Colorimetric study of malvidin-3-O-glucoside copigmented by phenolic compounds: The effect of molar ratio, temperature, pH, and ethanol content on color expression of red wine model solutions.

In the recent research, the copigmentations of malvidin-3-O-glucoside with eight types of phenolic copigments have been investigated. The influence of the pigment/copigment molar ratio, the reaction temperature, the pH and the ethanol content of solutions has been examined. The results showed that the copigmentation effect was dependent on not only the particular structures of the phenolic compounds but also the factors of the reaction systems. The increase of the copigment concentration can strengthen the copigmentation effect, improve the solution color, and enhance the red-purple features. Different temperatures had different influences on the copigmentation reactions. The destruction of the copigmentation complexes can result in the hypsochromic shift of the reaction solution when the temperature was higher than 20°C. The bathochromic shift of the solution gradually progressed with the increase of the pH value. A significant copigmentation feature was spotted when pH reached 3.0, which demonstrates obvious red-purple characterization. The addition of the ethanol weakened the copigmentation effect. According to measurement through color analysis, it was found that the color differences caused by ethanol in red wine were typically attributed to quantitative changes. Remarkably, all of the above delicate color deviations caused by the structural or environmental factors can be precisely and conveniently depicted via the CIELAB space analysis.

[Synergistic effect of targeted inhibition of MEK/ERK and PI3K/AKT survival signaling pathways on induction of apoptosis in melanoma].

OBJECTIVE: The treatment of metastatic melanoma by conventional chemotherapeutic agents remains unsatisfactory. The present study was undertaken to reveal the role of co-inhibition of survival signaling pathways in apoptosis of melanoma cells. METHODS: A panel of human melanoma cell lines and fresh melanoma isolates was assessed for their sensitivity to the MEK inhibitor U0126 and/or AKT inhibitor LY294002. The proliferation and apoptosis of the cells were examined after treatment with the inhibitors. RESULTS: Constitutive activation of ERK1/2 and AKT was closely related to concentrations of serum in the culture medium (extracellular signals). The sensitivity of melanoma cells to apoptosis induced by inhibition of MEK/ERK was not correlated with the active BRAF mutation (BRAF(V600E)). Inhibition of MEK/ERK predominantly induced apoptosis; whereas inhibition of PI3K/AKT primarily inhibited proliferation. Co-inhibition of MEK/ERK1/2 and PI3K/AKT synergistically induced apoptosis. CONCLUSION: Co-targeting MEK/ERK and PI3K/AKT pathways may further improve treatment for melanoma.