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The article discusses a study which examined the inhibitory effect of whisky congeners on melanogenesis in B16 melanoma cells of mouse. It is indicated that treatment with whisky congeners significantly alter melanogenesis in mouse cells. It is concluded that the inhibitory effects of whisky congeners on melanogenesis is associated with the direct inhibition of tyrosinase activity and the suppression of tyrosinase protein levels.

The article presents a study which investigates the effect of theaflavins found in black tea on melanogenesis. It states that the various theaflavins were investigated by their effects on mouse B16 melanoma cells and assessed by melanin content. Moreover, the study reveals that TF-3, a component of theaflavins, mediated by tyrosine enzyme messenger ribonucleic acid (mRNA).

The article presents a study which examined the effect of naringenin on melanogenesis in mouse B16 melanoma cells. Naringenin is a naturally occurring citrus flavonone. It has been reported that this compound shows various biological and pharmacological activities. The study was designed to gain insight into the role of naringenin in melanogenic signaling in mouse B16 melanoma cells.

Synthesis of melanin starts from the conversion of l-tyrosine to 3,4-dihydroxyphenylalanine (l-dopa) and then the oxidation of l-dopa yields dopaquinone by tyrosinase. Therefore, tyrosinase inhibitors have been established as important constituents of depigmentation agents. Recently, polyhydroxystilbene compounds, which are trans-resveratrol (3,4′,5-trihydroxy-trans-stilbene) analogs, have been demonstrated as potent tyrosinase inhibitors. However, their detailed inhibitory mechanisms are not clearly understood. In the present study, a variety of synthesized hydroxystilbene compounds were tested for their inhibitory effects against murine tyrosinase activity. The inhibitory potencies of the hydroxy-trans-stilbene compounds were remarkably elevated by increasing number of phenolic hydroxy substituents. Methylated hydroxy-trans-stilbene lost the inhibitory activity. Furthermore, hydrogenated hydroxystilbene or hydroxy-cis-stilbene exerted little or no inhibitory effect compared with hydroxy-trans-stilbene on tyrosinase activity. The structure–activity relationships demonstrated in the present study suggest that the phenolic hydroxy groups and trans-olefin structure of the parent stilbene skeleton contribute to the inhibitory potency of hydroxystilbene for tyrosinase activity. [Copyright &y& Elsevier]

Abstract: (−)-Cubebin showed a melanogenesis stimulation activity in a concentration-dependent manner in murine B16 melanoma cells without any significant effects on cell proliferation. Tyrosinase activity was increased at 24–72h after addition of cubebin to B16 cells, and then intracellular melanin amount was increased at 48–96h after the treatment. The expression levels of tyrosinase were time-dependently enhanced after the treatment with cubebin. At the same time, the expression levels of tyrosinase mRNA were also increased after addition of cubebin. Furthermore Western blot analysis revealed that cubebin elevated the level of phosphorylation of p38 mitogen-activated protein kinase (MAPK). SB203580, a selective inhibitor of p38 MAPK, completely blocked cubebin-induced expression of tyrosinase mRNA in B16 cells. These results suggested that cubebin increased melanogenesis in B16 cells through the enhancement of tyrosinase expression mediated by activation of p38 MAPK. [Copyright &y& Elsevier]