In the presence of tyrosinase, red blood cells are Ipsed. Lysis follows an enzyme-mediated reaction, with the amount of lysis being proportional to the tyrosinase concentration. Cyanide, which inhibits tyrosinase, prevents lysis of the red blood cells by tyrosinase. Heat-denatured tyrosinase has no effect on red blood cells. Tyrosinase also exhibits a pronounced effect on the permeability of is...

Anisaldehyde characterized in the seeds of Pimpinella anisum L. (Umbelliferae), also known as aniseed, was found to inhibit the oxidation of L-3,4-dihydroxyphenylalanine (L-DOPA) by mushroom tyrosinase (EC 1.14.18.1) with an ID50 of 43 μg/mL (0.32 mM). The inhibition kinetics analyzed by a Lineweaver-Burk plot established anisaldehyde to be a noncompetitive inhibitor for this oxidation. On the ...

The effects of lucidone on tyrosinase and antimelanogenic activity were investigated. Initially, we found that lucidone strongly inhibits the activity of mushroom tyrosinase. The effects of lucidone on tyrosinase were further examined in alpha-MSH-induced B16 melanoma cells. Lucidone significantly inhibits tyrosinase activity and leads to decreased melanin content in cultured B16 melanoma cells...

Tyrosinase inhibition studies are needed due to the medicinal applications such as hyperpigmentation. For probing effective inhibitors of tyrosinase, a combination of computational prediction and enzymatic assay via kinetics was important. We predicted the 3D structure of tyrosinase, used a docking algorithm to simulate binding between tyrosinase and phthalic acid (PA), and studied the reversib...

[Z-W]Thiouracil and [%]thiouracil are incorporated into the melanin of chick retinal pigment epithelium incubated in vitro. This synthesis of a thiouracil pheomelanin (thiolcuntaining melanin) can be used to measure the rate of melanin synthesis in living cells. Thiouracil incorporation is dependent on tyrosinase activity: incorporation is inhibited by phenylthiourea, a tyrosinase inhibitor, an...

[Z-W]Thiouracil and [%]thiouracil are incorporated into the melanin of chick retinal pigment epithelium incubated in vitro. This synthesis of a thiouracil pheomelanin (thiolcuntaining melanin) can be used to measure the rate of melanin synthesis in living cells. Thiouracil incorporation is dependent on tyrosinase activity: incorporation is inhibited by phenylthiourea, a tyrosinase inhibitor, an...

In the present study, three kinds of phlorotannins, marine algal polyphenol, were isolated from a brown alga Ecklonia cava, and their inhibitory effect on melanogenesis as well as the protective effect against photo-oxidative stress induced by UV-B radiation was investigated. The effect on melanogenesis was evaluated via the inhibitory effects of tyrosinase and melanin synthesis. Among the phlo...

Experimental autoimmune vitiligo was induced by the intradermal injection of the purified mushroom tyrosinase emulsified in Complete Freund’s Adjuvant (CFA) in female C57BL/6 mice. The onset of vitiligo was characterized by hair hypopigmentation and total melanocyte depletion in the basal layer of the epidermis. Oral administration of semipurified mushroom tyrosinase prevented experimental auto...

ETHNOPHARMACOLOGICAL RELEVANCE Sargassum polycystum, a type of brown seaweed, has been used for the treatment of skin-related disorders in traditional medicine. AIM OF THE STUDY The aim of the present study is to investigate the antimelanogenesis effect of Sargassum polycystum extracts by cell-free mushroom tyrosinase assay followed by cell viability assay, cellular tyrosinase assay and melan...

Tyrosinase-negative oculocutaneous albinism (OCA1A) is characterized by lifelong white hair and skin, a phenotype that has been described in most mammalian species worldwide. Tyrosinase is the key enzyme in melanin biosynthesis, and mutations in the tyrosinase gene result in OCA1A. We examined sequence variation at exon 1 of the tyrosinase gene in 66 humpback whale samples collected from the ea...