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Scientific Reports
Springer Nature
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Abstract: |
Tyrosinase is a binuclear copper-containing enzyme that catalyzes the conversation of monophenols
to diphenols via o-hydroxylation and then the oxidation of o-diphenols to o-quinones which is
profoundly linked to eukaryotic melanin synthesis and fruits browning. The hyperpigmentation due
to unusual tyrosinase activity has gained growing health concern. Plants and their metabolites are
considered promising and effective sources for potent antityrosinase enzymes. Hence, searching
for potent, specific tyrosinase inhibitor from different plant extracts is an alternative approach in
regulating overproduction of tyrosinase. Among the tested extracts, the hydro-alcoholic extract
of Moringa oleifera L. leaves displayed the potent anti-tyrosinase activity (
IC50 = 98.93 μg/ml) in a
dose-dependent manner using L-DOPA as substrate; however, the kojic acid showed IC50
of 88.92 μg/
ml. The tyrosinase-diphenolase (TYR-Di) kinetic analysis revealed mixed inhibition type for the
Ocimum basilicum L. and Artemisia annua L. extracts, while the Coriandrum sativum L. extract
displayed a non-competitive type of inhibition. Interestingly, the extract of Moringa oleifera L.
leaves exhibited a competitive inhibition, low inhibition constant of free enzyme ( K
app
ii
) value and
no Pan-Assay Interfering Substances, hinting the presence of strong potent inhibitors. The major
putative antityrosinase compound in the extract was resolved, and chemically identified as rutin
based on various spectroscopic analyses using UV–Vis, FTIR, mass spectrometry, and 1H NMR. The
in silico computational molecular docking has been performed using rutin and A. bisporus tyrosinase
(PDB code: 2Y9X). The binding energy of the predicted interaction between tropolone native ligand,
kojic acid, and rutin against 2Y9X was respectively − 5.28, − 4.69, and − 7.75 kcal/mol. The docking
simulation results revealed the reliable binding of rutin to the amino acid residues (
ASN260, HIS259,
SER282)
in the tyrosinase catalytic site. Based on the developed results, rutin extracted from M.
oleifera L. leaves has the capability to be powerful anti-pigment agent with a potential application
in cosmeceutical area. In vivo studies are required to unravel the safety and efficiency of rutin as
antityrosinase compound.
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