The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Yoon-sik Lee - One of the best experts on this subject based on the ideXlab platform.
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Kojic Acid amino Acid conjugates as tyrosinase inhibitors
Bioorganic & Medicinal Chemistry Letters, 2009Co-Authors: Jin-mi Noh, Seon-yeong Kwak, Hyosuk Seo, Joohyun Seo, Byunggee Kim, Yoon-sik LeeAbstract:Kojic Acid (KA), a well known tyrosinase inhibitor, has insufficient inhibitory activity and stability. We modified KA with amino Acids and screened their tyrosinase inhibitory activity. Among them, Kojic Acid-phenylalanine amide (KA-F-NH(2)) showed the strongest inhibitory activity, which was maintained for over 3 months at 50 degrees C, and acted as a noncompetitive inhibitor as determined by kinetic analysis. It also exhibited dopachrome reducing activity. We also propose a new tyrosinase inhibition mechanism based on the docking simulation data.
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Kojic Acid–tripeptide amide as a new tyrosinase inhibitor
Biopolymers, 2007Co-Authors: Jin-mi Noh, Seon-yeong Kwak, Do-hyun Kim, Yoon-sik LeeAbstract:Twenty two Kojic Acid–tripeptide amides were prepared using a solid-phase Fmoc/tBu strategy with Rink Amide SURE® resin. To effectively obtain Kojic Acid–tripeptide amide conjugates, the coupling conditions of Kojic Acid to the tripeptide on the resin were optimized. The tyrosinase inhibitory activity of Kojic Acid–tripeptide amides and the effect of the amino Acid sequence on the activity were compared with those of Kojic Acid–tripeptide Acids. The stability of Kojic Acid–tripeptide amides were then compared with those of Kojic Acid and Kojic Acid–tripeptides Acids. As a consequence, Kojic Acid-FWY-NH2 proved to be the best compound, with the highest inhibitory activity, which was maintained over different storage times under various temperatures and pHs. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 300–307, 2007. This article was originally published online as an accepted preprint. The ‘Published Online’ date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
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Kojic Acid tripeptide amide as a new tyrosinase inhibitor
Biopolymers, 2007Co-Authors: Jin-mi Noh, Seon-yeong Kwak, Do-hyun Kim, Yoon-sik LeeAbstract:Twenty two Kojic Acid–tripeptide amides were prepared using a solid-phase Fmoc/tBu strategy with Rink Amide SURE® resin. To effectively obtain Kojic Acid–tripeptide amide conjugates, the coupling conditions of Kojic Acid to the tripeptide on the resin were optimized. The tyrosinase inhibitory activity of Kojic Acid–tripeptide amides and the effect of the amino Acid sequence on the activity were compared with those of Kojic Acid–tripeptide Acids. The stability of Kojic Acid–tripeptide amides were then compared with those of Kojic Acid and Kojic Acid–tripeptides Acids. As a consequence, Kojic Acid-FWY-NH2 proved to be the best compound, with the highest inhibitory activity, which was maintained over different storage times under various temperatures and pHs. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 300–307, 2007. This article was originally published online as an accepted preprint. The ‘Published Online’ date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Jin-mi Noh - One of the best experts on this subject based on the ideXlab platform.
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Kojic Acid amino Acid conjugates as tyrosinase inhibitors
Bioorganic & Medicinal Chemistry Letters, 2009Co-Authors: Jin-mi Noh, Seon-yeong Kwak, Hyosuk Seo, Joohyun Seo, Byunggee Kim, Yoon-sik LeeAbstract:Kojic Acid (KA), a well known tyrosinase inhibitor, has insufficient inhibitory activity and stability. We modified KA with amino Acids and screened their tyrosinase inhibitory activity. Among them, Kojic Acid-phenylalanine amide (KA-F-NH(2)) showed the strongest inhibitory activity, which was maintained for over 3 months at 50 degrees C, and acted as a noncompetitive inhibitor as determined by kinetic analysis. It also exhibited dopachrome reducing activity. We also propose a new tyrosinase inhibition mechanism based on the docking simulation data.
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Kojic Acid–tripeptide amide as a new tyrosinase inhibitor
Biopolymers, 2007Co-Authors: Jin-mi Noh, Seon-yeong Kwak, Do-hyun Kim, Yoon-sik LeeAbstract:Twenty two Kojic Acid–tripeptide amides were prepared using a solid-phase Fmoc/tBu strategy with Rink Amide SURE® resin. To effectively obtain Kojic Acid–tripeptide amide conjugates, the coupling conditions of Kojic Acid to the tripeptide on the resin were optimized. The tyrosinase inhibitory activity of Kojic Acid–tripeptide amides and the effect of the amino Acid sequence on the activity were compared with those of Kojic Acid–tripeptide Acids. The stability of Kojic Acid–tripeptide amides were then compared with those of Kojic Acid and Kojic Acid–tripeptides Acids. As a consequence, Kojic Acid-FWY-NH2 proved to be the best compound, with the highest inhibitory activity, which was maintained over different storage times under various temperatures and pHs. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 300–307, 2007. This article was originally published online as an accepted preprint. The ‘Published Online’ date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
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Kojic Acid tripeptide amide as a new tyrosinase inhibitor
Biopolymers, 2007Co-Authors: Jin-mi Noh, Seon-yeong Kwak, Do-hyun Kim, Yoon-sik LeeAbstract:Twenty two Kojic Acid–tripeptide amides were prepared using a solid-phase Fmoc/tBu strategy with Rink Amide SURE® resin. To effectively obtain Kojic Acid–tripeptide amide conjugates, the coupling conditions of Kojic Acid to the tripeptide on the resin were optimized. The tyrosinase inhibitory activity of Kojic Acid–tripeptide amides and the effect of the amino Acid sequence on the activity were compared with those of Kojic Acid–tripeptide Acids. The stability of Kojic Acid–tripeptide amides were then compared with those of Kojic Acid and Kojic Acid–tripeptides Acids. As a consequence, Kojic Acid-FWY-NH2 proved to be the best compound, with the highest inhibitory activity, which was maintained over different storage times under various temperatures and pHs. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 300–307, 2007. This article was originally published online as an accepted preprint. The ‘Published Online’ date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Seon-yeong Kwak - One of the best experts on this subject based on the ideXlab platform.
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Kojic Acid amino Acid conjugates as tyrosinase inhibitors
Bioorganic & Medicinal Chemistry Letters, 2009Co-Authors: Jin-mi Noh, Seon-yeong Kwak, Hyosuk Seo, Joohyun Seo, Byunggee Kim, Yoon-sik LeeAbstract:Kojic Acid (KA), a well known tyrosinase inhibitor, has insufficient inhibitory activity and stability. We modified KA with amino Acids and screened their tyrosinase inhibitory activity. Among them, Kojic Acid-phenylalanine amide (KA-F-NH(2)) showed the strongest inhibitory activity, which was maintained for over 3 months at 50 degrees C, and acted as a noncompetitive inhibitor as determined by kinetic analysis. It also exhibited dopachrome reducing activity. We also propose a new tyrosinase inhibition mechanism based on the docking simulation data.
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Kojic Acid–tripeptide amide as a new tyrosinase inhibitor
Biopolymers, 2007Co-Authors: Jin-mi Noh, Seon-yeong Kwak, Do-hyun Kim, Yoon-sik LeeAbstract:Twenty two Kojic Acid–tripeptide amides were prepared using a solid-phase Fmoc/tBu strategy with Rink Amide SURE® resin. To effectively obtain Kojic Acid–tripeptide amide conjugates, the coupling conditions of Kojic Acid to the tripeptide on the resin were optimized. The tyrosinase inhibitory activity of Kojic Acid–tripeptide amides and the effect of the amino Acid sequence on the activity were compared with those of Kojic Acid–tripeptide Acids. The stability of Kojic Acid–tripeptide amides were then compared with those of Kojic Acid and Kojic Acid–tripeptides Acids. As a consequence, Kojic Acid-FWY-NH2 proved to be the best compound, with the highest inhibitory activity, which was maintained over different storage times under various temperatures and pHs. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 300–307, 2007. This article was originally published online as an accepted preprint. The ‘Published Online’ date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
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Kojic Acid tripeptide amide as a new tyrosinase inhibitor
Biopolymers, 2007Co-Authors: Jin-mi Noh, Seon-yeong Kwak, Do-hyun Kim, Yoon-sik LeeAbstract:Twenty two Kojic Acid–tripeptide amides were prepared using a solid-phase Fmoc/tBu strategy with Rink Amide SURE® resin. To effectively obtain Kojic Acid–tripeptide amide conjugates, the coupling conditions of Kojic Acid to the tripeptide on the resin were optimized. The tyrosinase inhibitory activity of Kojic Acid–tripeptide amides and the effect of the amino Acid sequence on the activity were compared with those of Kojic Acid–tripeptide Acids. The stability of Kojic Acid–tripeptide amides were then compared with those of Kojic Acid and Kojic Acid–tripeptides Acids. As a consequence, Kojic Acid-FWY-NH2 proved to be the best compound, with the highest inhibitory activity, which was maintained over different storage times under various temperatures and pHs. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 300–307, 2007. This article was originally published online as an accepted preprint. The ‘Published Online’ date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Varda Zakin - One of the best experts on this subject based on the ideXlab platform.
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Effect of Kojic Acid on the hydroxylation of L-tyrosine and tyramine by mushroom tyrosinase
Journal of Food Biochemistry, 1998Co-Authors: Varda Kahn, Noah Ben Shalom, Varda ZakinAbstract:Kojic Acid inhibits effectively the rate of L-tyrosine and tyramine hydroxylation by mushroom tyrosinase. It also affects the spectrum of product (s) formed, this being due to the ability of dopaquinone and dopamine-o-quinone to oxidize Kojic Acid to a yellow product(s). Kojic Acid prevents the conversion of these o-quinones to their corresponding melanins. An insoluble yellow product(s) is formed when tyramine, but not L-tyrosine, is incubated with tyrosinase for 20 h in the presence of excess Kojic Acid.
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Effect of Kojic Acid on the Oxidation of N-Acetyldopamine by Mushroom Tyrosinase
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Varda Kahn, Noah Ben-shalom, Varda ZakinAbstract:Kojic Acid inhibited mushroom tyrosinase, as judged by the inhibition it exerted on the rate of oxygen uptaked during N-acetyldopamine (NADA) oxidation. Preincubation of mushroom tyrosinase with Kojic Acid did not result in the inactivation of the enzyme (irreversible loss of activity). Kojic Acid had a pronounced effect on the spectrum of product(s) obtained when NADA was oxidized by mushroom tyrosinase. In its absence, NADA quinone (λmax = 390 ± 10 nm) was formed; in its presence, a stable final yellow product(s), characterized by a peak at 340 ± 20 nm, was obtained. A maximum level of the final yellow product(s) was formed when the ratio between NADA quinone and Kojic Acid was 1:1. Spectral data suggest that NADA quinone oxidizes Kojic Acid to the yellow product(s). Keywords: N-Acetyldopamine (NADA); mushroom tyrosinase; Kojic Acid inhibition
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Kojic Acid conversion to a yellow product(s) via the horseradish peroxidase/H2O2 system
Journal of Food Biochemistry, 1995Co-Authors: Varda Kahn, Pinchas Lindner, Varda ZakinAbstract:Horseradish peroxidase in the presence of hydrogen peroxide oxidizes Kojic Acid (5-hydroxy-2-hydroxymethyl)-4H-pyran-4-one) to a yellow product(s). The yellow product(s) formed has a major absorbance peak at 375 nm and is fluorescent. The relationships between, and effects of, various concentrations of horseradish peroxidase, Kojic Acid and hydrogen peroxide on the rate of oxidation of Kojic Acid to the yellow product(s) are described. The observation that the oxidation of Kojic Acid to the yellow product(s) occurs best in the presence of very low concentrations of hydrogen peroxide, relative to that of Kojic Acid, suggests that Kojic Acid is a poor hydrogen donor (AH2) for horseradish peroxidase.
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Kojic Acid CONVERSION TO A YELLOW PRODUCT(S) BY THE HEMOGLOBLIN/H2O2 SYSTEM
Journal of Food Biochemistry, 1995Co-Authors: Varda Kahn, Pinhas Lindner, Varda ZakinAbstract:Kojic Acid (5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one; also named 5-hydroxy-2-(hydroxymethyl)-γ-pyrone) in the presence of hydrogen peroxide, but not in its absence, can be oxidized by hemoglobin (Hb) to a yellow product(s). The yellow product(s) formed is characterized by a peak at 370-380 nm and is fluorescent. The relationship between the rate of oxidation of Kojic Acid and various concentrations of hemoglobin and of H 2 O 2 is described. The changes with time in the spectrum of product(s) obtained when Kojic Acid is acted upon by the Hb/H 2 O 2 system and the relationship between the various concentrations of hemoglobin, of Kojic Acid and of H 2 O 2 on the spectrum of the final yellow product(s) are shown.
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Effect of Kojic Acid on the oxidation of o-dihydroxyphenols by mushroom tyrosinase
Journal of Food Biochemistry, 1994Co-Authors: Varda Kahn, Varda ZakinAbstract:Kojic Acid [5-hydroxy-2-(hydroxymethyl)-4-pyrone] inhibited effectively the rate of pigment formation during the oxidation of pyrogallol, 2, 3,4-THAP (2, 3,4-trihydroxyacetophenone) and 2, 4,5-THBP (2, 4,5-trihydroxybutyrophenone) by tyrosinase. On the other hand, Kojic Acid had a synergistic effect on the rate of methyl gallate and n-propyl gallate oxidation to pigmented product(s) (λmax= 360 nm and λmax= 380 nm, respectively). However, Kojic Acid inhibited effectively the rate of oxygen uptake when each of the above trihydroxyphenols was oxidized by tyrosinase. These results suggest that Kojic Acid inhibits tyrosinase per se (probably due to its ability to bind copper at the active site of the enzyme) and that it exerts only an apparent stimulatory effect during the formation of pigmented product (s) from methyl gallate and n-propyl gallate. Proof for the latter was obtained by a time-course experiment of Kojic Acid addition and examination of the spectra of pigmented product(s) formed in the absence versus presence of Kojic Acid, which suggested that the o-quinone of n-propyl gallate and the o-quinone of methyl gallate can each convert Kojic Acid to a yellow product(s) absorbing at the 360–380 nm region.
Jaehui Choi - One of the best experts on this subject based on the ideXlab platform.
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solid phase synthesis of Kojic Acid tripeptides and their tyrosinase inhibitory activity storage stability and toxicity
Bioorganic & Medicinal Chemistry Letters, 2004Co-Authors: Jaehui ChoiAbstract:A small library of Kojic Acid-tripeptides (Ko-X 1 X 2 X 3 ) was prepared by solid-phase parallel synthesis and assayed to evaluate their tyrosinase inhibitory activity. Most of the Kojic Acid-tripeptides showed better activities than Kojic Acid. Kojic Acid-FWY was the best compound, and it exhibited 100-fold tyrosinase inhibitory activity compared with Kojic Acid. In addition, their storage stabilities were approximately 15 times higher and their toxicity was lower than that of Kojic Acid.
