Isovaleryl Sucrose Esters from Atractylodes japonica and Their Cytotoxic Activity

Abstract

Cancer represents one of the most significant health challenges currently facing humanity, and plant-derived antitumour drugs represent a prominent class of anticancer medications in clinical practice. Isovaleryl sucrose esters, which are natural constituents, have been identified as having potential antitumour effects. However, the mechanism of action remains unclear. In this study, 12 isovaleryl sucrose ester components, including five new (1-5) and seven known compounds (6-12), were isolated from the roots of Atractylodes japonica. The structures of the compounds were elucidated using 1D and 2D-NMR spectroscopy, complemented by HR-ESI-MS mass spectrometry. The cytotoxic activities of all the compounds against human colon cancer cells (HCT-116) and human lung adenocarcinoma cells (A549) were also evaluated using the CCK8 assay. The results demonstrated that compounds 2, 4, and 6 were moderately inhibitory to HCT-116 cells, with IC₅₀ values of 7.49 ± 0.48, 9.03 ± 0.21, and 13.49 ± 1.45 μM, respectively. Compounds 1 and 6 were moderately inhibitory to A549, with IC₅₀ values of 8.36 ± 0.77 and 7.10 ± 0.52 μM, respectively. Molecular docking revealed that compounds 1-9 exhibited a stronger affinity for FGFR3 and BRAF, with binding energies below -7 kcal/mol. Compound 2 exhibited the lowest binding energy of -10.63 kcal/mol to FGFR3. We screened the compounds with lower binding energies, and the protein-ligand complexes already obtained after molecular docking were subjected to exhaustive molecular dynamics simulation experiments, which simulated the dynamic behaviour of the molecules in close proximity to the actual biological environment, thus providing a deeper understanding of their functions and interaction mechanisms. The present study provides a reference for the development and use of iso-valeryl sucrose esters in the antitumour field.

Keywords: cytotoxic activity; isovaleryl sucrose esters; molecular docking; molecular dynamics simulation; phytochemistry.

Figure 1

Structures of compounds 1–12.

Figure 2

Key HMBC and ¹H, ¹H-COSY correlation of compounds 1–5.

Figure 3

Key NOESY of compounds 1–5 (Dark grey represents carbon atoms, blue represents hydrogen atoms and red represents oxygen atoms in the diagram).

Figure 4

Binding energy (kcal/mol) heat map of compounds 1–12 docked to BRAF and FGFR3 proteins, respectively.

Figure 5

Visualisation results of molecular docking of compounds to proteins: (A) is compound 2 with BRAF (binding energy −9.95 kcal/mol), (B) is compound 4 with BRAF (binding energy −10.42 kcal/mol), (C) is compound 6 with BRAF (binding energy −9.27 kcal/mol), (D) is compound 2 with FGFR3 (binding energy −10.63 kcal/mol), (E) is compound 7 with FGFR3 (binding energy −10.45 kcal/mol), and (F) is compound 8 with FGFR3 (binding energy −10.48 kcal/mol). (In the three-dimensional diagram, green represents small molecule ligands, blue represents receptor proteins, and purple represents amino acid residues interacting with the ligand. In the two-dimensional diagram, purple represents ligands and red represents amino acid residues interacting with the ligand).

Figure 5

Visualisation results of molecular docking of compounds to proteins: (A) is compound 2 with BRAF (binding energy −9.95 kcal/mol), (B) is compound 4 with BRAF (binding energy −10.42 kcal/mol), (C) is compound 6 with BRAF (binding energy −9.27 kcal/mol), (D) is compound 2 with FGFR3 (binding energy −10.63 kcal/mol), (E) is compound 7 with FGFR3 (binding energy −10.45 kcal/mol), and (F) is compound 8 with FGFR3 (binding energy −10.48 kcal/mol). (In the three-dimensional diagram, green represents small molecule ligands, blue represents receptor proteins, and purple represents amino acid residues interacting with the ligand. In the two-dimensional diagram, purple represents ligands and red represents amino acid residues interacting with the ligand).

Figure 6

Molecular dynamics simulation results: graph (A) RMSD of compounds 2, 4, and 6 with BRAF. (B) RMSF of compounds 2, 4, and 6 with BRAF. (C) Rg of compounds 2, 4, and 6 with BRAF. (D) H bond number of compounds 2, 4, and 6 with BRAF.

Figure 7

Molecular dynamics simulation results: graph (A) is RMSD of compounds 2, 7 and 8 with FGFR3. (B) RMSF of compounds 2, 7, and 8 with FGFR3. (C) Rg of compounds 2, 7, and 8 with FGFR3. (D) H bond number of compounds 2, 7, and 8 with FGFR3.

Figure 8

Gibbs free energy analysis. (A) compound 2 with BRAF. (B) compound 4 with BRAF. (C) compound 6 with BRAF.

Figure 9

Gibbs free energy analysis. (A) is compound 2 with FGFR3. (B) compound 7 with FGFR3. (C) is compound 8 with FGFR3.