Effect of xanthohumol on melanogenesis in B16 melanoma cells

Xanthohumol (XH), the principal prenylflavonoid of the hop plant (Humulus lupulus L.), dose-dependently inhibited isobutylmethylxanthine (IBMX)-induced melanogenesis in B16 melanoma cells, with little cytotoxicity at the effective concentrations. Decreased melanin content was accompanied by reduced tyrosinase enzyme activity, protein and mRNA expression. The levels of tyrosinase-related protein 1 and 2 mRNAs were decreased by XH. XH also inhibited alpha-melanocyte stimulating hormone- or forskolin-induced increases in melanogenesis, suggesting an action on the cAMP-dependent melanogenic pathway. XH downregulated the protein and mRNA expression of microphthalmia-associated transcription factor (MITF), a master transcriptional regulator of key melanogenic enzymes. These results suggest that XH might act as a hypo-pigmenting agent through the downregulation of MITF in the cAMP-dependent melanogenic pathway.

Efeitos da Propafenona sobre o estado contrátil, trabalho sistólico e perfusäo miocárdica do coraçäo "in situ" / Effects of Propafenon on contractile state stroke work and myocardial perfusion of heart \"in situ\"

Os efeitos de diferentes doses de Propafenona foram analisados em cäes, estudando-se as variaçöes do estado inotrópico e da performance do coraçäo. Os resultados demonstram que, na dose de 1 mg/kg de peso, o composto tem propriedade antiarrítmica, sem alterar significativamente o estado contrátil nem o desempenho cardíaco