Abstract:
The hyperpigmentation caused by melanin production excessive on the skin. One of the way to
prevent hyperpigmentation is to inhibit the production of melanin called tyrosinase inhibitors.
One of the compounds that has the activity as an inhibitor of the tyrosinase enzyme is pyrazolin.
Pyrazoline is a heterocyclic compound with two adjacent nitrogen atoms in a five rings. The
pyrazoline compound 2-(5-(3-bromophenyl)-1-phenyl-4,5-dihydro-1H-pyrazole-3-yl) phenol
(PF-2OH-3Br) was synthesized by reacting 2-hydroxyacetophenone, 3-bromobenzaldehyde, and
phenylhydrazine through one reaction step in one container (one pot) using the method sealed
vessel reactor at 80ºC with a stirring speed of 1000 rpm for 2 hours with the help of a
monowave. The structure of the synthesized compound was confirmed through spectroscopic
analysis of UV, FTIR, 1H-NMR, 13C-NMR and HRMS. The yield obtained from the synthesis of
pyrazoline compounds was 12,21%. The pure synthesized compound was tested for activity as a
tyrosinase inhibitor with molecular docking (in silico) and in vitro studies. Studies were
molecular docking carried out on the crystal structure of tyrosinase (PDB ID: 2Y9X) with natural
ligands tropolone and kojic acid as positive controls. The results of docking show that the
pyrazoline compound has a bond free energy (S score) = -9,6368 kcal/mol, while the free bond
energy for kojic acid is -8,0543 kcal/mol. Results of in vitro studies testify the compound PF-
2OH-3BR relatively weak in the inhibition of tyrosinase enzyme with value of IC50 519,67
μg/mL.
