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Variations in IC50 Values with Purity of Mushroom Tyrosinase  [PDF]
Elizabeth Neeley,George Fritch,Autumn Fuller,Jordan Wolfe,Jessica Wright,William Flurkey
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10093811
Abstract: The effects of various inhibitors on crude, commercial and partially purified commercial mushroom tyrosinase were examined by comparing IC50 values. Kojic acid, salicylhydroxamic acid, tropolone, methimazole, and ammonium tetrathiomolybdate had relatively similar IC50 values for the crude, commercial and partially purified enzyme. 4-Hexylresorcinol seemed to have a somewhat higher IC50 value using crude extracts, compared to commercial or purified tyrosinase. Some inhibitors (NaCl, esculetin, biphenol, phloridzin) showed variations in IC50 values between the enzyme samples. In contrast, hydroquinone, lysozyme, Zn2+, and anisaldehyde showed little or no inhibition in concentration ranges reported to be effective inhibitors. Organic solvents (DMSO and ethanol) had IC50 values that were similar for some of the tyrosinase samples. Depending of the source of tyrosinase and choice of inhibitor, variations in IC50 values were observed.
Inhibitory Effects of Resveratrol Analogs on Mushroom Tyrosinase Activity  [PDF]
Danielle Cristina Zimmermann Franco,Gustavo Senra Gon?alves de Carvalho,Paula Rafaela Rocha,Raquel da Silva Teixeira,Adilson David da Silva,Nádia Rezende Barbosa Raposo
Molecules , 2012, DOI: 10.3390/molecules171011816
Abstract: 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 of hyperpigmentation is suggested. Six resveratrol analogs were tested for tyrosinase inhibitory activity in vitro. Among the analogs tested, compound D was the most powerful tyrosinase inhibitor (IC50 = 28.66 μg/mL), two times more active than resveratrol (IC50 = 57.05 μg/mL), followed by the analogs A, E, B, F and C, respectively. This demonstrated that the hydroxylation at C4' on the phenolic ring was the molecular modification with most importance for the observed activity.
Effect of vanillin and its acid and alcohol derivatives on the diphenolase activity of mushroom tyrosinase  [cached]
Masoomeh Bagheri-Kalmarzi,Reza H.Sajedi,Elham Asadollahi,Nosrat O. Mahmoodi
Molecular Biology Research Communications , 2012,
Abstract: For the first time in the present study the effects of vanillin, vanillyl alcohol, vanillic acid, as well as the newly synthesized vanillin derivative, bis-vanillin, were investigated on the oxidation of dopamine hydrochloride by mushroom tyrosinase. Among them, vanillin and bis-vanillin act as activators, while vanillyl alcohol and vanillic acid exhibited inhibitory effects, the IC50 values being estimated 1.5 and 1.0 mM, respectively. These compounds were mixed inhibitors. The presence of aldehyde and metoxy groups at the meta position of aromatic compounds seems to cause them to react as tyrosinase activators, as observed in the case of vanillin and bis-vanillin. The presence of both groups in bis-vanillin results in a stronger activation effect compared to vanillin. The results indicate that the electron-withdrawing capacity of the functional group at the C-1 position is essential for the inhibitory potency of vanillin derivatives. In comparison with other benzoic acid derivatives, the results obtained in this study suggest that the relative positioning of hydroxy and methoxy groups at meta and para positions plays an important role in the inhibition effects of benzoic acids and their inhibition potency.
Immobilization of Mushroom Tyrosinase by Different Methods in Order to Transform L-Tyrosine to L-3, 4 Dihydroxyphenylalanine (L-dopa)  [PDF]
Dariush Norouzian,Azim Akbarzadeh,Saeed Mirdamadi,Shohreh Khetami
Biotechnology , 2007,
Abstract: Tyrosinase of edible mushroom was immobilized on activated agar particles, blocks and egg shell powder coated with polyethyleneimine (PEI) so as to study their efficiency in the transformation of L-tyrosine to L-dopa. The reaction rate for each form (PEI coated egg shell powder, activated agar blocks and activated agar particles) of the immobilized tyrosinase was calculated to be 0.0021, 0.018 and 0.0032 min, respectively. Desorption of tyrosinase from each support was found to be negligible. The production of L-dopa was 25, 73 and 42 mg L-1 for tyrosinase immobilized onto egg shell powder coated with PEI, activated agar particles and blocks, respectively.
Effects of Quercetin on Mushroom Tyrosinase and B16-F10 Melanoma Cells  [PDF]
Isao Kubo,Teruhiko Nitoda,Ken-ichi Nihei
Molecules , 2007, DOI: 10.3390/12051045
Abstract: In searching for tyrosinase inhibitors from plants using L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate, quercetin was found to be partially oxidized to the corresponding o-quinone under catalysis by mushroom tyrosinase (EC 1.14.18.1). Simultaneously, L-DOPA was also oxidized to dopaquinone and both o-quinones were further oxidized, respectively. The remaining quercetin partially formed adducts with dopaquinone through a Michael type addition. In general, flavonols form adducts with dopaquinone as long as their 3-hydroxyl group is free. Quercetin enhanced melanin production per cell in cultured murine B16-F10 melanoma cells, but this effect may be due in part to melanocytotoxicity. The concentration leading to 50% viable cells lost was established as 20 μM and almost complete lethality was observed at 80 μM.
The Inhibitory Effect of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) on the Monophenolase and Diphenolase Activities of Mushroom Tyrosinase  [PDF]
Kazuomi Sato,Masaru Toriyama
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12063998
Abstract: In the present work, we investigated the effect of non-steroidal anti-inflammatory drugs (NSAIDs) on the monophenolase and diphenolase activity of mushroom tyrosinase. The results showed that diflunisal and indomethacin inhibited both monophenolase and diphenolase activity. For monophenolase activity, the lag time was extended in the presence of diflunisal. In the presence of indomethacin, the lag time did not change. IC 50 values of monophenolase activity were estimated to be 0.112 mM (diflunisal) and 1.78 mM (indomethacin). Kinetic studies of monophenolase activity revealed that both diflunisal and indomethacin were non-competitive inhibitors. For diphenolase activity, IC 50 values were estimated to be 0.197 mM (diflunisal) and 0.509 mM (indomethacin). Diflunisal and indomethacin were also found to be non-competitive diphenolase inhibitors.
A calorimetric investigation for the bindings of mushroom tyrosinase to p-phenylene-bis dithiocarbamate and xanthates  [PDF]
Rezaei Behbehani Gholam Reza,Mehreshtiagh Melisa,Barzegar Lyla,Saboury Akbar Ali
Journal of the Serbian Chemical Society , 2013, DOI: 10.2298/jsc101005103r
Abstract: A comprehensive, simple and rapid thermodynamic study on the interaction of Mushroom Tyrosinase, MT, with three iso-alkyldithiocarbonates (xanthates), as sodium salts, C3H7OCS2Na (I), C4H9OCS2Na (II), C5H11OCS2Na (III) and p-phenylene-bis dithiocarbamate (IV), by using isothermal titration calorimetry was carried out to clarify thermodynamics of these bindings as well as structural changes of the enzyme due to its interaction with inhibitors at 300K in phosphate buffer (10 m molL-1; pH 6.8).The extended solvation theory was used to elucidate the effect of the inhibitors on the stability of enzyme. The obtained results indicate that there are two identical and non-cooperative binding sites for these inhibitors.
Essential Oils and Their Constituents: Anticonvulsant Activity  [PDF]
Reinaldo Nóbrega de Almeida,Maria de Fátima Agra,Flávia Negromonte Souto Maior,Dami?o Pergentino De Sousa
Molecules , 2011, DOI: 10.3390/molecules16032726
Abstract: A literature-based survey of plants species and their essential oils with anticonvulsant activity was carried out. As results, 30 species belonging to 13 families and 23 genera were identified for their activities in the experimental models used for anticonvulsant drug screening. Thirty chemical constituents of essential oils with anticonvulsant properties were described. Information on these 30 species is presented together with isolated bioactive compound studies.
Extracts from Amazonian plants have inhibitory activity against tyrosinase: an in vitro evaluation
Macrini, Daclé Juliani;Suffredini, Ivana Barbosa;Varella, Antonio Drauzio;Younes, Riad Naim;Ohara, Mitsuko Taba;
Brazilian Journal of Pharmaceutical Sciences , 2009, DOI: 10.1590/S1984-82502009000400015
Abstract: dermatological disorders related to pigmentation result in tenuous hyper or hypopigmentation cosmetic and pharmaceutical products containing depigmenting substances are used in the treatment of patients who have high pigmentation disorders, such as melasma or chloasma, post-inflammatory hyperpigmentation, senile lentigo and ephelides. skin lightening agents are not yet totally effective or safe and therefore intensive research for the discovery of new agents is continuous. enzyme inhibitors involved in melanogenesis, such as tyrosinase, have been discovered in asian countries, including those isolated from plant extracts. the brazilian flora has the highest species diversity in the world, and the chemical, pharmacological and cosmetic potential for the discovery of new skin whitening agents is in proportion with this biodiversity. for these reasons, 25 aqueous and 24 organic extracts obtained from 19 plants native to the amazon rain forest and to the atlantic forest, belonging to 11 different families, were evaluated as tyrosinase inhibitors. nine out of 49 extracts showed inhibitory activity in the screening process. the 50% inhibitory activity (ia50) was calculated, revealing that the most active extracts were the organic extracts from the leaves and stem of ruprechtia sp. (ia50 33.76 mg.ml-1) and the organic extract from the aerial organs of rapanea parviflora (ia50 64.19 mg.ml-1).
Ferrous Ion Chelating, Superoxide Anion Radical Scavenging and Tyrosinase Inhibitory Properties of Pure and Commercial Essential Oils of Anetrhum Graveolens
M Dadashpour,I Rasooli,F Sefidkon,M Bagher Rezaei
Journal of Shahid Sadoughi University of Medical Sciences , 2013,
Abstract: Introduction: Despite slight toxicities of essential oils, they are not under strict control in many countries. Anethum graveolens is widely consumed and its essential oils are at public reach. This study was designed to study essential oils of Anethum graveolens. Methods: The biological properties of pure and commercial essential oils of Anethum graveolens were investigated. In fact, Ferrous ion chelating activity, superoxide anion radical scavenging property, tyrosinase inhibition and total flavonoids of the oils were determined. Results: Chelating activity of 7.8 μg of EDTA was equivalent to 2 μg of the pure oil. The oils had superoxide anion radical scavenging activities which may be related to their total phenol and flavonoid contents. IC50 of ferrous ion chelating, antityrosiase and superoxide anion radical scavenging activities of pure and commercial oils were 1.3, 1.4, 1 and (171.6, 589, 132) μg respectively. Antityrosiase activity of 6.4 μg pure oil was equal to 1000 μg of the commercial oil. Conclusion: Anethum possesses antioxidative and free radical scavenging properties. This oil chelates ferrous ions and superoxide radicals. It is effective in formation of reactive toxic products. Anethum has good potentials regarding its applications in food and drug industries.
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