• The Korean Journal of Physiology and Pharmacology
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• v.10 no.4
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• pp.207-212
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• 2006

Mitochondrial permeability transition has been shown to be involved in neuronal cell death. Mitochondrial monoamine oxidase (MAO)-B is considered to play a part in the progress of nigrostriatal cell death. The present study examined the effect of MAO inhibitors against the toxicity of 1-methyl-4-phenylpyridinium $(MPP^+)$ in relation to the mitochondrial permeability transition. Chlorgyline (a selective inhibitor of MAO-A), deprenyl (a selective inhibitor of MAO-B) and tranylcypromine (nonselective inhibitor of MAO) all prevented cell viability loss, cytochrome c release, caspase-3 activation, formation of reactive oxygen species and depletion of GSH in differentiated PC12 cells treated with $500\;{\mu}M$$MPP^+$. The MAO inhibitors at $10\;{\mu}M$ revealed a maximal inhibitory effect and beyond this concentration the inhibitory effect declined. On the basis of concentration, the inhibitory potency was tranylcypromine, deprenyl and chlorgyline order. The results suggest that chlorgyline, deprenyl and tranylcypromine attenuate the toxicity of $MPP^+$ against PC12 cells by suppressing the mitochondrial permeability transition that seems to be mediated by oxidative stress.

• Natural Product Sciences
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• v.11 no.3
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• pp.145-149
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• 2005

A methanol soluble extract from the dried hooks and stems of Uncaria rhynchophylla showed a strong inhibitory activity against monoamine oxidase in mouse brain. Using a bioassay-guided purification of this extract, a known ${\beta}-carboline$ type alkaloid, harman (1), was obtained as an active constituent. In addition, five known indole alkaloids, isocorynoxeine (2), isorhynchophylline (3), corynoxeine (4), cadambine (5), and $3{\alpha}-dihydrocadambine$ (6), were isolated and found to be weakly active or inactive.

• The Korean Journal of Pharmacology
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• v.20 no.2
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• pp.73-80
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• 1984

The effect of higenamine and its derivatives on the activity of rat bran mitochondrial monoamine oxidase(MAO) was studied. Methoxyhigenamine of drugs tested had no effect on isometric contraction of heart and reversibly inhibited MAO towards 5-hydroxytryptamine(5-HT) and phenylethylamine(PEA) in a pure competitive fashion and in a hyperbolic mixed fashion, respectively, but was found to be relatively MAO-A selective inhibitor, with IC50 value for 5-HT lower ten fold than for PEA. The results suggest that methoxyhigenamine is a reversible, relatively MAO-A specific inhibitor in virto.

• Journal of Microbiology and Biotechnology
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• v.25 no.9
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• pp.1425-1428
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• 2015

Monoamine oxidase (MAO) is found in most cell types and catalyzes the oxidation of monoamines. Three anithiactins (A-C, modified 2-phenylthiazoles) isolated from Streptomyces sp. were tested for inhibitory activity of two isoforms, MAO-A and MAO-B. Anithiactin A was effective and selective for the inhibition of MAO-A, with an IC₅₀ value of 13.0 μM; however, it was not effective for the inhibition of MAO-B. Anithiactins B and C were weaker inhibitors for MAO-A and MAO-B. Anithiactin A was a reversible and competitive inhibitor for MAO-A with a K_i value of 1.84 μM. The hydrophobic methyl substituent in anithiactin A may play an important role in the inhibition of MAO-A. It is suggested that anithiactin A is a selective reversible inhibitor for MAO-A, with moderate potency, and can be considered a new potential lead compound for further development of novel reversible inhibitors for MAO-A.

• Biomolecules & Therapeutics
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• v.20 no.2
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• pp.214-219
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• 2012

This research was designed to determine what components of Gardenia jasminoides play a major role in inhibiting the enzymes related antidepressant activity of this plant. In our previous research, the ethyl acetate fraction of G. jasminosides fruits inhibited the activities of both monoamine oxidase-A (MAO-A) and monoamine oxidase-B (MAO-B), and oral administration of the ethanolic extract slightly increased serotonin concentrations in the brain tissues of rats and decreased MAO-B activity. In addition, we found through in vitro screening test that the ethyl acetate fraction showed modest inhibitory activity on dopamine-${\beta}$ hydroxylase (DBH). The bioassay-guided fractionation led to the isolation of five bio-active compounds, protocatechuic acid (1), geniposide (2), 6'-O-trans-p-coumaroylgeniposide (3), 3,5-dihydroxy-1,7-bis(4-hydroxyphenyl) heptanes (4), and ursolic acid (5), from the ethyl acetate fraction of G. jasminoides fruits. The isolated compounds showed different inhibitory potentials against MAO-A, -B, and DBH. Protocatechuic acid showed potent inhibition against MAO-B ($IC_{50}$ $300{\mu}mol/L$) and DBH ($334{\mu}mol/L$), exhibiting weak MAO-A inhibition (2.41 mmol/L). Two iridoid glycosides, geniposide ($223{\mu}mol/L$) and 6'-O-trans-p-coumaroylgeniposide ($127{\mu}mol/L$), were selective MAO-B inhibitor. Especially, 6'-O-trans-p-coumaroylgeniposide exhibited more selective MAO-B inhibition than deprenyl, well-known MAO-B inhibitor for the treatment of early-stage Parkinson's disease. The inhibitory activity of 3,5-dihydroxy-1,7-bis (4-hydroxyphenyl) heptane was strong for MAO-B ($196{\mu}mol/L$), modest for MAO-A ($400{\mu}mol/L$), and weak for DBH ($941{\mu}mol/L$). Ursolic acid exhibited significant inhibition of DBH ($214{\mu}mol/L$), weak inhibition of MAO-B ($780{\mu}mol/L$), and no inhibition against MAO-A. Consequently, G. jasminoides fruits are considerable for development of biofunctional food materials for the combination treatment of depression and neurodegenerative disorders.

• The Journal of the Korean life insurance medical association
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• v.1 no.1
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• pp.84-87
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• 1984

1. Effect of bretylium on the pressor response of the whole and spinal rabbits to tyramine was observed in conditions of monoamine oxidase inhibition brought about by catron administration. 2. Bretylium increased the prossor response to tyramine in the whole and spinal rabbits. 3. Bretylium failed to increase the tyramine effect if bretylium was given after administration of catron, a monoamine oxidase inhibitor. Actually the tyramine effect was decreased by bretylium in this situation. 4. The increase of the tyramine effect by bretylium will be due to its monoamine oxidase inhibitory property, and the decrease of the tyramine effect will be due to its adrenergic neurone b1coking property.

• Journal of Microbiology and Biotechnology
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• v.27 no.2
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• pp.316-320
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• 2017

Alternariol monomethyl ether (AME), a dibenzopyrone derivative, was isolated from Alternaria brassicae along with altertoxin II (ATX-II). The compounds were tested for the inhibitory activity of monoamine oxidase (MAO), which catalyzes neurotransmitting monoamines. AME was found to be a highly potent and selective inhibitor of human MAO-A with an $IC_{50}$ value of $1.71{\mu}M$; however, it was found to be ineffective for MAO-B inhibition. ATX-II was not effective for the inhibition of either MAO-A or MAO-B. The inhibition of MAO-A using AME was apparently instantaneous. MAO-A activity was almost completely recovered after the dilution of the inhibited enzyme with an excess amount of AME, suggesting AME is a reversible inhibitor. AME showed mixed inhibition for MAO-A in Lineweaver-Burk plots with a $K_i$ value of $0.34{\mu}M$. The findings of this study suggest that microbial metabolites and dibenzopyrone could be potent MAO inhibitors. In addition, AME could be a useful lead compound for developing reversible MAO-A inhibitors to treat depression, Parkinson's disease, and Alzheimer's disease.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2008.04a
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• pp.166-166
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• 2008

• Archives of Pharmacal Research
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• v.11 no.3
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• pp.230-239
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• 1988

Thirty kinds of medicinal plants were screened to examine inhibitory activities on rat brain monoamine oxidase A, using serotonin as a substrate. As active principles, various kinds of stilbenes were isolated from Veratri Rhizoma, Reynoutriae Radix and Rhei undulati Rhizoma, and several kinds of flavonoids from Sophorae Flos, Chrisanthemi Flos and Glycine max. Among the compounds isolated, resveratrol(I) strongly inhibited MAO-A competitively, and its $IC_{50}$ and Ki values were 2 ${\mu}M$ and 2.5 ${\mu}M$, respectively. Inhibitory potencies towards MAO-A of some stilbenes and flavonoids were also compared.

• Archives of Pharmacal Research
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• v.18 no.4
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• pp.271-276
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• 1995

Changes in the distribution of dopamine and its metabolites, activities of monoamine oxidase, and dopamine uptake were studied inhyperglycemic rat striatum. The hyperglycemia was induced by the administration of streptozotocin (STZ, 40 mg/kg, i.p. for 3 days.). The levels of dihydroxyphenylacetic acid (DOPAC) and homovanillic acid were significantly decreased without change in dopamine level in the synatic cleft 14 days after STZ treatment. In the synaptosome, the dopamine level, however, was significanly increased after the treatment. But the DOPAC level in the synaptosome was decreased 14 days after the treatment. The affinity of dopamine uptake was significantly decreased without changes in the velocity 14 days after the treatment. However the response to uptqke inhibitor was unchanged. The striatal monoamine oxidase activities were also decreased in the hyperglycemic state. These results indicate that various parameters of striatal dopamine activities were decreased in the hyperglycemic rats. Furthermore, it suggests that the increase in dopamine level of synaptosome might be due to the decrease in the release of dopaine in hyperglycemic state.