In Vitro: Ebselen oxide, is a covalent inhibitor of c-di-GMP allosteric binding to I-site containing proteins, diguanylate cyclase (DGC) activity. Ebselen oxide inhibits diguanylate cyclase from synthesizing c-di-GMP. Ebselen oxide exhibits increased potency on HDAC8 (IC50=0.2 μM) in comparison with Ebselen.