Considerations about the kinetic mechanism of tyrosinase in its action on monophenols: A review

García-Molina, Pablo; García‐Molina, Francisco; Teruel, José A.; Rodrı́guez-López, José Neptuno; Garcı́a-Cánovas, Francisco; Muñoz‐Muñoz, José Luis

doi:10.1016/j.mcat.2021.112072

Cited by 16 publications

(16 citation statements)

References 93 publications

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“…Similar observations were also recorded for the glucosidase inhibition assay, in which the order was: stem bark-MeOH (3.82 mmol ACAE/g) > leaves-MeOH (2.77 mmol ACAE/g) > stem bark-infusion (2.74 mmol ACAE/g) > leaves-infusion (0.85 mmol ACAE/g). Tyrosinase catalyses the production of melanin, and its inhibition is an important mechanism in controlling hyperpigmentation problems [ 63 ]. As can be seen from Table 1 , the highest tyrosinase inhibitory effects were detected in the methanol extracts (stem bark: 64.41 mg KAE/g; leaves: 59.72 mg KAE/g).…”

Section: Resultsmentioning

confidence: 99%

Bridging the Chemical Profiles and Biological Effects of Spathodea campanulata Extracts: A New Contribution on the Road from Natural Treasure to Pharmacy Shelves

et al. 2022

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Spathodea campanulata is an important medicinal plant with traditional uses in the tropical zone. In the current work, we aimed to determine the chemical profiles and biological effects of extracts (methanolic and infusion (water)) from the leaves and stem bark of S. campanulata. The chemical components of the tested extracts were identified using LC-ESI-QTOF-MS. Biological effects were tested in terms of antioxidant (radical scavenging, reducing power, and metal chelating), enzyme inhibitory (cholinesterase, amylase, glucosidase, and tyrosinase), antineoplastic, and antiviral activities. Fifty-seven components were identified in the tested extracts, including iridoids, flavonoids, and phenolic acids as the main constituents. In general, the leaves-MeOH extract was the most active in the antioxidant assays (DPPH, ABTS, CUPRAC, FRAP, metal chelating, and phosphomolybdenum). Antineoplastic effects were tested in normal (VERO cell line) and cancer cell lines (FaDu, HeLa, and RKO). The leaf infusion, as well as the extracts obtained from stem bark, showed antineoplastic activity (CC50 119.03–222.07 µg/mL). Antiviral effects were tested against HHV-1 and CVB3, and the leaf methanolic extract (500 µg/mL) exerted antiviral activity towards HHV-1, inhibiting the viral-induced cytopathic effect and reducing the viral infectious titre by 5.11 log and viral load by 1.45 log. In addition, molecular docking was performed to understand the interactions between selected chemical components and viral targets (HSV-1 DNA polymerase, HSV-1 protease, and HSV-1 thymidine kinase). The results presented suggest that S. campanulata may be a bright spot in moving from natural sources to industrial applications, including novel drugs, cosmeceuticals, and nutraceuticals.

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Section: Resultsmentioning

confidence: 99%

Bridging the Chemical Profiles and Biological Effects of Spathodea campanulata Extracts: A New Contribution on the Road from Natural Treasure to Pharmacy Shelves

et al. 2022

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“…Regarding BChE inhibitory assay, the best action was observed in #1TT (4.30 mg GALAE/g). Tyrosinase is a key enzyme in the synthesis of melanin; it plays a vital role in the progression of hyperpigmentation problems [ 39 ]. All extracts exhibited inhibitory effects on tyrosinase, and the most active one was #4TT (66.44 mg KAE/g).…”

Section: Resultsmentioning

confidence: 99%

A Comparative Study on Phytochemical Fingerprint of Two Diverse Phaseolus vulgarisvar. Tondino del Tavo and Cannellino Bio Extracts

et al. 2022

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Common bean (Phaseolus vulgaris) represents one of the most famous foods with antiobesity activity showing a significant efficacy against fat accumulation, insulin resistance and dyslipidaemia. In this work, two Italian varieties of common bean, i.e., Tondino del Tavo and Cannellino Bio, from the centre of Italy were studied to characterise their phenolic profile by HPLC-PDA in relation to different fractions after a straightforward extraction procedure. Antioxidant property and enzymatic inhibition power were also evaluated in order to delineate a possible biological profile. Results show a considerable phenolic content (0.79 and 1.1 µg/mg of 3-hydroxybenzoic acid for hexane extract of Tondino del Tavo and Cannellino Bio, respectively; 0.30 µg/mg p-coumaric acid for n-hexane extract of Tondino del Tavo) for both varieties, and a strong antioxidant activity according to the major phenolic concentration of the extracts. The anti-inflammatory activity of the decoction extracts was also investigated through a zymosan-induced edema formation assay, revealing a moderate ability for both of them. These preliminary data prompt us to further explore the nutrient components of these two varieties in the future.

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“…Grid parameter files were built using AutoGrid 4.2.6 [ 64 ]. Other docking parameters were used as in [ 65 ]. PyMOL 2.3.0 (Schrödinger) was employed to build and inspect the molecule structures and docked conformations [ 66 ].…”

Section: Methodsmentioning

confidence: 99%

The Relationship between the IC50 Values and the Apparent Inhibition Constant in the Study of Inhibitors of Tyrosinase Diphenolase Activity Helps Confirm the Mechanism of Inhibition

et al. 2022

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Tyrosinase is the enzyme involved in melanization and is also responsible for the browning of fruits and vegetables. Control of its activity can be carried out using inhibitors, which is interesting in terms of quantitatively understanding the action of these regulators. In the study of the inhibition of the diphenolase activity of tyrosinase, it is intriguing to know the strength and type of inhibition. The strength is indicated by the value of the inhibition constant(s), and the type can be, in a first approximation: competitive, non-competitive, uncompetitive and mixed. In this work, it is proposed to calculate the degree of inhibition (iD), varying the concentration of inhibitor to a fixed concentration of substrate, L-dopa (D). The non-linear regression adjustment of iD with respect to the initial inhibitor concentration [I]0 allows for the calculation of the inhibitor concentration necessary to inhibit the activity by 50%, at a given substrate concentration (IC50), thus avoiding making interpolations between different values of iD. The analytical expression of the IC50, for the different types of inhibition, are related to the apparent inhibition constant (KIapp). Therefore, this parameter can be used: (a) To classify a series of inhibitors of an enzyme by their power. Determining these values at a fixed substrate concentration, the lower IC50, the more potent the inhibitor. (b) Checking an inhibitor for which the type and the inhibition constant have been determined (using the usual methods), must confirm the IC50 value according to the corresponding analytical expression. (c) The type and strength of an inhibitor can be analysed from the study of the variation in iD and IC50 with substrate concentration. The dependence of IC50 on the substrate concentration allows us to distinguish between non-competitive inhibition (iD does not depend on [D]0) and the rest. In the case of competitive inhibition, this dependence of iD on [D]0 leads to an ambiguity between competitive inhibition and type 1 mixed inhibition. This is solved by adjusting the data to the possible equations; in the case of a competitive inhibitor, the calculation of KI1app is carried out from the IC50 expression. The same occurs with uncompetitive inhibition and type 2 mixed inhibition. The representation of iD vs. n, with n=[D]0/KmD, allows us to distinguish between them. A hyperbolic iD vs. n representation that passes through the origin of coordinates is a characteristic of uncompetitive inhibition; the calculation of KI2app is immediate from the IC50 value. In the case of mixed inhibitors, the values of the apparent inhibition constant of meta-tyrosinase (Em) and oxy-tyrosinase (Eox), KI1app and the apparent inhibition constant of metatyrosinase/Dopa complexes (EmD) and oxytyrosinase/Dopa (EoxD), KI2app are obtained from the dependence of iD vs. n, and the results obtained must comply with the IC50 value.

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Considerations about the kinetic mechanism of tyrosinase in its action on monophenols: A review

Cited by 16 publications

References 93 publications

Bridging the Chemical Profiles and Biological Effects of Spathodea campanulata Extracts: A New Contribution on the Road from Natural Treasure to Pharmacy Shelves

Bridging the Chemical Profiles and Biological Effects of Spathodea campanulata Extracts: A New Contribution on the Road from Natural Treasure to Pharmacy Shelves

A Comparative Study on Phytochemical Fingerprint of Two Diverse Phaseolus vulgarisvar. Tondino del Tavo and Cannellino Bio Extracts

The Relationship between the IC50 Values and the Apparent Inhibition Constant in the Study of Inhibitors of Tyrosinase Diphenolase Activity Helps Confirm the Mechanism of Inhibition

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