Development of activators for SERCA2a for heart failure treatments.

The sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) is a central regulator of cardiac Ca2+ handling and an emerging therapeutic target for heart failure. Here, we report a comprehensive structure-activity relationship (SAR) study around small-molecule activator compound 1, integrating Ca2+-ATPase and Ca2+-uptake assays, isoform selectivity profiling, and ADMET characterization across more than fifty analogues. Systematic modification of the left-hand aryl/heteroaryl region revealed a strong dependence of activity on aromaticity and lipophilicity, with CF3- and Br-substituted analogues providing substantial gains in potency. Optimization of the central amide linker established the importance of N-alkyl chain length, subtle hydrogen-bonding capacity, and a bent ligand geometry for productive SERCA2a engagement. Electronic tuning of the right-hand benzyl group further modulated efficacy, highlighting the essential contribution of an ortho-donor substituent. Functional evaluation across multiple Ca2+ concentrations identified several analogues with ATPase activation but inhibitory Ca2+-uptake effects, underscoring the need for dual-assay assessment to ensure bona fide activation. Among the series, compound 25 emerged as a balanced lead, displaying micromolar potency, robust concordant enhancement of ATPase and Ca2+-uptake activity, favorable solubility, and improved cytotoxicity relative to compound 1. Collectively, these findings define key structural determinants governing SERCA2a activation and provide a rational framework for developing next-generation, drug-like cardiac SERCA2a modulators.