Discovery and structure-based optimization of adenain inhibitors.

The cysteine protease adenain is the essential protease of adenovirus and, as such, represents a promising target for the treatment of ocular and other adenoviral infections. Through a concise two-pronged hit discovery approach we identified tetrapeptide nitrile 1 and pyrimidine nitrile 2 as complementary starting points for adenain inhibition. These hits enabled the first high-resolution X-ray cocrystal structures of adenain with inhibitors bound and revealed the binding mode of 1 and 2. The screening hits were optimized by a structure-guided medicinal chemistry strategy into low nanomolar drug-like inhibitors of adenain.