EHNA (51350-19-7) inhibits phosphodiesterase 2 (PDE2) (IC50 = 0.8 – 5.5 μM in a variety of tissues and species) over PDE1, PDE3, or PDE4 (IC50 values > 100 μM).1,2 It also inhibits adenosine deaminase (ADA), IC50 = 1.2 and 1.5 μM in human RBCs and astrocytoma cells, respectively3, which may be responsible for its ability to induce apoptosis in malignant pleural mesothelioma cell lines4. Because it blocks breakdown of adenosine to inosine and hypoxanthine, EHNA prevents formation of free radical substrates, protecting against cardiac reperfusion-mediated injury.5 It inhibits differentiation and maintains expression of pluripotency markers in hESCs, but not through inhibition of PDEs or ADA.6
