BioScience Trends. 2014;8(3):149-154. (DOI: 10.5582/ bst.2014.01034)

Evaluation of human D-amino acid oxidase inhibition by antipsychotic drugs in vitro.

Shishikura M, Hakariya H, Iwasa S, Yoshio T, Ichiba H, Yorita K, Fukui K, Fukushima T


It is of importance to determine whether antipsychotic drugs currently prescribed for schizophrenia exert D-amino acid oxidase (DAO)-inhibitory effects. We first investigated whether human (h)DAO can metabolize D-kynurenine (D-KYN) to produce the fluorescent compound kynurenic acid (KYNA) by using high-performance liquid chromatography with mass spectrometry, and fluorescence spectrometry. After confirmation of KYNA production from D-KYN by hDAO, 8 first- and second-generation antipsychotic drugs, and 6 drugs often prescribed concomitantly, were assayed for hDAO-inhibitory effects by using in vitro fluorometric methods with D-KYN as the substrate. DAO inhibitors 3-methylpyrazole-5-carboxylic acid and 4H-thieno[3,2-b]pyrrole-5-carboxylic acid inhibited KYNA production in a dose-dependent manner. Similarly, the second-generation antipsychotics blonanserin and risperidone were found to possess relatively strong hDAO-inhibitory effects in vitro (5.29 ± 0.47 μM and 4.70 ± 0.17 μM, respectively). With regard to blonanserin and risperidone, DAO-inhibitory effects should be taken into consideration in the context of their in vivo pharmacotherapeutic efficacy.

KEYWORDS: Schizophrenia, D-kynurenine, D-serine, second-generation antipsychotic drug, risperidone, blonanserin

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