Synthesis and preliminary biological evaluation of new phthalazinone derivatives with PARP-1 and cholinesterase inhibitory activities

The inhibition of Poly (ADP-ribose) polymerases-1 (PARP-1) has a potentially therapeutical value for AD. In order to search for a new agent based on multitarget-directed ligands (MTDLs) strategy, a series of 21 novel compounds incorporated the respective pharmacophores of two marketed drugs, namely 4-benzyl phthalazinone moiety of PARP-1 inhibitor Olaparib and N-benzylpiperidine moiety of AChE inhibitor Donepezil, into one molecule was synthesized. The inhibitory activities of all the synthesized compounds against the enzymes PARP-1, AChE and BChE were evaluated. Among them, 30 exhibited the most potent inhibitory effect on PARP-1 enzyme (8.18±2.81 nM) and moderate BChE inhibitory activity (1.63±0.52µM), while its AChE inhibitory activity (13.48±2.15µM) was weaker than Donepezil (0.04±0.01µM). Further molecular docking studies revealed that four hydrogen bonds were formed between 30 and PARP-1 which were similar with the interactions between Olaparib and PARP-1. 30 interacted with the critical residues His438 and Trp82 of huBChE through hydrogen bond and hydrophobic interaction which were necessary for huBChE inhibitory potency. Our research gave a clue to search for new agents based on PARP-1 and cholinesterase dual-inhibited activities to treat Alzheimer's disease.

Synthesis and Evaluation of the Acetylcholinesterase Inhibitory Activities of Some Flavonoids Derived from Naringenin

Alzheimer’s disease (AD) is an irreversible neurodegenerative disease that affects many older people adversely. AD has been putting a huge socioeconomic burden on the healthcare systems of many developed countries with aging populations. The need for new therapies that can halt or reverse the progression of the disease is now extremely great. A research approach in the finding new treatment for AD that has attracted much interest from scientists for a long time is the reestablishment of cholinergic transmission through inhibition of acetylcholinesterase (AChE). Naringenin is a flavonoid with the potential inhibitory activity against AChE. From naringenin, many other flavonoid derivatives, such as flavanones and chalcones, can be synthesized. In this study, by applying the Williamson method, nine flavonoid derivatives were synthesized, including four flavanones and five chalcones. The evaluation of AChE inhibitory activity by the Ellman method showed that there were four substances (2, 4, 5, and 7) with relatively good biological activities (IC50 < 100 μM), and these biological activities were better than that of naringenin. The molecular docking revealed that strong interactions with amino acid residue Ser200 of the catalytic triad and those of the peripheral region of the enzyme were crucial for strong effects against AChE. Compound 7 had the strongest AChE inhibitory activity (IC50 13.0 ± 1.9 μM). This substance could be used for further studies.

Chemical Profile and Evaluation of the Antioxidant and Anti-Acetylcholinesterase Activities of Annona squamosa L. (Annonaceae) Extracts

This study presents the chemical profile of extracts from the pulp and seed of Annona squamosa L., as well as the evaluation of their antioxidant and acetylcholinesterase inhibition activities. In the chemical prospection, qualitative assays were performed, and the contents of total phenols, flavonoids, vitamin C, and carotenoids were quantified. For the compounds identification, analyses of the extracts were performed by liquid chromatography coupled to mass spectrometry. Antioxidant evaluation was performed using the DPPH, ABTS, Fe3+ reduction, 2-DR protection, and β-carotene protection methods. The assay for inhibition of acetylcholinesterase activity was determined using the method described by Ellman. The secondary metabolites identified were anthocyanidins, flavones, flavonols, and alkaloids. Phenol analysis showed a higher quantitative value of total phenols and flavonoids for the seed extract, and the vitamin C content was higher in the pulp extract. There was no significant difference in relation to the carotenoids quantification. The best results obtained for antioxidant activity, for both seed and pulp extracts, were with the ABTS method with IC50 of 0.14 ± 0.02 and 0.38 ± 0.02 mg/mL, respectively. Compared to A. squamosa seed extract, the pulp extract demonstrates higher AChE inhibitory activity with IC50 of 18.82 ± 0.17 µg/mL. A. squamosa is a nutritious food source. The continuity of the studies is fundamental to relate the consumption of this food and its effects on neurodegenerative diseases.

New Galantamine Derivatives with Inhibitory Effect on Acetylcholinesterase Activity

Background: Inhibitors of acetylcholinesterase (AChE) are used to treat many disorders, among which are neurodegenerative upsets, like Alzheimer’s disease (AD). One of the limited licensed AChE inhibitors (AChEIs) used as drugs is the natural compound galantamine (Gal). Objective: As Gal is a toxic compound, here we expose data about its four derivatives in hybrid peptide-norgalantamine molecules, which have shown 100 times lower toxicity. Methods: Four newly synthesized galantamine derivatives have been involved in docking analysis made by Molegro Virtual Docker. Biological assessments were performed on ICR male mice. The change in short and long-term memory performance was evaluated by passive avoidance test. AChE activity and levels of main oxidative stress parameters: lipid peroxidation, total glutathione (GSH), enzyme activities of catalase (CAT), superoxide dismutase, and glutathione peroxidase were measured in brain homogenates. Results: Our experimental data revealed that the new hybrid molecules did not impair memory performance in healthy mice. Two of the compounds demonstrated better than Gal AChE inhibitory activity in the brain. None of them changed the level of lipid peroxidation products, one of the compounds increased GSH levels, and all of them increased CAT enzyme activity. Conclusion: The new galantamine-peptide hybrids demonstrated a potential for inhibition of AChE and antioxidant activity and deserve further attention.

Imidazopyridazine Acetylcholinesterase Inhibitors Display Potent Anti-Proliferative Effects in the Human Neuroblastoma Cell-Line, IMR-32

Imidazo[1,2-b]pyridazine compounds are a new class of promising lead molecules to which we have incorporated polar nitro and amino moieties to increase the scope of their biological activity. Two of these substituted 3-nitro-6-amino-imidazo[1,2-b]pyridazine compounds (5c and 5h) showed potent acetylcholinesterase (AChE) inhibitory activity (IC50 40–50 nM), which we have previously reported. In this study, we wanted to test the biological efficacy of these compounds. Cytotoxicity assays showed that compound 5h mediated greater cell death with over 43% of cells dead at 100 μM and activation of caspase 3-mediated apoptosis. On the other hand, compound 5c mediated a dose-dependent decrease in cell proliferation. Both compounds showed cell cycle arrest in the G0/G1 phase and reduced cellular ATP levels leading to activation of adenosine monophosphate-activated protein kinase (AMPK) and enhanced mitochondrial oxidative stress. It has to be noted that all these effects were observed at doses beyond 10 μM, 200-fold above the IC50 for AChE inhibition. Both compounds also inhibited bacterial lipopolysaccharide-mediated cyclooxygenase-2 and nitric oxide release in primary rat microglial cells. These results suggested that the substituted imidazo (1,2-b) pyridazine compounds, which have potent AChE inhibitory activity, were also capable of antiproliferative, anti-migratory, and anti-inflammatory effects at higher doses.

Chemical composition, acetylcholine esterase and Anti-bacterial activities of essential oils of Elaeosilenum thapsioides (Desf.) Maire from Algeria

Background: Traditionally, The Algerian medicinal plant Elaeosilenum thapsioides have been used for many diseases. Objective: The present research work is aimed to explore the chemical and biological characterization of essential oil of, Elaeoselinum thapsioides (Desf.) Maire. Methods : The essential oils were obtained by hydrodistillation of different Elaeosilenum thapsioides (Apiaceae) aerial parts samples collected from two different regions (Mahouane and Megres) Setif, Eastern Algeria. The chemical characterization of the obtained essential oils was investigated in the present work for the first time by GC and GC-MS. Besides, they were evaluated for their in-vitro acetylcholinesterase (AChE) inhibitory activity whose enzyme hyperactivity is involved in Alzheimer’s disease. Using Ellman’s spectrophotometric method, additionally, their in-vitro antimicrobial activity was assessed by the disc diffusion method. Both activities were performed at various oil concentrations. Results: The GC/MS analysis of the aerial parts (leaves, stems, flowers, and seeds) essential oils of E. thapsioides revealed the presence of dominant compounds and others in small quantities, identifying 47 chemical molecules. Monoterpene hydrocarbons were the main components, ranging from 72.78 % to 99.13 %. Oxygenated monoterpenes and oxygenated sesquiterpenes ranged between (1.37 % -17.25 %) and (0.12 % -3.53 %) in leaves and stem essential oils. Sesquiterpene hydrocarbons were present in small to large quantities in the essential oils of both populations, with contents ranging from 0.69 % to 13.44 %. For the Isothiocyanates, their presence was recorded in leaves and stem essential oils from Mahouane and Merges with 9.73 % and 3.72 %, consecutively. Indeed, the essential oil of the Mahouane stem showed the highest AChE inhibitory activity among all the tested essential oils. Whereas the highest antibacterial activity was shown by the essential oil obtained from Megres leaves against Bacillus cereus ATCC 11778. Conclusion: The oils exhibited a moderate inhibitory activity in both activities.

An integrated strategy for rapid screening of multi-target lead compounds for the treatment of Alzheimer's disease from traditional Chinese medicines by UHPLC combined with high-throughput screening: A case study on Salviae Miltiorrhizae Radix et Rhizoma

Background: Salviae Miltiorrhizae Radix et Rhizoma (Red Sage root) is widely used in traditional Chinese medicine (TCM) for the treatment of Alzheimer’s disease (AD) with demonstrated curative effects, based on the concept of "one drug with multiple therapeutic targets," which appears to be a good strategy for AD treatment. Objective: This study aimed to develop of high-throughput screening (HTS) method for multi-therapeutic target components found in complex TCMs, which are active against AD, using Red Sage root as the case study. Method: Acetylcholinesterase (AChE) inhibitors (AChEIs) from Red Sage root extracts were pre-screened by ultrafiltration-HPLC (UF-HPLC) analysis, in which AChE was added to the extract and then ultrafiltered to remove non-binding compounds. Potential AChEIs were identified by HPLC analysis of compounds bound to AChE. A microplate-based HTS was then used to quantify the AChE inhibitory activity and antioxidant activity of the pre-screened compounds. Results: Pre-screening found ten potential inhibitors, which were identified by ESI-TOF/MS; six of these were purified by semi-preparative HPLC: Oleoyl neocryptotanshinone (1), Dihydrotanshinone Ⅰ (2), Cryptotanshinone (3), Tanshinone Ⅰ (4), Tanshinone ⅡA (5) and Miltirone (6). All six compounds had good AChE inhibitory activity and weak DPPH scavenging capacity. Conclusion: This study provides a platform and technology support for the rapid discovery of multi-target components, potentially active against AD, from complex TCMs and with strong potential for adaptation to the discovery of treatments for other diseases.

1,3,5-Triazine Nitrogen Mustards with Different Peptide Group as Innovative Candidates for AChE and BACE1 Inhibitors

A series of new analogs of nitrogen mustards (4a–4h) containing the 1,3,5-triazine ring substituted with dipeptide residue were synthesized and evaluated for the inhibition of both acetylcholinesterase (AChE) and β-secretase (BACE1) enzymes. The AChE inhibitory activity studies were carried out using Ellman’s colorimetric method, and the BACE1 inhibitory activity studies were carried out using fluorescence resonance energy transfer (FRET). All compounds displayed considerable AChE and BACE1 inhibition. The most active against both AChE and BACE1 enzymes were compounds A and 4a, with an inhibitory concentration of AChE IC50 = 0.051 µM; 0.055 µM and BACE1 IC50 = 9.00 µM; 11.09 µM, respectively.

Cholinesterase Inhibition Activity and Molecular Docking Study of Eugenol Derivatives

The study was conducted to explore the anticholinesterase inhibition property of eugenol derived molecules. Ten eugenol derivatives were synthesized and evaluated for the inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) by Ellman’s method. Most of the tested derivatives showed higher inhibition on BChE than AChE, however, their overall inhibitory activity was weak. In contrast, three derivatives (compounds 3,6,9) showed higher and good AChE inhibitory activity of more than 50% inhibition at 10 μg/mL. Among them, compound 9bearing a ethyl substituent at para position of the benzoyl ring showed the most potent AChE inhibition, with IC50 of 5.64 μg/mL. Ligand-protein docking simulation was also performed for the most active derived molecules (compounds 3,6,9).