diphlorethohydroxycarmalol and Melanoma

Diphlorethohydroxycarmalol (DPHC) is a marine polyphenolic compound derived from brown alga Ishige okamurae. A previously study has suggested that DPHC possesses strong mushroom tyrosinase inhibitory activity. However, the anti-melanogenesis effect of DPHC has not been reported at cellular level. The objective of the present study was to clarify the melanogenesis inhibitory effect of DPHC and its molecular mechanisms in murine melanoma cells (B16F10) and zebrafish model. DPHC significantly inhibited tyrosinase activity and melanin content dose-dependently in α-melanocyte stimulating hormone (α-MSH)-stimulated B16F10 cells. This polyphenolic compound also suppressed the expression of phosphorylation of cAMP response element-binding protein (CREB) by attenuating phosphorylation of cAMP-dependent protein kinase A, resulting in decreased MITF expression levels. Furthermore, DPHC downregulated MITF protein expression levels by promoting the phosphorylation of extracellular signal-regulated kinase. It also inhibited tyrosinase, tyrosinase-related protein 1 (TRP-1), and TRP-2 in α-MSH stimulated B16F10 cells. In in vivo studies using zebrafish, DPHC also markedly inhibited melanin synthesis in a dose-dependent manner. These results demonstrate that DPHC can effectively inhibit melanogenesis in melanoma cells in vitro and in zebrafish in vivo, suggesting that DPHC could be applied in fields of pharmaceutical and cosmeceuticals as a skin-whitening agent. Significance of study: The present study showed for the first time that DPHC could inhibit a-MSH-stimulated melanogenesis via PKA/CREB and ERK pathway in melanoma cells. It also could inhibit pigmentation in vivo in a zebrafish model. This evidence suggests that DPHC has potential as a skin whitening agent. Taken together, DPHC could be considered as a novel anti-melanogenic agent to be applied in cosmetic, food, and medical industry.

Topics: alpha-MSH; Animals; Antineoplastic Agents; Cell Survival; Cyclic AMP Response Element-Binding Protein; Cyclic AMP-Dependent Protein Kinases; Dose-Response Relationship, Drug; Down-Regulation; Drug Screening Assays, Antitumor; Extracellular Signal-Regulated MAP Kinases; Heterocyclic Compounds, 3-Ring; Melanoma; Mice; Microphthalmia-Associated Transcription Factor; Molecular Structure; Phaeophyceae; Structure-Activity Relationship; Tumor Cells, Cultured; Zebrafish

In this study, potential inhibitory effect of 21 species of marine algae on melanogenesis was assessed via tyrosinase inhibitory effect. The Ishige okamurae extract tested herein evidenced profound tyrosinase inhibitory effect, compared to that exhibited by other marine algae extracts. Thus, I. okamurae was selected for use in further experiments, and was partitioned with different organic solvents. Profound tyrosinase inhibitory effect was detected in the ethyl acetate fraction, and the active compound was identified as the carmalol derivative, diphlorethohydroxycarmalol (DPHC), which evidenced higher levels of activity than that of commercial whitening agent. Intracellular reactive oxygen species (ROS) induced by ultraviolet (UV)-B radiation was reduced by the addition of DPHC and cell viability was dose-dependently increased. Moreover, DPHC demonstrated strong protective properties against UV-B radiation via damaged DNA tail length and morphological changes in fibroblast. Hence, these results indicate that DPHC isolated from I. okamurae has potential whitening effects and prominent protective effects on UV-B radiation-induced cell damages which might be used in pharmaceutical and cosmeceutical industries.

Topics: Adult; Animals; Antioxidants; Cell Line, Tumor; Cell Survival; Chemical Fractionation; Comet Assay; DNA; DNA Damage; Enzyme Inhibitors; Eukaryota; Heterocyclic Compounds, 3-Ring; Humans; Male; Melanocytes; Melanoma; Mice; Monophenol Monooxygenase; Oxidative Stress; Plant Extracts; Radiation-Protective Agents; Reactive Oxygen Species; Ultraviolet Rays; Young Adult