Structure-Based Design of Novel MAO-B Inhibitors: A Review

New phenylpiperazine-thiazolidine-2,4-dione hybrids targeting MAO inhibition: Synthesis, biological evaluation, kinetic study and in silico insights

Monoamine oxidase inhibitors are promising drug targets for many neurological diseases such as depression, Alzheimer's disease, and Parkinson's disease. The current study developed new hybrid compounds by merging phenyl piperazines, and 2,4-thiazolidinedione moieties based on their reported MAO inhibitory activities. The newly synthesized derivatives were screened for their MAOs inhibitory activity using in-vitro fluorometric assay. Most newly synthesized compounds elicited strong inhibitory activity against both hMAO isozymes. Hybrids 4a and 4c were the most potent hMAO-A inhibitors with IC50 values of 0.194 and 0.188 µM, respectively, compared to toloxatone as reference (IC50 = 1.080 µM), meanwhile, compound 4g exhibited the most potent inhibitory activity against MAO-B with an IC50 value of 0.330 µM. The kinetic study of compound 4c revealed that it exhibited a mixed inhibition mode with a Ki value of 3.4 nM. Compound 4c was evaluated against the normal SH-SY5Y cell line and found to be non-cytotoxic at its active inhibition concentration. ADME profiles of the most active hybrids 4a, 4c, 4j, and 4k revealed that they could serve as successful drug candidates showing good CNS penetration. Molecular docking simulations were executed for the most active motifs 4a and 4c to demonstrate the binding pattern with the target proteins explaining their potential inhibitory activity. Lastly, this study will significantly contribute to developing novel safe, effective medications for treating various neurological disorders in the foreseeable future.

Pelargonium graveolens Attenuates Rotenone-Induced Parkinson's Disease in a Rat Model: Role of MAO-B Inhibition and In Silico Study

Parkinson's disease (PD), the second most common neurodegenerative condition, is primarily characterized by motor dysfunctions due to dopaminergic neuronal loss in the Substantia Nigra (SN), with oxidative stress playing a significant role in its progression. This study investigates the neuroprotective potential of Pelargonium graveolens (Thunb.) L'Hér leaves in a rotenone-induced PD rat model. The total ethanolic extract and its fractions, obtained via Diaion HP-20 column chromatography, were evaluated for monoamine oxidase-B (MAO-B) inhibition in vitro. The 50% methanol fraction (PG50) demonstrated the highest MAO-B inhibition (IC50 5.26 ± 0.12 µg/ml) compared to the reference drug selegiline (IC50 0.021 ± 0.003 µg/ml). In a rotenone-induced PD rat model, PG50 (100 mg/kg, p.o.) alleviated motor deficits (assessed via the wire hanging test), and restored norepinephrine, dopamine, and serotonin levels. PG50 and L-dopa reduced α-synuclein levels by 367.60% and 377.48%, respectively. Oxidative balance was restored with increased glutathione (23.12%) and decreased malondialdehyde (164.19%) in brain tissues. PG50 significantly reduced serum TNF-α (572.79%) and IL-6 (70.84%) levels, and improved succinate dehydrogenase (14.47%) and lactate dehydrogenase (7.74%) activities in brain tissues. Histopathological alterations in the SN were also ceased. UPLC-MS/MS analysis identified 61 metabolites, including 32 flavonoids, 13 phenolic acids, 7 coumarins, 5 phenolic glycosides, and 4 dicarboxylic acids, with in silico docking showing strong MAO-B binding by methoxylated flavonoids like methoxyluteolin dimethyl ether (docking score: - 8.0625 kcal/mol), surpassing that of safinamide (- 8.2615 kcal/mol). These findings suggest that P. graveolens holds promise as a neuroprotective agent against rotenone-induced PD.

Elucidating the monoamine oxidase B inhibitory effect of kaurene diterpenoids from Xylopia aethiopica: An in silico approach

Parkinson disease is a neurogenerative disease common in adults and results in different kinds of memory dysfuntions. This study evaluated the monoamine oxidase B (MAO-B) inhibitory potential of kaurane diterpenoids previously isolated from Xylopia aethiopica through comprehensive computational approaches. Molecular docking study and molecular dynamics simulation were used to access the binding mode and interaction of xylopic acid and MAO-B enzyme. The ADMET properties of the phytochemical were evaluated to provide information on its druggability. The molecular docking and molecular dynamics simulation revealed xylopic acid as potential MAO-B inhibitor due to the good binding energy elicited and stability throughout the 100 ns simulation period. The ADMET properties of the ligand showed it as a promising drug candidate. The study recommend further comprehensive in vitro investigation towards the development of xylopic acid as potent MAO-B inhibitor.

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.

Investigating In silico and In vitro Therapeutic Potential of Diosmetin as the Anti-Parkinson Agent

AIM

This study aimed to investigate how diosmetin interacts with seven target receptors associated with oxidative stress (OS) and validate its antioxidant properties for the potential management of Parkinson's disease (PD).

BACKGROUND

In PD, the degeneration of dopaminergic cells is strongly influenced by OS. This stressor is intricately connected to various mechanisms involved in neurodegeneration, such as mitochondrial dysfunction, neuroinflammation, and excitotoxicity induced by nitric oxide.

OBJECTIVE

The aim of this research was to establish a molecular connection between diosmetin and OS-associated target receptors was the goal, and it investigated how this interaction can lessen PD.

METHODS

Seven molecular targets - Adenosine A2A (AA2A), Peroxisome Proliferator-Activated Receptor Gamma (PPARγ), Protein Kinase AKT1, Nucleolar Receptor NURR1, Liver - X Receptor Beta (LXRβ), Monoamine Oxidase - B (MAO-B) and Tropomyosin receptor kinase B (TrkB) were obtained from RCSB. Molecular docking software was employed to determine molecular interactions, while antioxidant activity was assessed through in vitro assays against various free radicals.

RESULTS

Diosmetin exhibited interactions with all seven target receptors at their binding sites. Notably, it showed superior interaction with AA2A and NURR1 compared to native ligands, with binding energies of -7.55, and -6.34 kcal/mol, respectively. Additionally, significant interactions were observed with PPARγ, AKT1, LXRβ, MAO-B, and TrkB with binding energies of -8.34, -5.42, -7.66, -8.82, -8.45 kcal/mol, respectively. Diosmetin also demonstrated antioxidant activity against various free radicals, particularly against hypochlorous acid (HOCl) and nitric oxide (NO) free radicals.

CONCLUSION

Diosmetin possibly acts on several target receptors linked to the pathophysiology of PD, demonstrating promise as an OS inhibitor and scavenger.

Cheminformatics approach for identification of N-HyMenatPimeMelly as a novel potential ligand against RAS and renal chloride channel

Some angiotensin receptor (AR) blockers interfere with the renal chloride channel (ClC-K), which plays an important role in urine concentration. Identifying ligands targeting this channel, whether activating or blocking, is highly desirable because it could open the way for interventions that modulate their activity. In this study, the Asinex (BioDesign) complete library was screened to identify a compound with favorable physicochemical and pharmacokinetic properties, which have both AR blocking and ClC-Ka-modulating activities to present it as a novel potential oral candidate which could be useful for treatment of salt-sensitive hypertension without major ClC-K affection. A compound, N-{[4-Hydroxy-1-(2-methyl-1,6-naphthyridin-4-yl)-4-piperidinyl]methyl}-N-methyl-L-lysinamide (N-HyMenatPimeMelly) (Chem Spider ID 68416221), was identified as a potent potential oral ligand of the renin-angiotensin system (RAS) and ClC-Ka with docking scores ranging from -10.978 to -7.324 with the four selected proteins (4YAY: AR type 1, 2PFI: Cytoplasmic domain of ClC-Ka, 6JOD: AR type 2 and 6M0J: Angiotensin-converting enzyme 2). The protein-ligand complex was used to perform molecular dynamics (MD) simulation for 100 ns. The QikProp and SwissADME tools' results showed that the compound has ADME/T and drug-likeness properties, which are within the permissible ranges for 95% of known drugs. The density functional theory (DFT) analysis and MD simulation extended the study toward computational validation. Throughout the study, N-HyMenatPimeMelly has shown good interactions and stable performance in MD simulation and DFT analysis. The whole analysis has produced promising results, and N-HyMenatPimeMelly can be treated as a novel potential RAS and ClC-K oral ligand, however, experimental validation is needed before human use.Communicated by Ramaswamy H. Sarma.