Discovery of A Novel Series of Quinazoline-Thiazole Hybrids as Potential Antiproliferative and Anti-Angiogenic Agents

Abstract

Considering the pivotal role of angiogenesis in solid tumor progression, we developed a novel series of quinazoline-thiazole hybrids (SA01-SA07) as antiproliferative and anti-angiogenic agents. Four out of the seven compounds displayed superior antiproliferative activity (IC₅₀ =1.83-4.24 µM) on HepG2 cells compared to sorafenib (IC₅₀ = 6.28 µM). The affinity towards the VEGFR2 kinase domain was assessed through in silico prediction by molecular docking, molecular dynamics studies, and MM-PBSA. The series displayed a high degree of similarity to sorafenib regarding the binding pose within the active site of VEGFR2, with a different orientation of the 4-substituted-thiazole moieties in the allosteric pocket. Molecular dynamics and MM-PBSA evaluations identified SA05 as the hybrid forming the most stable complex with VEGFR2 compared to sorafenib. The impact of the compounds on vascular cell proliferation was assessed on EA.hy926 cells. Six compounds (SA01-SA05, SA07) displayed superior anti-proliferative activity (IC₅₀ = 0.79-5.85 µM) compared to sorafenib (IC₅₀ = 6.62 µM). The toxicity was evaluated on BJ cells. Further studies of the anti-angiogenic effect of the most promising compounds, SA04 and SA05, through the assessment of impact on EA.hy296 motility using a wound healing assay and in ovo potential in a CAM assay compared to sorafenib, led to the confirmation of the anti-angiogenic potential.

Keywords: VEGFR2; anti-angiogenic; antiproliferative; cancer; drug discovery; hybrid compounds; quinazoline; small molecules; structure design; synthesis; thiazole; tyrosine kinase inhibitors.

Figure 1

Chemical structures of the clinically approved VEGFR2 inhibitors and the distinctive structural features of the compounds in correlation with occupied regions of the catalytic cleft.

Figure 2

Structural design by scaffold hopping of the thiazole–quinazoline hybrid series SA01–SA07.

Figure 3

Synthetic procedure for the quinazoline–thiazole hybrid compounds SA01-SA07. (a) The 4-hydroxy-benzaldehyde, K₂CO₃, MeCN, reflux 10 h; (b) thiosemicarbazide, ethanol, H₂SO₄ conc., reflux 20 h; (c) corresponding α-haloketones, acetone/DMF 10:1, rt 8 h or reflux.

Figure 4

Cytotoxic effect of SA04 (A,B), SA05 (C,D), and sorafenib (E,F) after a 48 h exposure of EA.hy926, HepG2, and BJ cells. The results are expressed as relative means ± standard deviations of three biological replicates. Data are expressed as relative values compared to the negative control (NC) (100%). Asterisks (*) indicate significant differences (p < 0.05) compared to NC.

Figure 5

Visualization of the binding mode of (A) SA05 and (B) sorafenib in the active site of human VEGFR2 kinase domain co-crystalized in the complex 4ASD from PDB using UCFS Chimera 1.10.2. The molecular skeleton is colored with magenta and H-bonds are indicated by thick red lines.

Figure 6

A 3D-surface visualization of the predicted binding mode of SA05 (black skeleton) superposed with sorafenib (magenta skeleton) in the active site of the human VEGFR2 kinase domain co-crystalized in the complex 4ASD from PDB using UCFS Chimera 1.10.2.

Figure 7

Graphical representation of the MD parameters during the 100 nm simulations: RMSD trajectories of the heavy atoms of VEGFR2 for SA05 (A) and sorafenib (B); radius of gyration trajectories for SA05 (C) and sorafenib (D); RMSDs of the ligands’ heavy atoms for SA05 (E) and sorafenib (F); number of H-bonds encountered for SA05 (G) and sorafenib (H).

Figure 8

Graphical representation of free energy decomposition of the involvement of each amino acid found within 5Å during the last 25 ns of the MD simulations for: SA02 (A); SA03 (B); SA04 (C); SA05 (D); sorafenib (E).

Figure 9

Graphical representation of molecular orbitals’ surface distribution and energy levels of HOMO and LUMO of the studied compounds SA04, SA05, and sorafenib at the B3LYB/6-311G++(d,p) level.

Figure 10

Migration of EA.hy926 cells after 12 h (T12) (A) in the presence of the negative control (DMSO 0.2%); (B) in the presence of sorafenib; (C) in the presence of SA04; (D) in the presence of SA05; wound heal (%) correlated with the concentration of the tested samples (SA04, SA05, sorafenib) (E).

Figure 11

(A) The assessment of angiogenesis in the chick chorioallantoic membrane subjected to SA04, SA05, and sorafenib applications entailed the acquisition of indicative stereomicroscopic images throughout the experimental period from day 1 to day 5. The comparative control group was administered solely with the solvent (0.2% DMSO). (B) Quantitative assessment of the number of vascular branches and (C) quantitative assessment of the total vessel area with IKOSA Prism AI Cam Assay (V3.1.0) for SA04, SA05, sorafenib, and the control sample (DMSO 0.2%) from day 1 to day 5.