Vanillin-Based Indolin-2-one Derivative Bearing a Pyridyl Moiety as a Promising Anti-Breast Cancer Agent via Anti-Estrogenic Activity

Abstract

The structure-based design introduced indoles as an essential motif in designing new selective estrogen receptor modulators employed for treating breast cancer. Therefore, here, a series of synthesized vanillin-substituted indolin-2-ones were screened against the NCI-60 cancer cell panel followed by in vivo, in vitro, and in silico studies. Physicochemical parameters were evaluated with HPLC and SwissADME tools. The compounds demonstrated promising anti-cancer activity for the MCF-7 breast cancer cell line (GI = 6-63%). The compound with the highest activity (6j) was selective for the MCF-7 breast cancer cell line (IC₅₀ = 17.01 μM) with no effect on the MCF-12A normal breast cell line supported by real-time cell analysis. A morphological examination of the used cell lines confirmed a cytostatic effect of compound 6j. It inhibited both in vivo and in vitro estrogenic activity, triggering a 38% reduction in uterine weight induced by estrogen in an immature rat model and hindering 62% of ER-α receptors in in vitro settings. In silico molecular docking and molecular dynamics simulation studies supported the stability of the ER-α and compound 6j protein-ligand complex. Herein, we report that indolin-2-one derivative 6j is a promising lead compound for further pharmaceutical formulations as a potential anti-breast cancer drug.

Figure 1

Structures of indole-based SERMs bazedoxifene I, pipendoxifene II, the previously reported anti-breast cancer indole derivative compound III, and the studied compounds 6a–o.

Scheme 1. Compounds 5a–c and 6a–o, Which Have Been Previously Synthesized and Screened for Anti-Cancer Activity with the NCI-60 Cancer Cell Line Panel in This Study

Figure 2

Dynamic monitoring of the effects of compound 6j on MCF-7 and MCF-12A cells with the iCELLigence real-time cell analysis system (A) MCF-7 and (B) MCF-12A cell lines.

Figure 3

Effects of different concentrations of 6j on the MCF-7 and MCF-12A cell morphology photographed under an inverted microscope 48 h after 6j treatment. Scale bar represents 200 μm.

Figure 4

Bar chart showing the in vivo antiestrogenic activity of tamoxifen (TMX) and compound 6j. ## denotes a significant difference from the control group at p < 0.01 * denotes a significant difference from the estrogen group at p < 0.05.

Figure 5

(A) Radar plot and (B) BOILED-Egg diagram obtained from the SwissADME server of compound 6j.

Figure 6

Glide molecular docking interactions of ER-α with compound 6j. (A) Binding pose of 6j in an ER-α active site. (B) Protein–ligand schematic interaction diagram of the ER-α and 6j complex. (PDB ID: 5W9C).

Figure 7

Molecular dynamics simulation trajectory analysis. (A) rmsd plot showing the stability of compound 6j with respect to the ER-α. (B) Number of H bonds formed between compound 6j and ER-α active site residues over 150 ns. (C,D) Binding poses of compound 6j with ER-α at 100 and 150 ns, respectively.