Monoamine Oxidase Inhibitory Activity Research Articles

Synthesis and biological evaluation of 4-arylcoumarins as potential anti-Alzheimer’s disease agents

Alzheimer's disease (AD) is a progressive neurological degenerative disease that has complex pathogenesis. A variety of studies in humans indicate that several enzymes inhibitors can be useful in the treatment of AD, including acetylcholinesterase (AchE), butyrylcholinesterase (BuChE) and monoamine oxidase (MAO). Various substituted 4-arylcoumarin derivatives were synthesised, and their activity in vitro were investigated, including AChE/BuChE inhibitory activity, MAO inhibitory activity, and antioxidant activity. Most of the compounds were found to exhibit high inhibitory activity, and individual compounds have extremely excellent activities. Therefore 4-arylcoumarins provides an idea for drugs design for the development of therapeutic or preventive agents for AD.

Wortmannine H, a phenylpentenol isolated from an endophytic fungus, Talaromyces wortmannii LGT-4

A new phenylpentenol, wortmannine H (1) was isolated from Talaromyces wortmannii LGT-4, an endophytic fungus of Tripterygium wilfordii. The structure of 1 was elucidated by IR, MS, 1D and 2D NMR spectra and comparison of the experimental and calculated optical rotatory dispersion (ORD). Monoamine oxidase (MAO), acetylcholinesterase (AChE) and phosphoinositide 3-kinase (PI3Kα) inhibitory activities of 1 was also tested. The compound did not show good biological activity.

Monoamine oxidase inhibitory activity of flavoured e-cigarette liquids

Background and aimsMonoamine oxidase inhibitors have been hypothesised to be important in tobacco dependence, reinforcing the brain's response to nicotine by delaying the degradation of neurotransmitters by monoamine oxidases.The development of electronic cigarettes has provided an alternative nicotine delivery system, which is widely viewed as less toxic than tobacco smoke. However, significant data gaps remain. This paper reports the results of measurements of monoamine oxidase inhibitory activity in a small sample of commercially available, flavoured e-liquids. MethodsTwelve e-liquids were tested for monoamine oxidase inhibitory activity, using the kynuramine assay and monoamine oxidase enzymes (human, recombinant). Control samples of carrier liquids, propylene glycol and glycerol, and nicotine were also tested. ResultsFour e-liquids contained high levels of inhibitory activity, four more were moderately inhibitory. The remaining four e-liquids were mildly inhibitory, while the carrier liquids, and nicotine were inactive at relevant concentrations. The active compounds in the e-liquids were subsequently identified as vanillin and ethyl vanillin.Under some conditions of use, the sampled e-liquids with the highest concentrations of monoamine oxidase inhibitory activity have the potential to expose consumers to physiologically significant levels of MAO inhibitory activity. ConclusionsWhile only a small sample of e-liquids was tested, the findings suggest that some flavours have pharmacological actions, with potential to enhance the response to nicotine or to other drugs. The public health implications of these preliminary findings on addiction and smoking cessation warrant exploration and further research.

Coumarin analogue 3-methyl-7H-furo[3,2-g] chromen-7-one as a possible antiparkinsonian agent

Introduction: Parkinson’s disease is the second most common neurodegenerative disease. Monoamine oxidase B inhibitors are used in the treatment of this disease concomitantly with levodopa or as monotherapy. Several substituted coumarins have shown activity as inhibitors of monoamine oxidase B.Objective: To evaluate the possible antiparkinsonian effects of the coumarin analogue FCS005 (3-methyl-7H-furo[3,2-g]chromen-7-one) in mouse models, as well as its inhibitory activity towards monoamine oxidases (MAO) and its antioxidant activity.Materials and methods: FCS005 was synthesized and the reversal of hypokinesia was evaluated in the reserpine and levodopa models. Moreover, in the haloperidol model, its anticataleptic effects were evaluated. Additionally, the monoamine oxidase inhibitory activity and antioxidant activity of FCS005 were evaluated using in vitro and ex vivo studies, respectively.Results: FCS005 (100 mg/kg) caused the reversal of hypokinesia in the reserpine and levodopa models. This furocoumarin also presented anti-cataleptic effects at the same dose. Besides, it showed selective inhibitory activity towards the MAO-B isoform and antioxidant activity.Conclusion: These results attribute interesting properties to the compound FCS005. It is important to continue research on this molecule considering that it could be a potential antiparkinsonian agent.

Synthesis, biological evaluation, and molecular modeling of nitrile-containing compounds: Exploring multiple activities as anti-Alzheimer agents.

Based on the monoamine oxidase (MAO) inhibition properties of aminoheterocycles with a carbonitrile group we have carried out a systematic exploration to discover new classes of carbonitriles endowed with dual MAO and AChE inhibitory activities, and Aβ anti-aggregating properties. Eighty-three nitrile-containing compounds, 13 of which are new, were synthesized and evaluated. in vitro screening revealed that 31, a new compound, presented the best lead for trifunctional inhibition against MAO A (0.34 μM), MAO B (0.26 μM), and AChE (52 μM), while 32 exhibited a lead for selective MAO A (0.12 μM) inhibition coupled to AChE (48 μM) inhibition. Computational analysis revealed that the malononitrile group can find an advantageous position with the aromatic cleft and FAD of MAO A or MAO B. However, the total binding energy can be handicapped by an internal penalty caused by twisting of the ligand molecule and subsequent disruption of the conjugation (32 in MAO B compared to the conjugated 31). Conjugation is also important for AChE as well as the hydrophilic character of malononitrile that allows this group to be in close contact with the aqueous environment as seen for 83. Although the effect of 31 and 32 against Aβ1-42 , was very weak, the effect of 63 and 65, and of the new compound 75, indicated that these compounds were able to disaggregate Aβ1-42 fibrils. The most effective was 63, a (phenylhydrazinylidene)propanedinitrile derivative that also inhibited MAO A (1.65 μM), making it a potential lead for Alzheimer's disease application.

Novel isoxazole derivatives as potential antiparkinson agents: synthesis, evaluation of monoamine oxidase inhibitory activity and docking studies

Selective monoamine oxidase B inhibitors are potential drug candidates for the treatment of Parkinson’s disease. A series of phenyl substituted isoxazole carbohydrazides was designed by structural modification of isocarboxazid, a nonselective MAO inhibitor and evaluated as inhibitors of MAO-A and MAO-B. The compounds were not able to inhibit MAO-A significantly, but most of the compounds exhibited potent inhibitory activity against MAO-B. The enzyme kinetic study of the most active compounds 5d, 5-phenyl-N′-(1-(p-tolyl)ethylidene)isoxazole-3-carbohydrazide and 5g, N′-(1-(3,4-dimethoxyphenyl)ethylidene)-5-phenylisoxazole-3-carbohydrazide displayed reversible and competitive MAO-B inhibition. In molecular modeling studies, compounds 5d and 5g exhibited strong binding affinity on MAO-B active site. The administration of compounds 5d and 5g exhibited prevention of MPTP-induced Parkinsonism as indicated by footprint analysis and horizontal wire tests. Further optimization studies are essential to exploit their potential for MAO-B associated neurodegenerative pathologies.

English

Peganum harmala seed extract has been frequently reported to possess antibacterial potential through in vivo studies. P. harmala L. (Zygophyllaceae) is one of the most famous medicinal plants used in traditional medicine of Iraq. The harmaline, harmalol and harmine exerted many pharmacodynemic effects on the central nervous system: stimulation and depression depending on the dose. P. harmala indicates a great variety of pharmacological activities such as antimicrobial, antitumor, antinociceptive and monoamine oxidase (MNO) inhibitory activities. The most important components of P. harmala seeds are harmaline, vasicinone and deoxyrsinone. The antibacterial effect of P. harmala was studied. The antibacterial activity of aqueous extracts was determined by agar well diffusion method. It inhibited the growth of Escherichia coli and Staphylococcus aureus. All animals injected with 100 mg/kg b. w of aqueous extract of P. harmala show myorelaxation or incoordination; so the animals dropped down from the wire 3 consecutive times i n 60 s. Aqueous extract of P. harmala also induced muscle relaxation and prolonged the sleeping time induced by pentoparpitol. These data suggest that P. harmala extract could inhibit the growth of S. aureus and E. coli strain in vitro and this activity may contribute to its chemopreventive effect. Key words: Antibacterial, muscle relaxant, hypnotic, Peganum harmala.

Two new compounds, Talaromycin A and B, isolated from an endophytic fungus, Talaromyces aurantiacus

Two new compounds Talaromycin A (1) and Talaromycin B (2) were isolated from a liquid culture of Talaromyces aurantiacus. The structures of 1 and 2 were elucidated by IR, MS, 1D and 2D NMR spectra and comparison of the experimental and calculated electronic circular dichroism spectra. Additional known compounds (3–6) were also isolated. These compounds were tested for monoamine oxidase, acetylcholinesterase and PI3K inhibitory activity, but showed only weak activity.

Isoflavones prevent oxidative stress and inhibit the activity of the enzyme monoamine oxidase in vitro.

Oxidative stress occurs due to an imbalance between antioxidant defenses and pro-oxidant agents in brain. This condition has been associated to the pathogenesis of several brain diseases; therefore, increasing the use of compounds that exert antioxidant activity. Thus, the objective of this study was to evaluate, in vitro, the effect of isoflavones in: (1) lipid peroxidation, catalase activity and thiol groups in the presence of pro-oxidants: sodium nitroprusside or Fe2+/EDTA complex in rat brain homogenates; (2) the activity of the enzyme monoamine oxidase (MAO). As a result, the isoflavones reduced lipid peroxidation in a manner dependent on the concentration and protected against the reduction of catalase activity as well as the induced thiol oxidation in brain tissue. In addition, isoflavones inhibited MAO activity (MAO-A and MAO-B). Taken together, our results showed that isoflavones avoided oxidative stress and decreased the MAO activity, suggesting a promissory use in the treatment of neurodegenerative diseases.

Synthesis, X-ray crystal and monoamine oxidase inhibitory activity of 4,6-dihydrobenzo[c]pyrano[2,3-e][1,2]thiazine 5,5-dioxides: In vitro studies and docking analysis

We report the synthesis and biological evaluation of two new series of 2-amino-6-benzyl-4-phenyl-4,6-dihydrobenzo[c]pyrano[2,3-e][1,2]thiazine-3‑carbonitrile 5,5-dioxides and 2-amino-6-methyl-4-phenyl-4,6-dihydrobenzo[c]pyrano[2,3-e][1,2]thiazine-3‑carbonitrile 5,5-dioxides. The synthetic methodology involves a multistep reaction starting with methyl anthranilate which was coupled with methane sulfonyl chloride. The product of the reaction was subjected to N-benzylation and N-methylation reactions followed by ring closure with sodium hydride resulting in the formation of respective 2,1-benzothiazine 2,2-dioxides. These 2,1-benzothiazine precursors were subjected to multicomponent reaction with malononitrile and substituted benzaldehydes for the synthesis of two new series of pyranobenzothiazines (6a–r and 7a–r). The synthesized compounds were screened as selective inhibitors of monoamine oxidase A and monoamine oxidase B. The in vitro results suggested that compound 6d and 7q are the selective inhibitors of monoamine oxidase A, however, the selective and potent inhibitors of monoamine oxidase B included compounds 6h and 7r. Moreover, some dual inhibitors were noticed like 7l having more inhibitory activity towards both the isozymes. Moreover, the binding modes of the selective and potent inhibitors of monoamine oxidase A and B were investigated by molecular docking analysis. The results suggested that the synthetic derivatives may be potential towards the monoamine oxidase isozymes.

Synthesis, monoamine oxidase inhibitory activity and computational study of novel isoxazole derivatives as potential antiparkinson agents

Monoamine oxidase (MAO) enzymes are one of the most promising targets for the treatment of neurological disorders. A series of phenylisoxazole carbohydrazides was designed, synthesized and screened for both MAO-A and MAO-B inhibition using Amplex Red assays. None of the compounds inhibited the MAO-A activity while most of them significantly inhibited MAO-B in the micromolar to nanomolar range. Among them, the compound N'-(4-methylbenzylidene)-5-phenylisoxazole-3-carbohydrazide (6c) exhibited the most potent inhibitory activity towards MAO-B. Enzyme kinetic studies revealed the reversible and competitive nature of compound 6c towards MAO-B inhibition. The results of the enzyme inhibition assay were in agreement with molecular docking study, in which compound 6c displayed a strong binding affinity for MAO-B with a docking score of -10.98 Kcal/mol. In order to explore the neuroprotective effect of compound 6c, MPTP-induced mouse model for Parkinson’s disease was used, and motor behavioural assessment of experimental animals was carried out. The compound 6c was able to significantly prevent the MPTP-induced neurotoxicity as revealed by improvement in gait behaviour in footprint test and increase in grip strength score in horizontal wire test. Thus, phenylisoxazole carbohydrazides can be promising leads in the development of potent, selective and reversible MAO-B inhibitors for the treatment of Parkinson’s disease.

Synthesis and biological evaluation of 3-arylcoumarins as potential anti-Alzheimer's disease agents

Alzheimer's disease, a neurodegenerative illness, has the extremely complex pathogenesis. Accumulating evidence indicates there is a close relationship between several enzymes and Alzheimer's disease. Various substituted 3-arylcoumarin derivatives were synthesised, and their in vitro activity, including cholinesterase inhibitory activity, monoamine oxidase inhibitory activity, and antioxidant activity were investigated. Most of the compounds exhibited high activity; therefore 3-arylcoumarin compounds have the potential as drug candidates for the treatment of Alzheimer's disease.

In Silico Cholinesterase and Monoamine Oxidase Inhibitory Activities of Perillaldehyde and D-Limonene, Main Compounds of Essential Oil of Algerian Ammodaucus leucotrichus

In a continuation of our previous work for the exploration of novel enzyme inhibitors, molecular modeling was used to inspect the binding mode of perillaldehyde and D-limonene, the major compounds of essential oil of Algerian Ammodaucus leucotrichus into the active site pocket of cholinesterase (AChE and BuChE) and Monoamine Oxidase (MAO). The molecular docking was carried out using Molecular Operating Environment (MOE) software package. Docking analysis showed that this compounds (perilladehyde and D-limonene) can interact with both the Catalytic Active Site (CAS) of AChE, BuChE and MAO. For D-limonene, molecular docking showed favorable H-phi interaction with catalytic residue of AchE and BuChE. The perillaldehyde showed best interaction profile with BuChE as compared with compound D-Limonene. The best interaction between perilladehyde and monoamine oxidase was also revealed. This paper shows best correlation between the in vitro study and the in silico molecular docking study of anti-cholinesterase and anti-monoamine oxidase activities.

Inhibition of monoamine oxidase activity by repetitive transcranial magnetic stimulation: implications for inter-train interval and frequency.

Repetitive transcranial magnetic stimulation (rTMS) is a neuromodulation technique that stimulates cortical regions via time-varying electromagnetic fields; in several countries this technique has been approved as a treatment for major depressive disorder. One empirically established target in antidepressant pharmacotherapy is the flavin-containing monoamine oxidoreductase (MAO). The function of MAO enzymes is based on oxidation processes that may be sensitive towards strong electromagnetic fields. Therefore, we hypothesized that rTMS-induced electromagnetic fields impact the activity of this enzyme. Using crude synaptosomal cell preparations from human SH-SY5Y neuroblastoma cells and rat cortex as well as viable cells, we assessed the effects of rTMS on MAO-A and -B activity in a well-controlled in vitro set up. In short, samples were stimulated at maximal intensity with an equal number of total stimuli at frequencies of 5, 20, and 100Hz. Sham stimulation was performed in parallel. Treatment at frequencies of 5 and 20Hz significantly decreased mainly MAO-B activity in all tissue preparations and species, whereas 100Hz stimulation remained without effect on any MAO activity. Our results support the hypothesis, that rTMS-induced electromagnetic fields affect MAO activity and provide further evidence for intracellular effects possibly contributing to therapeutic effects of this neuromodulatory method. On a cautionary note, however, our findings are solely based on in vitro evidence.

Absolute configuration and biological profile of pyrazoline enantiomers as MAO inhibitory activity.

A new racemic pyrazoline derivative was synthesized and resolved to its enantiomers using analytic and semipreparative high-pressure liquid chromatography. The absolute configuration of both fractions was established using vibrational circular dichroism. The in vitro monoamine oxidase (MAO) inhibitory profiles were evaluated for the racemate and both enantiomers separately for the two isoforms of the enzyme. The racemic compound and both enantiomers were found to inhibit hMAO-A selectively and competitively. In particular, the R enantiomer was detected as an exceptionally potent and a selective MAO-A inhibitor (Ki =0.85×10-3 ±0.05×10-3 μM and SI: 2.35×10-5 ), whereas S was determined as poorer compound than R in terms of Ki and SI (0.184±0.007 and 0.001). The selectivity of the enantiomers was explained by molecular modeling docking studies based on the PDB enzymatic models of MAO isoforms.

Multi-targeting aurones with monoamine oxidase and amyloid-beta inhibitory activities: Structure-activity relationship and translating multi-potency to neuroprotection

Previously, a series of aurones bearing amine and carbamate functionalities was synthesized and evaluated for their cholinesterase inhibitory activity and drug-like attributes. In the present study, these aurones were evaluated for their multi-targeting properties in two Alzheimer’s disease (AD)-related activities namely, monoamine oxidase (MAO) and amyloid-beta (Aβ) inhibition. Evaluation of the aurones for MAO inhibitory activity disclosed several potent selective inhibitors of MAO-B, particularly those with 6-methoxyl group attached at ring A. Of the different amine moieties attached as side chains, pyrrolidine-bearing aurones were prominent as represented by 2-2, the most potent inhibitor. Evaluation on the Aβ aggregation inhibition identified 4-3 as the best inhibitor with a percentage inhibition comparable to that of a known Aβ inhibitor curcumin. Examination on the neuroprotective ability of the more drug-like aurone 4-3 in two Caenorhabditis elegans neurodegeneration models showed 4-3 to protect the nematodes against both Aβ- and 6-hydroxydopamine-induced toxicities. These new activities further support 4-3 as a promising lead to develop the aurones as potential multipotent agents for neurodegenerative diseases.

The essential oil of Algerian Ammodaucus leucotrichus Coss. & Dur. and its effect on the cholinesterase and monoamine oxidase activities

This study aims at performing a chemical analysis of the essential oil (EO) of Ammodaucus leucotrichus Coss. & Dur. and investigating the anticholinesterase and anti-monoamine oxidase activities.The EO of the A. leucotrichus aerial part was analyzed by Gas Chromatography Mass Spectrometry (GC-MS). The inhibitory potency against Acetylcholinesterase (AChE) and Butyrylcholinesterase (BChE) were evaluated in vitro using modified Ellman's method. Monoamine oxidase activity was measured using the spectrophotometric method described by Weissbach.The chemical analysis of EO showed that the main constituents were perillaldehyde (by about 58.3%) and limonene (by about 23.33%). Further, the essential oil extracted from A. leucotrichus exhibited a promising anti-butyrylcholinesterase activity with an IC50 of about 95.2 μg/mL, where the perillaldehyde and limonene IC50 corresponded to 42.7 μg/mL and 66.7 μg/mL, respectively. The anti-acetylcholinesterase activity was observed only with limonene with IC50 = 51.6 μg/mL. The highest monoamine oxidase inhibitor activity was observed by essential oil followed by perillaldehyde. The oil demonstrated IC50 values for monoamine oxidase-B (MAO-B) of 40.5 μg/mL and 98.9 μg/mL for perillaldehyde. While, IC50 values for monoamine oxidase-A (MAO-A) were 112.5 μg/mL and 159.1 μg/mL for EO and perillaldehyde, respectively. No inhibitory activity against monoamine oxidase has been reported with limonene.A. leucotrichus C. & D. essential oil may represent an alternative source useful as a moderate anticholinesterase agent, particularly against butyrylcholinesterase and monoamine oxidase.

Synthesis and Evaluation of 2-benzylidene-1-tetralone Derivatives for Monoamine Oxidase Inhibitory Activity.

Chalcone has been identified as a promising lead for the design of Monoamine Oxidase (MAO) inhibitors. This study attempted to discover potent and selective chalcone-derived MAO inhibitors by synthesising a series consisting of various cyclic chalcone derivatives. The cyclic chalcones were selected based on the possibility that their restricted structures would confer a higher degree of MAO isoform selectivity, and included the following chemical classes: 1-indanone, 1- tetralone, 1-benzosuberone, chromone, thiochromone, 4-chromanone and 4-thiochromanone. The cyclic chalcone derivatives were synthesised via a one-pot Claisen-Schmidt condensation reaction. The MAO inhibitory properties of the chalcone derivatives were evaluated with the recombinant human MAO-A and MAO-B enzymes and the potencies were expressed as the IC50 values. A selected inhibitor was docked into an active site model of MAO-B. The results showed that the cyclic chalcones are in general good potency, and in most instances specific inhibitors of the MAO-B isoform. Among these compounds, the 4-chromanone derivative was the most potent MAO-B inhibitor with an IC50 value of 0.156 µM. To further investigate the MAO inhibition of cyclic chalcones, a series of twenty-three 2-benzylidene-1-tetralone derivatives were synthesised and evaluated as MAO inhibitors. Most 2-benzylidene-1-tetralones possess good inhibitory activity and specificity for MAO-B with the most potent inhibitor displaying an IC50 value of 0.0064 µM, while the most potent MAO-A inhibitor possessed an IC50 value of 0.754 µM. This study thus shows that certain cyclic chalcones are human MAO-B inhibitors, compounds that could be suitable for the treatment of neurodegenerative disorders such as Parkinson's disease.

Investigation of monoamine oxidase inhibitory activities of new chalcone derivatives

Purpose: In the present study, it is aimed to investigate monoamine oxidase (MAO) enzyme inhibition potencies of some new chalcone derivatives. Materials and Methods: Nine novel chalcone derivatives were synthesized and structures of the synthesized compounds (2a-2i) were confirmed by spectroscopic methods. Inhibitory activities of the compounds against MAO-A and MAO-B enzymes have been determined via in-vitro fluorometric method. Effects of the compounds on substrate level were measured by an LC-MS/MS method. Enzyme kinetics studies were carried out for the most active compound 2i using Lineweaver–Burk plots.Results: Compounds 2c, 2e and 2i displayed notable inhibition against hMAO-B with lower IC50 values than 1 µM. The most active compound 2i displayed significant inhibition by IC50 of 0.13 µM. Results of substrate level quantification study were in an agreement with fluorometric enzyme inhibition assay. Competitive type of inhibition was determined for compound 2i as a result of enzyme kinetic studies. Conclusion: Synthesized compounds displayed more selectivity towards hMAO-B. In this study, the results of inhibitor effects of compounds 2c, 2f and 2i are promising for the synthesis of similar derivatives with enhanced MAO inhibitory activity and therefore for the development of new molecules which may be drug candidates against Parkinson's disease.

Perinatal MAO Inhibition Produces Long-Lasting Impairment of Serotonin Function in Offspring.

In addition to transmitter functions, many neuroamines have trophic or ontogenetic regulatory effects important to both normal and disordered brain development. In previous work (Mejia et al., 2002), we showed that pharmacologically inhibiting monoamine oxidase (MAO) activity during murine gestation increases the prevalence of behaviors thought to reflect impulsivity and aggression. The goal of the present study was to determine the extent to which this treatment influences dopamine and serotonin innervation of murine cortical and subcortical areas, as measured by regional density of dopamine (DAT) and serotonin transporters (SERT). We measured DAT and SERT densities at 3 developmental times (PND 14, 35 and 90) following inhibition of MAO A, or MAO B or both throughout murine gestation and early post-natal development. DAT binding was unaltered within the nigrostriatal pathway, but concurrent inhibition of MAO-A and MAO-B significantly and specifically reduced SERT binding by 10–25% in both the frontal cortex and raphe nuclei. Low levels of SERT binding persisted (PND 35, 90) after the termination (PND 21) of exposure to MAO inhibitors and was most marked in brain structures germane to the previously described behavioral changes. The relatively modest level of enzyme inhibition (25–40%) required to produce these effects mandates care in the use of any compound which might inhibit MAO activity during gestation.