Synthesis and Pharmacological Evaluation of Novel Triazole-Pyrimidine Hybrids as Potential Neuroprotective and Anti-neuroinflammatory Agents.

OBJECTIVE: Neuroprotection is a precise target for the treatment of neurodegenerative diseases, ischemic stroke, and traumatic brain injury. Pyrimidine and its derivatives have been proven to use antiviral, anticancer, antioxidant, and antimicrobial activity prompting us to study the neuroprotection and anti-inflammatory activity of the triazole-pyrimidine hybrid on human microglia and neuronal cell model. METHODS: A series of novel triazole-pyrimidine-based compounds were designed, synthesized and characterized by mass spectra, 1HNMR, 13CNMR, and a single X-Ray diffraction analysis. Further, the neuroprotective, anti-neuroinflammatory activity was evaluated by cell viability assay (MTT), Elisa, qRT-PCR, western blotting, and molecular docking. RESULTS: The molecular results revealed that triazole-pyrimidine hybrid compounds have promising neuroprotective and anti-inflammatory properties. Among the 14 synthesized compounds, ZA3-ZA5, ZB2-ZB6, and intermediate S5 showed significant anti-neuroinflammatory properties through inhibition of nitric oxide (NO) and tumor necrosis factor-α (TNF-α) production in LPS-stimulated human microglia cells. From 14 compounds, six (ZA2 to ZA6 and intermediate S5) exhibited promising neuroprotective activity by reduced expression of the endoplasmic reticulum (ER) chaperone, BIP, and apoptosis marker cleaved caspase-3 in human neuronal cells. Also, a molecular docking study showed that lead compounds have favorable interaction with active residues of ATF4 and NF-kB proteins. CONCLUSION: The possible mechanism of action was observed through the inhibition of ER stress, apoptosis, and the NF-kB inflammatory pathway. Thus, our study strongly indicates that the novel scaffolds of triazole-pyrimidine-based compounds can potentially be developed as neuroprotective and anti-neuroinflammatory agents.

Novel triazole-sulfonamide bearing pyrimidine moieties with carbonic anhydrase inhibitory action: Design, synthesis, computational and enzyme inhibition studies.

A series of new triazole-sulfonamide bearing pyrimidine derivatives were designed and synthesized via click chemistry. All new compounds (SH-1 to SH-28) were validated by 1HNMR, 13CNMR, HRMS, and SH-3 was further structurally validated by X-Ray single diffraction study. These compounds (SH-1 to SH-28) were tested as inhibitors of human carbonic anhydrase (hCA) isoforms, such as hCA I, II, IX and XII, using a stopped flow CO2 hydrase assay. Most of the compounds exhibited significant inhibitory activity against hCA II and weak inhibitory activity against hCA I. The target compounds also displayed moderate to excellent inhibitory activity against tumor-related hCAs IX and XII. Some compounds, e.g., SH-20 (Ki = 9.4 nM), SH-26 (Ki = 1.8 nM) and SH-28 (Ki = 0.82 nM) exhibited excellent inhibitory activity and selectivity profile against hCAs XII over IX. SH-23 displayed promising inhibitory activity and selectivity profile against both tumor-related hCAs IX (Ki = 2.9 nM) as well as XII (Ki = 0.82 nM) over hCA I and II. To understand the molecular interactions, molecular docking study of compounds SH-20, SH-23, SH-26 and SH-28 with hCA XII and SH-23 also with hCA IX were performed. The computational study evidenced favorable interaction between the inhibitors and active residues of both proteins. Some of these derivatives are promising leads for the development of selective, anticancer agents based on CA inhibitors.

Dual targeting of acetylcholinesterase and tau aggregation: Design, synthesis and evaluation of multifunctional deoxyvasicinone analogues for Alzheimer's disease.

Development of multitargeted ligands have demonstrated remarkable efficiency as potential therapeutics for Alzheimer's disease (AD). Herein, we reported a new series of deoxyvasicinone analogues as dual inhibitor of acetylcholinesterase (AChE) and tau aggregation that function as multitargeted ligands for AD. All the multitargeted ligands 11(a-j) and 15(a-g) were designed, synthesized, and validated by 1HNMR, 13CNMR and mass spectrometry. All the synthesized compounds 11(a-j) and 15(a-g) were screened for their ability to inhibit AChE, BACE1, amyloid fibrillation, α-syn aggregation, and tau aggregation. All the screened compounds possessed weak inhibition of BACE-1, Aß42 and α-syn aggregation. However, several compounds were identified as potential hits in the AChE inhibitory screening assay and cellular tau aggregation screening. Among all compounds, 11f remarkably inhibited AChE activity and cellular tau oligomerization at single-dose screening (10 µM). Moreover, 11f displayed a half-maximal inhibitory concentration (IC50) value of 0.91 ± 0.05 µM and half-maximal effective concentration (EC50) value of 3.83 ± 0.51 µM for the inhibition of AChE and cellular tau oligomerization, respectively. In addition, the neuroprotective effect of 11f was determined in tau-expressing SH-SY5Y cells incubated with Aß oligomers. These findings highlighted the potential of 11f to function as a multifunctional ligand for the development of promising anti-AD drugs.

Discovery of Quinolinone Hybrids as Dual Inhibitors of Acetylcholinesterase and Aß Aggregation for Alzheimer's Disease Therapy.

The development of multitargeted therapeutics has evolved as a promising strategy to identify efficient therapeutics for neurological disorders. We report herein new quinolinone hybrids as dual inhibitors of acetylcholinesterase (AChE) and Aß aggregation that function as multitargeted ligands for Alzheimer's disease. The quinoline hybrids (AM1-AM16) were screened for their ability to inhibit AChE, BACE1, amyloid fibrillation, α-syn aggregation, and tau aggregation. Among the tested compounds, AM5 and AM10 inhibited AChE activity by more than 80% at single-dose screening and possessed a remarkable ability to inhibit the fibrillation of Aß42 oligomers at 10 µM. In addition, dose-dependent screening of AM5 and AM10 was performed, giving half-maximal AChE inhibitory concentration (IC50) values of 1.29 ± 0.13 and 1.72 ± 0.18 µM, respectively. In addition, AM5 and AM10 demonstrated concentration-dependent inhibitory profiles for the aggregation of Aß42 oligomers with estimated IC50 values of 4.93 ± 0.8 and 1.42 ± 0.3 µM, respectively. Moreover, the neuroprotective properties of the lead compounds AM5 and AM10 were determined in SH-SY5Y cells incubated with Aß oligomers. This work would enable future research efforts aiming at the structural optimization of AM5 and AM10 to develop potent dual inhibitors of AChE and amyloid aggregation. Furthermore, the in vivo assay confirmed the antioxidant activity of compounds AM5 and AM10 through increasing GSH, CAT, and SOD activities that are responsible for scavenging the ROS and restoring its normal level. Blood investigation illustrated the protective activity of the two compounds against lead-induced neurotoxicity through retaining hematological and liver enzymes near normal levels. Finally, immunohistochemistry investigation revealed the inhibitory activity of ß-amyloid (Aß) aggregation.

Identification, in-vitro anti-plasmodial assessment and docking studies of series of tetrahydrobenzothieno[2,3-d]pyrimidine-acetamide molecular hybrids as potential antimalarial agents.

Malaria is the most lethal parasitic infections in the world. To address the emergence of drug resistance to current antimalarials, here we report the design and synthesis of new series of tetrahydrobenzothieno[2,3-d]pyrimidine-acetamide hybrids by using multicomponent Petasis reaction as the key step and evaluated in vitro for their antimalarial effectiveness. The structure of all the compounds were confirmed by NMR Spectroscopy and mass spectrometry. Most of the compounds showed potent antimalarial activity against both CQ-sensitive (3D7) and CQ-resistant (W2) strains. A8, A5, and A4 are the most potent compounds that showed excellent anti-plasmodial activity against CQ-resistant strain in the nanomolar range with IC50 values 55.7 nM, 60.8 nM, and 68.0 nM respectively. To assess the parasite selectivity, the in vitro cytotoxicity of selected compounds (A3-A6, A8) was tested against HPL1D cells, demonstrating low cytotoxicity with high selectivity indices. Furthermore, these compounds were also evaluated on two additional human cancerous cell lines (A549 and MDA-MB-231), confirming their anticancer effectiveness. The in vitro hemolysis assay also showed the non-toxicity of these compounds on normal uninfected human RBCs. The interaction of these hybrids was also investigated by the molecular docking studies in the binding site of wild type Pf-DHFR-TS and quadruple mutant Pf-DHFR-TS. The in silico ADMET profiling also revealed promising physicochemical and pharmacokinetic parameters for the most active hybrids, which provide strong vision for further development of potential antimalarials.

Development of benzene and benzothiazole-sulfonamide analogues as selective inhibitors of the tumor-associated carbonic anhydrase IX.

With an aim to develop novel potential antitumor agents, two series of benzene- and benzothiazole-sulfonamide derivatives, acting as effective human carbonic anhydrase (hCA, EC 4.2.1.1) inhibitors, have been developed using the tail approach. The synthesized compounds (XS-1 to XS-22) were assayed for the inhibition of physiologically relevant isoforms of hCA, the cytosolic CA I and II, the membrane-bound CA IV and tumor-associated CA IX. It was found the compounds of both series displayed low to medium nanomolar range inhibition against CA I, II and IX, and weak inhibition against CA IV. Some of the derivatives displayed selective inhibition towards tumor-associated CA IX isoform, within the nanomolar range. These potent compounds were also screened for their selective toxicity to evaluate their in vitro anti-proliferative effects on Human Gingival Fibroblasts (HGFs) and breast adenocarcinoma cell line (MCF7). Lastly, molecular docking studies were carried out to explain those structural requirements that were liable for the discrimination among selected human carbonic anhydrase isoforms.

Design, synthesis, crystal structure and anti-plasmodial evaluation of tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidine derivatives.

Effective chemotherapy is essential for controlling malaria. However, resistance of Plasmodium falciparum to existing antimalarial drugs has undermined attempts to control and eventually eradicate the disease. In this study, a series of 2-((substituted)(4-(5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-4-yl)piperazin-1-yl)methyl)-6-substitutedphenol derivatives were prepared using Petasis reaction with a view to evaluate their activities against P. falciparum. The development of synthesized compounds (F1-F16) was justified through the study of H1 NMR, C13 NMR, mass spectra. Compound F1 and F2 were also structurally validated by single crystal X-ray diffraction analysis. All the compounds were evaluated for their in vitro antiplasmodial assessment against the W2 strain (chloroquine-resistant) of P. falciparum IC50 values ranging from 0.74-6.4 µM. Two compounds, F4 and F16 exhibited significant activity against W2 strain of P. falciparum with 0.75 and 0.74 µM. The compounds (F3-F6 and F16) were also evaluated for in vitro cytotoxicity against two cancer cell lines, human lung (A549) and cervical (HeLa) cells, which demonstrated non-cytotoxicity with significant selectivity indices. In addition, in silico ADME profiling and physiochemical properties predicts drug-like properties with a very low toxic effect. Thus, all these results indicate that tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidine scaffolds may serve as models for the development of antimalarial agents.

Discovery of new phenyl sulfonyl-pyrimidine carboxylate derivatives as the potential multi-target drugs with effective anti-Alzheimer's action: Design, synthesis, crystal structure and in-vitro biological evaluation.

Alzheimer's disease (AD) is multifactorial, progressive neurodegeneration with impaired behavioural and cognitive functions. The multitarget-directed ligand (MTDL) strategies are promising paradigm in drug development, potentially leading to new possible therapy options for complex AD. Herein, a series of novel MTDLs phenylsulfonyl-pyrimidine carboxylate (BS-1 to BS-24) derivatives were designed and synthesized for AD treatment. All the synthesized compounds were validated by 1HNMR, 13CNMR, HRMS, and BS-19 were structurally validated by X-Ray single diffraction analysis. To evaluate the plausible binding affinity of designed compounds, molecular docking study was performed, and the result revealed their significant interaction with active sites of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). The synthesized compounds displayed moderate to excellent in vitro enzyme inhibitory activity against AChE and BuChE at nanomolar (nM) concentration. Among 24 compounds (BS-1 to BS-24), the optimal compounds (BS-10 and BS-22) displayed potential inhibition against AChE; IC50 = 47.33 ± 0.02 nM and 51.36 ± 0.04 nM and moderate inhibition against BuChE; IC50 = 159.43 ± 0.72 nM and 153.3 ± 0.74 nM respectively. In the enzyme kinetics study, the compound BS-10 displayed non-competitive inhibition of AChE with Ki = 8 nM. Respective compounds BS-10 and BS-22 inhibited AChE-induced Aß1-42 aggregation in thioflavin T-assay at 10 µM and 20 µM, but BS-10 at 10 µM and 20 µM concentrations are found more potent than BS-22. In addition, the aggregation properties were determined by the dynamic light scattering (DLS) and was found that BS-10 and BS-22 could significantly inhibit self-induced as well as AChE-induced Aß1-42 aggregation. The effect of compounds (BS-10 and BS-22) on the viability of MC65 neuroblastoma cells and their capability to cross the blood-brain barrier (BBB) in PAMPA-BBB were further studied. Further, in silico approach was applied to analyze physicochemical and pharmacokinetics properties of the designed compounds via the SwissADME and PreADMET server. Hence, the novel phenylsulfonyl-pyrimidine carboxylate derivatives can act as promising leads in the development of AChE inhibitors and Aß disaggregator for the treatment of AD.

A comprehensive review of monoamine oxidase inhibitors as Anti-Alzheimer's disease agents: A review.

Monoamine oxidases (MAO-A and MAO-B) are mammalian flavoenzyme, which catalyze the oxidative deamination of several neurotransmitters like norepinephrine, dopamine, tyramine, serotonin, and some other amines. The oxidative deamination produces several harmful side products like ammonia, peroxides, and aldehydes during the biochemical reaction. The concentration of biochemical neurotransmitter alteration in the brain by MAO is directly related with several neurological disorders like Alzheimer's disease and Parkinson's disease (PD). Activated MAO also contributes to the amyloid beta (Aß) aggregation by two successive cleft ß-secretase and γ-secretase of amyloid precursor protein (APP). Additionally, activated MAO is also involved in aggregation of neurofibrillary tangles and cognitive destruction through the cholinergic neuronal damage and disorder of the cholinergic system. MAO inhibition has general anti-Alzheimer's disease effect as a consequence of oxidative stress reduction prompted by MAO enzymes. In this review, we outlined and addressed recent understanding on MAO enzymes such as their structure, physiological function, catalytic mechanism, and possible therapeutic goals in AD. In addition, it also highlights the current development and discovery of potential MAO inhibitors (MAOIs) from various chemical scaffolds.