Drug repositioning is the application of the existing drugs to new uses and has the potential to reduce the time and cost required for the typical drug discovery process. In this study, we repositioned thiopurine drugs used for the treatment of acute leukaemia as new tyrosinase inhibitors. Tyrosinase catalyses two successive oxidations in melanin biosynthesis: the conversions of tyrosine to dih...

2,3,5,4'-Tetrahydroxystilbene-2-O-β-D-glucopyranoside (1), isolated from Polygonum multiflorum, is a noncompetitive inhibitor of tyrosinase in cell-free kinetics; it reduced the Vmax values in a dose-dependent manner. Compound 1 inhibited PKA-induced melanogenesis, reduced the protein expression of tyrosinase and its transcription factor, the microphthalmia-associated transcription factor, and ...

The twigs of Morus alba L. were found to show strong tyrosinase inhibition activity, and the responsible active components in the extract were further investigated in this study. A flavone, named morusone (1), and sixteen known compounds 2-17 were isolated from M. alba twigs and their structures were identified by interpretation of the corresponding ESI-MS and NMR spectral data. In the tyrosina...

The aim of the present work was to clarify the anti-melanogenic mechanism of the catechin group. In this study, we used (-)-epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), (-)-catechin (C), and gallic acid (GA). The catechin group inhibited melanin synthesis in B16 melanoma cells. To elucidate the anti-melanogenic mechanism of the catechin group, we performed Western blotting ana...

Rosmarinus officinalis or Rosemary is a highly valued medicinal vegetal, owing to its notable antispasmodic, anti-inflammatory, and antibacterial properties. In the current work, we aimed identify chemical components of essential oil (EO) R. evaluate biological properties using an in vitro approach. High performance liquid chromatography time-of-flight mass spectrometry (HPLC-TOF-MS) was utiliz...

Tea contains polyphenols and is one of the most popular beverages consumed worldwide. Because most tyrosinase inhibitors that regulate melanogenesis are phenol/catechol derivatives, this study investigated the inhibitory effects of Camellia sinensis water extracts (CSWEs), including black tea, green tea, and white tea extracts, on melanogenesis using immortalized melanocytes. CSWEs inhibited me...

The authors designed and synthesized 17 (2-substituted phenyl-1,3-dithiolan-4-yl) methanol (PDTM) derivatives to find a new chemical scaffold, showing excellent tyrosinase-inhibitory activity. Their tyrosinase-inhibitory activities were evaluated against mushroom tyrosinase at 50 μM, and five of the PDTM derivatives (PDTM3, PDTM7-PDTM9, and PDTM13) were found to inhibit mushroom tyrosinase more...

Many tyrosinase inhibitors have been alleged to have serious side effects. To search for relatively mild and safe tyrosinase inhibitors, two new 8-O-4′ neolignans, named huangnin A (1) and B (2), and four known analogs (3-6) were isolated from the seeds of Crataegus pinnatifida. Their structures were elucidated by spectroscopic analyses (1D, 2D NMR, HRESIMS, CD and Rh2(OCOCF3)4-induced CD). In ...