Monoamine Oxidase A Inhibitory Activity Research Articles

Study on the interventional effects of Chlamydomonas reinhardtii peptides on chronic unpredictable mild stress-induced depressive-like model mice through metabolomics and microbiota

Depression is a progressive neurodegenerative disease characterized by high prevalence, high suicide rate and high recurrence rate. In this study, the protein from Chlamydomonas reinhardtii was extracted and neutral protease hydrolysate (NPH) was obtained. Its in vitro MAO-A (Monoamine oxidase A) inhibitory activity and in vivo anti-depressive effects in chronic unpredictable mild stress (CUMS) model mice were investigated. The results demonstrated that NPH can improve depressive behaviour in CUMS model mice by elevating neurotransmitter levels and alleviating hippocampal tissue structure damage. The metabolomic analysis of brain and serum samples showed that their common metabolic pathways associated with anti-depressive effects are mainly alanine, aspartate, and glutamate metabolism, glycerophospholipid metabolism, tryptophan metabolism, and caffeine metabolism. Then, the gut microbiota analysis of feces indicated that 8 species with significant changes were associated with anti-depressive effects. Finally, 5 pairs of highly correlated metabolite-bacterium pairs were identified to modulate depressive behaviours. Taken together, the present data suggests that Chlamydomonas reinhardtii-derived hydrolysate could be used for development of functional foods with potential to improve depression.

The intracellular monoamine oxidase-A inhibitory activity and the protective effect of small hairtail-related peptides in nerve cells (SH-SY5Y).

This study was to investigate the inhibitory activity of small hairtail-related peptides (VFEVFW, LPNSLYQQ, LPNSLYQK, and FADAME) on intracellular monoamine oxidase-A (MAO-A) and their protective effects in a cell model. Specifically, the inhibition activity in SH-SY5Y cells indicated that VFEVFW and LPNSLYQK reduced ∼50% of MAO-A activity in cells, at 0.5m m. The survival experiment demonstrated that the toxic effect of dexamethasone (DEX) on cells can be significantly alleviated in the presence of peptides, and these peptides can restore (>20%) the mitochondrial membrane potential of SH-SY5Y cells reduced by DEX. Circular dichroism displayed that peptides affected the secondary structure of MAO-A in a concentration-dependent manner. Finally, the real-time quantitative polymerase chain reaction assay revealed that the MAO-A inhibitory activity of the peptides was associated with the upregulation of brain derived neurotrophic factor/cAMP (Cyclic adenosine monophosphate) response element binding protein)/B-cell lymphoma-2 mRNA levels.

Repurposing of a monoamine oxidase A inhibitor‑heptamethine carbocyanine dye conjugate for paclitaxel‑resistant non‑small cell lung cancer.

Non‑small cell lung cancer (NSCLC) remains an intractable disease, which is primarily due to tumor metastasis and the acquisition of resistance to chemotherapy. Therefore, there is an urgent need for novel therapeutics to overcome these obstacles. It was recently demonstrated that upregulated expression of monoamine oxidase A (MAOA) contributes to the progression of NSCLC. G10, a tumor‑targeting representative conjugate of heptamethine carbocyanine dye and an inhibitor of MAOA, was shown to exert potent cytotoxic effects, comparable to those of doxorubicin, against prostate cancer cell lines, as well as moderate MAOA inhibitory activity. The research described herein aimed to extend our previous study on the antitumor function of G10 in NSCLC invitro and invivo, and to elucidate the mechanisms through which G10 exerts its antineoplastic effects. G10 markedly inhibited the proliferation of paclitaxel‑resistant NSCLC cells (H460/PTX) and reduced tumor cell migration and invasion. Gene expression profiling of paclitaxel‑resistant NSCLC cells following treatment with G10 demonstrated that the expression of genes associated with the extracellular matrix was significantly affected, particularly the metastasis‑related genes matrix metallopeptidase (MMP)2, MMP14 and COL6A, which exhibited notably reduced expression. Additionally, the results also demonstrated that MAOA‑related pathways, including AKT and hypoxia‑inducible factor‑1α, were also inhibited by G10 treatment and, subsequently, the downstream molecules of these pathways, such as p21, MMP2 and vascular endothelial growth factor, were also downregulated, highlighting a possible mechanism through which G10 suppresses tumor cell migration, invasion and proliferation. Importantly, in mouse NSCLC xenografts, combined treatment with G10 and paclitaxel resulted in pronounced inhibition of tumor growth. Taken together, the results of the present study highlight the potential of G10 as a novel therapeutic targeting MAOA in paclitaxel‑resistant NSCLC.

Discovery of monoamine oxidase A inhibitory peptides from hairtail (Trichiurus japonicus) using in vitro simulated gastrointestinal digestion and in silico studies

The aim of this study was to effectively obtain monoamine oxidase A (MAO-A) inhibitory peptides from in vitro simulated gastrointestinal digestion and to assess the correspondences between in silico prediction and in vitro confirmation. Fractions (<3 kDa) from ultrafiltration of pepsin and simulated gastrointestinal enzymes hydrolysates exhibited the highest MAO-A inhibitory activity with IC50 values of 0.61 and 2.54 mg/mL, respectively. After sequencing and then screening by HPEPDOCK, 11 high-score peptides and 2 low-score peptides were selected for further synthesis. Remarkable correlation was found between (-)docking scores and MAO-A inhibitory activity of the synthesized peptides, and among which VVFEVFW showed the highest MAO-A inhibitory activity (IC50 = 0.405 mM). Current research suggested that in silico is an effective method to screen MAO-A inhibitory peptides from hairtail protein hydrolysates, and these peptides can be used as functional ingredients for MAO-A inhibition or potential alternatives for antidepressant.

Rapid screening and identification of monoamine oxidase-A inhibitors from Corydalis Rhizome using enzyme-immobilized magnetic beads based method

Monoamine oxidase-A (MAO-A) is considered an important therapeutic target in depression. In order to rapidly screen and identify novel MAO-A inhibitors from natural products, a magnetic bead (MB) based drug discovery tool was developed in this study. MAO-A was first immobilized onto the surface of MBs, and the resulting MAO-A-immobilized MBs (MAO-A-MBs) were then applied to ligand fishing by combining them with high-performance liquid chromatography (HPLC) coupled with quadrupole time-of-flight tandem mass spectrometry (Q-TOF-MS/MS). The inherent catalytic activity and kinetic parameters of the immobilized-MAO-A were determined by measuring the peak area of the oxidation product. The immobilized MAO-A activity was found to remain over 80% after storage at 4 °C for about 7 days. Seven compounds (tetrahydrocolumbamine, protopine, jatrorrhizine, glaucine, tetrahydropalmatine, palmatine, dehydrocorydaline) with high binding affinity to MAO-A were fished out from the ethyl acetate fraction extract of Corydalis Rhizome. Their MAO-A inhibitory activity was further verified by enzymatic inhibition assay. These results show that the developed approach using MAO-A-MBs combined with HPLC-Q-TOF-MS/MS is suitable for the fast screening and identification of MAO-A inhibitors in complex mixtures.

Selectivity Profiling and Biological Activity of Novel β-Carbolines as Potent and Selective DYRK1 Kinase Inhibitors.

DYRK1A is a pleiotropic protein kinase with diverse functions in cellular regulation, including cell cycle control, neuronal differentiation, and synaptic transmission. Enhanced activity and overexpression of DYRK1A have been linked to altered brain development and function in Down syndrome and neurodegenerative diseases such as Alzheimer’s disease. The β-carboline alkaloid harmine is a high affinity inhibitor of DYRK1A but suffers from the drawback of inhibiting monoamine oxidase A (MAO-A) with even higher potency. Here we characterized a series of novel harmine analogs with minimal or absent MAO-A inhibitory activity. We identified several inhibitors with submicromolar potencies for DYRK1A and selectivity for DYRK1A and DYRK1B over the related kinases DYRK2 and HIPK2. An optimized inhibitor, AnnH75, inhibited CLK1, CLK4, and haspin/GSG2 as the only off-targets in a panel of 300 protein kinases. In cellular assays, AnnH75 dose-dependently reduced the phosphorylation of three known DYRK1A substrates (SF3B1, SEPT4, and tau) without negative effects on cell viability. AnnH75 inhibited the cotranslational tyrosine autophosphorylation of DYRK1A and threonine phosphorylation of an exogenous substrate protein with similar potency. In conclusion, we have characterized an optimized β-carboline inhibitor as a highly selective chemical probe that complies with desirable properties of drug-like molecules and is suitable to interrogate the function of DYRK1A in biological studies.

Evaluation of the Inhibitory Effects of Quercetin-Related Flavonoids and Tea Catechins on the Monoamine Oxidase-A Reaction in Mouse Brain Mitochondria

Quercetin, a typical dietary flavonoid, is thought to exert antidepressant effects by inhibiting the monoamine oxidase-A (MAO-A) reaction, which is responsible for regulation of the metabolism of the neurotransmitter 5-hydroxytryptamine (5-HT) in the brain. This study compared the MAO-A inhibitory activity of quercetin with those of O-methylated quercetin (isorhamnetin, tamarixetin), luteolin, and green tea catechins ((-)-epicatechin, (-)-epicatechin gallate, (-)-epigallocatechin, and (-)-epigallocatechin gallate) by measuring the formation of the oxidative deamination product of 5-HT, 5-hydroxyindole aldehyde (5-HIAL), in mouse brain mitochondria. Quercetin was inferior to luteolin in the inhibition of MAO-A activity, whereas isorhamnetin, tamarixetin, and tea catechins scarcely exerted inhibitory activity. Quercetin did not affect MAO-A activity in mouse intestinal mitochondria, indicating that it does not evoke side effects on the metabolism of dietary monoamines in the gut. These data suggest that quercetin is a weak (but safe) MAO-A inhibitor in the modulation of 5-HT levels in the brain.

Antidepressant-like profile and MAO-A inhibitory activity of 4-propyl-2H-benzo[h]-chromen-2-one

Aims To evaluate the central nervous pharmacological profile of 4-propyl-2H-benzo[h]-chromen-2-one (FCS-304) in ICR mice and its monoamine oxidase inhibitor activity. Main methods FCS-304 was evaluated in screening test of central nervous system in ICR mice and against MAO activity. Key findings FCS-304 (25–200 mg/Kg, p.o.) significantly reduced immobility time during the forced swimming test (FST) and tail suspension test (TST), but did not show effects in the rota-rod tests, maximal electroshock seizures (MES), pentylenetetrazole seizures, light–dark box, barbiturate sleeping time and cold plate tests. Furthermore, FCS-304 inhibited monoamine oxidase A (MAO-A) with IC 50: 2.28 ± 0.15 µM, but not MAO-B. Significance These results suggest that FCS-304 could elicit antidepressant effects related to MAO-A inhibitory activity.

MAO-A inhibitory activity of quercetin from Calluna vulgaris Hull

Anecdotal evidence from Danish folk medicine suggests that the tea of Calluna vulgaris Hull. has a nerve calming effect [1]. Unpublished results from our department show that the methanol extract of C. vulgaris has an inhibitory effect on monoamine oxidase A (MAO-A). For bioassay-guided isolation, dried, ground aerial parts of C. vulgaris (100g) were defatted twice with 1000ml heptane. The plant material was extracted twice with 1000ml methanol. The combined methanol extracts were evaporated to dryness, re-dissolved in 1000ml 80:20 methanol: water and partitioned three times against 300ml heptane. Methanol was removed from the methanol: water fraction by evaporation and the volume was made up with water. The resulting water fraction was partitioned three times against 300ml ethyl acetate. The three fractions (heptane, ethyl acetate and water) were tested for MAO-A inhibitory activity [2]. The active ethyl acetate fraction was fractionated on a VLC column (240g silica gel 60), eluted with heptane, mixures of heptane: ethyl acetate: methanol, mixtures of dichloromethane: methanol and methanol. A total of 34 fractions were spotted on a TLC plate and fractions showing similar patterns were combined. The fractions were tested in the MAO-A assay. The most active fraction was investigated by HPLC (C18) employing a gradient from 0 to 100% acetonitrile over 30min, revealing one major peak in the chromatogram. This peak was active in the MAO-A assay. The compound was re-crystallised from acetone yielding 14.3mg pure compound which was investigated by 1H-NMR. By comparison with 1H-NMR literature data [3, 4] the compound was identified as quercetin. LC-MS analysis revealed a molecular weight of 302.1g/mol confirming the identification. The IC50-value of quercetin was 18±2µM in the MAO-A assay (clorgylin: 0.2±0.02µM).

Eugenol and its structural analogs inhibit monoamine oxidase A and exhibit antidepressant-like activity

Eugenol ( 1) is an active principle of Rhizoma acori graminei, a medicinal herb used in Asia for the treatment of symptoms reminiscent of Alzheimer’s disease (AD). It has been shown to protect neuronal cells from the cytotoxic effect of amyloid β peptides (Aβs) in cell cultures and exhibit antidepressant-like activity in mice. Results from this study show that eugenol inhibits monoamine oxidase A (MAOA) preferentially with a K i = 26 μM. It also inhibits MAOB but at much higher concentrations ( K i = 211 μM). In both cases, inhibition is competitive with respect to the monoamine substrate. Survey of compounds structurally related to eugenol has identified a few that inhibit MAOs more potently. Structure activity relationship reveals structural features important for MAOA and MAOB inhibition. Molecular docking experiments were performed to help explain the SAR outcomes. Four of these compounds, two ( 1, 24) inhibiting MAOA selectively and the other two ( 19, 21) inhibiting neither MAOA nor MAOB, were tested for antidepressant-like activity using the forced swim test in mice. Results suggest a potential link between the antidepressant activity of eugenol and its MAOA inhibitory activity.

Inhibition of monoamine oxidase–A activity in rat brain by synthetic hydrazines: Structure-activity relationship (SAR)

A series of hydrazine derivatives was synthesized in order to evaluate their monoamine oxidase A (MAO-A) inhibitory effects. MAO-A inhibitory activity of 4-tosyl benzoic acid carbohydrazide was quite potent, similarly to that of the corresponding 4-benzyloxy-benzoic acid carbohydrazide and its N-cyanoethylated derivative. Structural variations of these compounds, such as the replacement of the 4-substitutent, of the aromatic ring on which the carbohydrazide moiety is grafted, as well as cyclization of the hydrazide moiety in five- or six-membered rings caused either significant decline or complete loss of MAO inhibitory properties. The most active compound (4-tosyl benzoic acid carbohydrazide) was also subjected to the forced swim test, an animal model of depression, eliciting a marked reduction in immobility time in rats, without affecting the locomotor activity, implying that it possesses anti-depressant properties due to inhibition of MAO type-A.

Sulfur-Substituted α-Alkyl Phenethylamines as Selective and Reversible MAO-A Inhibitors: Biological Activities, CoMFA Analysis, and Active Site Modeling

A series of phenethylamine derivatives with various ring substituents and with or without N-methyl and/or C-alpha methyl or ethyl groups was synthesized and assayed for their ability reversibly to inhibit monoamine oxidase A (MAO-A) and monoamine oxidase B (MAO-B). Several compounds showed potent and selective MAO-A inhibitory activity (IC(50) in the submicromolar range) but none showed appreciable activity toward MAO-B. A three-dimensional quantitative structure-activity relationship study for MAO-A inhibition was performed on the series using comparative molecular field analysis (CoMFA). The resulting model gave a cross-validated q(2) of 0.72 and showed that in this series of compounds steric properties of the substituents were more important than electrostatic effects. Molecular modeling based on the recently published crystal structure of inhibitor-bound MAO-A provided detailed evidence for specific interactions of the ligands with the enzyme, supported by previous references and consistent with results from the CoMFA. On the basis of these results, structural determinants for selectivity of substituted amphetamines for MAO-A are discussed.

Monoamine oxidase inhibitory activities of the scorpion Mesobuthus gibbosus (Buthidae) venom peptides

In the present study, crude venom of Mesobuthus gibbosus (Buthidae), a scorpion distributed all over Anatolia was isolated and purified by the Sephadex G-50 gel filtration and high pressure liquid chromatographic (HPLC) separation. Two of the five fractions (fractions 4 and 5) obtained from the Sephadex G-50 filtration and detected as lethal on mice and Musca domestica larvae in in vivo toxicity tests, were independently subjected to the HPLC separation. Only one of seven fractions (fraction 5.5*) obtained from the HPLC separation of the fraction 5 was found to be extremely lethal. Sodium dodecylsulfate polyacrylamide gel electrophoretic (SDS-PAGE) analysis of the crude venom and its chromatographic fractions demonstrated that crude venom consisted of peptides with molecular weights of 6500–210,000 Da. The neurotoxic fraction 5.5* appeared as a single band of 28,000 Da and two bands of 6200 and 22,000 Da in SDS-PAGE under non-reducing and reducing conditions, respectively, suggesting that it might consist of two chains attached by a disulfide bridge. Fractions 5 and 5.5* inhibited monoamine oxidase A (MAO-A) of rat liver reversibly and non-competitively, in a concentration-dependent manner. Fraction 5.5* appeared as a potent and specific MAO-A inhibitor with a K i value of 0.12 mg venom protein ml −1. The inhibitory effect of venom peptide 5.5* on MAO-A was found to be dependent on the preincubation time suggesting that the peptide binds to some site other than the substrate-binding site. Results of the present study demonstrated that M. gibbosus venom contains a peptide with specific MAO-A inhibitory activity which may be responsible for the anxiogenic effects of the scorpion venoms on animals and humans.

Endogenous monoamine oxidase inhibitory activity and HPA activation in the pig

Previously we have shown that an increase in endogenous monoamine oxidase A inhibitory activity (MAO-AI), measured in human saliva, both precedes and predicts psychological stress-induced activation of the hypothalamic pituitary adrenal (HPA) axis, as determined by the cortisol response. We now report the relationship between endogenous MAO-AI and the cortisol response in the plasma of prepubertal pigs (n = 5 or 6) under two experimental paradigms of HPA activation. In the first condition, pigs were physically restrained (snaring) for 15 minutes. Blood samples were taken from indwelling catheters at intervals before and after snaring (a sampling period of about 1 hour), and at the same time intervals on a separate day to provide baseline measures. Both cortisol concentration and percentage MAO-AI were determined in each plasma sample. There was a pronounced cortisol response on the snaring day (cortisol peaked 30 minutes after the start of the snaring). There was also a significant MAO-AI response to snaring which peaked 15 minutes after the start of the stress challenge. In the second experimental paradigm, bacterial endotoxin (LPS: 20μg/pig) was used to induce HPA activation and plasma cortisol and MAO-AI were determined. This time, however, the cortisol response was not preceded by any change in MAO-AI. We conclude that generation of MAO-AI, which is associated with HPA activation induced by psychological stress, is not a component of the pathways involved in immunological stimulation of the HPA axis.

Inhibition of monoamine oxidase-B by condensed pyridazines and pyrimidines: effects of lipophilicity and structure-activity relationships.

A number of condensed pyridazines and pyrimidines were synthesized and tested for their monoamine oxidase-A (MAO-A) and MAO-B inhibitory activity. Their lipophilicity was examined by measuring partition coefficients and RP-HPLC capacity factors, revealing some peculiar electronic and conformational effects. Further insights were obtained by X-ray crystallography and a thermodynamic study of RP-HPLC retention. Structure-activity relations highlighted the main factors determining both selectivity and inhibitory potency. Thus, while most of the condensed pyridazines were reversible inhibitors of MAO-B with little or no MAO-A effects, the pyrimidine derivatives proved to be reversible and selective MAO-A inhibitors. Substituents on the diazine nucleus modulated enzyme inhibition. A QSAR analysis of X-substituted 3-X-phenyl-5H-indeno[1,2-c]pyridazin-5-ones showed lipophilicity to increase MAO-B and not MAO-A inhibitory activity.

Endogenous monoamine oxidase A inhibitory activity (tribulin), measured in saliva, is related to cardiovascular reactivity in normal individuals.

Salivary monoamine oxidase A inhibitory activity (MAO-AI), mean arterial blood pressure (MAP) and heart rate (HR) were determined simultaneously in healthy male students (n = 13) at rest, before a mild psychological stressor, twice during the task and 18 minutes after the end of the task. The sample as a whole showed significant differences in MAP and HR across occasions (respectively, p < 0.001 for both). Salivary MAO-AI could distinguish novice and experienced game players (p < 0.02) and was consistently positively correlated with MAP (r = 0.58, p < 0.05 on occasion 2). Pre-task measures of MAO-AI for an increased sample (n = 18) were associated with higher MAP (but not HR) throughout the experiment (p < 0.05). Those subject with falling MAO-AI profiles from task to recovery showed significantly greater simultaneous decline in HR than those with a rising MAO-AI profile (p < 0.05).

THE CORTISOL RESPONSE TO PSYCHOLOGICAL CHALLENGE IS PRECEDED BY A TRANSIENT RISE IN ENDOGENOUS INHIBITOR OF MONOAMINE OXIDASE

The salivary cortisol response to an acute psychological stress challenge was investigated in normal male undergraduate students. A modified version of the Trier Social Stress Test (TSST) was used and saliva collected on 6 occasions before during and after the stress challenge. Control subjects were allowed to read quietly. As expected the cortisol response in experimental subjects was robust and peaked 12 minutes after the end of the stress. Endogenous monoamine oxidase A inhibitory activity (MAO-AI) was measured in the same saliva samples. MAO-AI also changed in response to the stress challenge, peaking in the saliva sample collected immediately after the stress challenge, 12 minutes prior to the cortisol peak sample. Furthermore the degree of increase in salivary MAO-AI was found to predict the degree of cortisol increase in the test subjects (r=0.76; n=14; p<0.001). These results are consistent with the hypothesis that elevated central monoamines, driven by inhibition of their main metabolic enzyme, can activate the hypothalamic-pituitary-adrenal (HPA) axis in the stress response. This finding lends further support to the notion that endogenous generation of MAO-AI is a normal homeostatic regulatory mechanism.

Antioxidant activity of resveratrol closely correlates with its monoamine oxidase-A inhibitory activity

Polyhydroxystilbenes including resveratrol were reported to competitively inhibit monoamine oxidase-A without structural relation with substrates and synthetic inhibitors for the enzyme. We attempt to explore a plausible mechanism for their inhibitory activity on MAO-A. All the polyhydroxystilbenes tested showed the antioxidant activity on liver homogenate. Furthermore, the antioxidant activity turned out to closely correlate with the MAO-A inhibitory activity.