The effects of RS-8359 on cardiovascular function in healthy subjects and depressed patients

Asakawa

Hoshino

et al. 2009

Aldehyde oxidase (AO, EC 1.2.3.1) and xanthine oxidase are major members of the molybdenum hydroxylase family. Both enzymes consist of a homodimer with a subunit molecular mass of about 150 kDa. Each subunit is made up of a 20 kDa domain containing two different 2Fe-2S clusters in which reducing equivalents necessary for catalysis are stored, a 40 kDa domain containing a flavine adenine dinucleotide (FAD), and an 80 kDa domain containing a molybdenum cofactor (MoCo) in which a substrate binding site is located. 1)AO catalyzes the oxidation of a wide range of endogenous and exogenous aldehydes and N-heterocyclic aromatic compounds. The representative N-heterocyclic-containing drugs that serve as substrates for AO are famciclovir, methotrexate, 6-mercaptopurine, and cinchona alkaloids. [1][2][3][4][5][6] In addition, the atypical antipsychotic drug, ziprasidone, is mainly metabolized by AO-catalyzed reductive ring cleavage in human. 7,8) AO has several pharmacokinetically interesting properties of remarkable species differences, large strain differences in rat, and individual differences in some kinds of rat strains. Among those phenomena, species differences have been widely demonstrated in the metabolism of many drugs catalyzed by AO. They include an ocular hypotensive agent, brimonidine, 9) antiviral drugs, famciclovir and 6-deoxypenciclovir, 10) an antineoplastic drug, methotrexate, 11) an ultrashort acting hypnotic, zaleplon, 12) and an oral antitumor agent, zebularine.13) Thus, it is now well established that the variations in AO activity may be dependent on not only animal species, but also on the chemical structure of the substrate. Roughly speaking, AO activity is high in monkeys and humans, moderate to low in rats and mice, and deficient in dogs. Similar to those reports, we observed remarkable species differences, rat strain differences, and polymorphism-based individual differences in Donryu strain rat in the AO-catalyzed 2-oxidation activity of the (S)-enantiomer of RS-8359,14-18) The compound is a reversible and selective monoamine oxidase (MAO)-A inhibitor 19,20) and has been developed as an anti-depressant. 21,22) As to species differences, monkeys showed the highest activity followed by humans. Furthermore, monkey and human liver cytosol preparations exhibited a biphasic pattern in the Eadie-Hofstee plots for the 2-oxidation activity of (S)-RS-8359, but not rat and mouse liver cytosols. The expression system of monkey AO full cDNA suggested that the biphasic Eadie-Hofstee profile might be produced by the existence of two active sites in a single AO enzyme rather than by the existence of two AO isoforms. 23)Molecular cloning of AO cDNA has been accomplished in mouse, 24,25) rat, 26) rabbit, 27) bovine, 28) and human. 29-31) The deduced primary structure of AO proteins have been characterized with regard to consensus sequences for two distinct 2Fe-2S clusters and five MoCo-binding sites. Wright et al. 26) indicated that the kinetic differences of AO activity between male and female rats are due...

Section: )mentioning

confidence: 99%

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confidence: 99%

Functional Analysis of Aldehyde Oxidase Using Expressed Chimeric Enzyme between Monkey and Rat

Asakawa

Hoshino

et al. 2009

“…19) We also observed phenomena related to species differences, 20,21) rat strain differences, 22) and rat individual differences 23) in the metabolism of RS-8359, which is a selective and reversible MAO-A inhibitor [24][25][26] and has been developed as an antidepressant. 27,28) AO is a homodimer with a subunit molecular mass of approximately 150 kDa. Each monomeric subunit contains a molybdopterin cofactor, a FAD, and two different 2Fe-2S redox centers.…”

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confidence: 99%

Cloning, Expression, and Characterization of Male Cynomolgus Monkey Liver Aldehyde Oxidase

Hoshino

Masubuchi

et al. 2007

In this study, we investigated the properties of monkey liver aldehyde oxidase directed toward the clarification of species differences. The aldehyde oxidase preparation purified from male cynomolgus monkey liver cytosol showed a major 150 kDa Coomassie brilliant blue (CBB)-stained band together with a minor 130 kDa band using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Both bands were identified as being aldehyde oxidase by a database search of the MS data obtained with nano-liquid chromatography, quardrupole time of flight, mass spectrometry (nano-LC Q/TOF MS). Based on the sequence coverage, the 130 kDa protein was presumed to be deficient in 20-30 kDa mass from the N-terminus. Full male cynomolgus monkey aldehyde oxidase cDNA was cloned and sequenced with the four degenerate primers designed by considering the peptide sequences containing the amino acids specific for monkey aldehyde oxidase. The deduced amino acid sequences had 96% amino acid identity with those of human enzyme. The aldehyde oxidase expressed in Escherichia coli also exhibited two immunoreactive bands on SDS-PAGE/Western blot analysis. Further, the biphasic pattern was observed for Eadie-Hofstee plots of the (S)-enantiospecific 2-oxidation activity of RS-8359 with the expressed and cytosolic monkey liver aldehyde oxidase. The results suggested that two forms of aldehyde oxidase in monkey were the expression products by a single gene. In contrast, the similarly expressed rat aldehyde oxidase showed only one immunoreactive protein and monophasic pattern. The biphasic phenomenon could be caused by the existence of two aldehyde oxidase isoforms or two active sites in a single enzyme or some other reasons. Further studies on the problems of the biphasic pattern and species differences in aldehyde oxidase are needed.

“…We have been studying the metabolism of RS-8359, [(Ϯ)-4-(4-cyanoanilino)-5,6-dihydro-7-hydroxy-7H-cyclopenta-[d]-pyrimidine], which is a reversible and selective monoamine oxidase A (MAO-A) inhibitor 16,17) and has been developed as an anti-depressant. 18,19) The main metabolic pathway of the compound is the AO-catalyzed 2-oxidation on the pyrimidine ring of the molecule. Similar to many reports on AO, we observed a remarkable species differences, 20-22) a large strain difference in rat, 23) and an individual difference in Donryu strain rat 24) in the 2-oxidation activity.…”

Section: )mentioning

confidence: 99%

“…18,19) The main metabolic pathway of the compound is the AO-catalyzed 2-oxidation on the pyrimidine ring of the molecule. Similar to many reports on AO, we observed a remarkable species differences, [20][21][22] a large strain difference in rat, 23) and an individual difference in Donryu strain rat 24) in the 2-oxidation activity.…”

Section: )mentioning

confidence: 99%

Properties of 130 kDa Subunit of Monkey Aldehyde Oxidase

Asakawa

Adachi

et al. 2008

Aldehyde oxidase (AO, EC 1.2.3.1) is a major member of the molybdenum hydroxylase family along with xanthine oxidase. Both enzymes consist of a homodimer with a subunit molecular mass of about 150 kDa. Each subunit contains a molybdopterin cofactor, a flavin-adenine dinucleotide (FAD), and two different 2Fe-2S redox centers that are essential for catalytic activity. AO catalyzes the oxidation of a wide range of endogenous and exogenous aldehydes and N-heterocyclic aromatic compounds. Representative N-heterocyclic-containing drugs that serve as substrates for AO are famciclovir, methotrexate, 6-mercaptopurine, and cinchona alkaloids. [1][2][3][4][5][6] The oxidation mode by cytosolic AO is a nucleophilic attack at an electron-deficient carbon, which is different from an electrophilic attack at an electron-rich carbon by microsomal cytochrome P450, indicating that AO has complementary substrate specificities with P450 in the metabolism of xenobiotics. In addition, AO can catalyze in vitro reduction of a variety of functional groups including sulfoxides, N-oxides, azo dyes, and N-hydroxycarbamoyl substituents in the presence of an appropriate electron donor. 6) In fact, the atypical antipsychotic drug, ziprasidone, is mostly metabolized to its reductive ring-cleaved S-methyldihydroziprasidone by AO in human. 7,8) One of characteristics of AO is a marked species difference. For example, Sugihara et al. 9) investigated the enzyme activity in several animal species using a few model substrates with relatively simple chemical structures. Extremely high benzaldehyde oxidase activity was observed in monkey and low activity in guinea pig. 2-Hydroxypyrimidine was oxidized at the highest rate in rabbit and rat and at a low rate in mouse. Monkey showed the highest phthalazine oxidase activity among the animal species studied. N 1 -methylnicotinamide oxidase activity was highest in rabbit and low in rat and mouse. Preliminary experiments demonstrated that human AO shows similar substrate specificity to that of monkey. Further, many medicines have been reported to show significant species differences in AO-catalyzed metabolism. They include an ocular hypotensive agent, brimonidine, 10) an antiviral drug, famciclovir and 6-deoxypenciclovir, 11) an antineoplastic drug, methotrexate, 12,13) an ultra-short acting hypnotic, zaleplon, 14) and an oral antitumor agent, zebularine. 15)Thus, it is now well established that the variations of AO activity may be dependent on not only animal species, but also on the chemical structures of the substrate. Roughly speaking, AO activity is high in monkey and human, moderate to low in rat and mouse, and deficient in dog. We have been studying the metabolism of RS-8359, [(Ϯ)-4-(4-cyanoanilino)-5,6-dihydro-7-hydroxy-7H-cyclopenta-[d]-pyrimidine], which is a reversible and selective monoamine oxidase A (MAO-A) inhibitor 16,17) and has been developed as an anti-depressant. 18,19) The main metabolic pathway of the compound is the AO-catalyzed 2-oxidation on the pyrimidine ring of the molecule. Simi...