A magnetic beads-based ligand fishing method for rapid discovery of monoterpene indoles as monoamine oxidase A inhibitors from Hunteria zeylanica.

In this study, a novel magnetic bead-based ligand fishing method was developed for rapid discovery of monoterpene indoles as monoamine oxidase A inhibitors from natural products. In order to improve the screening efficiency, two different magnetic beads, i.e. amine and carboxyl terminated magnetic beads, were comprehensively compared in terms of their ability to immobilize monoamine oxidase A (MAOA), biocatalytic activity and specific adsorption rates for affinity ligands. Carboxyl terminated magnetic beads performed better for MAOA immobilization and demonstrated superior performance in ligand fishing. The MAOA immobilized magnetic beads were applied to screen novel monoamine oxidase inhibitors in an alkaloid-rich plant, Hunteria zeylanica. Twelve MAOA affinity ligands were screened out, and ten of them were identified as monoterpene indole alkaloids by HPLC-Obitrap-MS/MS. Among them, six ligands, namely geissoschizol, vobasinol, yohimbol, dihydrocorynanthenol, eburnamine and (+)-isoeburnamine which exhibited inhibitory activity against MAOA with low IC50 values. To further explore their inhibitory mechanism, enzyme kinetic analysis and molecular docking studies were conducted.

Machine learning accelerates pharmacophore-based virtual screening of MAO inhibitors.

Nowadays, an efficient and robust virtual screening procedure is crucial in the drug discovery process, especially when performed on large and chemically diverse databases. Virtual screening methods, like molecular docking and classic QSAR models, are limited in their ability to handle vast numbers of compounds and to learn from scarce data, respectively. In this study, we introduce a universal methodology that uses a machine learning-based approach to predict docking scores without the need for time-consuming molecular docking procedures. The developed protocol yielded 1000 times faster binding energy predictions than classical docking-based screening. The proposed predictive model learns from docking results, allowing users to choose their preferred docking software without relying on insufficient and incoherent experimental activity data. The methodology described employs multiple types of molecular fingerprints and descriptors to construct an ensemble model that further reduces prediction errors and is capable of delivering highly precise docking score values for monoamine oxidase ligands, enabling faster identification of promising compounds. An extensive pharmacophore-constrained screening of the ZINC database resulted in a selection of 24 compounds that were synthesized and evaluated for their biological activity. A preliminary screen discovered weak inhibitors of MAO-A with a percentage efficiency index close to a known drug at the lowest tested concentration. The approach presented here can be successfully applied to other biological targets as target-specific knowledge is not incorporated at the screening phase.

Enzyme Inhibition Assays for Monoamine Oxidase.

Monoamine oxidase (MAO) catalyzes the oxidative deamination of monoamines with two isoforms, namely, MAO-A and MAO-B, in mitochondrial outer membranes. These two types of MAO-A and MAO-B participate in changes in levels of neurotransmitter such as serotonin (5-hydroxytryptamine) and dopamine. Selective MAO-A inhibitors have been targeted for anti-depression treatment, while selective MAO-B inhibitors are targets of therapeutic agents for Alzheimer's disease and Parkinson's disease. For this reason, study on the development of MAO inhibitors has recently become important. Here, we describe methods of MAO activity assay, especially continuous spectrophotometric methods, which give relatively high accuracy. MAO-A and MAO-B can be assayed using kynuramine and benzylamine as substrates, respectively, at 316 nm and 250 nm, respectively, to measure their respective products, 4-hydroxyquinoline and benzaldehyde. Inhibition degree and pattern can be analyzed by using the Lineweaver-Burk and secondary plots in the presence of inhibitor, and reversibility of inhibitor can be determined by using the dialysis method.

Dual Inhibitors of Brain Carbonic Anhydrases and Monoamine Oxidase-B Efficiently Protect against Amyloid-ß-Induced Neuronal Toxicity, Oxidative Stress, and Mitochondrial Dysfunction.

We report here the first dual inhibitors of brain carbonic anhydrases (CAs) and monoamine oxidase-B (MAO-B) for the management of Alzheimer's disease. Classical CA inhibitors (CAIs) such as methazolamide prevent amyloid-ß-peptide (Aß)-induced overproduction of reactive oxygen species (ROS) and mitochondrial dysfunction. MAO-B is also implicated in ROS production, cholinergic system disruption, and amyloid plaque formation. In this work, we combined a reversible MAO-B inhibitor of the coumarin and chromone type with benzenesulfonamide fragments as highly effective CAIs. A hit-to-lead optimization led to a significant set of derivatives showing potent low nanomolar inhibition of the target brain CAs (KIs in the range of 0.1-90.0 nM) and MAO-B (IC50 in the range of 6.7-32.6 nM). Computational studies were conducted to elucidate the structure-activity relationship and predict ADMET properties. The most effective multitarget compounds totally prevented Aß-related toxicity, reverted ROS formation, and restored the mitochondrial functionality in an SH-SY5Y cell model surpassing the efficacy of single-target drugs.

Safety, Tolerability, and Pharmacokinetics of the Monoamine Oxidase B Inhibitor, HEC122505, and its Major Metabolite After Single- and Multiple- Ascending Dose, and Food Effect Study in Healthy Chinese Subjects.

BACKGROUND AND OBJECTIVES: HEC122505 is a potent and selectively monoamine oxidase B inhibitor that is safe and well-tolerated in preclinical models of Parkinson's disease. The objectives of single ascending dose and multiple dose pharmacokinetic trials of HEC122505 oral tablets were to determine the safety and tolerability of HEC122505, and to examine the food effect on the pharmacokinetic parameters of HEC122505 and its major metabolite HEC129870. METHODS: The phase I study (NCT04625361) consisted of three arms: single ascending dose study (5, 20, 50, 100, 200, 300 or 400 mg HEC122505 tablets or placebo), multiple ascending dose study (20, 50 or 100 mg HEC122505 tablets or placebo once daily), and food effect (100 mg HEC122505 tablets single dose after a high-fat, high-calorie meal). All subjects completed all trial arms and were analyzed as planned. RESULTS: Pharmacokinetic analysis showed that HEC122505 rapidly absorbed with the time to peak plasma concentration (Tmax) ranged from 0.5 to 1.75 h. In addition, maximum plasma drug concentration (Cmax) and area under the plasma concentration-time curve (AUC) increased in a dose proportional manner. Food effect study showed that a high-fat, high-calorie meal had no significant effect on the pharmacokinetics of HEC122505 and its major metabolite HEC129870, suggesting that HEC122505 could be administered in both fasted and fed state in clinical trials. The subsequent multiple-dose study evaluated doses from 20 to 100 mg dose once daily for up to 8 days. HEC122505 reached steady state after approximately 5 days with a once daily dose. In these studies, all dose of HEC122505 was generally safe and well tolerated. No grade ≥ 3 drug related adverse events (AEs) occurred. CONCLUSION: HEC122505 was generally safe and well tolerated in the single ascending dose (ranging from 5 to 400 mg) and multiple ascending dose (50 to 200 mg once daily doses) studies. All the drug related adverse events (AEs) were Grade ≤ 2. There were no deaths, no subjects discontinued the trial due to AEs, and there were no other serious AEs. The safety and pharmacokinetic profile support once daily administration of HEC122505.

Potent, selective and reversible hMAO-B inhibition by benzalphthalides: Synthesis, enzymatic and cellular evaluations and virtual docking and predictive studies.

Monoaminooxidases (MAOs) are important targets for drugs used in the treatment of neurological and psychiatric disorders and particularly on Parkinson's Disease (PD). Compounds containing a trans-stilbenoid skeleton have demonstrated good selective and reversible MAO-B inhibition. Here, twenty-two (Z)-3-benzylidenephthalides (benzalphthalides, BPHs) displaying a trans-stilbenoid skeleton have been synthesised and evaluated as inhibitors of the MAO-A and MAO-B isoforms. Some BPHs have selectively inhibited MAO-B, with IC50 values ranging from sub-nM to µM. The most potent compound with IC50 = 0.6 nM was the 3',4'-dichloro-BPH 16, which showed highly selective and reversible MAO-B inhibitory activity. Furthermore, the most selective BPHs displayed a significant protection against the apoptosis, and mitochondrial toxic effects induced by 6-hydroxydopamine (6OHDA) on SH-SY5Y cells, used as a cellular model of PD. The results of virtual binding studies on the most potent compounds docked in MAO-B and MAO-A were in agreement with the potencies and selectivity indexes found experimentally. Additionally, related to toxicity risks, drug-likeness and ADME properties, the predictions found for the most relevant BPHs in this research were within those ranges established for drug candidates.

Probing the inhibition of MAO-B by chalcones: an integrated approach combining molecular docking, ADME analysis, MD simulation, and MM-PBSA calculations.

CONTEXT: Monoamine oxidase B (MAO-B), an enzyme of significant relevance in the realm of neurodegenerative disorders, has garnered considerable attention as a potential target for therapeutic intervention. Natural compounds known as chalcones have shown potential as MAO-B inhibitors. In this particular study, we employed a multimodal computational method to evaluate the inhibitory effects of chalcones on MAO-B. METHODS: Molecular docking methods were used to study and assess the complicated binding interactions that occur between chalcones and MAO-B. This extensive analysis provided a valuable and deep understanding of possible binding methods as well as the key residues implicated in the inhibition process. Furthermore, the ADME investigation gave valuable insights into the pharmacokinetic properties of chalcones. This allowed them to be assessed in terms of drug-like attributes. The use of MD simulations has benefited in the research of ligand-protein interactions' dynamic behaviour and temporal stability. MM-PBSA calculations were also done to estimate the binding free energies and acquire a better knowledge and understanding of the binding affinity between chalcones and MAO-B. Our thorough method gives a thorough knowledge of chalcones' potential as MAO-B inhibitors, which will be useful for future experimental validation and drug development efforts in the context of neurodegenerative illnesses.

Synergistic utility of NBD-Cl fluorogenic loading activity and salting-out assisted liquid-liquid extraction as sample pretreatment in rasagiline tracking in different matrices.

A typical drug used to treat Parkinson's disease is called rasagiline. It belongs to an assortment of drugs known as monoamine oxidase inhibitors, which function by raising dopamine levels in the brain. This work created a unique spectrofluorimetric method for the analytical assay of rasagiline for the first time. The approach utilized the synergistic utility of the fluorogenic properties of benzofurazan and salting-out assisted liquid-liquid extraction. By combining these techniques an ultrasensitive, and highly selective methodology for the assay of rasagiline was established. Measurements were made of the resultant yellow fluorescent product at 533 nm by applying an excitation wavelength of 475.3 nm. The calibration graph was examined to assess its linearity across a range of 30-600 ng/ml. Through estimation, the limit of detection was discovered to be 8.9 ng/ml, while the quantitation limit was estimated to be 27 ng/ml. All relevant parameters influencing the fulfillment of the developed method were thoroughly examined and tuned. Following the directives set by the (ICH) the suggested approach was confirmed and demonstrated its capability for the accurate determination of rasagiline in tablets, as well as for testing content uniformity. The incorporation of salting-out assisted liquid-liquid extraction technology enables effective tracking of rasagiline in plasma samples, providing a novel and innovative approach for its analysis in biological matrices.

Novel 6-hydroxybenzothiazol-2-carboxamides as potent and selective monoamine oxidase B inhibitors endowed with neuroprotective activity.

In neurodegenerative diseases, using a single molecule that can exert multiple effects to modify the disease may have superior activity over the classical "one molecule-one target" approach. Herein, we describe the discovery of 6-hydroxybenzothiazol-2-carboxamides as highly potent and selective MAO-B inhibitors. Variation of the amide substituent led to several potent compounds having diverse side chains with cyclohexylamide 40 displaying the highest potency towards MAO-B (IC50 = 11 nM). To discover new compounds with extended efficacy against neurotoxic mechanisms in neurodegenerative diseases, MAO-B inhibitors were screened against PHF6, R3 tau, cellular tau and α-synuclein (α-syn) aggregation. We identified the phenethylamide 30 as a multipotent inhibitor of MAO-B (IC50 = 41 nM) and α-syn and tau aggregation. It showed no cytotoxic effects on SH-SY5Y neuroblastoma cells, while also providing neuroprotection against toxicities induced by α-syn and tau. The evaluation of key physicochemical and in vitro-ADME properties revealed a great potential as drug-like small molecules with multitarget neuroprotective activity.

Machine learning driven web-based app platform for the discovery of monoamine oxidase B inhibitors.

Monoamine oxidases (MAOs), specifically MAO-A and MAO-B, play important roles in the breakdown of monoamine neurotransmitters. Therefore, MAO inhibitors are crucial for treating various neurodegenerative disorders, including Parkinson's disease (PD), Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS). In this study, we developed a novel cheminformatics pipeline by generating three diverse molecular feature-based machine learning-assisted quantitative structural activity relationship (ML-QSAR) models concerning MAO-B inhibition. PubChem fingerprints, substructure fingerprints, and one-dimensional (1D) and two-dimensional (2D) molecular descriptors were implemented to unravel the structural insights responsible for decoding the origin of MAO-B inhibition in 249 non-reductant molecules. Based on a random forest ML algorithm, the final PubChem fingerprint, substructure fingerprint, and 1D and 2D molecular descriptor prediction models demonstrated significant robustness, with correlation coefficients of 0.9863, 0.9796, and 0.9852, respectively. The significant features of each predictive model responsible for MAO-B inhibition were extracted using a comprehensive variance importance plot (VIP) and correlation matrix analysis. The final predictive models were further developed as a web application, MAO-B-pred ( https://mao-b-pred.streamlit.app/ ), to allow users to predict the bioactivity of molecules against MAO-B. Molecular docking and dynamics studies were conducted to gain insight into the atomic-level molecular interactions between the ligand-receptor complexes. These findings were compared with the structural features obtained from the ML-QSAR models, which supported the mechanistic understanding of the binding phenomena. The presented models have the potential to serve as tools for identifying crucial molecular characteristics for the rational design of MAO-B target inhibitors, which may be used to develop effective drugs for neurodegenerative disorders.

α-Viniferin, a dietary phytochemical, inhibits Monoamine oxidase and alleviates Parkinson's disease associated behavioral deficits in a mice model.

Parkinson's disease (PD) is one of the most prevalent age-related neurodegenerative disorders. Behavioral complexities worsen over time due to progressive dopaminergic (DArgic) neuronal loss at substantia nigra region of brain. Available treatments typically aim to increase dopamine (DA) levels at striatum. DA is degraded by Monoamine oxidase (MAO), thus dietary phytochemicals with MAO inhibitory properties can contribute to elevate DA levels and reduce the ailment. Characterization of naturally occurring dietary MAO inhibitors is inadequate. Based on available knowledge, we selected different classes of molecules and conducted a screening process to assess their potential as MAO inhibitors. The compounds mostly derived from food sources, broadly belonging to triterpenoids (ursane, oleanane and hopane), alkaloid, polyphenolics, monoterpenoids, alkylbenzene, phenylpropanoid and aromatic alcohol classes. Among all the molecules, highest level of MAO inhibition is offered by α-viniferin, a resveratrol trimer. Cell viability, mitochondrial morphology and reactive oxygen species (ROS) generation remained unaltered by 50 µM α-viniferin treatment in-vitro. Toxicity studies in Drosophila showed unchanged gross neuronal morphology, ROS level, motor activity or long-term survival. α-Viniferin inhibited MAO in mice brain and elevated striatal DA levels. PD-related akinesia and cataleptic behavior were attenuated by α-viniferin due to increase in striatal DA. Our study implies that α-viniferin can be used as an adjunct phytotherapeutic agent for mitigating PD-related behavioral deterioration.

Monoamine oxidase B activatable red fluorescence probe for bioimaging in cells and zebrafish.

A real-time and specific for the detection of Monoamine Oxidase B (MAO-B) to investigate the MAO-B-relevant disease development and treatment process is urgently desirable. Here, we utilized MAO-B to catalyze the conversion of propylamino groups to aldehyde groups, which was then quickly followed by a ß-elimination process to produce fluorescent probes (FNJP) that may be used to detect MAO-B in vitro and in vivo. The FNJP probe possesses unique properties, including favorable reactivity (Km = 10.8 µM), high cell permeability, and NIR characteristics (λem = 610 nm). Moreover, the FNJP probe showed high selectivity for MAO-B and was able to detect endogenous MAO-B levels from a mixed population of NIH-3 T3 and HepG2 cells. MAO-B expression was found to be increased in cells under lipopolysaccharide-stimulated cellular oxidative stress in neuronal-like SH-SY5Y cells. In addition, the visualization of FNJP for MAO-B activity in zebrafish can be an effective tool for exploring the biofunctions of MAO-B. Considering these excellent properties, the FNJP probe may be a powerful tool for detecting MAO-B levels in living organisms and can be used for accurate clinical diagnoses of related diseases.

Exploration of oxadiazole clubbed benzhydrylpiperazine pharmacophoric features as structural feature for antidepressant activity: In vitro, in vivo and in silico analysis.

Arylpiperazine clubbed various heterocyclic molecules present potential pharmacophoric structural features for the development of psychoactive drugs. There are various CNS active molecules possessing arylpiperazine moiety in their pharmacophore approved by USFDA. In the current study, we have explored the benzhydrylpiperazine moiety clubbed with various substituted oxadiazole moieties (AP1-12) for their monoamine oxidase (MAO) inhibition and antidepressant potential. Compounds AP3 and AP12 exhibited highly potent and selective MAO-A inhibition with IC50 values of 1.34 ± 0.93 µM and 1.13 ± 0.54 µM, respectively, and a selectivity index of 10- and 13-folds, respectively. Both the compounds displayed reversible binding character at the active site of MAO-A. In further in vivo evaluation, both the compounds AP3 and AP12 displayed potential antidepressant-like character in FST and TST studies via significantly reduced immobility time in comparison to non-treated animals. These compounds displayed no cytotoxicity in SH-SY5Y cell lines, which indicates that these compounds are safe for further evaluation. In silico studies reveal that synthesized compounds possess drug-likeness with minimal to no toxicity. In silico studies were conducted to understand the binding interactions and stability of compounds at the binding pocket of enzyme and observed that both the best compounds fit well at the active site of MAO-A lined by amino acid residues Tyr69, Asn181, Phe208, Ile335, Leu337, Phe352, and Tyr444 similar to standard MAO-A inhibitor clorgiline. The molecular dynamic studies demonstrated that AP3 and AP12 formed quite a stable complex at the active site of MAO-A and did not break under small abruption forces. The favourable binding interactions and appropriate ADMET properties present the benzhydrylpiperazine clubbed oxadiazole pharmacophoric features as a potential structural skeleton for further clinical evaluation and development of a new antidepressant drug molecule.

Update Lessons from PET Imaging Part II: A Systematic Critical Review on Therapeutic Plasma Concentrations of Antidepressants.

BACKGROUND: Compared with antipsychotics, the relationship between antidepressant blood (plasma or serum) concentrations and target engagement is less well-established. METHODS: We have discussed the literature on the relationship between plasma concentrations of antidepressant drugs and their target occupancy. Antidepressants reviewed in this work are citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, venlafaxine, duloxetine, milnacipran, tricyclic antidepressants (amitriptyline, nortriptyline, and clomipramine), bupropion, tranylcypromine, moclobemide, and vortioxetine. Four electronic databases were systematically searched. RESULTS: We included 32 articles published 1996-2022. A strong relationship between serotonin transporter (SERT) occupancy and drug concentration is well established for selective serotonin reuptake inhibitors. Lower limits of recommended therapeutic reference ranges largely corroborate with the findings from positron emission tomography studies (80% SERT occupancy). Only a few novel studies have investigated alternative targets, that is, norepinephrine transporters (NETs), dopamine transporters (DATs), or monoamine oxidase A (MAO-A). For certain classes of drugs, positron emission tomography study data are inconclusive. Low DAT occupancy after bupropion treatment speculates its discussed mechanism of action. For MAO inhibitors, a correlation between drug concentration and MAO-A occupancy could not be established. CONCLUSIONS: Neuroimaging studies are critical in TDM-guided therapy for certain antidepressants, whereas for bupropion and MAO inhibitors, the available evidence offers no further insight. Evidence for selective serotonin reuptake inhibitors is strong and justifies a titration toward suggested ranges. For SNRIs, duloxetine, and venlafaxine, NETs are sufficiently occupied, well above the SERT efficacy threshold. For these drugs, a titration toward higher concentrations (within the recommended range) should be considered in case of no response at lower concentrations.

KDS2010, a reversible MAO-B inhibitor, extends the lifetime of neural probes by preventing glial scar formation.

Implantable neural probes have been extensively utilized in the fields of neurocircuitry, systems neuroscience, and brain-computer interface. However, the long-term functionality of these devices is hampered by the formation of glial scar and astrogliosis at the surface of electrodes. In this study, we administered KDS2010, a recently developed reversible MAO-B inhibitor, to mice through ad libitum drinking in order to prevent glial scar formation and astrogliosis. The administration of KDS2010 allowed long-term recordings of neural signals with implantable devices, which remained stable over a period of 6 months and even restored diminished neural signals after probe implantation. KDS2010 effectively prevented the formation of glial scar, which consists of reactive astrocytes and activated microglia around the implant. Furthermore, it restored neural activity by disinhibiting astrocytic MAO-B dependent tonic GABA inhibition induced by astrogliosis. We suggest that the use of KDS2010 is a promising approach to prevent glial scar formation around the implant, thereby enabling long-term functionality of neural devices.

Isatin-tethered halogen-containing acylhydrazone derivatives as monoamine oxidase inhibitor with neuroprotective effect.

Sixteen isatin-based hydrazone derivatives (IS1-IS16) were synthesized and assessed for their ability to inhibit monoamine oxidases (MAOs). All the molecules showed improved inhibitory MAO-B activity compared to MAO-A. Compound IS7 most potently inhibited MAO-B with an IC50 value of 0.082 µM, followed by IS13 and IS6 (IC50 = 0.104 and 0.124 µM, respectively). Compound IS15 most potently inhibited MAO-A with an IC50 value of 1.852 µM, followed by IS3 (IC50 = 2.385 µM). Compound IS6 had the highest selectivity index (SI) value of 263.80, followed by IS7 and IS13 (233.85 and 212.57, respectively). In the kinetic study, the Ki values of IS6, IS7, and IS13 for MAO-B were 0.068 ± 0.022, 0.044 ± 0.002, and 0.061 ± 0.001 µM, respectively, and that of IS15 for MAO-A was 1.004 ± 0.171 µM, and the compounds were reversible-type inhibitors. The lead compounds were central nervous system (CNS) permeable, as per parallel artificial membrane permeability assay (PAMPA) test results. The lead compounds were examined for their cytotoxicity and potential neuroprotective benefits in hazardous lipopolysaccharide (LPS)-exposed SH-SY5Y neuroblastoma cells. Pre-treatment with lead compounds enhanced anti-oxidant levels (SOD, CAT, GSH, and GPx) and decreased ROS and pro-inflammatory cytokine (IL-6, TNF-alpha, and NF-kB) production in LPS-intoxicated SH-SY5Y cells. To confirm the promising effects of the compound, molecular docking, dynamics, and MM-GBSA binding energy were used to examine the molecular basis of the IS7-MAO-B interaction. Our findings indicate that lead compounds are potential therapeutic agents to treat neurological illnesses, such as Parkinson's disease.

Identification and Characterization of Neuroprotective Properties of Thaumatin-like Protein 1a from Annurca Apple Flesh Polyphenol Extract.

BACKGROUND: Alzheimer's disease (AD) and Parkinson's disease (PD) are multifactorial neurodegenerative disorders that are mostly treated with drugs inhibiting key enzymes of cholinergic and aminergic neurotransmission, such as acetyl and butyryl cholinesterase (AChE, BuChE) or monoamine oxidases (MAO)-A/B, and of Aß1-40 aggregation. Diet plant components with multitarget functions are promising compounds in the prevention of AD and PD. Our aim was to identify neuroprotective compounds from Annurca apple polyphenol extract (AFPE). METHODS: AFPE was fractionated by gel filtration, and the eluted peaks were subjected to chemical analyses (i.e., RP-HPLC and mass spectrometry), determination of inhibitory enzyme activity and cell effects by MTT, and morphology assays. RESULTS: In AFPE, we identified thaumatin-like protein 1a, belonging to the pathogenesis-related protein (PR) family. This protein showed the best inhibitory activity on AChE, MAO-A (IC50 = 5.53 µM and 1.71 µM, respectively), and Aß1-40 fibril aggregation (IC50 = 9.16 µM), compared to AFPE and other polyphenol-containing fractions. Among the latter, Peak 4 reverted Aß fibril formation (IC50 = 104.87 µM). Moreover, thaumatin-like protein 1a protected AGS and MKN-28 cells from serum-deprivation-induced stress conditions. CONCLUSIONS: We showed that AFPE exerted neuroprotective functions not only through its polyphenols but also through thaumatin-like protein 1a, which acted like a multitarget molecule.

Potential of Tryptamine Derivatives as Multi-Target Directed Ligands for Alzheimer's Disease: AChE, MAO-B, and COX-2 as Molecular Targets.

Extensive research has been dedicated to develop compounds that can target multiple aspects of Alzheimer's disease (AD) treatment due to a growing understanding of AD's complex multifaceted nature and various interconnected pathological pathways. In the present study, a series of biological assays were performed to evaluate the potential of the tryptamine analogues synthesized earlier in our lab as multi-target-directed ligands (MTDLs) for AD. To assess the inhibitory effects of the compounds, various in vitro assays were employed. Three compounds, SR42, SR25, and SR10, displayed significant AChE inhibitory activity, with IC50 values of 0.70 µM, 0.17 µM, and 1.00 µM, respectively. These values superseded the standard drug donepezil (1.96 µM). In the MAO-B inhibition assay, SR42 (IC50 = 43.21 µM) demonstrated superior inhibitory effects as compared to tryptamine and other derivatives. Moreover, SR22 (84.08%), SR24 (79.30%), and SR42 (75.16%) exhibited notable percent inhibition against the COX-2 enzyme at a tested concentration of 100 µM. To gain insights into their binding mode and to validate the biological results, molecular docking studies were conducted. Overall, the results suggest that SR42, a 4,5 nitro-benzoyl derivative of tryptamine, exhibited significant potential as a MTDL and warrants further investigation for the development of anti-Alzheimer agents.

Effect of Hydroxytyrosol Derivatives of Donepezil on the Activity of Enzymes Involved in Neurodegenerative Diseases and Oxidative Damage.

Monoamine oxidase and xanthine oxidase inhibitors represent useful multi-target drugs for the prevention, attenuation, and treatment of oxidative damage and neurodegenerative disorders. Chimeric molecules, constituted by naturally derived compounds linked to drugs, represent lead compounds to be explored for the discovery of new synthetic drugs acting as enzyme inhibitors. We have previously reported that seven hydroxytyrosol-donepezil hybrid compounds play a protective role in an in vitro neuronal cell model of Alzheimer's disease. In this work, we analyzed the effects exerted by the hybrid compounds on the activity of monoamine oxidase A (MAO-A) and B (MAO-B), as well as on xanthine oxidase (XO), enzymes involved in both neurodegenerative disorders and oxidative stress. The results pointed to the identification, among the compounds tested, of selective inhibitors between the two classes of enzymes. While the 4-hydroxy-3-methoxyphenethyl 1-benzylpiperidine-4-carboxylate- (HT3) and the 4-hydroxyphenethyl 1-benzylpiperidine-4-carboxylate- donepezil derivatives (HT4) represented the best inhibitors of MAO-A, with a scarce effect on MAO-B, they were almost ineffective on XO. On the other hand, the 4,5-dihydroxy-2-nitrophenethyl 1-benzylpiperidine-4-carboxylate donepezil derivative (HT2), the least efficient MAO inhibitor, acted like the best XO inhibitor. Therefore, the differential enzymatic targets identified among the hybrid compounds synthesized enhance the possible applications of these polyphenol-donepezil hybrids in neurodegenerative disorders and oxidative stress.

Synthesis of 2,8-Dioxabicyclo[3.3.1]nonane Derivatives and Their Neuroprotective Activities.

Twenty natural-product-like 2,8-dioxabicyclo[3.3.1]nonane derivatives were synthesized and their neuroprotective activities were tested using human monoamine oxidases (MAO) A and B and acetyl and butyryl cholinesterases (ChE). Compound 1s showed inhibitory activity for MAO-A, MAO-B and acetylcholinesterase (AChE) (IC50 values 34.0, 2.3 and 11.0 µM, respectively). The inhibition mode of (-)-1s for MAO-B was investigated. Chiral HPLC of (±)-1s separated the enantiomers and (-)-1s showed MAO-B inhibitory activity. Molecular docking simulation of (-)-1s and MAO-B revealed the binding mode.