Structure-based design and synthesis of a novel long-chain 4′′-alkyl ether derivative of EGCG as potent EGFR inhibitor: <i>in vitro</i> and <i>in silico</i> studies

Abstract

Herein, we report the discovery of a novel long-chain ether derivative of (-)-epigallocatechin-3-gallate (EGCG), a major green tea polyphenol as a potent EGFR inhibitor. A series of 4''-alkyl EGCG derivatives have been synthesized <i>via</i> regio-selectively alkylating the 4'' hydroxyl group in the D-ring of EGCG and tested for their antiproliferative activities against high (A431), moderate (HeLa), and low (MCF-7) EGFR-expressing cancer cell lines. The most potent compound, 4''-C₁₄ EGCG showed the lowest IC₅₀ values across all the tested cell lines. 4''-C₁₄ EGCG was also found to be significantly more stable than EGCG under physiological conditions (PBS at pH 7.4). Further western blot analysis and imaging data revealed that 4''-C₁₄ EGCG induced cell death in A431 cells with shrunken nuclei, nuclear fragmentation, membrane blebbing, and increased population of apoptotic cells where BAX upregulation and BCL_XL downregulation were observed. In addition, autophosphorylation of EGFR and its downstream signalling proteins Akt and ERK were markedly inhibited by 4''-C₁₄ EGCG. MD simulation and the MM/PBSA analysis disclosed the binding mode of 4''-C₁₄ EGCG in the ATP-binding site of EGFR kinase domain. Taken together, our findings demonstrate that 4''-C₁₄ EGCG can act as a promising potent EGFR inhibitor with enhanced stability.