vitro .

Methods

Ten healthy adults (five male and five female) were treated by moxibustion at the “Jiudianfeng” point for 30 minutes once daily for 3 months. The effects of treatment with serum obtained following moxibustion on melanocyte proliferation, melanin content, tyrosinase activity, cell cycle progression, and c-kit mRNA and protein expression were assessed in vitro before and after moxibustion for 1, 2, and 3 months.

Results

Exposure to sera from healthy adults following moxibustion therapy promoted melanocyte proliferation, melanin synthesis, tyrosinase activity, and c-kit mRNA and protein expression in vitro . Melanin synthesis and tyrosinase activity increased in the first 2 months following moxibustion and a synchronous decline was observed during the third month. Serum also promoted melanocyte entry into the G1 phase of the cell cycle.

Conclusions

Serum treatment following moxibustion at the “Jiudianfeng” point promoted melanocyte proliferation and melanin synthesis. Further exploration of this intriguing phenomenon is essential.

Mannosylerythritol lipids: antimicrobial and biomedical properties

Mannosylerythritol lipids (MELs) have attracted particular interest of medical, pharmaceutical, and cosmetic fields, due to their specific characteristics, including non-toxicity, easy biodegradability, and environmental compatibility. Therefore, this review aims to highlight recent findings on MEL biological properties, focusing on issues related to therapeutic applications. Among the main findings is that MELs can play a fundamental role due to their antimicrobial properties against several nosocomial pathogen microorganisms. Other remarkable biological properties of MELs are related to skincare, as antiaging (active agent), and in particular on recover of skin cells that were damaged by UV radiation. MEL is also related to the increased efficiency of DNA transfection in liposome systems. Regarding the health field, these glycolipids seem to be associated with disturbance in the membrane composition of cancerous cells, increasing expression of genes responsible for cytoplasmic stress and apoptosis. Moreover, MELs can be associated with nanoparticles, as a capping agent, also acting to increase the solubility and cytotoxicity of them. Furthermore, the differences in the chemical structure of MEL could improve and expand their biochemical diversity and applications. Such modifications could change their interfacial properties and, thus, reduce the surface tension value, enhance the solubility, lower critical micelle concentrations, and form unique self-assembly structures. The latest is closely related to molecular recognition and protein stabilization properties of MEL, that is, essential parameters for their effective cosmetical and pharmaceutical effects. Thus, this current research indicates the huge potential of MEL for use in biomedical formulations, either alone or in combination with other molecules.