Synthesis, biological evaluations, and in silico assessments of phenylamino quinazolinones as tyrosinase inhibitors

Abstract

A series of novel phenylamino quinazolinone derivatives were designed and synthesized as potential tyrosinase inhibitors. Among these compounds, 9r emerged as the most potent derivative, exhibiting IC₅₀ values of 17.02 ± 1.66 µM, compared to kojic acid as the positive control with an IC₅₀ value of 27.56 ± 1.27 µM. Antioxidant assessment of 9r compounds showed 24.67% inhibition at 100 µM. Molecular docking studies of these derivatives were conducted, revealing their proper fitting within the enzyme's active site. Additionally, density functional theory analysis was performed on the potent derivatives, indicating their stability and reactivity. Notably, the highest values of the energy gap were observed in 9r and 9s derivatives, underscoring their potential efficacy. Further kinetic studies of compound 9r, identified as the most potent derivative, demonstrated a competitive mode of inhibition with a K_i value of 14.87 µM. Molecular dynamics simulations of the 9r-tyrosinase complex revealed stability over time, with a reduction in critical residual fluctuation during the simulation. Overall, these findings contribute to a deeper understanding of the potential therapeutic value of these derivatives as tyrosinase inhibitors.

Keywords: DFT; Molecular dynamics simulation; Phenylamino quinazolinone; Tyrosinase.

Fig. 1

Strategy for the design of nitrophenylamino quinazolinone unit incorporating amino methylene 1,2,3-triazole derivatives.

Scheme 1

Synthesis of compounds 9a–t.

Fig. 2

The Lineweaver–Burk plot of the most potent inhibitor 9r against tyrosinase.

Fig. 3

Double reciprocal Lineweaver–Burk plot of 9r against tyrosinase.

Fig. 4

2D interaction pattern of 9c, 9h, 9j, 9r, and 9s within tyrosinase active site resulting from the docking studies.

Fig. 5

DFT calculated HOMO, LUMO, and their energies for 9c, 9h, 9j, 9r, and 9s.

Fig. 6

ESP calculated of 9c, 9h, 9j, 9r, and 9s.

Fig. 7

RMSD plot of the tyrosinase in complex with 9r in the MD simulation time. RMSD values of the apoenzyme are depicted in green, and the 9r-enzyme is exhibited in red.

Fig. 8

RMSF of the tyrosinase (green) and tyrosinase in complex with 9r (red).

Fig. 9

Timeline representation of the interactions and contacts (a). A schematic of detailed 9r interactions with the protein residues (b).