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In Silico Approach to Inhibition of Tyrosinase by Ascorbic Acid Using Molecular Docking Simulations

Authors:
Fatma Sezer Senol Deniz at Gazi University
Fatma Sezer Senol Deniz
Mahmud Tareq Hassan Khan at Drug Discovery & Design, Tromso, Norway
Mahmud Tareq Hassan Khan
  • Drug Discovery & Design, Tromso, Norway
Gürdal Orhan
Gürdal Orhan
Erdem Gurkas at Gulhane Training and Research Hospital
Erdem Gurkas
  • Gulhane Training and Research Hospital
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Abstract and Figures

Current evidence suggests that endogenous dopamine may act as a neurotoxin following its oxidation to an o-quinone and reaction with cellular thiols, which are neutoxic, which may occur spontaneously or via reaction with tyrosinase or some other enzymes. Tyrosinase (E.C. 1.14.18.1) with two cupper ions coordinated by three histidines is a bifunctional enzyme that catalyses both the hydroxylation of tyrosine to L-DOPA and the consequent oxidation of the resulting catechol-containing species to an o-quinone. Therefore, tyrosinase may play a role in neuromelanin formation in the brain and could be central to dopamine neurotoxicity by contributing to the neurodegeneration associated with Parkinson's disease. In the present study, inhibitory effect of ascorbic acid against tyrosinase has been investigated and it has shown a remarkable inhibitory effect in in vitro assays. Then, the in silico-based experiments established through molecular docking calculations and scoring, docking search algorithm, and data plotting indicated that ascorbic acid is strong inhibitor of tyrosinase by interacting with four amino acid units (histidine 263, serine 282, phenylalanine 264, and valin 283) in the active site of the enzyme. The compound also had two long distant hydrogen bindings with Cu1 and Cu2 with distances of 3.57 and 3.41 Å, respectively, through its O5 atom.
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Current Topics in Medicinal Chemistry, 2014, 14, 1469-1472 1469
1568-0266/14 $58.00+.00 © 2014 Bentham Science Publishers
In Silico Approach to Inhibition of Tyrosinase by Ascorbic Acid Using
Molecular Docking Simulations
F. Sezer Senol1, M. Tareq Hassan Khan2, Gurdal Orhan3, Erdem Gurkas3, Ilkay Erdogan Orhan1,*,
Nese Subutay Oztekin3 and Fikri Ak3
1Department of Pharmacognosy, Faculty of Pharmacy, Gazi University, 06330 Ankara, Turkey; 2Holmboevegen 3B,
9010 Tromso, Norway; 3Neurology Clinic, Numune Training and Research Hospital, The Ministry of Health, Ankara,
06610, Turkey
Abstract: Current evidence suggests that endogenous dopamine may act as a neurotoxin following its oxidation to an o-
quinone and reaction with cellular thiols, which are neutoxic, which may occur spontaneously or via reaction with ty-
rosinase or some other enzymes. Tyrosinase (E.C. 1.14.18.1) with two cupper ions coordinated by three histidines is a bi-
functional enzyme that catalyses both the hydroxylation of tyrosine to L-DOPA and the consequent oxidation of the result-
ing catechol-containing species to an o-quinone. Therefore, tyrosinase may play a role in neuromelanin formation in the
brain and could be central to dopamine neurotoxicity by contributing to the neurodegeneration associated with Parkin-
son’s disease. In the present study, inhibitory effect of ascorbic acid against tyrosinase has been investigated and it has
shown a remarkable inhibitory effect in in vitro assays. Then, the in silico -based experiments established through molecu-
lar docking calculations and scoring, docking search algorithm, and data plotting indicated that ascorbic acid is strong in-
hibitor of tyrosinase by interacting with four amino acid units (histidine 263, serine 282, phenylalanine 264, and valin
283) in the active site of the enzyme. The compound also had two long distant hydrogen bindings with Cu1 and Cu2 with
distances of 3.57 and 3.41 Å, respectively, through its O5 atom.
Keywords: Ascorbic acid, in silico, in vitro, molecular docking, tyrosinase inhibition, vitamin C.
1. INTRODUCTION
Tyrosinase (EC 1.14.18.1) (syn. monophenol monooxy-
genase, polyphenoloxidase, catechol oxidase, and oxi-
doreductase) catalyzes the hydroxylation of monophenols
and the oxidation of o-diphenols to o-quinols, both depend-
ing on molecular oxygen. The term tyrosinase refers to its
typical substrate, tyrosine. It is a copper-containing enzyme
found in plant and mammal tissues that catalyzes the produc-
tion of melanin and other pigments from tyrosine by oxida-
tion. Its active site is characterized by two coupled copper
ions, coded as CuA and CuB, each one of which is ligated to
three histidines [1]. In humans, tyrosinase is encoded by the
TYR gene. At least two proteins linked to tyrosinase have
been found to exist in mammals; one of these proteins is
known as TRP-1 (TYRP1), which is responsible for the con-
version of 5,6-dihydro-xyindole-2-carboxylic acid (DHICA)
to indole-5,6-quinone-2-carboxylic acid; and the second one
is TRP-2 (TYRP2), which is the melanogenic enzyme DO-
PAchrome tautomerase that catalyzes the conversion of DO-
PAchrome to DHICA [2,3].
The well-known function of tyrosinase is the of melanin
formation from L-tyrosine via L-dihydroxyphenylalanine (L-
DOPA). Oxidized metabolites of dopamine known as dopa-
mine quinone derivatives have been shown to take part in the
*Address correspondence to this author at the Department of Pharma-
cognosy, Faculty of Pharmacy, Gazi University, 06330 Ankara, Turkey;
Tel: +90-312-2023186; Fax: +90-312-2235018;
E-mail: iorhan@gazi.edu.tr
degeneration of nigrostriatal dopaminergic neurons in Park-
inson’s disease (PD) [4] (Fig. 1). In fact, these quinone de-
rivatives are usually produced by way of the autoxidation of
catecholamines or tyrosinase, which is the chief enzyme in
melanin biosynthesis via the production of DOPA and sub-
sequent molecules, can potentially accelerate the induction
of catecholamine quinone derivatives by its oxidase activity.
Besides, dopamine quinones may interact with -synuclein,
the protein responsible for familial type of PD, leading to
formation of a toxic intermediate in nigral cells [5,6]. Pres-
ence of tyrosinase is favorable or harmful to neurons still
remains uncertain; nevertheless, the enzyme activity of ty-
rosinase generates dopamine quinones and other oxidizing
compounds. Finally, occurring neuromelanins, the dopa-
mine-derived pigments in the mammalian central nervous
system, may host for radical species [7]. The existence of
neuromelanins, which is biochemically similar to melanin
occurring in peripheral tissues, identifies groups of neurons
prone to PD. Therefore, inhibitors of tyrosinase, already used
for the treatment of hyperpigmentation and melasma as well
as melanoma [8,9], may be also of help in the treatment of
PD in future.
Ascorbic acid (vitamin C) is water-soluble vitamin with a
high antioxidant potential. Up to date, several studies have
been published on tyrosinase inhibitory effect of ascorbic
acid and its derivatives [10-13]. However, some of those
studies performed on the effect of ascorbic acid against ty-
rosinase on several substrates have been reported contradic-
tory results.
1470 Current Topics in Medici nal Chemistry, 2014, Vo l . 14, No. 12 Orhan et al.
Fig. (1). Formation of L-DOPA quinone via the reaction catalyzed by tyrosinase.
Hence, in the present work, we attempt to ascertain in-
hibitory potential of ascorbic acid against tyrosinase by in
vitro and in silico methods. In vitro inhibitory activity of
ascorbic acid towards tyrosinase was determined by the mi-
crotiter plate assay using ELISA microplate reader, while its
in silico inhibitory effect was investigated by molecular
docking simulations using Molegro Virtual Docker (MVD).
2. MATERIAL AND METHODS
2.1. Ascorbic Acid
L(+) form of ascorbic acid (CAS Nr: 50-81-7) used in
this study was purchased from Carlo Erba Reagents Ltd.
(Italy).
2.2. In vitro Determination of Tyrosinase Inhibitory Ac-
tivity
Inhibition of tyrosinase (EC 1.14.1.8.1, 30 U, mushroom
tyrosinase, Sigma) was determined using the modified do-
pachrome method with L-DOPA as substrate [14]. The as-
says were conducted in a 96-well microplate using ELISA
microplate reader (VersaMax Molecular Devices, USA) to
measure absorbance at 475 nm. An aliquot of the extracts
dissolved in DMSO with 80 μL of phosphate buffer (pH
6.8), 40 μL of tyrosinase, and 40 μL of L-DOPA were put in
each well. Results were compared with control (DMSO).
Alpha-kojic acid (Sigma, St. Louis, MO, USA) was used as
the reference.
2.3. Data Processing for In vitro Enzyme Inhibition Assay
The measurements and calculations were evaluated by
using Softmax PRO 4.3.2.LS software. Percentage inhibition
of tyrosinase was determined by comparison of rates of reac-
tion of test samples relative to blank sample (DMSO). Extent
of the enzymatic reaction was calculated based on the fol-
lowing equation: E = (C-T)/C 100, where E is the activity
of the enzyme. E value expresses the effect of the test sample
or the positive control on tyrosinase enzyme activity articu-
lated as the percentage of the remaining activity in the pres-
ence of test sample or positive control. C value is the absor-
bance of the control solvent (blank) in the presence of en-
zyme, where T is the absorbance of the tested sample (or
positive control in the solvent) in the presence of enzyme.
Data are expressed as average inhibition ± standard error
mean (S.E.M.) and the results were taken from at least three
independent experiments performed in triplicate.
2.4. Docking Calculations Using Molegro Virtual Docker
See “Supplementary materials”.
3. RESULTS AND DISCUSSION
In our in vitro assays, ascorbic acid was found to exhibit
a strong inhibitory activity against tyrosinase in concentra-
tion-dependant manner (Table 1). The molecular docking
simulations of ascorbic acid have been performed at the ac-
tive site of tyrosinase. Fig. (2) displays docked illustration of
ascorbic acid into the active site. Docking simulations using
MVD revealed MolDock score of -72.63 Kcal/mol and re-
ranking score of -63.58 Kcal/mol with a total interaction
energy (TIE) of -79.85, ligand efficiency (LE) of -5.85, and
hydrogen bond (Hbond) scoring of -0.08 Kcal/mol. These
energy features indicated that the compound ascorbic acid is
a strong binder of the tyrosinase enzyme.
The overall structure of ascorbic acid displayed hydro-
phobic interactions with four amino acid residues of Phe264,
His263, Ser282, and Val283 of the active site as illustrated in
(Fig. 2). Moreover O5 atoms of the compound exhibited two
long distant hydrogen bindings with Cu1 and Cu2 which
have distances of 3.57 and 3.41 Å, respectively. Further-
more, C6 also showed a third long distant hydrogen binding
with Cu1 with a distance of 3.7 Å.
The enzyme has been described to possess two binding
sites for aromatic substrates and a different binding site for
Table 1. Inhibitory effect of ascorbic acid against tyrosinase through in vitro assay.
Tyrosinase Inhibitio n (%Inhibition±S.E.M.)a
0.1 mM 0.5 mM 1 mM 5 mM 10 mM
Ascorbic acid 3.46±0.64 5.27±0.85 10.84±1.17 48.59±2.06 89.95±1.58
aStandard error mean (n=3)
Ascorbic Acid and Tyrosinase Inhibition Current Topics in Medicinal Chemistry, 2014, Vol. 14, No. 12 1471
oxygen, which is the copper-containing site [26]. Several
reports published on tyrosinase inhibitory effect of ascorbic
acid demonstrated contradictory results. Some of them
claimed that ascorbic acid could inhibit the enzyme directly,
whilst some studies suggested that ascorbic acid did not have
any effect on active site of the enzyme [27,28]. Those am-
biguous results directed us to perform the present study
whose outcomes underlined that ascorbic acid is a strong
binder of tyrosinase. During our literature survey, it was also
revealed that ascorbic acid is the irreversible inhibitor of
tyrosinase, which displayed a potent affinity for copper ions
in the active site of the enzyme, which is consistent with our
current findings [29].
Fig. (3). LigPlot of ascorbic acid interactions at the active site of
tyrosinase.
CONCLUSION
In conclusion, our in silico data suggests that ascorbic
acid, as a reducing agent leading a reduction in dopaquinone
formation, can inhibit tyrosinase acting on the active site of
tyrosinase by interactions with four amino acid residues as
well as long distant hydrogen bindings with Cu1 and Cu2.
To the best of our knowledge, the current work is the first
study on tyrosinase inhibitory effect of L-ascorbic acid by in
silico methods.
CONFLICT OF INTEREST
The authors confirm that this article content has no con-
flict of interest.
ACKNOWLEDGEMENTS
One of us (F.S. Senol) would like to express her sincere
thanks to the Scientific and Technological Research Council
of Turkey (TUBITAK) for the scholarship provided during
her Ph.D. program at Gazi University (Ankara, Turkey).
SUPPLEMENTARY MATERIALS
Supplementary material is available on the publishers
web site along with the published article.
ABBREVIATIONS
DHICA = 5,6-Dihydro-xyindole-2-carboxylic acid
EPLP = Piecewise linear potential
Escore = Docking Score
Hbond = Hydrogen bond
L-DOPA = L-Dihydroxyphenylalanine
LE = Ligand efficiency
MVD = Molegro virtual docking
PD = Parkinson’s disease
TIE = Total interaction energy
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Received: January 19, 2013 Revised: January 21, 2014 Accepted: January 22, 2014
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Full-text available
  • Sep 2021
p id="docs-internal-guid-fa145b0a-7fff-0af1-a074-1cbfd7cb8daf" style="line-height: 1.2; margin-left: 0.35pt; margin-right: -0.1pt; text-align: justify; margin-top: 6pt; margin-bottom: 6pt;" dir="ltr"> Limbah kulit buah cokelat diketahui mengandung berbagai senyawa aktif, termasuk di antaranya adalah golongan flavonoid. Senyawa flavonoid diketahui berpotensi memiliki aktivitas inhibitor enzim tirosinase, suatu enzim yang menstimulasi proses pembentukan melanin. Penelitian ini bertujuan untuk mengevaluasi interaksi antara senyawa flavonoid dari kulit buah cokelat dengan enzim tirosinase menggunakan metode penambatan molekuler secara in silico . Pengujian dilakukan dengan beberapa tahapan yakni preparasi makromolekul enzim, pemodelan molekul senyawa uji, identifikasi sisi aktif molekul enzim, identifikasi dan evaluasi penambatan molekuler, serta simulasi dinamika molekuler senyawa uji dengan molekul enzim. Hasil simulasi penambatan molekuler antara molekul enzim dengan ligan alaminya yakni tirosin memberikan energi ikatan sebesar -4,91 kkal/mol. Senyawa flavonoid dari kulit buah cokelat yakni apigenin, epikatekin, katekin, kaemferol, kuersetin, dan kuersitrin diketahui memiliki afinitas pada sisi aktif enzim tirosinase dengan energi ikatan berturut turut -6,14; -6,17; -6,01; -5,89; -6,13; -6,81 kkal/mol. Hasil simulasi dinamika molekuler menunjukkan kuersitrin memiliki stabilitas yang baik dengan nilai RMSD rata-rata dan nilai energi bebas ikatan MM/PBSA masing-masing sebesar ±1,73 Å dan -80,12 kJ/mol. Hasil penelitian menunjukkan bahwa senyawa turunan flavonoid tersebut mampu berikatan dengan sisi aktif enzim tirosinase dengan afinitas yang lebih baik dibandingkan dengan ligan alaminya diamati dari nilai energi ikatannya. Senyawa turunan flavonoid yang terkandung dalam kulit buah cokelat berpotensi menjadi inhibitor kompetitif dari enzim tirosinase. Identification of In Silico Tyrosinase Inhibitory Activity of Flavonoid Derivative Compounds in Cocoa Pod Husk ( Theobroma cacao L.). Cocoa pod husk was known to contain several active compounds, such as flavonoids. Flavonoid compounds are known to potentially have inhibitory activity of the tyrosinase, the enzyme which stimulates melanin synthesis. This study was conducted to evaluate the molecular interaction between flavonoids from cocoa pod husk with tyrosinase enzyme using in silico molecular docking method. The study was carried out through several stages, including preparation of enzyme macromolecules, modeling the molecule of the test compound, identifying the active site of the enzyme molecule, identifying and evaluating molecular docking, and molecular dynamics simulations of the test compound with the enzyme molecule. Molecular docking simulation between the enzyme and its natural ligand (tyrosine) produces binding energy of -4.91 kcal/mol. Flavonoid compounds from cocoa pod husk, including apigenin, epicatechin, catechin, kaempferol, quercetin, dan quercitrin, have an affinity on the active site of the enzyme with binding energy were -6.14; -6.17; -6.01; -5.89; -6.13; -6.81 kcal/mol, respectively. Then the molecular dynamics simulation shows quercitrin has good stability interaction with the average RMSD value and the MM/PBSA binding-free energy values of ±1.73 Å and -80.12 kJ/mol, respectively. The results showed that flavonoids of cocoa pod husc extract have an affinity to the active site of the enzyme, with a stronger binding energy than the original ligand. The flavonoid compounds of cocoa pod husk potential as a competitive inhibitor of the tyrosinase enzyme. </p
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... Various tyrosinase inhibitors regulate melanin synthesis by modulating tyrosinase activity in two ways: (i) inactivation of the tyrosinase and (ii) competitive displacement of the tyrosinase substrates, L-tyrosine and L-DOPA. Thus, tyrosinase is not only responsible for skin pigmentation, but also linked to Parkinson's disease and other neurodegenerative diseases (Senol et al., 2014). A well-known inhibitory compound of tyrosinase is kojic acid (Chang, 2009). ...
... In a recent study, we could find that the p-coumaric acid affects the development of the zebrafish embryo, especially down-regulates the melanogenesis via tight docking into the tyrosinase enzyme. Tyrosinase, a copper-containing membrane-bound glycoprotein, is the rate-limiting enzyme that catalyzes the biosynthetic pathway of melanin (Orhan and Khan, 2014). For the past several decades, numerous tyrosinase enzyme blockers have been investigated for their use in cosmetics and pharmaceutical products to prevent the over production of melanin (Chang, 2009). ...
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... This compound is water-soluble and heat-labile and has been shown to have anti-aging effects by inducing the production of collagen-1 and 3 which are important enzymes in collagen formation and inhibiting MMP1 [6]. In addition, ascorbic acid can also inhibit tyrosinase at protein active sites [7]. Research related to natural ingredients in sunscreens is increasing to minimize skin irritation due to sunscreen use or referred to as green sunscreens [5]. ...
Virtual Prediction of The Potency of Common Jasmine (Jasminum officinale L.) Bioactive Compounds as Anti-Aging Agents for Natural Sunscreen
Article
Full-text available
  • Oct 2022
UV exposure causes protein denaturation in the skin, leading to wrinkles and photoaging. Matrix metalloproteinases (MMPs) are enzymes that degrade the matrix and are associated with destruction processes like skin aging. Tyrosinase is the rate-limiting enzyme in the melanin synthesis process. We predict that Jasminum officinale L. bioactive compounds can be used as inhibitors for MMP1, MMP3, and tyrosinase. This study aims to compare the potential of bioactive compounds in Jasminum officinale L. as an inhibitor for the MMP1, MMP3, and tyrosinase receptors to prevent anti-aging. Vanillin, hydroxytyrosol, salicylic acid, 3,4-dihydroxy benzoic acid, oleoside-11-methyl ester, ursolic acid, oleanolic acid, and jasminine were retrieved from PubChem database as ligands, to dock with MMP1, MMP3, and tyrosinase as receptors that were retrieved from RCSB PDB. ADMET analysis was performed using pKCSM. Target-based virtual screening was performed using AutoDock Vina in PyRx. Visualization and interactions of amino acid residues was performed using Biovia Discovery Studio 2021. The complex structure was analyzed by molecular dynamics using the CABS-Flex 2.0 website. The oleoside-11-methyl ester compound has the highest potential as an MMP1 inhibitor, the 3,4-dihydroxy benzoic acid compound has the potential to inhibit MMP3, and hydroxytyrosol has the potential to inhibit tyrosinase involved in skin aging because it has low toxicity, highest binding affinity, and low fluctuations based on RMSF values in molecular dynamics simulations. Thus, this study indicated that bioactive compounds in common jasmine (Jasminum officinale L.) can be used as a candidate for organic sunscreen.
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... Finally, vitamin C is a well-known antioxidant that inhibits tyrosinase by interacting with copper ions at tyrosinase active sites, thus decreasing melanogenesis [10]. According to a recent review, vitamin C has been cited in the top 10 cosmetics for the prevention of facial hyperpigmentation and is commonly used in nutraceutical formulations with polyphenol-rich extracts for skin health [11][12][13][14]. ...
Effect of an Oral Formulation on Skin Lightening: Results from In Vitro Tyrosinase Inhibition to a Double-Blind Randomized Placebo-Controlled Clinical Study in Healthy Asian Participants
Article
Full-text available
  • Oct 2023
Oral formulations with natural plant-based extracts represent a safe and promising strategy for skin lightening and anti-dark-spot effects, especially in Asia. This study evaluated the effect of an oral formulation including polyphenol-rich extracts and vitamin C (Belight3TM) on in vitro tyrosinase inhibitory activity and investigated its skin lightening and anti-dark-spot effects in vivo. Tyrosinase inhibitory activity of the formulation was measured with spectrophotometry. A randomized, double-blind, placebo-controlled clinical study was carried out on 58 healthy Asian males and females, aged 45–65. Skin color was measured at baseline, 6 weeks and 12 weeks with digital photographs. Color of dark spots was assessed with spectrophotometry. In vitro, the formulation showed a significant synergistic tyrosinase inhibitory activity of 85% compared to the control. In vivo, 12-week oral administration of the formulation significantly lightened the skin and was significantly better than the placebo. In addition, this formulation induced a slight and significant lightening effect of the dark spots after 6 and 12 weeks. Our findings suggest that the daily oral administration of Belight3TM during 12 weeks appears as an efficient and safe nutricosmetic to lighten the color of the facial skin and dark spots in Asian subjects.
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... Ascorbic acid has been identified as a potent tyrosinase inhibitor, exhibiting hydrophobic interactions with the amino acid residues Phe264, His263, Ser282, and Val283. It also forms two hydrogen bonds with Cu 2+ (1) and Cu 2+ (2), at distances of 3.57 and 3.41 Å, respectively [28]. The aromatic ring of resorcinol is reported to engage in a pi-pi interaction with His367 and a hydrophobic interaction with the blocking residue Val377 in the TRP1 active site [29]. ...
Molecular docking Study of Nuciferine as a Tyrosinase Inhibitor and Its Therapeutic Potential for Hyperpigmentation
Article
Full-text available
  • Sep 2023
Melanin is synthesized by tyrosinase to protect the skin from ultraviolet light. However, overproduction and accumulation of melanin can result in hyperpigmentation and skin melanoma. Tyrosinase inhibitors are commonly used in the treatment of hyperpigmentation. Natural tyrosinase inhibitors are often favored over synthetic ones due to the potential side effects of the latter, which can include skin irritation, allergies, and other adverse reactions. Nuciferine, an alkaloid derived from Nelumbo nucifera, exhibits potent antioxidant and anti-proliferative properties. This study focused on the in silico screening of nuciferine for anti-tyrosinase activity, using kojic acid, ascorbic acid, and resorcinol as standards. The tyrosinase protein target was selected through homology modeling. The residues of the substrate binding pocket and active site pockets were identified for the purposes of grid box optimization and docking. Nuciferine demonstrated a binding energy of –7.0 kcal/mol and a Ki of 5 µM, both of which were comparatively higher than the corresponding values of kojic acid, which showed –5.3 kcal/mol and 122 µM respectively. Therefore, nuciferine is a potent natural tyrosinase inhibitor and shows promising potential for application in the treatment of hyperpigmentation and skin melanoma.
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... The distance between the surface of the enzyme macromolecule and the test compound molecule is limited to a maximum radius limit of 0.375 Å. All simulations were carried out using a grid box size of 64 x 60 x 60, then the Lamarckian Genetic Algorithm method with 100 conformations was used[10]. ...
The Effect of Adding Cinnamon Bark Oil to the Tyrosinase Inhibitory Activity of Emulgel Containing Cocoa Pod Husk Extract
Article
  • Dec 2022
Our previous study showed that cocoa pod husk extract has tyrosinase inhibitory properties and the potential to prevent skin hyperpigmentation. Another natural source that is known to have tyrosinase inhibitory properties is cinnamon bark oil. This paper aims to analyze the tyrosinase inhibitory properties of cinnamon bark oil through molecular docking. It also aims to determine the effect of adding cinnamon bark oil to the tyrosinase inhibitory properties of emulgel containing cocoa pod husk extract. The constituents of cinnamon bark oil were determined using gas chromatography-mass spectrometry. The molecular docking was conducted using autodock. The emulgels were prepared by adding 2% of cocoa pod husk extract with and without the addition of cinnamon bark oil (1%). Tyrosinase inhibitory properties were analyzed using a colorimetric enzymatic assay and the dopachrome method. The GCMS result showed the cinnamon bark oil containing 53.37% cinnamaldehyde. The in-silico study showed cinnamaldehyde properties as a tyrosinase inhibitor, since it can bind on the active site of the enzyme with free binding energy at -4.88 kcal/mol. The addition of cinnamon bark oil (1%) to the emulgel preparation increased the tyrosinase inhibitory activity by 63.33% based on in vitro study. Keywords: emulgel, cocoa pod husk extract, cinnamon bar oil, tyrosinase inhibitor
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Medicinal Prospects of Targeting Tyrosinase: A Feature Review
Article
  • Sep 2022
Tyrosinase is a bifunctional polyphenol oxidase (PPO), catalyzing two oxidative reactions: monophenols to o-quinones (monophenolase activity) and o-diphenols to o-quinones (diphenolase activity). As tyrosinase is the rate-limiting enzyme for the melanogenesis process, it is an attractive target for melanogenesis inhibition. Aiming at skin whitening, anticancer, Parkinson’s disease (PD) treatment, antibacterial, fruit and vegetable preservation and other anti-pigmentation effect, medicinal chemists have exploited diverse tyrosinase inhibitors through various approaches. In addition to discovering inhibitors with novel scaffold, good activity and high safety, researchers also focused on developing strategies for synergistic effects of multiple inhibitors and simultaneously regulating multiple targets to treat cancer or neurodegenerative diseases. This review focused on multiple natural and synthetic tyrosinase inhibitors which could contribute to preventing fruit and vegetable browning, skin whitening, antibacterial, anticancer, Parkinson's Disease etc.
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Towaroznawcze aspekty kształtowania barwy soków na przykładzie mętnego soku jabłkowego
Book
  • Nov 2017
Książka z zakresu współczesnej technologii przetwórstwa surowców na produkty akceptowalne przez konsumentów. Poświęcona zagadnieniu enzymatycznego brązowienia mętnego soku jabłkowego, prezentuje badania na temat możliwości wykorzystania na przykład ekstraktów z roślin czy innych soków do przedłużania trwałości mętnych soków jabłkowych w aspekcie ich barwy. Badania te wpisują się w nurt dotyczący roli naturalnych przeciwutleniaczy jako inhibitorów brązowienia enzymatycznego.
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Differential Evolution: A Simple and Efficient Adaptive Scheme for Global Optimization Over Continuous Spaces
Article
Full-text available
  • Jan 1995
A new heuristic approach for minimizing possibly nonlinear and non differentiable continuous space functions is presented. By means of an extensive testbed, which includes the De Jong functions, it will be demonstrated that the new method converges faster and with more certainty than Adaptive Simulated Annealing as well as the Annealed Nelder&Mead approach, both of which have a reputation for being very powerful. The new method requires few control variables, is robust, easy to use and lends itself very well to parallel computation.
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Effect of ascorbic acid, sodium bisulfite, and thiol compounds on mushroom polyphenol oxidase
Article
Full-text available
  • Sep 1984
The effect of ascorbic acid, sodium bisulfite, glutathione (reduced), and dithiothreitol on the observed activity of mushroom polyphenol oxidase (PPO) was determined by spectrophotometry (color formation) and by polarography (O2 uptake). By polarography, O2 uptake began immediately on adding enzyme. Ascorbic acid and sodium bisulfite had little effect on the initial velocity while dithiothreitol and glutathione decreased the initial velocity by 35%, with no further decrease at higher concentrations. By spectrophotometry, there was an initial lag in the absorbance change followed by a slower increase in absorbance than for the control at zero time. By spectrophotometry, the I50 values were as follows: dithiothreitol, 0.06 mM; glutathione, 0.17 mM; sodium bisulfite, 0.20 mM; ascorbic acid, 0.24 mM. The direct effect of the reductants was determined by (1) incubation of the reductant with PPO and then measuring the remaining activity by polarography and (2) gel electrophoresis. At 0.1 mM, dithiothreitol caused a complete loss of activity after 70 min at 25°C (t1/2 = 8 min) while sodium bisulfite, glutathione, and ascorbic acid caused 50% inactivation after 28, 106, and 130 min, respectively, at 5 mM.
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Automated docking using Lamarckian genetic algorithm and an empirical binding free energy function
Article
  • Nov 1998
  • J COMPUT CHEM
A novel and robust automated docking method that predicts the bound conformations of flexible ligands to macromolecular targets has been developed and tested, in combination with a new scoring function that estimates the free energy change upon binding. Interestingly, this method applies a Lamarckian model of genetics, in which environmental adaptations of an individual's phenotype are reverse transcribed into its genotype and become heritable traits (sic). We consider three search methods, Monte Carlo simulated annealing, a traditional genetic algorithm, and the Lamarckian genetic algorithm, and compare their performance in dockings of seven protein–ligand test systems having known three-dimensional structure. We show that both the traditional and Lamarckian genetic algorithms can handle ligands with more degrees of freedom than the simulated annealing method used in earlier versions of AUTODOCK, and that the Lamarckian genetic algorithm is the most efficient, reliable, and successful of the three. The empirical free energy function was calibrated using a set of 30 structurally known protein–ligand complexes with experimentally determined binding constants. Linear regression analysis of the observed binding constants in terms of a wide variety of structure-derived molecular properties was performed. The final model had a residual standard error of 9.11 kJ mol⁻¹ (2.177 kcal mol⁻¹) and was chosen as the new energy function. The new search methods and empirical free energy function are available in AUTODOCK, version 3.0. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1639–1662, 1998
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Automated docking using a Lamarckian genetic algorithm and empirical binding free energy function
Article
  • Nov 1998
A novel and robust automated docking method that predicts the bound conformations of flexible ligands to macromolecular targets has been developed and tested, in combination with a new scoring function that estimates the free energy change upon binding. Interestingly, this method applies a Lamarckian model of genetics, in which environmental adaptations of an individual's phenotype are reverse transcribed into its genotype and become . heritable traits sic . We consider three search methods, Monte Carlo simulated annealing, a traditional genetic algorithm, and the Lamarckian genetic algorithm, and compare their performance in dockings of seven protein)ligand test systems having known three-dimensional structure. We show that both the traditional and Lamarckian genetic algorithms can handle ligands with more degrees of freedom than the simulated annealing method used in earlier versions of AUTODOCK, and that the Lamarckian genetic algorithm is the most efficient, reliable, and successful of the three. The empirical free energy function was calibrated using a set of 30 structurally known protein)ligand complexes with experimentally determined binding constants. Linear regression analysis of the observed binding constants in terms of a wide variety of structure-derived molecular properties was performed. The final model had a residual standard y1 y1 .
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LIGPLOT: A program to generate schematic diagrams of protein-ligand interactions
Article
  • Feb 1995
The LIGPLOT program automatically generates schematic 2-D representations of protein-ligand complexes from standard Protein Data Bank file input. The output is a colour, or black-and-white, PostScript file giving a simple and informative representation of the intermolecular interactions and their strengths, including hydrogen bonds, hydrophobic interactions and atom accessibilities. The program is completely general for any ligand and can also be used to show other types of interaction in proteins and nucleic acids. It was designed to facilitate the rapid inspection of many enzyme complexes, but has found many other applications.
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How to Solve It: Modern Heuristics
Chapter
  • Jan 2004
If you spend any significant amount of time trying to solve problems, “racking your brain,” you will inevitably contemplate the prospects of automating your thinking process. The dream is to make a computer simulation that simulates the way your brain functions so that it can solve problems the same way you do. But brains don’t function with the same mechanisms as serial digital computers. Biological processing is inherently and massively parallel in character, whereas traditional computing is sequential. Each step in an algorithm is conducted in turn until a final halting condition is reached. Further, although there are conceptual similarities between neurons in living brains and logic gates in computers, the firing rates of biological neurons are much slower than computer logic gates (on the order of milliseconds for neurons versus nanoseconds for computers). These and other differences in design lead to an intuition that these alternative input—output devices should each be able to tackle different problems with efficiency.
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Automated Docking Using a Lamarckian Genetic Algorithm and Empirical Binding Free Energy Function
Article
  • Nov 1998
  • J COMPUT CHEM
A novel and robust automated docking method that predicts the bound conformations of flexible ligands to macromolecular targets has been developed and tested, in combination with a new scoring function that estimates the free energy change upon binding. Interestingly, this method applies a Lamarckian model of genetics, in which environmental adaptations of an individual's phenotype are reverse transcribed into its genotype and become . heritable traits sic . We consider three search methods, Monte Carlo simulated annealing, a traditional genetic algorithm, and the Lamarckian genetic algorithm, and compare their performance in dockings of seven protein)ligand test systems having known three-dimensional structure. We show that both the traditional and Lamarckian genetic algorithms can handle ligands with more degrees of freedom than the simulated annealing method used in earlier versions of AUTODOCK, and that the Lamarckian genetic algorithm is the most efficient, reliable, and successful of the three. The empirical free energy function was calibrated using a set of 30 structurally known protein)ligand complexes with experimentally determined binding constants. Linear regression analysis of the observed binding constants in terms of a wide variety of structure-derived molecular properties was performed. The final model had a residual standard y1 y1. error of 9.11 kJ mol 2.177 kcal mol and was chosen as the new energy
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Resveratrol as a k(cat) type inhibitor for tyrosinase: Potentiated melanogenesis inhibitor
Article
  • Dec 2011
Resveratrol exhibited the inhibitory activity against mushroom tyrosinase (EC1.14.18.1) through a k(cat) inhibition. Resveratrol itself did not inhibit tyrosinase but rather was oxidized by tyrosinase. In the enzymatic assays, resveratrol did not inhibit the diphenolase activity of tyrosinase when l-3,4-dihydroxyphenylalanin (L-DOPA) was used as a substrate; however, L-tyrosine oxidation by tyrosinase was suppressed in presence of 100 μM resveratrol. Oxidation of resveratrol and inhibition of L-tyrosine oxidation suggested the inhibitory effects of metabolites of resveratrol on tyrosinase. After the 30 min of preincubation of tyrosinase and resveratrol, both monophenolase and diphenolase activities of tyrosinase were significantly suppressed. This preincubational effect was reduced with the addition of L-cysteine, which indicated k(cat) inhibition or suicide inhibition of resveratrol. Furthermore, investigation was extended to the cellular experiments by using B16-F10 murine melanoma cells. Cellular melanin production was significantly suppressed by resveratrol without any cytotoxicity up to 200 μM. trans-Pinosylvin, cis-pinosylvin, dihydropinosylvin were also tested for a comparison. These results suggest that possible usage of resveratrol as a tyrosinase inhibitor and a melanogenesis inhibitor.
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