Differential regulation of melanosomal proteins after hinokitiol treatment

Inhibitory Effects of 2-Amino-3H-phenoxazin-3-one on the Melanogenesis of Murine B16 Melanoma Cell Line

“…[32][33][34] The reason APO did not reduce the expression of TRP-2 and TRP-1 protein, yet efficiently reduced MITF expression, remains unclear. In accord with our observations, linoleic acid was also reported to reduce tyrosinase protein levels without affecting the expression of TRP-2 or TRP-1 protein.…”

Inhibitory effects of hinokitiol on tyrosinase activity and melanin biosynthesis and its antimicrobial activities

“…Melanin biosynthesis can be inhibited by avoiding ultraviolet (UV) exposure, by the inhibition of tyrosinase, and by the inhibition of melanocyte metabolism and proliferation 3 . Hinokitiol has been reported to strongly inhibit human and mushroom tyrosinase activity, and reductions in tyrosinase activity are known to be associated with marked reductions in melanin synthesis 8 . Sakuma et al 20 reported that hinokitiol acted as a representative type of competitive inhibitor and exhibited the most potent inhibition (IC 50 = 8.22 μM) followed by hydroquinone, resorcinol, hydroxyhydroquinone, kojic acid, l-ascorbic acid, phloroglucinol, p-nitrophenol, methyl p-hydroxybenzoate, and arbutin, while l-Tyr was used as substrate.…”

“…However, the inhibition mechanism and type on the enzyme by hinokitiol for oxidation of l-DOPA revealed that the inhibition belonged to mixed-I type, namely, the competitive effect being stronger than the uncompetitive effect, which indicated that this compound inhibited the enzyme-substrate complex more weakly than the free enzyme 22 . Choi et al 8 commented that hinokitiol observably inhibited melanin synthesis and also reduced the protein levels of tyrosinase, tyrosinase-related protein 1 (TYRP-1), tyrosinaserelated protein 2 (TYRP-2), and microphthalmia-associated transcription factor (MITF). In the present study, we also investigated the inhibitory effect of hinokitiol on cellular tyrosinase activity, which was markedly reduced by hinokitiol in B16 cells.…”

“…Inhibitory effects of hinokitiol on tyrosinase activity and melanin biosynthesis and its antimicrobial activities Hinokitiol (4-isopropyl tropolone, β-thujaplicin) is a constituent of the woody oils isolated from Cupressaceae heartwood, and is known to have antifungal and antibacterial activities 8 . In melanocytes, hinokitiol was found to reduce melanin content, and has been reported to be a potent tyrosinase inhibitor 9,10 .…”

Anti-inflammatory activity of 2,5-dihydroxycyclohepta-2,4,6-trienone in rats

“…Tropolones have an aromatic sevenmembered ring system (Ogata et al, 1999). Tropolones are isolated from plants and bacteria or obtained by synthesis (Arima et al, 2003;Budihas et al, 2005;Choi et al, 2006;Kitamura et al, 1986;Korth et al, 1982;Morita et al, 2002Morita et al, , 2004a and these compounds have chelating capacity with metal ions such as Fe, Cu, and Zn (Doulias et al, 2004;Miyamato et al, 1998). Tropolones exert various biological activities due to their interesting ring structure and chelation properties (Diouf et al, 2002;Doulias et al, 2004).…”