Abstract:
Hyperpigmentation is a darkening of the skin color caused by an increase in melanin production.
Darkening of the skin occurs due to the formation of the pigment melanin in the skin through the
oxidation of tyrosine which is assisted by the enzyme tyrosinase L-DOPA which will eventually
form the pigment melanin. In general, the amount of melanin in the skin will determine our skin
color. Tyrosinase is an enzyme that regulates melanin biosynthesis. Melanin formation can be
inhibited by reducing tyrosinase synthesis or inhibiting its activity. One of the compounds that
has acted an inhibitor of the tyrosinase enzyme is pyrazoline. Pyrazoline is a heterocyclic
compound with two nitrogen atoms adjacent in a ring of five. The compound 3-(3-3-
methoxyphenyl)-1-phenyl-4,5-dihydro-1H-pyrazole-5-yl)phenol was synthesized using a
monowave apparatus. The purity of the target compound was analyzed by TLC test, melting
point measurement, and HPLC. The synthesized compounds were then structurally confirmed by
UV, FTIR, 1H-NMR, and HRMS spectroscopy. The yield obtained from the synthesis of
pyrazoline compounds is 75%. The synthesized pure compound was tested for activity as a
tyrosinase inhibitor by molecular docking (in silico) and in vitro studies. Molecular docking
studies were carried out on the crystal structure of tyrosinase (PDB ID: 2Y9X) with natural
ligands tropolone and kojic acid as positive controls. The docking results showed that the
pyrazoline compound had free bond energy (S score) = -11.0206 kcal/mol, while the free bond
energy for kojic acid was -7.4610 kcal/mol.
