Development and Evaluation of Benzofuran Oxoacetic Acid Compounds as EPAC1 Activators

Exchange Protein Directly Activated by cAMP 1 (EPAC1) is a critical guanine nucleotide exchange factor that transduces cAMP signals to Rap GTPases, controlling pathways implicated in inflammation and fibrosis. Here, we report the design, synthesis, and biological evaluation of a novel series of benzofuran oxoacetic acid derivatives as selective EPAC1 agonists. A convergent synthetic route enabled late‐stage diversification at the benzofuran C2 position, yielding analogues in 3–7% overall yield despite challenges in reduction and oxidation steps. Structural modifications at C3 proved incompatible with the required reductive cyclization, whereas aryl ketone substitutions at C2 generated the most potent compounds. Biochemical characterization demonstrated that several analogues, notably DM243, DM245, and DM312, activate EPAC1 with complete selectivity over EPAC2 and no detectable Protein Kinase A activation. DM243 induced Rap1•GTP formation in EPAC1‐expressing cells to levels comparable to cyclic nucleotide benchmarks. In cellular assays, these compounds inhibited IL-6-driven JAK/STAT3 signalling and suppressed TGF-β1–induced fibroblast‐to‐myofibroblast transition (FMT), reducing α-smooth muscle actin and Collagen I expression with potencies rivalling the anti-fibrotic drug, nintedanib, yet exhibiting lower cytotoxicity, determined by nuclei count. Structure–activity relationship analysis revealed that C2 aryl ketone substituents enhance EPAC1 binding and functional efficacy, while subtle steric and electronic variations modulate isoform specificity. This work establishes benzofuran oxoacetic acids as a new chemotype for isoform‐selective EPAC1 activation. Our findings highlight the translational potential of targeted EPAC1 agonists as anti‐inflammatory and anti‐fibrotic agents in diseases driven by dysregulated cAMP signalling.