DAAO inhibitor-1 is a potent D-amino acid oxidase (DAAO) inhibitor with an IC50 of 0.12 μM.

DAAO:0.12 μM (cell free)

D-2-Amino-4-(2-aminophenyl)-4-oxobutanoic acid (D-kynurenine) was used to measure D-amino acid oxidase activity according to the protocol described in Ref. The measurements were carried out on a Citation3 cell imaging multi-mode microplate reader with 364 well plates. The applied wavelengths were 340 nm and 396 nm. The buffer contained 20 mM TRIS-HCl and 100 mM NaCl. Human DAAO was kept in 1 μg/10 μL aliquots at -80 °C.

Time courses of the unchanged pharmacons in hepatocytes and in hepatic microsomes were obtained. Each compound was incubated with cell suspension (2 × 10^6 cells/mL) or with microsomes (4 mg/mL) at 37 °C in a humid atmosphere containing 5% CO2. The parent compounds were added directly to the cell culture medium or to 0.1 M Tris-HCl buffer (pH 7.4) at the final concentration of 1 μM. The microsomal incubation mixtures contained an NADPH-regenerating system (1 mM NADPH, 10 mM glucose 6–phosphate, 5 mM MgCl2 and 2 units/mL glucose 6-phosphate dehydrogenase). At various time points (at 0, 15, 30, 45, 60, 90, 120, 180, 240 min for hepatocyte incubations; at 0, 15, 30, 45, 60, 90 min for microsomal incubations), the incubation mixtures were sampled (aliquots: 0.25 mL) and terminated by the addition of 0.17 mL ice-cold acetonitrile containing the internal standard, carbamazepine (0.13 μM). The cell and microsomal debris was separated by centrifugation, and the supernatant was analyzed by LC-MS/MS for quantitation of the parent compound.

Male NMRI mice of 25–30 g were housed in an air-conditioned (22 +/- 2 °C) animal room with 12 h light and dark cycle. They had free access to standard laboratory rodent chow and water. Five mice per group were treated intraperitoneally with 30 mg/kg D-serine in the absence or presence of 30 mg/kg DAAO inhibitor-1 dissolved in 5% DMSO containing saline. The test compound and D-serine were administered simultaneously. After 10, 20, 30, 60, 120, 240 and 360 min the mice were anesthetized by carbon dioxide, decapitated and their blood was collected using EDTA as anticoagulant. Plasma was obtained by centrifugation at 2000g, 4 °C for 5 min and the samples were stored frozen at -80 °C until analysis.