Novel Phenolic Compounds as Potential Dual EGFR and COX-2 Inhibitors: Design, Semisynthesis, in vitro Biological Evaluation and in silico Insights

Abstract

Introduction: Epidermal growth factor receptor (EGFR) inhibition is an imperative therapeutic approach targeting various types of cancer including colorectal, lung, breast, and pancreatic cancer types. Moreover, cyclooxygenase-2 (COX-2) is frequently overexpressed in different types of cancers and has a role in the promotion of malignancy, apoptosis inhibition, and metastasis of tumor cells. Combination therapy has been emerged to improve the therapeutic benefit against cancer and curb intrinsic and acquired resistance.

Methods: Three semi-synthetic series of compounds (C1-4, P1-4, and G1-4) were prepared and evaluated biologically as potential dual epidermal growth factor receptor (EGFR) and COX-2 inhibitors. The main phenolic constituents of Amaranthus spinosus L. (p-coumaric, caffeic and gallic) acids have been isolated and subsequently subjected to diazo coupling with various amines to get novel three chemical scaffolds with potential anticancer activities.

Results: Compounds C4 and G4 showed superior inhibitory activity against EGFR (IC₅₀: 0.9 and 0.5 µM, respectively) and displayed good COX-2 inhibition (IC₅₀: 4.35 and 2.47 µM, respectively). Moreover, the final compounds were further evaluated for their cytotoxic activity against human colon cancer (HT-29), pancreatic cancer (PaCa-2), human malignant melanoma (A375), lung cancer (H-460), and pancreatic ductal cancer (Panc-1) cell lines. Interestingly, compounds C4 and G4 exhibited the highest cytotoxic activity with average IC₅₀ values of 1.5 µM and 2.8 µM against H-460 and Panc-1, respectively. The virtual docking study was conducted to gain proper understandings of the plausible-binding modes of target compounds within EGFR and COX-2 binding sites.

Discussion: The NMR of prepared compounds showed characteristic peaks that confirmed the structure of the target compounds. The synthesized benzoxazolyl scaffold containing compounds showed inhibitory activities for both COXs and EGFR which are consistent with the virtual docking study.

Keywords: BRAF; anti-inflammatory; anticancer; kinase inhibitors; multitarget agents.

Figure 1

Scaffold of the target compounds.

Scheme 1

Synthesis of compounds C1-2, G1-2 and P1-2; Conditions and reagents; HCl, and Sodium nitrite, at zero oC, added to phenolic acid in NaOH 10%, stirring for 48h, ice bath.

Scheme 2

Synthesis of compounds C3-4, G3-4 and P3-4; Conditions and reagents; 1) polyphosphoric acid, stirred for 4h at 220 oC, Na2CO3, crystallization from EtOH. 2) HCl, and Sodium nitrite, at zero oC, added to phenolic acid in NaOH 10%, stirring for 48h, ice bath.

Figure 2

3D representation of the superimposed co-crystallized conformers (Blue sticks) and docked conformers (green sticks).

Figure 3

Predicted 3D demonstration of binding modes of C4 inside the active site of EGFR (PDB ID: 5UGB).

Figure 4

The Predicted 3D demonstration of binding modes of G4 inside the active site of COX-2 (PDB ID: 1CX2).