Structure-guided design of N-alkylated benzazepine derivatives as potential CETP inhibitors

Cardiovascular diseases (CVDs) remain a leading cause of morbidity and mortality worldwide. Modulation of cholesteryl ester transfer protein (CETP), which plays an important role in exchanging neutral lipids between plasma lipoproteins, became a key target for combating CVDs. However, mixed clinical results of CETP inhibitors suggest the need for new analogues that maintain high CETP binding affinity and provide better therapeutic outcomes. In this study, a focused series of Evacetrapib-inspired tetrahydrobenzazepine analogs was computationally designed, synthesized, and experimentally tested as potential CETP inhibitors. Based on the structure-based docking of curated 24 analogues, the N-alkylated ester derivatives were found to be the most promising subset occluding CETP binding pocket. Molecular dynamics simulation results showed that the designed molecules do not alter the inherent dynamics of CETP, instead reorganize themselves for more persistent and stronger hydrophobic contacts with the protein core. Based on these findings, a common benzazepine intermediate was employed to synthesize the targeted ester analogues by straightforward N-alkylation sequence, followed by characterization using spectroscopic methods, which were tested on fluorescence-based CETP inhibition assay. Of the synthetic analogues, 6d emerged as the most active compound (IC₅₀ of 75.54 ± 8.70 nM). Although the best analogue remained less potent than Evacetrapib, the study suggested a preliminary chain-length-dependent activity pattern, where elongation of the N-alkyl ester chain was associated with improved CETP inhibition. Complementary in silico profiling further indicated that the designed esters occupy a lipophilicity range comparable to clinically evaluated CETP inhibitors. Taken together, these findings establish the N-alkylated benzazepine scaffold as a mechanistically informative lead platform and provide a clear direction for the future design of more potent CETP inhibitors.