Monoamine Oxidase Inhibitory Activity Research Articles

Colletotrilactam A–D, novel lactams from Colletotrichum gloeosporioides GT-7, a fungal endophyte of Uncaria rhynchophylla

Four novel lactams, colletotrilactam A–D (1–4), along with six known compounds (5–10) were isolated from the culture broth of Colletotrichum gloeosporioides GT-7, a fungal endophyte of Uncaria rhynchophylla. The structures of these compounds were elucidated by comprehensive NMR spectroscopy. Isolates were tested for monoamine oxidase (MAO) inhibitory activity and compound 9 showed potent MAO inhibitory activity with IC50 value of 8.93±0.34μg/mL, when the IC50 value of iproniazid as a standard was 1.80±0.5μg/mL.

Monoamine Oxidase Inhibitory Action of Chalcones: A Mini Review

Chalcones are one of the major classes of naturally occurring compounds and have a vast significance in medicinal chemistry, presenting with a wide scope of pharmacological actions. The present review focused our attention onto the monoamine oxidase inhibitory activity of natural and synthetic chalcones. The review also emphasises the structure-activity relationship studies and molecular recognition of chalcones towards MAO-A and B inhibition. Many of the studies clearly revealed that most of the chalcones showed selective, reversible and potent MAO-B inhibition compared to MAO-A. Recent studies also showed that heteroaryl-based chalcones are potent MAO-A inhibitors.

A new furanosteroid from Talaromyces sp. lgt-4, a fungal endophyte isolated from Tripterygium wilfordii

Wortmannolol (1), a new furanosteroid, along with five known compounds, wortmannolone (2), ergosterol (3), p-hydroxyphenyl ethanol (4), trans-6-dodecene (5), (2Z, 4E) -5-(8-hydroxy-1,5-dimethyl-3-oxo-6-oxabicyclo [3.2.1] octan-8-yl) -3-methylpenta-2,4-dienoic acid (6) were isolated from a fungal endophyte Talaromyces sp. lgt-4. Their structures were elucidated by IR, MS, 1D and 2D NMR spectra. Compound 1 show weak monoamine oxidase inhibitory activity.

The monoamine oxidase inhibitory activity of essential oils obtained from Eryngium species and their chemical composition

Context Monoamine oxidase (MAO) inhibitors are used in the treatment of depression, anxiety disorders, and the symptomatic treatment of Parkinson's disease. Eryngium, the most representative of the Apiaceae family, is well known for the presence of essential oils (EOs), which have already demonstrated MAO inhibitory potential. Objective The objective of this study is to evaluate the MAO inhibitory capacity of the EOs obtained from Eryngium floribundum Cham. & Schlecht. (EF), E. eriophorum Cham. & Schlecht. (EE), E. nudicaule Lam. (EN), E. horridum Malme (EH), and E. pandanifolium Cham. & Schlecht. (EP). Materials and methods EOs were obtained from fresh whole plants by hydrodistillation (3 h). Chemical analyses were performed by GC/MS using apolar and polar columns, with oven temperature from 60 to 300 °C at 3 °C/min. The MAO-A and -B activities were evaluated in vitro by an end-point method using kynuramine as the substrate and mitochondrial suspension or human recombinant enzymes as the enzymatic source. DMSO 2%, clorgyline 10−7 M, and pargyline 10−6 M were used as controls. Results and discussion EFEO, EEEO, ENEO, EHEO, and EPEO GC/MS analysis showed (E)-caryophyllene (4.9–10.8%), germacrene D (0.6–35.1%), bicyclogermacrene (10.4–17.2), spathulenol (0.4–36.0%), and globulol (1.4–18.6%) as main constituents. None of the EOs inhibited MAO-A activity (4 and 40 μg/mL). However, EHEO inhibited MAO-B activity with an IC50 value of 5.65 μg/mL (1–200 μg/mL). Pentadecane (10 μM), its major constituent (53.5%), did not display significant MAO-B inhibition. Conclusion The study demonstrates the promising application of Eryngium species as a source of potential central nervous system bioactive secondary metabolites, specially related to neurodegenerative disorders.

Evaluation of Natural and Synthetic 1,4-naphthoquinones as Inhibitors of Monoamine Oxidase.

Previous reports have documented that 1,4-naphthoquinones act as inhibitors of the monoamine oxidase (MAO) enzymes. In particular, fractionation of the extracts of cured tobacco leafs has led to the characterization of 2,3,6-trimethyl-1,4-naphthoquinone, a non-selective MAO inhibitor. To derive structure-activity relationships for MAO inhibition by the 1,4-naphthoquinone class of compounds, this study investigates the human MAO inhibitory activities of fourteen structurally diverse 1,4-naphthoquinones of natural and synthetic origin. Of these, 5,8-dihydroxy-1,4-naphthoquinone was found to be the most potent inhibitor with an IC50 value of 0.860 μm for the inhibition of MAO-B. A related compound, shikonin, inhibits both the MAO-A and MAO-B isoforms with IC50 values of 1.50 and 1.01 μm, respectively. It is further shown that MAO-A and MAO-B inhibition by these compounds is reversible by dialysis. In this respect, kinetic analysis suggests that the modes of MAO inhibition are competitive. This study contributes to the discovery of novel MAO inhibitors, which may be useful in the treatment for disorders such as Parkinson's disease, depressive illness, congestive heart failure and cancer.

Two new compounds, deacetylisowortmins A and B, isolated from an endophytic Fungus, Talaromyces wortmannii LGT-4

Two new compounds, deacetylisowortmins A (1) and B (2), were isolated from Talaromyces wortmannii LGT-4. Their structures were established by 1D and 2D NMR spectra, as well as comparison of the experimental and calculated electronic circular dichroism spectra. Monoamine oxidase and acetylcholinesterase inhibitory activities of 1 and 2 were also evaluated.

Design, synthesis, biological evaluation and docking studies of sulfonyl isatin derivatives as monoamine oxidase and caspase-3 inhibitors

Sulfonyl isatin derivatives as multifunctional agents showing monoamine oxidase and caspase-3 inhibitory activities in the low micromolar range.

Monoamine Oxidase Inhibitory Activity of Novel Pyrazoline Analogues: Curcumin Based Design and Synthesis.

A series of new 2-methoxy-4-(5-phenyl-4,5-dihydro-1H-pyrazol-3-yl)phenolderivatives, 4-13, were synthesized and tested for their human MAO inhibitory activity. All the compounds were found to be selective and reversible toward hMAO-A except 4, a selective inhibitor of hMAO-B and 12, a nonselective inhibitor. Compound 7 was found to be a potent inhibitor of hMAO-A with Ki = 0.06 ± 0.003 μM and was having selectivity index of (SI = 1.02 × 10(-5)). It was found to be better than standard drug, Moclobemide (hMAO-A with Ki = 0.11 ± 0.01 μM) with selectivity index of SI = 0.049. Molecular docking simulation was carried out to understand the crucial interactions responsible for selectivity and potency.

Monoamine Oxidase Inhibitory Activity of Ferulic Acid Amides: Curcumin-Based Design and Synthesis.

Ferulic acid has structural similarity with curcumin which is being reported for its monoamine oxidase (MAO) inhibitory activity. Based on this similarity, we designed a series of ferulic acid amides 6a-m and tested for their inhibitory activity on human MAO (hMAO) isoforms. All the compounds were found to inhibit the hMAO isoforms either selectively or non-selectively. Nine compounds (6a, 6b, 6g-m) were found to inhibit hMAO-B selectively, whereas the other four (6c-f) were found to be non-selective. There is a gradual shift from hMAO-B selectivity (6a,b) to non-selectivity (6c-f) as there is an increase in chain length at the amino terminus. In case of compounds having an aromatic nucleus at the amino terminus, increasing the carbon number between N and the aromatic ring increases the potency as well as selectivity toward hMAO-B. Compounds 6f, 6j, and 6k were subjected to membrane permeability and metabolic stability studies by in vitro assay methods. They were found to have a better pharmacokinetic profile than curcumin, ferulic acid, and selegiline. In order to understand the structural features responsible for the potency and selectivity of 6k, we carried out a molecular docking simulation study.

Involvement of the monoamine system in antidepressant-like properties of 4-(1-phenyl-1h-pyrazol-4-ylmethyl)-piperazine-1-carboxylic acid ethyl ester

Piperazinic derivatives have therapeutic potential by acting as analgesic, antidepressant-like, anticonvulsant and antipsychotic in preclinical studies. In order to develop new drugs to treat mental disorders, we designed and synthesized the 4-(1-phenyl-1H-pyrazol-4-ylmethyl)-piperazine-1-carboxylic acid ethyl ester (PPMP), a new piperazine derivative with putative activities on central nervous system that seems to involve serotonergic system. In order to investigate the antidepressant-like activity of PPMP, mice were treated acutely and tested in the forced swimming test (FST) and tail suspension test. Pretreatment with the 5-HT synthesis inhibitor p-chlorophenylalanine (PCPA, 100 mg/kg, i.p., 4 days), and the non-selective blocker of catecholamine synthesis α-methyl para-tyrosine (AMPT, 100 mg/kg, i.p.) were used to assay the involvement of serotonergic and catecholaminergic systems. “Ex vivo” monoamine oxidase (MAO) enzymatic assay and quantification of hippocampal level of brain derived neurotrophic factor (BDNF) were carried out. PPMP reduced the immobility time in both tests. PCPA or AMPT (100 mg/kg, i.p.) pretreatment blocked the effects of PPMP, thereby suggesting the involvement of serotonergic and catecholaminergic systems in the antidepressant-like effect of PPMP. PPMP did not inhibit the activity of MAO. Moreover, after 14 days of treatment, PPMP 15 mg/kg/day induced antidepressant-like effect and increased hippocampal level of BDNF. None of the treatments in this study altered the locomotor activity in the open field test. In conclusion, PPMP demonstrates antidepressant-like effect that involve both serotonergic and catecholaminergic systems without inhibition of MAO activity. PPMP administration increased the hippocampal levels of BDNF.

Secovironolide, a novel furanosteroid scaffold with a five-membered B ring from the endophytic fungus Talaromyces wortmannii LGT-4

Secovironolide (1) was purified from the culture broth of Talaromyces wortmanni and is the first example of a furanosteroid scaffold bearing a five-membered B ring. The structure of 1 was elucidated by comprehensive NMR spectroscopy and single-crystal X-ray crystallography. Additional known viridian derivatives (2–5, 7) were isolated, including the new epoxide containing compound, epoxyvirone (6). Isolates were tested for monoamine oxidase (MAO) inhibitory activity and showed only weak activity.

Monoamine oxidase inhibitory activities of heterocyclic chalcones.

Studies have shown that natural and synthetic chalcones (1,3-diphenyl-2-propen-1-ones) possess monoamine oxidase (MAO) inhibition activities. Of particular importance to the present study is a report that a series of furanochalcones acts as MAO-B selective inhibitors. Since the effect of heterocyclic substitution, other than furan (and more recently thiophene, piperidine and quinoline) on the MAO inhibitory properties of the chalcone scaffold remains unexplored, the aim of this study was to synthesise and evaluate further heterocyclic chalcone analogues as inhibitors of the human MAOs. For this purpose, heterocyclic chalcone analogues that incorporate pyrrole, 5-methylthiophene, 5-chlorothiophene and 6-methoxypyridine substitution were examined. Seven of the nine synthesised compounds exhibited IC50 values <1 μM for the inhibition of MAO-B, with all compounds exhibiting higher affinities for MAO-B compared to the MAO-A isoform. The most potent MAO-B inhibitor (4h) displays an IC50 value of 0.067 μM while the most potent MAO-A inhibitor (4e) exhibits an IC50 value of 3.81 μM. It was further established that selected heterocyclic chalcones are reversible and competitive MAO inhibitors. 4h, however, may exhibit tight-binding to MAO-B, a property linked to its thiophene moiety. We conclude that high potency chalcones such as 4h represent suitable leads for the development of MAO-B inhibitors for the treatment of Parkinson's disease and possibly other neurodegenerative disorders.

Synthesis and Preliminary Biological Evaluation of 1,3,5-Triazine Amino Acid Derivatives to Study Their MAO Inhibitors.

Three series of 4,6-dimethoxy-, 4,6-dipiperidino- and 4,6-dimorpholino-1,3,5-triazin-2-yl) amino acid derivatives were synthesized and characterized. A preliminary study for their monoamine oxidase inhibitory activity showed that compounds 7, 18, and 25 had MAO-A inhibition activity comparable to that of the standard clorgyline, with apparently more selective inhibitory activity toward MAO-A than MAO-B and no significant acute toxicity.

Monoamine Oxidase Inhibition and Molecular Modeling Studies of Piperidyl-thienyl and 2-Pyrazoline Derivatives of Chalcones.

A series of piperidyl-thienyl & 2-pyrazoline derivatives of quinolyl-thienyl chalcones were tested to observe the structural characteristics for the monoamine oxidase inhibitory (MAO) activity. In both these series, a diverse range of substituted thiophenes are used which enable the structure activity relationship. The compounds showed enhanced inhibition against MAO-A & B as compared to reference compounds. Compound 1c exhibited most potent MAO-A inhibition having IC50 value of 0.062 µM, while 1j showed excellent inhibitory potency against MAO-B having IC50 value of 0.088 µM. The present investigation demonstrated that among piperidyl-thienyl chalcones, almost all the compounds exhibit significant MAO-A inhibition, thus may have antidepressant activity. Whereas among the 2-pyrazoline derivatives of chal-cones, many compounds revealed MAOB inhibition and hence may be applied in the control of senile dementia. Molecular docking studies were carried out against human MAO-A and MAO-B to rationalize important binding site interactions.

Flavonoids from Sideritis Species: Human Monoamine Oxidase (hMAO) Inhibitory Activities, Molecular Docking Studies and Crystal Structure of Xanthomicrol.

The inhibitory effects of flavonoids on monoamine oxidases (MAOs) have attracted great interest since alterations in monoaminergic transmission are reported to be related to neurodegenerative diseases such as Parkinson’s and Alzheimer’s diseases and psychiatric disorders such as depression and anxiety, thus MAOs may be considered as targets for the treatment of these multi-factorial diseases. In the present study, four Sideritis flavonoids, xanthomicrol (1), isoscutellarein 7-O-[6'''-O-acetyl-β-d-allopyranosyl-(1→2)]-β-d-glucopyranoside (2), isoscutellarein 7-O-[6'''-O-acetyl-β-d-allopyranosyl-(1→2)]-6''-O-acetyl-β-d-glucopyranoside (3) and salvigenin (4) were docked computationally into the active site of the human monoamine oxidase isoforms (hMAO-A and hMAO-B) and were also investigated for their hMAO inhibitory potencies using recombinant hMAO isoenzymes. The flavonoids inhibited hMAO-A selectively and reversibly in a competitive mode. Salvigenin (4) was found to be the most potent hMAO-A inhibitor, while xanthomicrol (1) appeared as the most selective hMAO-A inhibitor. The computationally obtained results were in good agreement with the corresponding experimental values. In addition, the x-ray structure of xanthomicrol (1) has been shown. The current work warrants further preclinical studies to assess the potential of xanthomicrol (1) and salvigenin (4) as new selective and reversible hMAO-A inhibitors for the treatment of depression and anxiety.

Synthesis and evaluation of quinazoline amino acid derivatives as mono amine oxidase (MAO) inhibitors

A series of quinazolinone amino acid ester and quinazolinone amino acid hydrazides were prepared under microwave irradiation as well as conventional condition. The microwave irradiation afforded the product in less reaction time, higher yield and purity. The structures of the synthesized compounds were confirmed by IR, NMR, and elemental analysis. The new synthesized compounds were studied for their monoamine oxidase inhibitory activity. They showed more selective inhibitory activity toward MAO-A than MAO-B. Compounds 7, 10, and 15 showed MAO-A inhibition activity (IC50=3.6×10−9, 2.8×10−9, 2.1×10−9 M, respectively) comparable to that of the standard clorgyline (IC50=2.9×10−9M). 2-(2-(Benzo[d][1,3]dioxol-5-yl)-4-oxo-1,2-dihydroquinazolin-3(4H)-yl)acetohydrazide 15 showed selective MAO-A inhibition activity (SI=39524) superior to that of the standard clorgyline (SI=33793). The acute toxicity of the synthesized compounds was determined. In addition, computer-assisted simulated docking experiments were performed to rationalize the biological activity.

Changes in Neuronal Dopamine Homeostasis following 1-Methyl-4-phenylpyridinium (MPP+) Exposure

1-Methyl-4-phenylpyridinium (MPP(+)), the active metabolite of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, selectively kills dopaminergic neurons in vivo and in vitro via a variety of toxic mechanisms, including mitochondrial dysfunction, generation of peroxynitrite, induction of apoptosis, and oxidative stress due to disruption of vesicular dopamine (DA) storage. To investigate the effects of acute MPP(+) exposure on neuronal DA homeostasis, we measured stimulation-dependent DA release and non-exocytotic DA efflux from mouse striatal slices and extracellular, intracellular, and cytosolic DA (DAcyt) levels in cultured mouse ventral midbrain neurons. In acute striatal slices, MPP(+) exposure gradually decreased stimulation-dependent DA release, followed by massive DA efflux that was dependent on MPP(+) concentration, temperature, and DA uptake transporter activity. Similarly, in mouse midbrain neuronal cultures, MPP(+) depleted vesicular DA storage accompanied by an elevation of cytosolic and extracellular DA levels. In neuronal cell bodies, increased DAcyt was not due to transmitter leakage from synaptic vesicles but rather to competitive MPP(+)-dependent inhibition of monoamine oxidase activity. Accordingly, monoamine oxidase blockers pargyline and l-deprenyl had no effect on DAcyt levels in MPP(+)-treated cells and produced only a moderate effect on the survival of dopaminergic neurons treated with the toxin. In contrast, depletion of intracellular DA by blocking neurotransmitter synthesis resulted in ∼30% reduction of MPP(+)-mediated toxicity, whereas overexpression of VMAT2 completely rescued dopaminergic neurons. These results demonstrate the utility of comprehensive analysis of DA metabolism using various electrochemical methods and reveal the complexity of the effects of MPP(+) on neuronal DA homeostasis and neurotoxicity.

Modulation of monoamine oxidase (MAO) expression in neuropsychiatric disorders: genetic and environmental factors involved in type A MAO expression.

Monoamine oxidase types A and B (MAO-A, MAO-B) regulate the levels of monoamine neurotransmitters in the brain, and their dysfunction may be involved in the pathogenesis and influence the clinical phenotypes of neuropsychiatric disorders. Reversible MAO-A inhibitors, such as moclobemide and befloxatone, are currently employed in the treatment of emotional disorders by inhibiting the enzymatic degradation of dopamine, serotonin and norepinephrine in the central nervous system (CNS). It has been suggested that the irreversible MAO-B inhibitors selegiline and rasagiline exert a neuroprotective effect in Parkinson's and Alzheimer's diseases. This effect, however, is not related to their inhibition of MAO activity; in animal and cellular models, selegiline and rasagiline protect neuronal cells through their anti-apoptotic activity and induction of pro-survival genes. There is increasing evidence that MAO-A activity, but not that of MAO-B, is implicated in the pathophysiology of neurodegenerative disorders, but also in gene induction by MAO-B inhibitors; on the other hand, selegiline and rasagiline increase MAO-A mRNA, protein, and enzyme activity levels. Taken together, these results suggest that each MAO subtype exerts effects that modulate the expression and activity of the other isoenzyme. The roles of MAO-A and -B in the CNS should therefore be re-evaluated with respect to the "type-specificity" of their inhibitors, which may not be unconditional during chronic treatment. Mao-a expression, in particular, may be implicated in pathogenesis and phenotypes in neuropsychiatric disorders. MAO-A expression is modified by mao polymorphisms affecting its transcriptional efficiency, as well as by mutations and polymorphism of parkin, Sirt1, FOXO, microRNA, presenilin-1, and other regulatory proteins. In addition, childhood maltreatment has been shown to have an impact upon adolescent social behavior in children with mao-a polymorphisms of low transcriptional activity. Low MAO-A activity may increase the levels of serotonin and norepinephrine, resulting in disturbed neurotransmitter system development and behavior. This review discusses genetic and environmental factors involved in the regulation of MAO-A expression, in the contexts of neuropsychiatric function and of the regulation of neuronal survival and death.

Two new cyclic dipeptides from Rhinocladiella sp. lgt-3, a fungal endophyte isolated from Tripterygiun wilfordii Hook

Two new cyclic dipeptides, rhinocladin A (1) and rhinocladin B (2), were isolated from a fungal endophyte (Rhinocladiella sp. lgt-3) of Tripterygiun wilfordii Hook. Their structures were elucidated by 1D and 2D NMR spectra. The monoamine oxidase inhibitory activity of 1 and 2 was also evaluated.

Desmodeleganine, a new alkaloid from the leaves of Desmodium elegans as a potential monoamine oxidase inhibitor

Desmodeleganine (1), a new potential monoamine oxidase inhibitor, along with three known alkaloids, bufotenin (2), hydroxy-N, N-dimethyltryptamine N12-oxide (3), 2-(5-methoxy-1H-indol-3-yl)-N, and N-dimethylethylamine (4) were isolated from the leaves of Desmodium elegans. Their structures were elucidated by IR, MS, 1D and 2D NMR spectra. 1 showed strong monoamine oxidase inhibitory activity with IC50 value of 13.92±1.5μM, when the IC50 value of iproniazid as a standard was 6.5±0.5μM. The molecular modeling was also performed to explore the binding mode of compounds 1, 2 at the active site of MAO-A and MAO-B.