Antimelanogenesis Effect of Methyl Gallate through the Regulation of PI3K/Akt and MEK/ERK in B16F10 Melanoma Cells.

Methyl gallate is a polyphenolic compound found in many plants, and its antioxidant, antitumor, antibacterial, and anti-inflammatory effects have been extensively studied. More recently, antidepressant-like effects of methyl gallate have been demonstrated in some studies. In the present study, we examined the effects of methyl gallate on melanogenesis, including the tyrosinase inhibitory effect, the melanin content, and the molecular signaling pathways involved in this inhibition. The results showed that methyl gallate inhibited tyrosinase activity and significantly downregulated the expressions of melanin synthesis-associated proteins, including microphthalmia-associated transcription factor (MITF), tyrosinase, dopachrome tautomerase (Dct), and tyrosinase-related protein-1 (TRP1). In conclusion, our findings indicated that activation of MEK/ERK and PI3K/Akt promoted by methyl gallate caused downregulation of MITF and triggered its downstream signaling pathway, thereby inhibiting the production of melanin. In summary, methyl gallate showed significant inhibitory activity against melanin formation, implying that it may be a potential ingredient for application in skin-whitening cosmetics.

Characterization and human osteoblastic proliferation- and differentiation-stimulatory effects of phosphatidylcholine liposomes-encapsulated propranolol hydrochloride.

DMPC and DSPC liposomes were prepared via thin film hydration method followed by sonication. Propranolol solution was incorporated into liposomes at hydration stage. TEM images showed the sizes of DSPC and DMPC were around 88 and 137 nm, respectively. The highest encapsulation ratio of propranolol was approximately 70% using DSPC/CHO/OCT liposomes, which release the drug over 60% in 24 h and reached 100% in 48 h. Both propranolol (10⁻8-10⁻6 M) and DSCP liposomes-encapsulated propranolol showed over 1.5-fold increases in the proliferation of human osteoblastic cells hFOB1.19 while differentiation of the cells was approximately doubled by plain and liposomal propranolol, indicating that the stimulatory effects of liposomal propranolol are similar with those of propranolol on human osteoblastic hFOB1.19 cells. The phosphatidylcholine liposomes-encapsulated propranolol prepared in this study potentially possesses anabolic effects in vivo and is also a promising anti-osteoporotic agent in future.

Proteomic investigation of anti-tumor activities exerted by sinularin against A2058 melanoma cells.

The extracts from soft corals have been increasingly investigated for biomedical and therapeutic purposes. The aim of this study is to examine and analyze the anti-tumor effects of the genus Sinularia extract sinularin on A2058 melanoma cells using MTT assay, cell migration assay, wound healing assay, flow cytometric analysis, and proteomic analysis. Sinularin dose-dependently (1-5 µg/mL) inhibited melanoma cell proliferation while the treatment at identical concentrations suppressed cell migration. Sinularin dose-dependently enhanced apoptotic melanoma cells and caused tumor cell accumulation at G2/M phase, indicating that sinularin exerts apoptosis-induced and cell cycle-delayed activities in A2058 melanoma cells. Comparative proteomic analysis was conducted to investigate the effects of sinularin at the molecular level by comparison between the protein profiling of melanoma cells treated with sinularin and without the treatment. Thirty-five differential proteins (13 upregulated and 22 downregulated) concerning the treatment were identified by liquid chromatography-tandem mass spectrometry. Proteomic data and Western blot displayed the levels of several tumor inhibitory or apoptosis-associated proteins including annexin A1, voltage-dependent anion-selective channel protein 1 and prohibitin (upregulated), heat shock protein 60, heat shock protein beta-1, and peroxiredoxin-2 (downregulated) in A2058 melanoma cells exposed to sinularin. Increased expression of p53, cleaved-caspase-3, cleaved-caspase-8, cleaved-caspase-9, p21, and Bax and decreased expression of Bcl-2 in sinularin-treated melanoma cells suggest that the anti-tumor activities of sinularin against melanoma cells are particularly correlated with these pro-apoptotic factors. These data provide important information for the mechanisms of anti-tumor effects of sinularin on melanoma cells and may be helpful for drug development and progression monitoring of human melanoma.

Evaluation of the antioxidative capability of commonly used antioxidants in dermocosmetics by in vivo detection of protein carbonylation in human stratum corneum.

We present an in vivo test platform to evaluate the antioxidative capability of seven frequently used dermocosmetic antioxidants on the human stratum corneum (SC). It has been reported that the protein carbonylation could be used as a biomarker for oxidative stress. The current study detects the change of the level of exposed protein carbonyl group in the most outer layer of human SC. The concentration of the antioxidant in each subject emulsion formulation was 0.5% (w/w). The data indicated that alpha-tocopherol (α-Vit E) and ascorbic acid (Vit C) have excellent antioxidative capability and α-Vit E-acetate possesses better than the average antioxidative capability. The bioconversion of α-Vit E-acetate to α-Vit E may occur in the human SC during a less than 2 weeks time course test. Lipoic acid possessed moderate antioxidative capability. Ascorbyl 6-palmitate had a low antioxidative capability. Ascorbic acid 2-glucoside represented an insignificant antioxidative capability. Glutathion (GSH) had no effect on reducing oxidative damage to human SC proteins, implying that the GSH recycling system could be absent in human SC. This test platform is an useful tool to evaluate the antioxidative efficiency of antioxidants on human SC proteins.