In the present paper, we report the synthesis and pharmacological evaluation of a new series of azo compounds with different groups (1-naphthol, 2-naphthol, and N,N-dimethylaniline) and trifluoromethoxy and fluoro substituents in the scaffold. All synthesized compounds (5a-5f) showed the most potent mushroom tyrosinase inhibition (IC₅₀ values in the range of 4.39 ± 0.76-1.71 ± 0.49 µM), compara...

New melanin synthesis inhibitors, melanocins A, B and C, were isolated from the fermentation broth and mycelium extract of Eupenicillium shearii F80695. Melanocin A, an isocyanide compound, inhibited mushroom tyrosinase and melanin biosynthesis of B16 melanoma cells with IC50 value of 9.0 nM and MIC value of 0.9 microM, respectively. Melanocin A also inhibited growth of Streptomyces bikiniensis...

Tyrosinase enzymes (Tys) are involved in the key steps of melanin (protective pigments) biosynthesis and molecules targeting binuclear copper active site on tyrosinases represent a relevant strategy to regulate enzyme activities. In this work, possible synergic effect generated by combination known inhibitors is studied. For this, derivatives containing kojic acid (KA) 2-hydroxypyridine-N-oxide...

From the stems of Liriodendron tulipifera, seventeen known compounds have been extracted, isolated and purified. By using spectroscopic analysis, the structures of these pure constituents were determined as three lignans, four steroids and ten benzenoids. Identified compounds were screened for antioxidant abilities using: 1,1-diphenyl-2-picrylhydrazul (DPPH) and 2,2'-azino-bis(3-ethylbenzothi...

Non-toxic natural products employed in the formulation of cosmetics are of considerable interest. Recent efforts have focused on the identification of substances that inhibit tyrosinase activity (skin whitening properties) or suppress the formation of reactive oxygen species in skin cells (antiaging). In the present study, different parts of Ixora coccinea (IC) in various solvents were examined...

Skin pigmentation disorders typically involve an overproduction or uneven distribution of melanin, which results in skin spots. Resveratrol can inhibit tyrosinase, the active enzyme in the synthesis of melanin, but it does not inhibit the synthesis of melanin to an extent that enables its use alone as a skin whitening agent in pharmaceutical formulations, so its use as a coadjuvant in treatment...

A simple and rapid method was developed for the determination of 3,4-dihydroxyphenylalanine (dopa) and 5-S-cysteinyl-3,4-dihydroxyphenylalanine (5-S-cysteinyldopa) in proteins with the use of high-pressure liquid chromatography. With this method, it is demonstrated that mushroom tyrosinase can catalyse hydroxylation of tyrosine residues in proteins to dopa and subsequent oxidation to dopaquinon...

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, ...