Design, synthesis, anticancer activity and molecular docking of quinoline-based dihydrazone derivatives

Abstract

Based on the biologically active heterocycle quinoline, we successfully synthesized a series of quinoline-based dihydrazone derivatives (3a-3d). ¹H NMR, ¹³C NMR, ESI-HRMS, IR, element analysis, UV/Vis spectroscopy and fluorescence spectroscopy were performed to comprehensively characterize their chemical structures, spectral properties and stability. Nitrosamine impurities were not detected in 3a-3d, and the systemic toxicological assessment indicated that the toxicity of 3a-3d was lower. Furthermore, their anticancer activity was evaluated by MTT, AO/EB double staining, apoptosis detection and ROS detection. The time-dependent UV/Vis spectra revealed that 3a-3d had good stability in solution. For all the newly synthesized compounds, cytotoxic activities were carried out against human gastric cancer cell line BGC-823, human hepatoma cell line BEL-7402, human breast cancer cell line MCF-7 and human lung adenocarcinoma cell line A549 as well as human normal liver cell line HL-7702. MTT assay indicated that all the tested compounds exhibited important antiproliferative activity against selected cancer cell lines with IC₅₀ values ranging from 7.01 to 34.32 μM, while none of them had obvious cytotoxic activity to human normal liver cell line HL-7702. Further, the most potent compound 3c displayed stronger antiproliferative activity against all the selected cancer cell lines than the clinically used anticancer agent 5-FU. Especially, 3b and 3c displayed cytotoxic activity against MCF-7 cells with IC₅₀ values of 7.016 μM and 7.05 μM, respectively. AO/EB double staining, flow cytometry and ROS detection suggested that 3b and 3c could induce MCF-7 cell apoptosis in a dose-dependent manner. Molecular docking suggests that 3b and 3c could bind with DNA via partial insertion. Additionally, molecular docking also suggests that CDK2 may be one of the targets for 3b and 3c. In a word, 3b and 3c could be suitable candidates for further investigation as chemotherapeutic agents in cancer treatment.

Fig. 1. Anticancer agents (a–f) containing quinoline hydrazone moieties.

Fig. 2. CDK inhibitors containing amino-substituted heterocyclic scaffold.

Scheme 1. Synthesis of 3a–3d.

Scheme 2. Generalised nitrosation of secondary amines under acidic conditions.

Fig. 3. Biochemical indicators of different groups (a: ALT; b: AST; c: BUN; d: CREA).

Fig. 4. H&E staining of different organ groups (liver, spleen, kidney).

Fig. 5. Changes in morphology of AO/EB double stained MCF-7 cells treated with (a) 3b and (b) 3c (3.5 μM, 7 μM and 10.5 μM) for 24 h. (Three independent experiments were performed on each compound.)

Fig. 6. Apoptosis of MCF-7 cells treated with (a) 3b and (b) 3c (0 μM, 3.5 μM, 7 μM and 10.5 μM) for 48 h. (Three independent experiments were performed on each compound.)

Fig. 7. The inverted fluorescence microscope detection for the ROS fluorescence changes of MCF-7 cells treated with (a) 3b and (b) 3c (0 μM, 3.5 μM and 7 μM) for 24 h (independent experiments were performed on each compound). The flow cytometry detection for the ROS fluorescence changes of MCF-7 cells treated with (c) 3b.

Fig. 8. Visualizations of (a) 3b and (b) 3c docking with DNA (PDB ID: 2MG8).

Fig. 9. 3D diagram of (a, e and i) 3b and (c, g and k) 3c docking pose in the active site of CDK2, CDK1 and CDK8 (PDB: 4BGH; 6GU7; 5I5Z); 2D diagram of (b, f and i) 3b and (d, h and l) 3c docking pose in the active site of CDK2, CDK1 and CDK8.