Structure-based design and synthesis of a novel long-chain 4′′-alkyl ether derivative of EGCG as potent EGFR inhibitor: in vitro and in silico 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 via 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′′-C ₁₄ EGCG showed the lowest IC ₅₀ values across all the tested cell lines. 4′′-C ₁₄ 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′′-C ₁₄ 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′′-C ₁₄ EGCG. MD simulation and the MM/PBSA analysis disclosed the binding mode of 4′′-C ₁₄ EGCG in the ATP-binding site of EGFR kinase domain. Taken together, our findings demonstrate that 4′′-C ₁₄ EGCG can act as a promising potent EGFR inhibitor with enhanced stability.

Abstract

Among the synthesized 4′′-alkyl EGCG derivatives, 4′′-C ₁₄ EGCG inhibited EGF stimulated phosphorylation of EGFR and its downstream signaling pathways, ERK and Akt. 4′′-C ₁₄ EGCG showed significantly improved stability than EGCG and induced apoptosis.