Discovery of Novel Naphthoquinone-Chalcone Hybrids as Potent FGFR1 Tyrosine Kinase Inhibitors: Synthesis, Biological Evaluation, and Molecular Modeling

Abstract

This work presents a flexible synthesis of 10 novel naphthoquinone-chalcone derivatives (1-10) by nucleophilic substitution of readily accessible aminochalcones and 2,3-dichloro-1,4-naphthoquinone. All compounds displayed broad-spectrum cytotoxic activities against all the tested cancer cell lines (i.e., HuCCA-1, HepG2, A549, MOLT-3, T47D, and MDA-MB-231) with IC₅₀ values in the range of 0.81-62.06 μM, especially the four most potent compounds 1, 3, 8, and 9. The in vitro investigation on the fibroblast growth factor receptor 1 (FGFR1) inhibitory effect indicated that eight derivatives (1-2, 4-5, and 7-10) were active FGFR1 inhibitors (IC₅₀ = 0.33-3.13 nM) with more potency than that of the known FGFR1 inhibitor, AZD4547 (IC₅₀ = 12.17 nM). Promisingly, compounds 5 (IC₅₀ = 0.33 ± 0.01 nM), 9 (IC₅₀ = 0.50 ± 0.04 nM), and 7 (IC₅₀ = 0.85 ± 0.08 nM) were the three most potent FGFR1 inhibitors. Molecular docking, molecular dynamics simulations, and MM/GBSA-based free energy calculation revealed that the key amino acid residues involved in the binding of the compounds 5, 7, and 9 and the target FGFR1 protein were similar with those of the AZD4547 (i.e., Val492, Lys514, Ile545, Val561, Ala640, and Asp641). These findings revealed that the newly synthesized naphthoquinone-chalcone scaffold is a promising structural feature for an efficient inhibition of FGFR1.

Figure 1

Structures of AZD4547 and chalcone–naphthoquinone hybrids: previously reported hybrids I–III and our synthesized hybrids 1–10.

Figure 2

Chemical structures of naphthoquinone–chalcone derivatives (1–10).

Scheme 1. Synthesis of Naphthoquinone–Chalcone Derivatives (1–10)

Figure 3

Alignment of the docked compounds 5 (purple), 7 (black), and 9 (orange) inside the ATP-binding pocket of the FGFR1 tyrosine kinase domain. The binding orientation of crystallized AZD4547 (blue) was used as the reference.

Figure 4

Two-dimensional ligand–protein interaction profiles of three investigated naphthoquinone–chalcones in complex with FGFR1; (A) compound 5, (B) compound 7, (C) compound 9, and (D) cocrystallized AZD4547.

Figure 5

Time evolution of RMSD (top), # contacts (middle), and SASA (bottom) of compounds 5, 7, and 9 in complex with the FGFR1 tyrosine kinase domain.

Figure 6

(Left) ΔG_bind,residue of (A) compound 5, (B) compound 7, and(C) compound 9 in complex with the FGFR1 tyrosine kinase domain. (Right) Representative 3D structures showing the orientation of ligands in the ATP-binding site drawn from the last MD snapshot.

Figure 7

Energy contribution from electrostatic (ΔE_elec + ΔG_solv,polar, red line) and van der Waals (ΔE_vdW + ΔG_{solv,nonpolar}, blue line) terms from each residue of FGFR1 to the binding of (A) compound 5, (B) compound 7, and (C) compound 9.

Figure 8

Percentage of H-bond occupation of FGFR1 contributing to the binding of (A) compound 5, (B) compound 7, and (C) compound 9, where the ligand orientation in the enzyme active site is illustrated in the right panel.