Competitive Inhibition of Mushroom Tyrosinase by 4-Substituted Benzaldehydes
Departamento de Bioquímica y Biología Molecular A, Unidad Docente de Biología, Facultad de Veterinaria, Universidad de Murcia, E-30080, Murcia, Spain. Journal of Agricultural and Food Chemistry
(Impact Factor: 2.91).
09/2001; 49(8):4060-3. DOI: 10.1021/jf010194h
A kinetic study of the inhibition of mushroom tyrosinase by 4-substituted benzaldehydes showed that these compounds behave as classical competitive inhibitors, inhibiting the oxidation of L-3,4-dihydroxyphenylalanine (L-DOPA) by mushroom tyrosinase (o-diphenolase activity). The kinetic parameter (K(I)) characterizing this inhibition was evaluated for all of the seven compounds assayed. Cuminaldehyde showed the most potent inhibitory activity (K(I) = 9 microM). It also inhibited the oxidation of L-tyrosine by mushroom tyrosinase (o-monophenolase activity) in a competitive manner. The corresponding kinetic parameter for this inhibition was evaluated (K(I) = 0.12 mM).
- "It suggested that the position of the substituent influenced the tyrosinase inhibitory potency, and in the investigation, the amide group at the position-4 of the phenyl ring was more efficacious for the inhibitory activity. It was consistent with previous reports by Kubo , Jimenez . "
[Show abstract] [Hide abstract]
ABSTRACT: In this study, we developed 3-/4-aminoacetophenones and their structure-based 3-/4-aminophenylethylidenethiosemicarbazide derivatives, respectively, as novel tyrosinase activators and inhibitors. Notably, all the obtained thiosemicarbazones displayed more potent tyrosinase inhibitory activities than kojic acid. Especially, compound 7k was found to be the most active tyrosinase inhibitor with IC50 value of 0.291 μM. The structure-activity relationships (SARs) analysis showed that: (1) the amine group was absolutely necessarily for determining the tyrosinase activation activity; (2) the introduction of thiosemicarbazide group played a very vital role in transforming tyrosinase activators into tyrosinase inhibitors; (3) the phenylethylenethiosemicarbazide moiety was crucial for determining the tyrosinase inhibitory activity; (4) the type of acyl group had no obvious effect on the inhibitory activity; (5) the position of amide substituent on the phenyl ring influenced the tyrosinase inhibitory potency. Moreover, the inhibition mechanism and inhibition kinetics study revealed that compound 7k was reversible and non-competitive inhibitor, and compound 8h was reversible and competitive-uncompetitive mixed-II type inhibitor.
Copyright © 2015 Elsevier Masson SAS. All rights reserved.
European Journal of Medicinal Chemistry 03/2015; 93. DOI:10.1016/j.ejmech.2015.02.013 · 3.45 Impact Factor
Available from: Xiao-Xin Chen
- "Therefore, the reducing power of the condensed tannins might decrease the formation of o-quinones by oxidoreduction reaction toward the o-quinones. It is known that o-dopaquinone undergoes a fast intramolecular cyclization to yield leukodopachrome which is oxidized by another molecule of o-dopaquinone to render dopachrome . This aminechrome is relatively stable in the medium although it may eventually be converted into melanins. "
[Show abstract] [Hide abstract]
ABSTRACT: Condensed tannins from Ficus virens leaves, fruit, and stem bark were isolated and their structures characterized by 13C nuclear magnetic resonance spectrometry, high performance liquid chromatography electrospray ionization mass spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The results showed that the leaves, fruit, and stem bark condensed tannins were complex mixtures of homo- and heteropolymers of B-type procyanidins and prodelphinidins with degrees of polymerization up to hexamer, dodecamer, and pentadecamer, respectively. Antityrosinase activities of the condensed tannins were studied. The results indicated that the condensed tannins were potent tyrosinase inhibitors. The concentrations for the leaves, fruit, and stem bark condensed tannins leading to 50% enzyme activity were determined to be 131.67, 99.89, and 106.22 μg/ml on monophenolase activity, and 128.42, 43.07, and 74.27 μg/ml on diphenolase activity. The inhibition mechanism, type, and constants of the condensed tannins on the diphenolase activity were further investigated. The results indicated that the condensed tannins were reversible and mixed type inhibitors. Fluorescence quenching, copper interacting, and molecular docking techniques were utilized to unravel the molecular mechanisms of the inhibition. The results showed that the hydroxyl group on the B ring of the condensed tannins could chelate the dicopper irons of the enzyme. Moreover, the condensed tannins could reduce the enzyme product o-quinones into colourless compounds. These results would contribute to the development and design of antityrosinase agents.
PLoS ONE 03/2014; 9(3):e91809. DOI:10.1371/journal.pone.0091809 · 3.23 Impact Factor
Available from: link.springer.com
- "First 300 ȝL of 2.5 mM 3,4-dihydroxyphenylalanine (L-DOPA)solution was added to 700 ȝL of 0.1 M phosphate buffer (pH 7.5). The mixture was preincubated at 37Gfor 5 min and 100 ȝL of potato extract was added, and the reaction was monitored by dopachrome formation at 475 nm (İ = 3700 Mcm -1 ) (Jiménez et al., 2001 "
[Show abstract] [Hide abstract]
ABSTRACT: Tyrosinase is responsible for the enzymatic browning of fruits and vegetables and usually catalyze the conversion of monophenols to o-diphenols and oxidation of diphenols to corresponding quinines. However, when 3,4-dihydroxymandelic acid is provided as the substrate, it catalyzes the oxidative decarboxylation reaction to generate 3,4-dihydroxybenzaldehyde (protocatechualdehyde, PA. In the present study, tyrosinase was purified from potato with 27.9 purification fold by salting out with ammonium sulfate, DEAE-Sepharose and Sephadex G-150 column chromatography. The purified tyrosinase was confirmed by tyrosinase active staining following SDS-PAGE. Tyrosinase activity was visualized in the gel as a dark band. The molecular weight of tyrosinase from potato was 38kDa as determined by SDS-PAGE. Purified tyrosinase mediated oxidative decarboxylation of 3,4-dihydroxymandelate. The identity of the reaction product, PA was confirmed by high-performance liquid chromatography (HPLC) as well as ultraviolet spectral studies. Phenol oxidase inhibitors such as potassium cyanide, sodium azide, and phenylthiourea inhibited the participation of the active site copper of the enzyme in the catalysis.
Horticulture, Environment and Biotechnology 08/2012; 53(4). DOI:10.1007/s13580-012-0098-z · 0.73 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.