A series of hydroxy- or methoxy-substituted phenylmethylenethiosemicarbazones were designed, synthesized and evaluated as mushroom tyrosinase inhibitors. The results demonstrated that most of target compounds had remarkable inhibitory activities on mushroom tyrosinase. Interestingly, compound 2h was found to be the most potent tyrosinase inhibitor with IC50 value of 0.18 microM. The possible in...

Previously, split-thickness human skin grafted onto athymic mice has been shown to become markedly hyperpigmented, but the factor(s) responsible for this hyperpigmentation had not been isolated. The present study describes the isolation and characterization of a potent melanogenic inhibitor from grafted human skin. Extracts from grafted skin inhibited, in a concentration-dependent manner, tyros...

(HOROWITZ and SHEN 1952). The strain produces almost no tyrosinase activity when cultured at 35" C on a medium which favors the production of strong activity in 25" cultures. The evidence indicated that the temperature effect is not due to formation of a tyrosinase inhibitor, but to a net decrease in tyrosinase synthesis at the higher temperature. Attention has been called to the resemblance be...

A variant of the Cloudman 5-91 melanoma is described which is characterized by a low level of tyrosinase and dopa oxidase (phenolase complex) activity. On the ultrastructural level this is expressed by a preponderance of melanosomes (im mature melanin granules) rather than mature melanin particles. Extracts of the tumor exhibit only dopa oxidase activity. With tumor slices, tyrosinase activity ...

The aim of this study was to determine the effects of adlay extract on melanin production and the antioxidant characteristics of the extract. The seeds were extracted by the supercritical fluid CO2 extraction (SFE) method. The effect of adlay extract on melanin production was evaluated using mushroom tyrosinase activity assay, intracellular tyrosinase activity, antioxidant properties and melani...

The fine structure of integumental erythrophores and the intracellular location of pteridine and carotenoid pigments in adult goldfish, Carassius auratus, were studied by means of cytochemistry, paper and thin-layer chromatography, ionophoresis, density-gradient centrifugal fractionation, and electron microscopy. The ultrastructure of erythrophores is characterized by large numbers of somewhat ...

In the present work we report on the contribution of the coumarin moiety to tyrosinase inhibition. Coumarin-resveratrol hybrids 1-8 have been resynthesized to investigate the structure-activity relationships and the IC(50) values of these compounds were measured. The results showed that these compounds exhibited tyrosinase inhibitory activity. Compound 3-(3',4',5'-trihydroxyphenyl)-6,8-dihydrox...

The catalytic oxidation of catechol by crude preparations of mushroom tyrosinase was studied by a method yielding data on initial reaction velocities. Graphical analysis of the results suggests that an excess of catechol inhibits its own oxidation by a competitive process, thus accounting for the observed optimum in the substrate concentration. However, added phenol, though itself a substrate, ...