Arthrophytum scoparium inhibits melanogenesis through the down-regulation of tyrosinase and melanogenic gene expressions in B16 melanoma cells

Biochemical Composition and Biological Activities of Various Population of Brassica tournefortii Growing Wild in Tunisia

Brassica tournefortii Gouan, commonly known (Aslooz) in Tunisia, is an annual plant, native to the North Africa and Middle East. Brassica species are used as food, their young leaves can be cooked, providing nutrients and health-giving phytochemicals such as phenolic compounds, polyphenols and carotenoids. Phytochemical composition and bioactivity of Brassica tournefortii leaf extracts, collected from four different bioclimatic zones in Tunisia, are investigated in the present study. Results showed that location and climatic variations can alter the phytochemical composition of B. tournefortii. Interestingly, HPLC analysis enabled identifying lutein and beta-carotene at high concentrations, especially in extracts of B. tournefortii collected from Gabes (B2) (344 µg/g of lutein) and B. tournefortii collected from Zarzis (B3) (1364 µg/g of beta-carotene). In particular, the antioxidant activity measured by DPPH assay showed that the extract of the plants collected from the growing region of Zarzis exhibits the highest antioxidant activities (0.99 mg/mL). All the Brassica tournefortii extracts showed a relevant antiproliferative activity, especially toward the Caco-2 cell line. These preliminary data resulted in being useful to correlate growth environmental conditions with different accumulation of metabolites in Brassica species still being poorly studied.

The Modulation of Melanogenesis in B16 Cells Upon Treatment with Plant Extracts and Isolated Plant Compounds

Plants are a rich source of secondary metabolites that exhibit numerous desired properties. The compounds may influence the biology of melanocytes, pigment cells that produce melanin, by modulating numerous signaling pathways, including cAMP/PKA, MAPKs and PI3K/AKT. Its downstream target is microphthalmia-associated transcription factor, responsible for the expression of the tyrosinase enzyme, which plays a major role in melanogenesis. Therefore, this literature review aims to provide insights related to melanogenesis modulation mechanisms of plant extracts and isolated plant compounds in B16 cells. Database searches were conducted using online-based library search instruments from 2012 to 2022, such as NCBI-PubMed and Google Scholar. Upregulation or downregulation of signaling pathways by phytochemicals can influence skin hypo- and hyperpigmentation by changing the level of melanin production, which may pose a significant cosmetic issue. Therefore, plant extracts or isolated plant compounds may be used in the therapy of pigmentation disorders.

Structure and inhibition mechanism of some synthetic compounds and phenolic derivatives as tyrosinase inhibitors: review and new insight

Safety concerns are the primary consideration to identify and detection of enzyme inhibitors. In this regard, safe and potent tyrosinase inhibitors play important role in enhancing nutritional quality, health promotion and also prevent further damages. The present review focuses on the recent and efficient tyrosinase inhibitors discovered from both synthetic sources and synthesized phenolic compounds, including flavonoid, carvacrol, thymol, cinnamic acid and resorcinol derivatives. The inhibitory activity of these compounds was analyzed according to chemical structure, IC₅₀, K_i and their binding energy. Further, inhibition mechanism and the biological effects of some these inhibitors with potential application in food, agricultural, cosmetic and pharmaceutical industries were briefly discussed. Molecular docking procedure was performed on some derivatives and demonstrated favorable binding affinity with amino acid residues of mushroom tyrosinase (PDB ID: 2Y9X). The information offered showed that the substitution pattern of hydroxyl groups at the phenyl ring is an important factor of tyrosinase inhibitory activity. The results confirmed that understanding structural modification of inhibitors is a key role in finding novel and efficacious tyrosinase inhibitors.Communicated by Ramaswamy H. Sarma.

Skin cancer, including related pathways and therapy and the role of luteolin derivatives as potential therapeutics

Cutaneous malignant melanoma is the fastest growing and the most aggressive form of skin cancer that is diagnosed. However, its incidence is relatively scarce compared to the highest mortality rate of all skin cancers. The much more common skin cancers include nonmelanoma malignant skin cancers. Moreover, over the past several decades, the frequency of all skin cancers has increased much more dynamically than that of almost any other type of cancer. Among the available therapeutic options for skin cancers, chemotherapy used immediately after the surgical intervention has been an essential element. Unfortunately, the main problem with conventional chemopreventive regimens involves the lack of response to treatment and the associated side effects. Hence, there is a need for much more effective anticancer drugs. Correspondingly, the targeted alternatives have involved phytochemicals, which are safer chemotherapeutic agents and exhibit competitive anticancer activity with high therapeutic efficacy. Among polyphenolic compounds, some flavonoids and their derivatives, which are mostly found in medicinal plants, have been demonstrated to influence the modulation of signaling pathways at each stage of the carcinogenesis process, which is also important in the context of skin cancers. Hence, this review focuses on an exhaustive overview of the therapeutic effects of luteolin and its derivatives in the treatment and prevention of skin cancers. The bioavailability and structure–activity relationships of luteolin derivatives are also discussed. This review is the first such complete account of all of the scientific reports concerning this particular group of natural compounds that target a specific area of neoplastic diseases.

Pterostilbene Inhibits the Melanogenesis Activity in UVB-Irradiated B164A5 Cells

Pterostilbene is a potent antioxidant and anti-inflammatory agent. However, its chemopreventive effects via anti-tyrosinase activity and inhibitory effects on melanin content have not been reported previously. Hence, this study aimed to investigate the anti-melanogenic activity of pterostilbene on UVB-irradiated B164A5 mouse melanoma cells. The effects of pterostilbene and resveratrol on cell viability were determined by MTT assay, whereas melanin content and tyrosinase assay were employed to assess melanogenesis activity. Western blot analysis was performed to determine the tyrosinase expression. Based on the MTT assay, the IC₅₀ value of pterostilbene on UVB-irradiated B164A5 cells was 34.0 ± 3.43 μM, in comparison to resveratrol (>100 μM). Next, 5 and 10 μM pterostilbene showed a significant dose-dependent inhibition (P < .01) of tyrosinase activity in UVB-irradiated B164A5 cells at 37.14 ± 2.71% and 58.36 ± 6.8%, respectively. The findings from the tyrosinase assay also confirmed the downregulation of tyrosinase expression in UVB-irradiated B164A5 cells as measured by Western blot analysis. Finally, 10 μM pterostilbene showed a significantly decreased melanin content (P < .01) in UVB-irradiated B164A5 cells, at 27.34 ± .98 μg/mL. In conclusion, pterostilbene showed anti-melanogenic activity that was 10 times more potent than resveratrol in the UVB-irradiated B164A5 cell.

Grape Extract Promoted α-MSH-Induced Melanogenesis in B16F10 Melanoma Cells, Which Was Inverse to Resveratrol

Melanin is a natural pigment produced by cells to prevent damage caused by ultraviolet radiation. Previously, resveratrol was shown to reduce melanin synthesis. As a natural polyphenol with various biological activities, resveratrol occurs in a variety of beverages and plant foods, such as grapes. Therefore, we investigated whether grape extracts containing resveratrol also had the ability to regulate melanin synthesis. In this study, we used mouse B16F10 melanoma cells as a model for melanin synthesis with the melanogenesis-inducing α-melanocyte-stimulating hormone (α-MSH) as a positive control. Our results confirmed previous reports that resveratrol reduces melanin synthesis by reducing the activity of the rate-limiting enzyme tyrosinase. In contrast, the grape extract could not reduce melanin synthesis, and in fact promoted melanogenesis in the presence of α-MSH. The expression of genes related to melanin synthesis, such as tyrosinase, tyrosinase-related protein-1, tyrosinase-related protein-2, and microphthalmia-associated transcription factor, also supports these phenomena, which means that even in the presence of resveratrol, grape extract will strengthen the function of α-MSH in promoting melanin synthesis. Therefore, these results also provide a point of view for research on cosmetics.

Climatic Zone and Soil Properties Determine the Biodiversity of the Soil Bacterial Communities Associated to Native Plants from Desert Areas of North-Central Algeria

Algeria is the largest country in Africa characterized by semi-arid and arid sites, located in the North, and hypersaline zones in the center and South of the country. Several autochthonous plants are well known as medicinal plants, having in common tolerance to aridity, drought and salinity. In their natural environment, they live with a great amount of microbial species that altogether are indicated as plant microbiota, while the plants are now viewed as a “holobiont”. In this work, the microbiota of the soil associated to the roots of fourteen economically relevant autochthonous plants from Algeria have been characterized by an innovative metagenomic approach with a dual purpose: (i) to deepen the knowledge of the arid and semi-arid environment and (ii) to characterize the composition of bacterial communities associated with indigenous plants with a strong economic/commercial interest, in order to make possible the improvement of their cultivation. The results presented in this work highlighted specific signatures which are mainly determined by climatic zone and soil properties more than by the plant species.

The polyphenol/saponin-rich Rhus tripartita extract has an apoptotic effect on THP-1 cells through the PI3K/AKT/mTOR signaling pathway

Background

Hyperactivation of mechanistic target of rapamycin (mTOR) signaling pathway is involved in the regulation of cellular growth, proliferation, and more in general, is a common phenomenon in most types of cancers. Thus, natural substances targeting this pathway can be of great therapeutic potential in supporting the treatment of tumor patients. Rhus tripartita (Ucria) Grande is a plant growing in desertic areas which is traditionally used for the treatment of several diseases in Tunisia. In the present work, the biochemical profile of the main compounds present in the plant leaf extract was determined and the anti-leukemic potential of the plant extracts against acute monocytic leukaemia (AML) THP-1 cells was investigated.

Methods

After HPLC identification of some phenolic compounds present in the plant extract and the quantification of saponin content, the cytotoxic effect of Rhus tripartita extracts on THP-1 cell culture was evaluated using the colorimetric MTT assay for cell viability. THP-1 cells were incubated with medium containing the relative IC₅₀ concentrations of total plant extract, saponin extract and some standard compounds (rutin (R); kaempferol (K); mixture of catechin, epicatechin, and epicatechin-gallate (CEEG); ellagic acid (EA). Finally, qRT-PCR and western blotting analysis were used to evaluate the effect of some flavonoids present in a crude extract of polyphenols and the total extract of saponins on cell survival and apoptosis.

Results

Analysis of expression level of some gene (PIK3CA, PTEN, AKT1, mTOR, EIF4E, RPS6KB1, and TSC1) involved in the mTOR pathway and the phosphorylation of S6 and AKT proteins allowed to observe that a total Rhus tripartita extract and some of the compounds found in the extract controls THP-1 cell proliferation and apoptosis via regulation of the PI3K-Akt-mTOR signaling pathway.

Conclusion

Rhus tripartita-induced inhibition of cell cycle and induction of apoptosis may involve the mTOR pathway. Therefore, Rhus tripartita extract may be a useful candidate as a natural anti-cancer drug to support the treatment of AML.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03328-9.

Novel Quercetin Derivative of 3,7-Dioleylquercetin Shows Less Toxicity and Highly Potent Tyrosinase Inhibition Activity

Quercetin is a well-known plant flavonol and antioxidant; however, there has been some debate regarding the efficacy and safety of native quercetin as a skin-whitening agent via tyrosinase inhibition. Several researchers have synthesized quercetin derivatives as low-toxicity antioxidants and whitening agents. However, no suitable quercetin derivatives have been reported to date. In this study, a novel quercetin derivative was synthesized by the S_N2 reaction using quercetin and oleyl bromide. The relationship between the structures and activities of quercetin derivatives as anti-melanogenic agents was assessed using in vitro enzyme kinetics, molecular docking, and quenching studies; cell line experiments; and in vivo zebrafish model studies. Novel 3,7-dioleylquercetin (OQ) exhibited a low cytotoxic concentration level at >100 µg/mL (125 µM), which is five times less toxic than native quercetin. The inhibition mechanism showed that OQ is a competitive inhibitor, similar to native quercetin. Expression of tyrosinase, tyrosinase-related protein 1 (TRP-1) and tyrosinase-related protein 2 (TRP-2), and microphthalmia-associated transcription factor was inhibited in B16F10 melanoma cell lines. mRNA transcription levels of tyrosinase, TRP-1, and TRP-2 decreased in a dose-dependent manner. Melanin formation was confirmed in the zebrafish model using quercetin derivatives. Therefore, OQ might be a valuable asset for the development of novel skin-whitening agents.

α-Mangostin suppressed melanogenesis in B16F10 murine melanoma cells through GSK3β and ERK signaling pathway

Mangosteen (Garcinia mangostana L) fruit contains many xanthones in its pericarp, such as α-mangostin. Here, we aimed to elucidate the physiological effect of α-mangostin and the mechanism on melanogenesis in mouse B16F10 cells. The melanin production in B16F10 cells was decreased by α-mangostin treatment. α-Mangostin also suppressed the enzymatic activity of tyrosinase, the critical enzyme for melanin synthesis. Furthermore, Western blot analysis revealed that α-mangostin down-regulated the protein quantity of tyrosinase, tyrosinase relative protein (TRP)-2, and microphthalmia-associated transcription factor (MITF). We also used inhibitors of the extracellular signal-regulated kinase (ERK), and glycogen synthase kinase 3 (GSK-3β) to identify the upstream signaling cascade of MITF. Results showed us GSK3β plays a more important role in α-mangostin regulated melanogenesis. Further, the de-pigmentation effect on normal human epidermal melanocytes (NHEMs) of α-mangostin was also confirmed. These results suggested that α-mangostin is a reagent for depigmentation and it has the potential to be applied as a component of cosmetics or pharmaceuticals for the therapy of spots, chloasma, or melanosis.

α-Mangostin suppressed the melanin production in B16F10 cells.

α-Mangostin suppressed the activity of tyrosinase.

α-Mangostin suppressed the protein expression of tyrosinase, TRP-2 and MITF.

GSK3β is involved in α-mangostin-regulated melanogenesis.

α-Mangostin suppressed the melanin production in normal human melanocytes.

Spherical Nucleic Acids for Topical Treatment of Hyperpigmentation

Oligonucleotide-based materials such as spherical nucleic acid (SNA) have been reported to exhibit improved penetration through the epidermis and the dermis of the skin upon topical application. Herein, we report a self-assembled, skin-depigmenting SNA structure, which is based upon a bifunctional oligonucleotide amphiphile containing an antisense oligonucleotide and a tyrosinase inhibitor prodrug. The two components work synergistically to increase oligonucleotide cellular uptake, enhance drug solubility, and promote skin penetration. The particles were shown to reduce melanin content in B16F10 melanoma cells and exhibited a potent antimelanogenic effect in an ultraviolet B-induced hyperpigmentation mouse model.

Tyrosinase and Melanogenesis Inhibition by Indigenous African Plants: A Review

The indiscriminate use of non-regulated skin lighteners among African populations has raised health concerns due to the negative effects associated with skin lightener toxicity. For this reason, there is a growing interest in the cosmetic development of plants and their metabolites as alternatives to available chemical-derived skin lightening formulations. Approximately 90% of Africa’s population depends on traditional medicine, and the continent’s biodiversity holds plant material with various biological activities, thus attracting considerable research interest. This study aimed to review existing evidence and document indigenous African plant species capable of inhibiting the enzyme tyrosinase and melanogenesis for potential incorporation into skin lightening products. Literature search on melanin biosynthesis, skin lightening, and tyrosinase inhibitors resulted in the identification of 35 plant species were distributed among 31 genera and 21 families across 15 African countries and 9 South African provinces. All plants identified in this study showed competent tyrosinase and melanogenesis inhibitory capabilities. These results indicate that African plants have the potential to serve as alternatives to current chemically-derived skin lighteners.

Arthrophytum scoparium Extract Improves Memory Impairment and Affects Acetylcholinesterase Activity In Mice Brain

BACKGROUND

Arthrophytum scoparium (Pomel) Iljin (Amaranthaceae family) has been widely used in traditional Tunisian medicine to treat many disorders such as migraine, headache, and neurological disorders. This study investigates the effect of Arthrophytum scoparium Aqueous Extract (ASAE) on cognitive impairments and oxidative injury induced by galactose (10%) in a mouse model.

MATERIALS AND METHODS

The mice were divided randomly into 4 experimental groups, including the control group (saline water 9 ‰), Galactose group, Scop group (300 mg/kg/d), and Scop+Gal group (300 mg/kg/d). Mice received the corresponding solutions by intraperitoneal injection (i.p.) for 7 days before the Y-maze active tests. Galactose 10% was given to all groups except control and Scop groups, 30 min before the trial. Levels of Acetylcholinesterase Activity (AChE), Ascorbic Acid (AA), Gluthatione (GSH) and Malondialdehyde (MDA) in mice brains were examined.

RESULTS

Chronic administration of galactose significantly impaired cognitive performance in Y maze, caused marked oxidative damages and a significant increase in the acetylcholinesterase activity as compared to other groups. On the contrary, ASAE (300 mg/kg) treatment suppressed galactoseinduced oxidative damage by ameliorating the increased levels of GSH and AA. Moreover, ASAE treatment reduced brain AChE activities in the galactose-induced model.

CONCLUSION

These findings suggest that ASAE exerts potent anti-amnesic effects via the modulation of cholinergic and antioxidant activities. The observed pharmacological activities should be further evaluated by detailed experimental studies and validated by clinical trials.

Inhibitory Effect of Sesamolin on Melanogenesis in B16F10 Cells Determined by In Vitro and Molecular Docking Analyses

BACKGROUND

Melanin protects the skin against the harmful effects of ultraviolet irradiation. However, melanin overproduction can result in several aesthetic problems, including melasma, freckles, age spots and chloasma. Therefore, development of anti-melanogenic agents is important for the prevention of serious hyperpigmentation diseases. Sesamolin is a lignan compound isolated from sesame seeds with several beneficial properties, including potential for melanin inhibition.

OBJECTIVE

The aim of this study was to evaluate the anti-melanogenic effect of sesamolin in cell culture in vitro and the underlying mechanism of inhibition using molecular docking simulation.

METHODS

Melanogenesis was induced by 3-isobutyl-1-methylxanthine in B16F10 melanoma cells, and the inhibitory effects of sesamolin were evaluated using zymography, a tyrosinase inhibitory activity assay, western blotting, and real-time reverse transcription-polymerase chain reaction analysis. Docking simulations between sesamolin and tyrosinase were performed using Autodock vina.

RESULTS

Sesamolin significantly inhibited the expression of melanogenesis-related factors tyrosinase, and tyrosinase-related proteins 1 and 2 at the mRNA and protein levels. Treatment of melanoma cells with 50 µM sesamolin demonstrated the strongest inhibition against intercellular tyrosinase and melanin synthesis without exerting cytotoxic effects. Sesamolin significantly reduced mushroom tyrosinase activity in a dose-dependent manner via a competitive inhibition mechanism. Tyrosinase docking simulations supported that sesamolin (-6.5 kcal/mol) bound to the active site of tyrosinase more strongly than the positive control (arbutin, -5.7 kcal/mol).

CONCLUSION

Sesamolin could be developed as a melanogenesis inhibiting agent owing to its dual function in blocking the generation of melanogenesis-related enzymes and inhibiting the enzymatic response of tyrosinase.

The Impact of Herbal Products in the Prevention, Regeneration and Delay of Skin Aging

Skin aging is a complex process induced by intrinsic and extrinsic factors and causes alterations to the structural and functional aspects of the skin. Skin aging affects patients physically and physiologically. Understanding the process of skin aging can provide new knowledge on how to attenuate or reduce skin disorder symptoms. Herbs have been used for ages to prevent and treat skin aging, yet there are growing interests by researchers in this field globally. Various strategies have been developed for improving the quality and effectivity of herbal skin care products, both for topical and oral applications. This review will provide an overview of the relationship between herbal skin care products and the skin aging process.

Biochemical profile and in vitro biological activities of extracts from seven folk medicinal plants growing wild in southern Tunisia

Recently, much attention has been paid to the extracts obtained from plant species in order to analyse their biological activities. Due to the climate diversity in Tunisia, the traditional pharmacopoeia consists of a wide arsenal of medicinal plant species since long used in folk medicine, in foods as spices, and in aromatherapy. Although many of these species are nearly facing extinction, only a small proportion of them have been scientifically studied. Therefore, this study explores the biochemical properties of seven spontaneous plants, which were harvested in the arid Tunisian desert: Marrubium vulgare (L.), Rhus tripartita (Ucria) D.C., Thymelaea hirsute (L.) Endl., Plantago ovata (Forsk.), Herniaria fontanesii (J. Gay.), Ziziphus lotus (L.) and Hyoscyamus albus (L.). Extracts from these plants were found to contain different types of secondary metabolites (polyphenols, flavonoids, condensed tannins, crude saponins, carotenoids and alkaloids) that are involved in important biological activities. The biological activity of the extracts obtained from each Tunisian plant was assessed: first of all, leukaemia and colon cancer cell lines (K-562 and CaCo-2 respectively) were treated with different concentrations of extracts, and then the anti-proliferative activity was observed. The results showed, in particular, how the plant extract from Rhus tripartita significantly inhibits cell proliferation, especially on the K-562 tumour cell line. Subsequently, the anti-inflammatory activity was also assessed, and the results showed that Herniaria fontanesii and Marrubium vulgare possess the highest activity in the group of analysed plants. Finally, the greatest acetylcholinesterase inhibitory effect was exhibited by the extract obtained from Rhus tripartita. In conclusion, all the Tunisian plants we analysed were shown to contain a remarkable amount of different bio-active compounds, thus confirming their involvement in several biological activities. Rhus tripartita and Ziziphus lotus were shown to be particularly effective in anti-proliferative activity, while Herniaria fontanesii were shown to have the best anti-inflammatory activity.

p-Coumaric Acid as An Active Ingredient in Cosmetics: A Review Focusing on its Antimelanogenic Effects

Controlling unwanted hyperpigmentation is a major challenge in dermatology and cosmetology, and safe and efficacious antimelanogenic agents are deemed useful for this purpose. p-Coumaric acid is a natural metabolite contained in many edible plants, and its antioxidant activities in reducing oxidative stress and inflammatory reactions have been demonstrated in various experimental models. p-Coumaric acid has the optimal structure to be a competitive inhibitor of tyrosinase that catalyzes key reactions in the melanin biosynthetic pathway. Experimental evidence supports this notion as it was found to be a more potent inhibitor of tyrosinase, especially toward human enzymes, than other well-known tyrosinase inhibitors such as arbutin and kojic acid. p-Coumaric acid inhibited melanin synthesis in murine melanoma cells, human epidermal melanocytes, and reconstituted three-dimensional human skin models. Ex-vivo skin permeation experiments and in-vivo efficacy tests for p-coumaric acid confirmed its efficient transdermal delivery and functional efficacy in reducing erythema development and skin pigmentation due to ultraviolet radiation exposure. Human studies further supported its effectiveness in hypopigmentation and depigmentation. These findings suggest that p-coumaric acid has good potential to be used as a skin-lightening active ingredient in cosmetics. Future studies are needed to extensively examine its safety and efficacy and to develop an optimized cosmetic formulation for the best performance in skin lightening.

Oral supplementation of L-glutathione prevents ultraviolet B-induced melanogenesis and oxidative stress in BALB/c mice

Dietary antioxidant supplements such as L-glutathione have gained considerable attention in dermatology and cosmeceutical fields. L-glutathione possesses antiaging, antimelanogenic, antioxidant, and anticancer properties. This study aimed to investigate the inhibitory effects of L-glutathione on melanogenesis activity and oxidative stress in ultraviolet B (UVB)-irradiated BALB/c mice. Eighteen female BALB/c mice were randomly divided into 3 groups: a control group (n=6), a group without UVB irradiation and L-glutathione administration; a UVB irradiated group (n=6), a group irradiated with a UVB dose of 250 mJ/cm² for 3 min; and a treatment group (n=6), a group irradiated with UVB and treated with 100 mg/kg of L-glutathione by oral gavage. Treatment was given for 14 days, and UVB irradiation was given on days 9, 11, and 13. Oral L-glutathione significantly (P<0.05) reduced lipid peroxidation and elevated superoxide dismutase activity the and glutathione level. L-glutathione also inhibited melanin content and tyrosinase activity significantly (P<0.05) as compared with the UVB-irradiated group. Histopathological examination also showed that L-glutathione reduced the deposition of melanin pigment in the basal layer of the epidermis as compared with that in UVB-irradiated mice. All in all, the present study demonstrated that L-glutathione has the potential to be developed as a photoprotection agent against UVB-induced oxidative stress and melanogenesis.

Attenuation of melanogenesis by Nymphaea nouchali (Burm. f) flower extract through the regulation of cAMP/CREB/MAPKs/MITF and proteasomal degradation of tyrosinase

Medicinal plants have been used to treat diseases from time immemorial. We aimed to examine the efficacy of the ethyl acetate fraction of Nymphaea nouchali flower extract (NNFE) against melanogenesis process, and the underlying mechanisms in vitro and in vivo. Paper spray ionisation mass spectroscopy and (+) mode electrospray ionisation revealed the presence of seven flavonoids, two spermidine alkaloids, 3,4,8,9,10-pentahydroxy-dibenzo[b,d]pyran-6-one, and shoyuflavone C in NNFE. NNFE (100 µg/mL) significantly inhibited the monophenolase and diphenolase activities of mushroom tyrosinase at 94.90 ± 0.003% and 93.034 ± 0.003%, respectively. NNFE significantly suppressed cellular tyrosinase activity and melanin synthesis in vitro in melan-a cells and in vivo in HRM2 hairless mice. Furthermore, NNFE inhibited tyrosinase (TYR), tyrosinase-related protein (TYRP)-1, TYRP-2, and microphthalmia-associated transcription factor (MITF) expression, thereby blocking melanin synthesis. In particular, NNFE suppressed cAMP production with subsequent downregulation of CREB phosphorylation. Additionally, it stimulated MAP kinase phosphorylation (p38, JNK, and ERK1/2) and the proteasomal debasement pathway, leading to degradation of tyrosinase and MITF and the suppression of melanin production. Moreover, selective inhibitors of ERK1/2, JNK, and p38 attenuated NNFE inhibitory effects on melanogenesis, and MG-132 (a proteasome inhibitor) prevented the NNFE-induced decline in tyrosinase protein levels. In conclusion, these findings indicate that NNFE is a potential therapy for hyperpigmentation.

Antimelanogenic Effect of an Oroxylum indicum Seed Extract by Suppression of MITF Expression through Activation of MAPK Signaling Protein

In this study, the antimelanogenic effect of an ethyl acetate fraction of Oroxylum indicum Vent. seeds (OISEA) and its underlying mechanisms in melan-a cells were investigated. Antimelanogenesis activity was confirmed by assessing inhibition of tyrosinase activity and melanin content in the cells. Both transcriptional and translational expression of microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase related protein-1 and 2 (TYRP-1 and TYRP-2), were also examined. The results depicted that pretreatment of OISEA significantly inhibits not only tyrosinase activity, but melanin production and intracellular tyrosinase activity. By repressing the expression of tyrosinase, TYRP-1, TYRP-2, and MITF, OISEA interrupted melanin production. Additionally, OISEA interfered with the phosphorylation of p38, extracellular signal-regulated kinase 1/2 (ERK1/2), and c-Jun N-terminal kinase (JNK), with the reversal of OISEA-induced melanogenesis inhibition after treatment with the specific inhibitors SB239063, U0126, and SP600125. Overall, these results suggest that OISEA can stimulate p38, ERK1/2, JNK phosphorylation, and subsequent suppression of melanin, leading to the inhibition of melanogenic enzymes and melanin production, possibly owing to the presence of polyphenolic compounds.

Effects of volatile oil from ginger on the murine B16 melanoma cells and its mechanism

In this study, the inhibitory effects of volatile oil from ginger on melanogenesis and its antioxidant characteristics were investigated. The effects of volatile oil from ginger on cell proliferation, melanin content and tyrosinase activity were determined using a microplate reader. In addition, the expression of melanogenesis-related protein was determined by western blotting. The results indicate that the tested concentrates of volatile oil from ginger showed inhibitory effects on cell proliferation and melanogenesis. This revealed that volatile oil from ginger exhibited apparent capacities for scavenging ROS and lipid peroxidation. Furthermore, volatile oil from ginger improved the activities of GSH, SOD and CAT in B16 melanoma cells. These results demonstrated that volatile oil from ginger suppressed melanin synthesis through its antioxidant properties and the inhibitory effects on tyrosinase activity and melanogensis-related proteins. Hence, volatile oil from ginger could be used as an effective skin-whitening agent applied in food industry.

Inhibition of melanogenesis by jineol from Scolopendra subspinipes mutilans via MAP-Kinase mediated MITF downregulation and the proteasomal degradation of tyrosinase

In this study, the authors investigated the anti-melanogenic effects of 3,8-dihydroxyquinoline (jineol) isolated from Scolopendra subspinipes mutilans, the mechanisms responsible for its inhibition of melanogenesis in melan-a cells, and its antioxidant efficacy. Mushroom tyrosinase activities and melanin contents were determined in melan-a cells, and the protein and mRNA levels of MITF, tyrosinase, TYRP-1, and TYRP-2 were assessed. Jineol exhibited significant, concentration-dependent antioxidant effects as determined by DPPH, ABTS, CUPRAC, and FRAP assays. Jineol significantly inhibited mushroom tyrosinase activity by functioning as an uncompetitive inhibitor, and markedly inhibited melanin production and intracellular tyrosinase activity in melan-a cells. In addition, jineol abolished the expressions of tyrosinase, TYRP-1, TYRP-2, and MITF, thereby blocking melanin production and interfering with the phosphorylations of ERK1/2 and p38. Furthermore, specific inhibitors of ERK1/2 and p38 prevented melanogenesis inhibition by jineol, and the proteasome inhibitor (MG-132) prevented jineol-induced reductions in cellular tyrosinase levels. Taken together, jineol was found to stimulate MAP-kinase (ERK1/2 and p38) phosphorylation and the proteolytic degradation pathway, which led to the degradations of MITF and tyrosinase, and to suppress the productions of melanin.

Anti-photoageing and anti-melanogenesis activities of chrysin

CONTEXT

Melanin plays an important role in preventing skin photoageing by blocking ultraviolet B (UVB). However, East Asian women prefer light and fair skin, therefore they want to keep their skin from photoageing and at the same time reduce the melanin in their skin. Chrysin is a kind of natural flavonoid with luxurious biological activities, which has a very promising effect on achieving this goal.

OBJECTIVE

To elucidate the effects and mechanisms of chrysin on photoageing and melanogenesis.

MATERIALS AND METHODS

Human dermal fibroblasts (HDF) and B16 murine melanoma cells were incubated with chrysin (0-25 μM) for 48 h. Anti-photoageing activity was examined in HDF by assessment of synthesis/degradation of collagen I, antioxidative and antisenescent activities through ELISA and colorimetric method. Anti-melanogenesis activity was tested by assessment of melanin, tyrosinase (TYR), melanogenic proteins inhibition activities in B16 cells using colorimetric and ELISA method.

RESULTS

Chrysin increased collagen I secretion (50-121.54% at 6.25-25 μM) and chrysin showed anti-photoageing activity by decreasing the degradation of collagen I, repairing oxidation damage and reducing the rate of HDF senescence. Furthermore, chrysin exhibited inhibitory activities with 3.00-20.35% reduction of melanin content at 6.25-25 μM, and inhibited melanin synthesis through the inhibition of TYR activity and the suppression of melanogenic proteins (TYR, TYR-related protein-1/2 and microphthalmia-associated transcription factor) expressions.

DISCUSSION AND CONCLUSION

Chrysin may have potential for developing a functional cosmetic agent because of its anti-photoageing and anti-melanogenesis activities.

The Potential of Plant Phenolics in Prevention and Therapy of Skin Disorders

Phenolic compounds constitute a group of secondary metabolites which have important functions in plants. Besides the beneficial effects on the plant host, phenolic metabolites (polyphenols) exhibit a series of biological properties that influence the human in a health-promoting manner. Evidence suggests that people can benefit from plant phenolics obtained either by the diet or through skin application, because they can alleviate symptoms and inhibit the development of various skin disorders. Due to their natural origin and low toxicity, phenolic compounds are a promising tool in eliminating the causes and effects of skin aging, skin diseases, and skin damage, including wounds and burns. Polyphenols also act protectively and help prevent or attenuate the progression of certain skin disorders, both embarrassing minor problems (e.g., wrinkles, acne) or serious, potentially life-threatening diseases such as cancer. This paper reviews the latest reports on the potential therapy of skin disorders through treatment with phenolic compounds, considering mostly a single specific compound or a combination of compounds in a plant extract.

(E)-4-(3,4-Dimethoxyphenyl)but-3-en-1-ol Enhances Melanogenesis through Increasing Upstream Stimulating Factor-1-Mediated Tyrosinase Expression

We investigated the potential melanogenic effect of compounds from Zingiber cassumunar Roxb. Our data revealed that chloroform-soluble extract of Z. cassumunar enhanced melanin synthesis in B16F10 melanoma cells. Among the components of the chloroform extract, (E)-4-(3,4-dimethoxyphenyl)but-3-en-1-ol (DMPB) increased melanogenesis in both B16F10 cells and human primary melanocytes. In B16F10 cells, DMPB enhanced the activation of ERK and p38, and the level of tyrosinase. Although the level of microphthalmia-associated transcription factor was unchanged in DMPB-treated B16F10 cells, DMPB increased levels and nuclear localization of upstream stimulating factor-1 (USF1). Consistently, DMPB-mediated melanin synthesis was diminished in USF1-knockdown cells. Furthermore, DMPB induced hyperpigmentation in brown guinea pigs in vivo. Together, these data suggest that DMPB may promote melanin synthesis via USF1 dependent fashion and could be used as a clinical therapeutic agent against hypopigmentation-associated diseases.

Isosakuranetin, a 4'-O-methylated flavonoid, stimulates melanogenesis in B16BL6 murine melanoma cells

AIMS

The beneficial effects of 4'-O-methylated flavonoids on induction of melanogenesis are well established. Here, we report the effect of isosakuranetin (Iso) on melanogenesis in B16BL6 melanoma cells and an analysis of the signaling pathways involved in this activity.

METHODS

B16BL6 melanoma cells were treated with several concentrations of Iso and melanin content was measured. Activation and expression of factors involved in melanogenesis were assessed via western blotting.

KEY FINDINGS

Iso (15 and 30μmol/L) strongly stimulated melanogenesis in a dose-dependent manner. Iso increased tyrosinase activity and up-regulated tyrosinase (Tyr), tyrosinase related protein 1 (TRP1), and tyrosinase related protein 2 (TRP2) in a time-dependent manner. Iso decreased B16 cell proliferation at a concentration above 45μmol/L, and had no effect on cell viability as revealed by MTT and trypan blue assays. Iso up-regulated expression of microphthalmia transcription factor (MITF), with a maximum effect after 12h. H89, a specific inhibitor of PKA, showed that MITF up-regulation is mediated through PKA/CREB activation. Furthermore, Iso decreased phosphorylation of MITF at Ser73 after 24h and 48h of exposure, activating MITF and leading to up-regulation of Tyr, TRP1, and TRP2. Iso inhibited phosphorylation and activation of ERK1/2 after 12h, while no significant effects on p38 and JNK phosphorylation were observed. Iso inhibited AKT phosphorylation and led to activation of GSK3β.

SIGNIFICANCE

Iso stimulates melanogenesis in B16 melanoma cells via up-regulation of MITF. Furthermore, Iso-induced inhibition of ERK1/2 and PI3K/AKT signaling pathways activate MITF and subsequent expression of Tyr, TRP1, and TRP2.

Sesamol decreases melanin biosynthesis in melanocyte cells and zebrafish: Possible involvement of MITF via the intracellular cAMP and p38/JNK signalling pathways

The development of antimelanogenic agents is important for the prevention of serious aesthetic problems such as melasma, freckles, age spots and chloasma. The aim of this study was to investigate the antimelanogenic effect of sesamol, an active lignan isolated from Sesamum indicum, in melan-a cells. Sesamol strongly inhibited melanin biosynthesis and the activity of intracellular tyrosinase by decreasing cyclic adenosine monophosphate (cAMP) accumulation. Sesamol significantly decreased the expression of melanogenesis-related genes, such as tyrosinase, tyrosinase-related protein-1,2 (TRP-1,2), microphthalmia-associated transcription factor (MITF) and melanocortin 1 receptor (MC1R). In addition, sesamol also induces phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun N-terminal kinase (JNK). Moreover, sesamol dose-dependently decreased zebrafish pigment formation, tyrosinase activity and expression of melanogenesis-related genes. These findings indicate that sesamol inhibited melanin biosynthesis by down-regulating tyrosinase activity and melanin production via regulation of gene expression of melanogenesis-related proteins through modulation of MITF activity, which promoted phosphorylation of p38 and JNK in melan-a cells. Together, these results suggest that sesamol strongly inhibits melanin biosynthesis, and therefore, sesamol represents a new skin-whitening agent for use in cosmetics.

Proton pump inhibitors decrease melanogenesis in melanocytes

Proton pump inhibitors (PPIs) are widely used as inhibitors of gastric juice secretion for treatment of gastroesophageal reflux disease. However, there are no previous studies of the effects on melanogenesis resulting from PPI treatments. Therefore, the aim of the present study was to investigate the effects of PPIs on melanogenesis in melan-a cells derived from immortalized mouse melanocytes. Tyrosinase activity and copper-chelating activity were measured spectrophotometrically. In addition, the melanin content and viability of melan-a cells treated with PPIs were assessed and the mRNA levels of melanogenesis-associated genes were measured by reverse transcription-polymerase chain reaction. Treatment with rabeprazole, but not the other PPIs tested, resulted in strong, dose-dependent inhibition of mushroom tyrosinase (TYR). By contrast, each of the PPIs tested exhibited copper-chelating activity. Treatment of melan-a cells with 100 µM concentrations of the PPIs resulted in significantly reduced melanin synthesis and reduced expression of several melanogenesis-associated genes, including TYR, TYR-related protein-1 (TRP-1) and TRP-2, and microphthalmia-associated transcription factor, but did not result in cytotoxic effects. These results suggest that PPIs inhibit melanin biosynthesis in melan-a cells via the downregulation of melanogenesis-associated genes. Furthermore, the findings indicate that PPIs in general could be utilized as skin-whitening agents and/or as biomaterial for treating hyperpigmentation disorders.

Cellular Anti-Melanogenic Effects of a Euryale ferox Seed Extract Ethyl Acetate Fraction via the Lysosomal Degradation Machinery

The aim of this study was to investigate the effect of ethyl acetate fraction of Euryale ferox seed extracts (Efse-EA) on melanogenesis in immortalized mouse melanocyte cell line, melan-a. Efse-EA showed strong dose-dependent mushroom tyrosinase inhibitory activity. Treatment of melan-a cells with 30 μg/mL Efse-EA produced strong inhibition of cellular tyrosinase and melanin synthesis. Efse-EA significantly reduced the levels of melanogenesis-related proteins, such as tyrosinase, tyrosinase-related proteins 1 and 2, and microphthalmia-associated transcription factor. Because Efse-EA treatment reduced tyrosinase protein levels without changing its mRNA expression, we investigated whether this decrease was related to proteasomal or lysosomal degradation of tyrosinase. We found that chloroquine, a lysosomal proteolysis inhibitor, almost completely abolished both the down-regulation of tyrosinase and the inhibition of melanin synthesis induced by Efse-EA. These results suggested that Efse-EA may contribute to the inhibition of melanogenesis by altering lysosomal degradation of tyrosinase, and that this extract may provide a new cosmetic skin-whitening agent.

Extracts of Artocarpus communis decrease α-melanocyte stimulating hormone-induced melanogenesis through activation of ERK and JNK signaling pathways

Artocarpus communis is an agricultural plant that is also used in folk medicine to prevent skin diseases, including acne and dermatitis. Extracts of A. communis have been used to effectively inhibit melanogenesis; however, the antimelanogenesis mechanism of these extracts has not yet been investigated. The present study utilized a cell-free tyrosinase assay as well as α-melanocyte stimulating hormone- (-MSH-) induced tyrosinase assay conducted in B16F10 cells, performed a cytotoxicity assay, and determined cellular melanin content to examine the effects of a methanolic extract of A. communis (ACM) and various organic partition fractions of A. communis on melanogenesis. In addition, we performed western blot analysis to elucidate the mechanism of their antimelanogenesis effect. Our results indicated that, except for the n-hexane extract, ACM and the various partition extracts at noncytotoxic concentrations effectively decreased melanin content and tyrosinase activity by downregulating microphthalmia-associated transcription factor (MITF) and phosphorylated cAMP response element-binding protein (p-CREB). Moreover, ACM and the partition fractions activated phosphorylation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) to inhibit the synthesis of MITF and finally to decrease melanin production. In conclusion, we suggest that noncytotoxic concentrations of ACM and the various partition fractions may be useful as references for developing skin-lighting agents for use in medicines or cosmetics.

Down-regulation of tyrosinase, TRP-1, TRP-2 and MITF expressions by citrus press-cakes in murine B16 F10 melanoma

OBJECTIVE

To investigate the suitability of citrus-press cakes, by-products of the juice industry as a source for the whitening agents for cosmetic industry.

METHODS

Ethylacetate extracts of citrus-press cakes (CCE) were examined for their anti-melanogenic potentials in terms of the inhibition of melanin production and mechanisim of melanogenesis by using Western Blot analysis with tyrosinese, tyrosinase-related protein-1 (TRP-1), TRP2, and microphthalmia-associated transcription factor (MITF) proteins. To apply the topical agents, citrus-press cakes was investigated the safety in human skin cell line. Finally flavonoid analysis of CCE was also determined by HPLC analysis.

RESULTS

Results indicated that CCE were shown to down-regulate melanin content in a dose-dependent pattern. The CCE inhibited tyrosinase, TRP-2, and MITF expressions in a dose-dependent manner. To test the applicability of CCE to human skin, we used MTT assay to assess the cytotoxic effects of CCE on human keratinocyte HaCaT cells. The CCE exhibited low cytotoxicity at 50 µg/mL. Characterization of the citrus-press cakes for flavonoid contents using HPLC showed varied quantity of rutin, narirutin, and hesperidin.

CONCLUSIONS

Considering the anti-melanogenic activity and human safety, CCE is considered as a potential anti-melanogenic agent and may be effective for topical application for treating hyperpigmentation disorders.