Effect of <scp>l</scp>-ascorbic acid on the monophenolase activity of tyrosinase

Ros, JoséRamón; Rodrı́guez-López, José Neptuno; Garcı́a-Cánovas, Francisco

doi:10.1042/bj2950309

Cited by 139 publications

(96 citation statements)

References 21 publications

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“…Now, if we measure dopachrome at the same time in both cases, the first may show activation and the second an inhibition [5,7 -9], but if the formation of TOH is measured, activation is observed and t decreases [11] (see Supplementary material, Figure S8). Similar results are obtained in the presence of AH 2 [23].…”

Section: Action Of 6bhsupporting

confidence: 78%

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Effect of tetrahydropteridines on the monophenolase and diphenolase activities of tyrosinase

Molina

Muñoz

Varón

et al. 2007

Journal of Enzyme Inhibition and Medicinal Chemistry

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This study explains the action of compounds such as 6-tetrahydrobiopterin, (6BH 4 ) and 6,7-dimethyltetrahydrobiopterin (6,7-di-CH 3 BH 4 ) on the monophenolase and diphenolase activities of tyrosinase. These reductants basically act by reducing the o-quinones, the reaction products, to o-diphenol. In the case of the diphenolase activity a lag period is observed until the reductant is depleted; then the system reaches the steady-state. In the action of the enzyme on monophenol substrates, when the reductant concentration is less than that of the o-diphenol necessary for the steady-state to be reached, the system undergoes an apparent activation since, in this way, the necessary concentration of o-diphenol will be reached more rapidly. However, when the reductant concentration is greater than that of the o-diphenol necessary for the steady-state to be reached, the lag period lengthens and is followed by a burst, by means of which the excess o-diphenol is consumed, the steady-state thus taking longer to be reached. Moreover, in the present kinetic study, we show that tyrosinase is not inhibited by an excess of monophenol, although, to confirm this, the system must be allowed to pass from the transition state and enter the steady-state, which is attained when a given amount of o-diphenol has accumulated in the medium.

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Section: Action Of 6bhsupporting

confidence: 78%

“…A similar result was obtained working with ascorbic acid [23]. Although the lag phase was longer, parallel lines were obtained when all the RH 2 was consumed.…”

Section: Action Of 6bhsupporting

confidence: 71%

Effect of tetrahydropteridines on the monophenolase and diphenolase activities of tyrosinase

Molina

Muñoz

Varón

et al. 2007

Journal of Enzyme Inhibition and Medicinal Chemistry

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“…Melanin can be changed from jet black to light tan by AsA by the reduction of oxidized melanin. 8 However, it is rapidly oxidized and decomposes in aqueous lotion and thus is not generally useful as a depigmenting agent. To resolve this problem, magnesium-L-ascorbyl-2-phosphate(VC-PMG) was synthesized 9 .…”

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confidence: 99%

“…Furthermore, natural extracts such as paper mulberry and glabridin are in development to utilize in whitening cosmetics 7 . Ascorbic acid(AsA) inhibits melanin production by reducing o-quinones 8 so that melanin cannot be formed by the action of tyrosinase until all AsA is oxidized. Melanin can be changed from jet black to light tan by AsA by the reduction of oxidized melanin.…”

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confidence: 99%

Whitening Effect of Cosmetics Containing Magnesium L-Ascorbyl-2-Phosphate(VC-PMG, Vitamin C Derivatives) Assessed by Colorimeter

Park¹,

Chung²,

Lee³

et al. 2002

Ann Dermatol

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Skin color varies depending on the genetics, age, race, seasonal change, UV irradiation, hormonal influences and the presence of pigmentary disease. Constitutive skin color is the genetically determined level of skin pigmentation in the absence of direct or indirect influences such as solar radiation and other environment factors. In contrast, facultative skin color is characterized by the increase in melanin pigmentation above the constitutive level and is brought about by ultraviolet(UV) rays, so called suntanning 1 . The increase in melanin after an exposure to UV rays results from the activation of tyrosinase in melanocytes and the increase in the number of active melanocytes 2 . The best way to avoid this UV-induced tanning or pigmentation is the usage of materials that screen out UV rays. Nevertheless, the materials that inhibit Backgrounds : An inhibitory effect of magnesium L-ascorbyl-2-phosphate(VC-PMG, a stable derivative of ascorbic acid) on melanogenesis has been described. Furthermore, glabridin in licorice is known to have inhibitory effects on melanogenesis and widely used for raw materials for depigmenting agents.Objective : The purposes of this study are to provide objective data by measuring the visual clinical effects of VC-PMG with the colorimeter and to promote the development of depigmenting agents.Methods : 20 volunteers joined the study. With an artificial UVB irradiation, eight tanned areas were made on the inner side of the forearm. During two months, each tanned area was treated with five whitening cosmetics with 3% VC-PMG and increasing concentration of licorice from 0% to 3%. Darkness degree of each area was measured weekly by the colorimeter and the visual assessment.Results : For all cosmetics, whitening effect was measured by colorimeter and visual assessment. The cosmetic containing VC-PMG 3% and licorice 1% had more whitening effect than any other cosmetics of different concentrations. Moreover, VC-PMG 3% alone also had whitening effect in some volunteers.Conclusion : VC-PMG was clinically found to have whitening effect.

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“…8,9) Therefore, the regulation of melanin synthesis by inhibiting the tyrosinase enzyme is the current research topic in context of preventing hyperpigmentation. In this regard, diverse tyrosinase inhibitors have been actively discovered such as kojic acid, 10,11) arbutin, 12) ascorbic acid derivatives, 13) hydroxylstilbine derivatives like resveratol [14][15][16] and methyl ester of genistic acid. 17,18) However, according to a recent study kojic acid has serious adverse effects such as skin cancer and dermatitis and has been banned as a cosmetic ingredient in many countries.…”

mentioning

confidence: 99%

Novel Benzo[d]imidazole-2(3H)-thiones as Potent Inhibitors of the .ALPHA.-Melanocyte Stimulating Hormone Induced Melanogenesis in Melanoma B16 Cells

Lee

Pillaiyar

Lee

et al. 2010

CHEMICAL & PHARMACEUTICAL BULLETIN

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Melanin is a heterogeneous biopolymer which is principally responsible for human phenotypic appearance and has major role in protecting human skin from harmful effect of UV-radiation from the sun.1) Melanin is formed by a series of enzymatic catalyzed reactions in melanocytes.2,3) The biosynthesis of melanin is initiated with oxidation of tyrosine to dopaquinone catalyzed by tyrosinase.4) This first step is the rate limiting step in melanogenesis because the remaining reaction sequence can proceed spontaneously at a physiological pH. 5) However, over expression of tyrosinase lead to induction of hyperpigmentary disorders such as melasma, freckles, age spot, and post-inflammatory melanoderma. 6,7)It is also reported to be linked to Parkinson diseases and some other neurodegerative diseases.8,9) Therefore, the regulation of melanin synthesis by inhibiting the tyrosinase enzyme is the current research topic in context of preventing hyperpigmentation. In this regard, diverse tyrosinase inhibitors have been actively discovered such as kojic acid, 10,11) arbutin, 12) ascorbic acid derivatives, 13) hydroxylstilbine derivatives like resveratol [14][15][16] and methyl ester of genistic acid. 17,18) However, according to a recent study kojic acid has serious adverse effects such as skin cancer and dermatitis and has been banned as a cosmetic ingredient in many countries.17) Thus other type of molecules, which inhibit cyclic adenosine monophosphate (cAMP) dependent melanogenesis proteins other than tyrosinase, are gaining attention. Using bioassay system for measuring the amount of melanin formed from melanoma B16 cells upon stimulation of a-melanocyte stimulating hormone (a-MSH), we have screened many different compounds. As a result, 6-methyl-3-phenethyl-3,4-dihydro-1H-quinoline-2-thione (Fig. 1, IC 50 ϭ0.8 mM) was discovered as highly potent compound against melanogenesis in melanoma B16 cell line.18) The mechanism of action of compound 1 is very much unique and important due to its suppression of the melanogenesis without affecting the tyrosinase activity. The preliminary study on the structure-activity relationship (SAR) of 1 has revealed quinazolidine-2-thione in 1 as an essential motif. 18)In order to explore the necessity of 6-membered cyclic thiourea scaffold in 1, benzo[d]imidazol-2(3H)-ones 4 (Fig. 1) containing 5-membered cyclic thiourea were designed, synthesized and evaluated for their inhibitory activity against melanin production in melanoma B16 cells under the stimulation of a-MSH. ChemistryBenzo [d]imidazol-2(3H)-ones 4 and benzo [d]imidazole-2(3H)-thiones 5 were synthesized with the synthetic procedure as shown in Chart 1. In the first step, commercially available amine 6 was treated with appropriate alkyl bromide using pyridine or sodium hydroxide to give an intermediate 7. 18,19) In case of benzylated amines 7, the reduction reaction In order to determine the optimum size of heterocycle of lead compound 1 (6-methyl-3-phenethyl-3,4-dihydro-1H-quinoline-2-thione; IC 50 ‫8.0؍‬ mM) for inhibition of mela...

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Effect of l-ascorbic acid on the monophenolase activity of tyrosinase

Cited by 139 publications

References 21 publications

Effect of tetrahydropteridines on the monophenolase and diphenolase activities of tyrosinase

Effect of tetrahydropteridines on the monophenolase and diphenolase activities of tyrosinase

Whitening Effect of Cosmetics Containing Magnesium L-Ascorbyl-2-Phosphate(VC-PMG, Vitamin C Derivatives) Assessed by Colorimeter

Novel Benzo[d]imidazole-2(3H)-thiones as Potent Inhibitors of the .ALPHA.-Melanocyte Stimulating Hormone Induced Melanogenesis in Melanoma B16 Cells

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