Development and Evaluation of Benzofuran Oxoacetic Acid Compounds as EPAC1 Activators

Exchange protein
directly activated by cAMP 1 (EPAC1) modulates
Rap signaling and fibrosis. We report benzofuran oxoacetic acids as
non-nucleotide EPAC1 agonists. Convergent synthesis delivered C2-diversified
analogues (overall yields ≈ 3–7%). Fluorescent competition
at isolated CNBDs mapped isoform engagement: several analogues favored
EPAC1 (e.g., DM244, DM357, and DM408), DM312 favored EPAC2, and small C2 changes tuned bias.
In cells, EPAC1-transfected U2OS assays showed significant Rap1-GTP
increases for DM243, DM244, and DM245, with no activation in EPAC2 cells and no detectable protein kinase
A activity. In disease-relevant contexts, the series attenuated IL-6/STAT3
signaling in human umbilical vascular endothelial cells and inhibited
TGF-β1-induced fibroblast-to-myofibroblast transition (αSMA,
Collagen I) with midmicromolar potencies; known drugs, SB525334 and nintedanib, remained more potent, yet nintedanib
was markedly more cytotoxic. Across assays, some binding-phenotype
disconnects emerged, plausibly reflecting exposure, signaling bias,
and cell-context effects. Overall, benzofuran oxoacetic acids provide
EPAC-pathway probes with a favorable tolerability window and scope
for potency optimization as antifibrotics.