L-690330 hydrate is a competitive inositol monophosphatase (IMPase) inhibitor. The Ki values of L-690330 hydrate for human and bovine frontal cortex IMPase is 0.30 and 0.42 μM, respectively. The Ki values of L-690330 hydrate for recombinant human and bovine IMPase is 0.27 and 0.19 μM, respectively [1].