The whitening effect of cuscutin responsible for traditional use of Bergenia purpurascens

ETHNOPHARMACOLOGICAL RELEVANCE

The roots and rhizomes of Bergenia purpurascens (Hook. f. et Thomson) Engl., was used as a sunscreen to protect against ultraviolet rays in Tibet of China historically, but its skin whitening constituents and pharmacological effects of this plant remained unknown.

AIM OF THE STUDY

To investigate the anti-melanogenesis effect of B. purpurascens in vitro and in vivo, and then explore the preliminary mechanism.

MATERIALS AND METHODS

An ultraviolet B (UVB)-induced skin injury model of mice was used to verify the ameliorative effect of B. purpurascens extract (BPE) on ultraviolet damage. Then, alpha-melanocyte stimulating hormone (α-MSH)-induced murine melanoma cell line (B16F10) melanin generation model was further adopted to approval the effects of BPE and its bioactive compound, cuscutin, in vitro. Moreover, α-MSH stimulated melanogenesis model in zebrafish was employed to confirm the anti-pigmentation effect of cuscutin. Then, proteins expressions associated with melanin production were observed using western blotting assay to explore preliminary mechanism.

RESULTS

BPE inhibited UVB-induced mice injury and restored skin barrier function observably in vivo. BPE and cuscutin suppressed the overproduction of melanin in α-MSH induced B16F10 significantly, in which cuscutin exhibited better effect than well-known whitening agent α-arbutin at same 10 μg/mL concentration. Moreover, the pigmentation of zebrafish embryo was decreased by cuscutin. Finally, cuscutin showed significant downregulation of expressions of tyrosinase (TYR) and tyrosinase related protein-1 (TRP-1), TRP-2 and microphthalmia-associated transcription factor (MITF) in the melanogenic signaling pathway.

CONCLUSION

B. purpurascens extract and its major bioactive constituent, cuscutin, showed potent anti-melanogenesis and skin-whitening effect by targeting TYR and TRP-2 proteins for the first time, which supported its traditional use.

Exploring the potential of white birch sap: A natural alternative to traditional skin whitening agents with reduced side effects

Common tyrosinase (TYR) inhibitors used in cosmetics, such as hydroquinone, kojic acid, and arbutin, can cause side effects including erythema, skin peeling, and dryness. Therefore, the development of natural whitening agents that offer excellent permeability, minimal irritation, and high safety has become a primary focus in the field of TYR inhibitors. In this study, we demonstrate that White birch sap (WBS), within a safe concentration range, effectively reduces TYR activity and melanin content in both B16F10 mouse melanoma cells and zebrafish larvae. Importantly, WBS exhibits minimal irritation to neutrophils in fluorescent zebrafish and does not affect the behavior of adult zebrafish. Furthermore, WBS downregulates the gene expression levels of microphthalmia-associated transcription factor, TYR, tyrosinase-related protein-1, and tyrosinase-related protein-2 in B16F10 cells. In conclusion, our research confirms that WBS, a naturally derived substance, offers high safety and mild effects, making it a promising candidate for a skin-whitening agent.

Skin healthcare protection with antioxidant and anti-melanogenesis activity of polysaccharide purification from Bletilla striata

In this study, we investigated the structural characterization and biological activities of Bletilla striata polysaccharides (BSPs) for their role as antioxidants and anti-melanogenesis agents in skin healthcare protection. Three neutral polysaccharides (BSP-1, BSP-2, and BSP-3) with molecular weights of 269.121 kDa, 57.389 kDa, and 28.153 kDa were extracted and purified. Their structural characteristics were analyzed by ion chromatography, GC-MS, and 1D/2D NMR. The results showed that BSP-1, which constitutes the major part of BSPs, was composed of α-D-Glcp, β-D-Glcp, β-D-Manp, and 2-O-acetyl-β-D-Manp, with the branched-chain accompanied by β-D-Galp and α-D-Glcp. BSP-1, BSP-2, and BSP-3 can enhance the total antioxidant capacity of skin fibroblasts with non-toxicity. Meanwhile, BSP-1, BSP-2, and BSP-3 could significantly inhibit the proliferative activity of melanoma cells. Among them, BSP-1 and BSP-2 showed more significance in anti-melanogenesis, tyrosinase inhibition activity, and cell migration inhibition. BSPs have effective antioxidant capacity and anti-melanogenesis effects, which should be further emphasized and developed as skin protection components.

Characterization and screening of anti-melanogenesis and anti-photoaging activity of different enzyme-assisted polysaccharide extracts from Portulaca oleracea L

BACKGROUND

The flavonoids and polysaccharides in Portulaca oleracea L. (PO) have significant antibacterial and antioxidant effects, which can inhibit common bacteria and remove free radicals in the body. However, there was little research on the use of PO to alleviate hyperpigmentation and photoaging damage.

PURPOSE

This study was to investigate the anti-photoaging and whitening activity mechanism of polysaccharide of PO (POP) in vitro and in vivo.

METHOD

In this study, 16 fractions obtained by four enzyme-assisted extraction from PO and their scavenging capabilities against 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radicals were evaluated. Among these fractions, a polysaccharide fraction (VPOP3) showed the strongest biological activity. VPOP3 was characterized by Fourier-transform infrared spectroscopy, molecular weight (MW), and monosaccharide composition analysis, and the protective effect of VPOP3 on photoaging and hyperpigmentation was researched.

RESULTS

VPOP3 is a low-MW acidic heteropolysaccharide with MW mainly distributed around 0.71KDa, arabinose as its main monosaccharide component. VPOP3 reliably reduced the reactive oxygen species levels in cells and zebrafish and the level of lipid peroxidation in zebrafish. In addition, VPOP3 inhibited UVB-induced apoptotic body formation and apoptosis by downregulating caspase-3 and Bax and upregulating Bcl-2 in mitochondrion-mediated signaling pathways. On the other hand, VPOP3 at high concentrations significantly downregulated the expression of microphthalmia-associated transcription factor, tyrosinase (TYR), and TYR-related protein-1 and TYR-related protein-2 in the melanogenic signaling pathway to achieve a whitening effect.

CONCLUSION

The above results showed that VPOP3 has superior activities of anti-photoaging and anti-melanogenesis and can be utilized as a safe resource in the manufacture of cosmetics.

Inhibition of melanogenesis by 3-(1'-methyltetrahydropyridinyl)-2,4-6-trihydroxy acetophenone via suppressing the activity of cAMP response element-binding protein (CREB) and nuclear exclusion of CREB-regulated transcription coactivator 1 (CRTC1)

Exposure to Ultraviolet radiation or α-melanocyte-stimulating hormone (α-MSH) stimulates the Cyclic Adenosine Monophosphate/Protein Kinase A signalling pathway, which leads to the synthesis and deposition of melanin granules in the epidermis. Skin pigmentation is the major physiological defence against inimical effects of sunlight. However, excessive melanin production and accumulation can cause various skin hyperpigmentation disorders. The present study involved the identification of 3-(1'-methyltetrahydropyridinyl)-2,4-6-trihydroxy acetophenone (IIIM-8) as an inhibitor of melanogenesis, IIIM-8 significantly inhibited pigment production both invitro and invivowithout incurring any cytotoxicity in Human Adult Epidermal Melanocytes (HAEM). IIIM-8 repressed melanin synthesis and secretion both at basal levels and in α-MSH stimulated cultured HAEM cells by decreasing the levels of Cyclic Adenosine Monophosphate (cAMP) and inhibiting the phosphorylation of cAMP response element-binding (CREB) protein, coupled with restoring the phosphorylation of CREB-regulated transcription coactivator 1 (CRTC1) and its nuclear exclusion in HAEM cells. This impeding effect correlates with diminished expression of master melanogenic proteins including microphthalmia-associated transcription factor (MITF), Tyrosinase (TYR), Tyrosinase related protein 1 (TRP1), and Tyrosinase related protein 2 (TRP2). Additionally, topical application of IIIM-8 induced tail depigmentation in C57BL/6 J mice. Furthermore, IIIM-8 efficiently mitigated the effect of ultraviolet-B radiation on melanin synthesis in the auricles of C57BL/6 J mice. This study demonstrates that IIIM-8 is an active anti-melanogenic agent against ultraviolet radiation-induced melanogenesis and other hyperpigmentation disorders.

Methoxyflavones from Black Ginger (Kaempferia parviflora Wall. ex Baker) and their Inhibitory Effect on Melanogenesis in B16F10 Mouse Melanoma Cells

Kaempferia parviflora Wall. ex Baker (Zingiberaceae), commonly known as Thai ginseng or black ginger, is a tropical medicinal plant in many regions. It has been traditionally used to treat various ailments, including ulcers, dysentery, gout, allergies, abscesses, and osteoarthritis. As part of our ongoing phytochemical study aimed at discovering bioactive natural products, we investigated potential bioactive methoxyflavones from K. parviflora rhizomes. Phytochemical analysis aided by liquid chromatography-mass spectrometry (LC-MS) led to the isolation of six methoxyflavones (1-6) from the n-hexane fraction of the methanolic extract of K. parviflora rhizomes. The isolated compounds were structurally determined to be 3,7-dimethoxy-5-hydroxyflavone (1), 5-hydroxy-7-methoxyflavone (2), 7,4'-dimethylapigenin (3), 3,5,7-trimethoxyflavone (4), 3,7,4'-trimethylkaempferol (5), and 5-hydroxy-3,7,3',4'-tetramethoxyflavone (6), based on NMR data and LC-MS analysis. All of the isolated compounds were evaluated for their anti-melanogenic activities. In the activity assay, 7,4'-dimethylapigenin (3) and 3,5,7-trimethoxyflavone (4) significantly inhibited tyrosinase activity and melanin content in IBMX-stimulated B16F10 cells. In addition, structure-activity relationship analysis revealed that the methoxy group at C-5 in methoxyflavones is key to their anti-melanogenic activity. This study experimentally demonstrated that K. parviflora rhizomes are rich in methoxyflavones and can be a valuable natural resource for anti-melanogenic compounds.

Natural polyphenols: a promising bioactive compounds for skin care and cosmetics

The physiological and morphological aspects of skin suffer from frequent change. Numerous internal and external factors have direct impact on inducing various skin problems like inflammation, aging, cancer, oxidative stress, hyperpigmentation etc. The use of plant polyphenols as a photo-ecting agent is gaining popularity nowadays. Polyphenols are known to enhance endogenic antioxidant system of skin thereby preventing various skin diseases. The biological activity of plant polyphenols is dependent on their physicochemical properties for overcoming the epidermal barriers to reach the specific receptor. Several evidences have reported the vital role polyphenols in mitigating adverse skin problems and reverting back the healthy skin condition. The interest in plant derived skin care products is emerging due to the changing notion of people to shift their focus towards use of plant-based products. The present review draws an attention to uncover the protective role of polyphenols in prevention of various skin problems. Several in vitro and in vivo studies have been summarized that claims the efficacious nature of plant extract having dermatological significance.

Morus alba L. root decreases melanin synthesis via sphingosine-1-phosphate signaling in B16F10 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Morus alba L. has long been used for beauty in many Asian countries and regions, including anti-aging and hyperpigmentation.

AIM OF THE STUDY

This study aimed at the inhibitory effect of Morus alba L. root on melanogenesis in B16F10 melanoma cells and the mechanism involved.

MATERIALS AND METHODS

This study evaluated the anti-melanogenic effect of Morus alba L. root extract (MAR) on B16F10 melanoma cells by assessing cell viability, melanin accumulation, cellular tyrosinase activity, intra/inter-cellular S1P levels, cellular S1P-related metabolic enzyme activity, and western blot analysis. In addition, the potential S1P lyase (S1PL) inhibitory constituents in MAR were identified by LC-MS/MS.

RESULTS

Without affecting the viability of B16F10 melanoma cells, MAR inhibited intracellular tyrosinase activity in a dose-dependent manner, thereby reducing the accumulation of melanin. MAR also downregulated the expression level of MITF via activating the ERK signaling pathway. Furthermore, MAR increased the intra/inter-cellular S1P by inhibiting S1PL. Several compounds with inhibitory S1PL activity have been identified in MAR, such as mulberroside A and oxyresveratrol.

CONCLUSIONS

The anti-melanogenic effects of MAR mainly involve promoting MITF degradation mediated via S1P-S1PR3-ERK signaling through increasing cellular S1P levels by inhibiting S1PL activity.

Undescribed alkyne-geranylcyclohexenetriols from the endophyte Diaporthe caulivora 09F0132 and their anti-melanogenic activity

To explore valuable endophytic fungus from Formosan Lauraceous plants as natural medicinal products, the fungus, Diaporthe caulivora isolated from leaves of Neolitsea daibuensis, was investigated. Through a thorough investigation of the ethanolic extract of the solid fermentation of D. caulivora 09F0132, six undescribed alkyne-geranylcyclohexenetriols, caulivotrioloxins A-F, one undescribed trichopyrone, diapopyrone, two undescribed sesquiterpenes, caulibysins A-B, one compound firstly isolated from the natural source, 3-O-desmethyl phomentrioloxin, and eight known compounds have been successfully identified. The absolute configuration of caulibysin A was confirmed by single-crystal X-ray diffraction, and those of (3R,8S)-5,7-dihydroxy-3-(1-hydroxyethyl)phthalide and (3S,8S)-5,7-dihydroxy-3-(1-hydroxyethyl)phthalide were determined by circular dichroism (CD) spectra. Among the isolated compounds, caulivotrioloxin A concentration-dependently decreased the cellular melanin contents and tyrosinase activities in mouse melanoma B16-F10 cells, suggesting the anti-melanogenic potentials. The anti-melanogenic effects of caulivotrioloxin A involved the decrease in the protein expressions of melanogenic enzymes, including tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2. Taken together, these results suggested that the isolates from D. caulivora could be served as natural melanogenesis inhibitors for cosmeceutical applications.

Triterpenoids from the leaves of Osmanthus fragrans var. aurantiacus with their anti-melanogenesis and anti-tyrosinase activities

Excessive production of melanin causes various dermatological disorders including hyperpigmentation. To search for anti-melanogenesis candidates from natural products, we discovered that leaves of Osmanthus fragrans var. aurantiacus (OFA) suppressed melanin production. The extract of OFA leaves and its fractions were subjected to bioactivity-guided separation by targeting active constituents and a total of four triterpenoids were obtained: 3α,24-dihydroxyurs-12-en-28 oic acid (1), pomolic acid (2), maslinic acid (3), and corosolic acid (4). Compounds 1 and 2 were isolated from this plant for the first time. All compounds were evaluated for their inhibitory activities against melanin production and tyrosinase activity. Active compounds were further investigated to understand their mechanisms of action. Results revealed that they significantly down-regulated TYRP-1 and TYRP-2 expression levels. Our results clarified the whitening property of this plant and provided evidence that active constituents of this plant possessed anti-melanogenesis effect and anti-tyrosinase activity for the first time.

Diversity of Adenostemma lavenia, multi-potential herbs, and its kaurenoic acid composition between Japan and Taiwan

Adenostemma lavenia (L.) Kuntze (Asteraceae) is widely distributed in tropical regions of East Asia, and both A. lavenia and A. madurense (DC) are distributed in Japan. In China and Taiwan, A. lavenia is used as a folk medicine for treating lung congestion, pneumonia, and hepatitis. However, neither phylogenic nor biochemical analysis of this plants has been performed to date. We have reported that the aqueous extract of Japanese A. lavenia contained high levels of ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic acid (11αOH-KA; a kaurenoic acid), which is a potent anti-melanogenic compound. Comparison of chloroplast DNA sequences suggested that A. lavenia is originated from A. madurense. Analyses of kaurenoic acids revealed that Japanese A. lavenia and A. madurense contained high levels of 11αOH-KA and moderate levels of 11α,15OH-KA, while Taiwanese A. lavenia mainly contained 9,11αOH-KA. The diverse biological activities (downregulation of Tyr, tyrosinase, gene expression [anti-melanogenic] and iNOS, inducible nitric oxide synthase, gene expression [anti-inflammatory], and upregulation of HO-1, heme-oxygenase, gene expression [anti-oxidative]) were associated with 11αOH-KA and 9,11αOH-KA but not with 11α,15OH-KA. Additionally, 11αOH-KA and 9,11αOH-KA decreased Keap1 (Kelch-like ECH-associated protein 1) protein levels, which was accompanied by upregulation of protein level and transcriptional activity of Nrf2 (NF-E2-related factor-2) followed by HO-1 gene expression. 11αOH-KA and 9,11αOH-KA differ from 11α,15OH-KA in terms of the presence of a ketone (αβ-unsaturated carbonyl group, a thiol modulator) at the 15^th position; therefore, thiol moieties on the target proteins, including Keap1, may be important for the biological activities of 11αOH-KA and 9,11αOH-KA and A. lavenia extract.

The anti-melanogenic effects of 3-O-ethyl ascorbic acid via Nrf2-mediated α-MSH inhibition in UVA-irradiated keratinocytes and autophagy induction in melanocytes

3-O-ethyl ascorbic acid (EAA) is an ether-derivative of ascorbic acid, known to inhibit tyrosinase activity, and is widely used in skincare formulations. Nevertheless, the molecular mechanisms underlying the EAA's effects are poorly understood. Here, the anti-melanogenic activity of EAA was demonstrated through Nrf2-mediated α-MSH inhibition in UVA-irradiated keratinocytes (HaCaT) and autophagy induction and inhibition of α-MSH-stimulated melanogenesis in melanocytes (B16F10). EAA pretreatment increased the HaCaT cell viability but suppressed ROS-mediated p53/POMC/α-MSH pathways in UVA-irradiated cells. Further, the conditioned medium from EAA-pretreated and UVA-irradiated HaCaT cells suppressed the MITF-CREB-tyrosinase pathways leading to the inhibition of melanin synthesis in B16F10 cells. EAA treatment increased nuclear Nrf2 translocation via the p38, PKC, and ROS pathways leading to HO-1, γ-GCLC, and NQO-1 antioxidant expression in HaCaT cells. However, Nrf2 silencing reduced the EAA-mediated anti-melanogenic activity, evidenced by impaired antioxidant gene expression and uncontrolled ROS (H₂0₂) generation following UVA irradiation. In B16F10 cells, EAA-induced autophagy was shown by enhanced LC3-II levels, AVO formation, Beclin-1 upregulation, and activation of p62/SQSTM1. Further, EAA-induced anti-melanogenic activity was substantially decreased in autophagy inhibitor (3-MA) pretreated or LC3 knockdown B16F10 cells. Notably, transmission electron microscopy data showed increased melanosome-engulfing autophagosomes in EAA-treated B16F10 cells. Moreover, EAA also down-regulated MC1R, TRP-1/-2, tyrosinase expressions, and melanin synthesis by suppressing the cAMP-CREB-mediated MITF expression in B16F10 cells stimulated with α-MSH. In vivo studies on the zebrafish model further confirmed that EAA inhibited tyrosinase expression/activity and endogenous pigmentation. In conclusion, 3-O-ethyl ascorbic acid is an effective skin-whitening agent and could be used as a topical agent for cosmetic purposes.

The in vitro and in vivo depigmenting activity of pterostilbene through induction of autophagy in melanocytes and inhibition of UVA-irradiated α-MSH in keratinocytes via Nrf2-mediated antioxidant pathways

Pterostilbene (Pt) is a natural polyphenol found in blueberries and several grape varieties. Pt's pharmacological importance was well documented. Nevertheless, the depigmenting effects are not demonstrated. We evaluated the Pt's depigmenting effects through autophagy induction in B16F10 cells and inhibition of UVA (3 J/cm²)-irradiated α-MSH in keratinocyte HaCaT cells via Nrf2-mediated antioxidant pathways. Pt (2.5–5μM) attenuated ROS production and downregulated the POMC/α-MSH pathway in HaCaT cells. The conditioned medium-derived from UVA-irradiated HaCaT pretreated with Pt suppressed melanogenesis in B16F10 through MITF-CREB-tyrosinase pathway downregulation. Interestingly, Pt-induced HaCaT autophagy was revealed by enhanced LC3-II accumulation, p62/SQSTM1 activation, and AVO formation. Pt significantly decreased melanosome gp100 but increased LC3-II levels in HaCaT cells exposed to B16F10-derived melanin. Pt activated and facilitated the Nrf2 antioxidant pathway in HaCaT cells leading to increased HO-1, γ-GCLC, and NQO-1 antioxidant protein expression. ERK, AMPK, and ROS pathways mediate the Nrf2 activation. However, Nrf2 knockdown suppressed Pt's antioxidant ability leading to uncontrolled ROS and α-MSH levels after UVA-irradiation suggested the essentiality of the Nrf2 pathway. Moreover, in α-MSH-stimulated B16F10 cells, Pt (10–30 μM) downregulated the MC1R, MITF, tyrosinase, TRP-1/-2, and melanin expression. Further, Pt showed potent anti-melanogenic effects through autophagy induction mechanism in B16F10 cells, verified by increased LC3-II/p62 levels, AVO formation, and Beclin-1/Bcl-2 ratio, decreased ATG4B levels and PI3K/AKT/mTOR pathway. Transmission electron microscopy provided direct evidence by showing autophagosomes engulfing melanosomes following Pt treatment in α-MSH-stimulated B16F10 cells. Moreover, Pt-induced anti-melanogenic activity through the downregulation of CREB-MITF pathway-mediated TRP-1/-2, tyrosinase expressions, melanosome formation, and melanin synthesis was substantially reversed due to 3-MA (autophagy inhibitor) pretreatment or LC3 silencing in B16F10 cells. In vivo results also confirmed that Pt-inhibited tyrosinase expression/activity and endogenous pigmentation in the zebrafish model. Therefore, pterostilbene is a potent skin-whitening and antioxidant agent and could be used in skin-whitening formulations as a topical applicant.

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Pt inhibits ROS-mediated POMC/α-MSH pathway in UVA-irradiated HaCaT cells.

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Pt activates Nrf2-mediated HO-1, γ-GCLC, and NQO-1 expression in HaCaT cells.

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Pt-induces autophagy in B16F10 cells leading to melanogenesis inhibition.

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Pt-mediates anti-melanogenic mechanisms in α-MSH-stimulated B16F10 cells.

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Pt-inhibits tyrosinase expression and endogenous pigmentation in zebrafish model.

The anti-melanogenic effects of ellagic acid through induction of autophagy in melanocytes and suppression of UVA-activated α-MSH pathways via Nrf2 activation in keratinocytes

Ellagic acid (EA) is a natural phenol antioxidant in different fruits, vegetables, and nuts. As a copper iron chelator from the tyrosinase enzyme's active site, EA was reported to inhibit melanogenesis in melanocytes. Here, we demonstrated the anti-melanogenic mechanisms of EA through autophagy induction in melanoma B16F10 cells and the role of Nrf2 and UVA (3 J/cm²)-activated α-melanocyte stimulating hormone (α-MSH) pathways in keratinocyte HaCaT cells. In vitro data showed that EA suppressed the tyrosinase activity and melanogenesis by suppressing cAMP-mediated CREB and MITF signaling mechanisms in α-MSH-stimulated B16F10 cells. ERK, JNK, and AKT pathways were involved in this EA-regulated MITF downregulation. Notably, EA induced autophagy in B16F10 cells was evidenced from increased LC3-II accumulation, p62/SQSTM1 activation, ATG4B downregulation, acidic vesicular organelle (AVO) formation, PI3K/AKT/mTOR inhibition, and Beclin-1/Bcl-2 dysregulation. Interestingly, 3-MA (an autophagy inhibitor) pretreatment or LC3 silencing (siRNA transfection) of B16F10 cells significantly reduced EA-induced anti-melanogenic activity. Besides this, in UVA-irradiated keratinocyte HaCaT cells, EA suppressed ROS production and α-MSH generation. Moreover, EA mediated the activation and nuclear translocation of Nrf2, leading to antioxidant γ-GCLC, HO-1, and NQO-1 protein expression in HaCaT cells. However, Nrf2 knockdown has significantly impaired this effect, and there was an uncontrolled ROS generation following UVA irradiation. JNK, PKC, and ROS pathways were involved in the activation of Nrf2 in HaCaT cells. In vivo experiments using the zebrafish model confirmed that EA inhibited tyrosinase activity and endogenous pigmentation. In conclusion, ellagic acid is an effective skin-whitening agent and might be used as a topical applicant.

In silico and in vitro insights into tyrosinase inhibitors with a 2-thioxooxazoline-4-one template

The β-phenyl-α,β-unsaturated carbonyl (PUSC) scaffold confers tyrosinase inhibitory activity, and in the present study, 16 (Z)-5-(substituted benzylidene)-3-phenyl-2-thioxooxazolidin-4-one analogues containing this scaffold were synthesized. Mushroom tyrosinase inhibitory activities were examined. Compound 1c (IC₅₀ = 4.70 ± 0.40 μM) and compound 1j (IC₅₀ = 11.18 ± 0.54 μM) inhibited tyrosinase by 4.9 and 2.1-fold, respectively, and did so more potently than kojic acid (IC₅₀ = 23.18 ± 0.11 μM). Kinetic analysis of tyrosinase inhibition revealed that 1c and 1j inhibited tyrosinase competitively. Results of docking simulation with mushroom tyrosinase using four docking programs suggested that 1c and 1j bind more strongly than kojic acid to the active site of tyrosinase and supported kinetic findings that both compounds are competitive inhibitors. The docking results of human tyrosinase homology model indicated that 1c and 1j can also strongly inhibit human tyrosinase. EZ-cytox assays revealed 1c and 1j were not cytotoxic to B16F10 melanoma cells. The effects of 1c and 1j on cellular tyrosinase activity and melanin production were also investigated in α-MSH- and IBMX-co-stimulated these cells. Both compounds significantly and dose-dependently reduced tyrosinase activity, and at 10 µM were more potent than kojic acid at 20 µM. Compounds 1c and 1j also inhibited melanogenesis, which suggested that the inhibitory effects of these compounds on melanin production were mainly attributable to their inhibitions of tyrosinase. These results indicate that compounds 1c and 1j with the PUSC scaffold have potential use as whitening agents for the treatment of hyperpigmentation-associated diseases.

Antioxidant, Anti-Melanogenic and Anti-Wrinkle Effects of Phellinus vaninii

In this study, the antioxidant, anti-xanthine oxidase, anti-melanogenic and anti-wrinkle effects of methanol (ME) and hot water (HE) extracts from the fruiting bodies of Phellinus vaninii were investigated. The 1,1-diphenyl-2-picryl-hydrazyl free radical scavenging activity of 2.0 mg/mL HE (95.38%) was comparable to that of butylated hydroxytoluene (96.97%), the reference standard. The hydroxyl radical scavenging activities of ME (98.19%) and HE (97.55%) were higher than that of butylated hydroxytoluene (92.66%) at 2.0 mg/mL. Neither ME nor HE was cytotoxic to murine melanoma B16-F10 cells at 25-750 µg/mL. Although the xanthine oxidase (XO) inhibitory effects of ME and HE were significantly lower than that of allopurinol, the values were higher than 84 percent. The in vitro tyrosinase inhibitory activities of ME and HE were comparable to kojic acid at 2.0 mg/mL. The cellular tyrosinase and melanin synthetic activities of ME and HE on B16-F10 melanoma cells at 500 µg/mL were higher than arbutin, indicating that the inhibitory effects of arbutin on the tyrosinase and melanin synthesis were higher than those of ME and HE. The collagenase inhibitory activity of HE was comparable to EGCG at 2.0 mg/mL, however, the elastase inhibitory activity of ME and HE was lower than EGCG at the concentration tested. The study results demonstrated that the fruiting bodies of Ph. vaninii possessed good antioxidant, anti-xanthine oxidase, cell-free anti-tyrosinase, cellular anti-tyrosinase, anti-collagenase, and moderate anti-elastase activities, which might be used for the development of novel anti-gout, skin-whitening, and skin anti-wrinkle agents.

A chemical compound from fruit extract of Juglans mandshurica inhibits melanogenesis through p-ERK-associated MITF degradation

BACKGROUND

Trials for regulation of abnormal hyperpigmentation from the use of natural products have been going on for years. Leaf and root extracts from Juglans mandshurica are reported to function as antioxidants and to suppress allergic dermatitis. However, studies evaluating its fruit extract and the chemical compounds from the fruit extract are lacking in dermatology fields, including melanogenesis.

PURPOSE

The aim of this study is to understand the effect of the fruit extract from J. mandshurica on pigmentation and to search for specific chemical compounds that affect melanogenesis.

METHODS

After screening out any anti-melanotic effects of the fruit extract from J. mandshurica in B16F10 melanoma cells, three major phenolic compounds isolated from the fruit extract were tested by western blot analysis for expression of microphthalmia-associated transcription factor (MITF) and tyrosinase. Their effect on B16F10 melanoma cells with regard to melanogenesis was also confirmed in primary human epidermal melanocytes (PHEMs). PD98059 was tested to observe the compounds' signaling role in the extracellular signal-regulated protein kinase (ERK)-pathway.

RESULTS

Fruit extract from J. mandshurica showed anti-melanotic effects in B16F10 melanoma cells. After chemical compounds were isolated from the fruit extracts, three phenolic compounds were evaluated for anti-melanotic effects. 2-[4-(3-hydroxypropyl)-2-methoxyphenoxy]-1,3-propanediol (compound 1) showed the highest suppression effect among the three compounds. In B16F10 melanoma cells and PHEMs, reduced melanin contents were observed after treatment with the compound (1). Experiments using a blocker of ERK showed that the inhibitory effect of the compound (1) on melanogenesis was dependent on ERK-associated MITF degradation.

CONCLUSION

A chemical constituent of Juglans mandshurica Maxim. induces an inhibitory mechanism to melanogenesis. It has the potential to become a whitening agent in the medical field, though this requires further clinical investigation.

Modulation effects of sweroside isolated from the Lonicera japonica on melanin synthesis

In the course of screening for the melanogenesis inhibitors, sweroside was isolated from Lonicera japonica. Its chemical structure was determined on the basis of spectroscopic analysis, including mass spectroscopy and nuclear magnetic resonance analysis. Sweroside inhibited potent melanogenesis in melan-a cells at 300μM without cytotoxicity. Also, sweroside decreased tyrosinase, tyrosinase-related protein-1 (TRP-1) and TRP-2 protein production in melan a cells. To identify the signaling pathway of sweroside, the ability of sweroside to influence Akt and extracellular signal-regulated protein kinase (ERK) activation was investigated. Sweroside induced Akt and ERK in a dose-dependent manner. In addition, the specific inhibition of the Akt and ERK signaling pathways were studied by specific inhibitor LY294002 and U0126, respectively and it was causing the increased melanin synthesis. Furthermore, sweroside presented inhibition of the body pigmentation and tyrosinase activity in zebrafish in vivo model. These results suggest that sweroside isolated from L. japonica may be an effective skin-whitening agent through the regulates the expression of MAP kinase and melanogenic enzymes.

Evaluation of the antioxidant and melanogenesis inhibitory properties of pracparatum mungo (lu-do huang)

Pracparatum mungo (Lu-Do Huang) is a traditional Chinese functional medicine made from the natural fermentation of mung bean (Lǜ Dòu) mixed with other Chinese medicines. It has been recognized as having liver protecting and detoxifying effects. As mung beans have been verified to possess anti-inflammatory, antioxidant, antipyretic, and whitening actions, the present research utilized the in vitro, ex vivo, and in vivo experimental models to investigate the antioxidant and melanin inhibiting effects of P. mungo on the skin. The in vitro experiment revealed that P. mungo methanol extract (PMME) and P. mungo ethanol extract (PMEE) possess the capacity to clear α,α-diphenyl-2-picrylhydrazyl (DPPH) radicals and inhibit tyrosinase activity. The ex vivo experiment indicated that PMEE can promote the growth of MDCK cells and increase the enzymatic activities of superoxide dismutase (SOD) and catalase in MDCK cells. On the other hand, PMME and PMEE can suppress the proliferation of A375 cells, and PMEE can reduce the enzymatic activities of SOD and catalase in A375 cells. The in vivo results showed that P. mungo can enhance the enzymatic performance of SOD, Catalase, and glutathione peroxidase (GPx) in the liver. The results also showed that P. mungo has antioxidant characteristics and can inhibit tyrosinase activity, thereby promoting the growth of skin tissues and suppressing the proliferation of A375 cells, and thus enhancing the effects that the antioxidant enzymatic performance has on the liver. These results can be applied in the development of tyrosinase inhibitors or antioxidants used for the inhibition of melanin biosynthesis or for auto-oxidation in further industrial applications, particularly those relating to functional food or cosmetic compositions.

Betulinic acid isolated from Vitis amurensis root inhibits 3-isobutyl-1-methylxanthine induced melanogenesis via the regulation of MEK/ERK and PI3K/Akt pathways in B16F10 cells

Previously, betulinic acid was identified as one of the main compounds responsible for the anti-melanogenic effect in Vitis amurensis root. In this study, we investigated the precise mechanism underlying the anti-melanogenic activity of betulinic acid in B16F10 cells. Betulinic acid significantly attenuated 3-isobutyl-1-methylxanthine (IBMX)-induced melanin production by inhibiting tyrosinase, tyrosinase related protein (TRP)-1, and TRP-2 expression through the modulation of their corresponding transcription factors, microphthalamia associated transcription factor (MITF) and cAMP response element binding protein (CREB), in B16F10 cells. In addition, phosphorylation of mitogen-activated protein kinase kinase (MEK)/extracellular regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K)/Akt, involved in the melanogenic processes, were ameliorated by betulinic acid treatment. Role of MEK/ERK and PI3K/Akt signaling pathway in the melanogenesis was confirmed by using specific inhibitors, PD98059 (for MEK/ERK) and LY294002 (for PI3K/Akt), respectively. As a result, betulinic acid inhibited melanin production by tyrosinase, TRP-1, and TRP-2 inhibition through the regulation of CREB and MITF, which was accompanied with MEK/ERK and PI3K/Akt inactivation in IBMX-stimulated B16F10 cells. Consequently, these results demonstrate a novel molecular function of betulinic acid derived from V. amurensis root in melanogenesis, which in turn enhances our understanding on the application of cosmetic therapy for reducing skin hyperpigmentation.

Chemical and pharmacological investigation of micropropagated Hygrophila pogonocalyx produced from leaf explants

BACKGROUND

An optimized method for indirect shoot organogenesis from the leaf explants of Hygrophila pogonocalyx, a rare and endemic species in Taiwan, was developed to supply enough quantity of plant materials for the first chemical and pharmacological investigation.

RESULTS

Incubation of the young leaves on Murashige and Skoog (MS) medium supplemented with 6-benzylaminopurine (0.5 mg/l) and indole-3-acetic acid (0.1 mg/l) resulted in the best multiplication rate for organogenesis. The average number of adventitious buds per leaf was 22.8 ± 1.9 after 8-week culture. The adventitious buds rooted and developed into plantlets when cultured simply on MS medium. Using this protocol, up to 37,600 plants were produced from a single leaf explant in one year. From the ethanol extract of the leaves of this micropropagated plant, 13 compounds were isolated and identified, including two flavones (1, 11), four flavonols (9, 10, 12, and 13), three phenylethanoid glycosides (6-8), two alkylated glycosides (2-3), and two steroids (4-5). Of these, acteoside (7) exhibited anti-tyrosinase activity in human epidermal melanocytes and luteolin 7-O-β-D-glucopyranoside (11) exhibited the greatest neurocytoprotective activity.

CONCLUSIONS

The method, indirect shoot organogenesis from leaf explants of H. pogonocalyx, could be developed to supply enough quantity of plant materials for the chemical and pharmacological investigation. In the present study, the isolated active compounds may develop for whitening agents or treating neurodegenerative diseases in the future.

Octaphlorethol A isolated from Ishige foliacea inhibits α-MSH-stimulated induced melanogenesis via ERK pathway in B16F10 melanoma cells

In this study, the potent skin-whitening effects of Octaphlorethol A (OPA) isolated from Ishige foliacea was investigated through inhibitory effect of melanin synthesis and tyrosinase activity in alpha-melanocyte stimulating hormone (α-MSH) induced B16F10 melanoma cells. OPA markedly inhibited melanin synthesis and tyrosinase activity in a concentration-dependent manner. We also found that OPA decreased microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 and -2 (TRP-1 and TRP-2) protein expressions. Moreover, OPA reduces p38 MAPK protein levels and activates extracellular signal-regulated kinase (ERK) and c-jun N-terminal kinases (JNKs) protein expressions in B16F10 cells. A specific ERK inhibitor PD98059 significantly blocks OPA-inhibited melanin synthesis and tyrosinase activity, whereas a p38MAP and JNK inhibitor had no effect. These findings provide evidence demonstrating that the anti-melanogenic effect of OPA is mediated through the activation of ERK signal pathway in B16F10 cells. These results indicate that OPA has the potential to be used as a melanogenesis inhibitor in the food and cosmetics industry.