N-Substituted piperidine-3-carbohydrazide-hydrazones against Alzheimer's disease: Synthesis and evaluation of cholinesterase, beta-amyloid inhibitory activity, and antioxidant capacity.

A series of piperidine-3-carbohydrazide-hydrazones bearing phenylethyl, phenylpropyl, and phenylbutyl substituents on piperidine nitrogen were designed and synthesized as cholinesterase (ChE) inhibitors. The title compounds were screened for acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) inhibitory activities and antioxidant capacities, and the active ones for Aß42 self-aggregation inhibition, in vitro. The chemiluminescence method was used to determine the effect of the selected compounds on the reactive oxygen species (ROS) levels in brain tissue. Physicochemical properties were calculated by the MOE program. Kinetic analysis and molecular modeling studies were also carried out for the most active compounds. Generally, the final compounds exhibited moderate to good AChE or BuChE inhibitory activity. Among them, 3g and 3j showed the most potent activity against AChE (IC50 = 4.32 µM) and BuChE (IC50 = 1.27 µM), respectively. The kinetic results showed that both compounds exhibited mixed-type inhibition. Among the selected compounds, nitro derivatives (3g, 4g, and 5g) provided better Aß42 inhibition. According to the chemiluminescence assay, 4i exhibited the most active superoxide free-radical scavenger activity and 3g, 3j, and 4i showed similar scavenger activity on other ROS. All results suggested that 3g, 3j, and 4i have good AChE/BuChE, Aß42 inhibitory potentials and antioxidant capacities and can therefore be suggested as promising multifunctional agents to combat Alzheimer's disease.

Design, synthesis, acetylcholinesterase, butyrylcholinesterase, and amyloid-ß aggregation inhibition studies of substituted 4,4'-diimine/4,4'-diazobiphenyl derivatives.

A series of 4,4'-diimine/4,4'-diazobiphenyl derivatives were designed, synthesized, and evaluated for their ability to inhibit both the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes, as well as Aß1-42 aggregation, in vitro. The AChE and BChE inhibition assays demonstrated that all compounds displayed moderate AChE inhibitory activity in the range of IC50 = 5.77-16.22 µM, while they displayed weak or no BChE inhibition. Among the title compounds, compound 2l, 4,4'-bis(quinolin-8-yldiazenyl)-1,1'-biphenyl, having a diazo-quinoline moiety demonstrated the most potent inhibition against AChE with an IC50 value of 5.77 µM. Furthermore, diazo derivatives 2d, 4,4'-bis[(4-methoxyphenyl)diazenyl]-1,1'-biphenyl, and 2i, 4,4'-bis(pyridin-3-yldiazenyl)-1,1'-biphenyl, provided better potency on Aß1-42 aggregation, with an inhibition value of 74.08% and 78.39% at 100 µM and 55.35% and 61.36% at 25 µM, respectively. Molecular modeling studies were carried out for the most active compound against AChE, compound 2l. All the results suggested that compounds 2d and 2i have better inhibitory potencies on Aß1-42 aggregation and moderate AChE enzyme activity, and therefore can be highlighted as promising compounds.

Synthesis, biological evaluation, and docking studies of some 5-chloro-2(3H)-benzoxazolone Mannich bases derivatives as cholinesterase inhibitors.

A series of N-substituted-5-chloro-2(3H)-benzoxazolone derivatives were synthesized and evaluated for their acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) inhibitory, and antioxidant activities. The structures of the title compounds were confirmed by spectral and elemental analyses. The cholinesterase (ChE) inhibitory activity studies were carried out using Ellman's colorimetric method. The free radical scavenging activity was also determined by in vitro ABTS (2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)) assay. The biological activity results revealed that all of the title compounds displayed higher AChE inhibitory activity than the reference compound, rivastigmine, and were selective for AChE. Among the tested compounds, compound 7 exhibited the highest inhibition against AChE (IC50 = 7.53 ± 0.17 µM), while compound 11 was found to be the most active compound against BuChE (IC50 = 17.50 ± 0.29 µM). The molecular docking study of compound 7 showed that this compound can interact with the catalytic active site (CAS) of AChE and also has potential metal chelating ability and a proper log P value. On the other hand, compound 2 bearing a methyl substituent at the ortho position on the phenyl ring showed better radical scavenging activity (IC50 = 1.04 ± 0.04 mM) than Trolox (IC50 = 1.50 ± 0.05 mM).

Multifunctional cholinesterase inhibitors for Alzheimer's disease: Synthesis, biological evaluations, and docking studies of o/p-propoxyphenylsubstituted-1H-benzimidazole derivatives.

This study indicates the synthesis, cholinesterase (ChE) inhibitory activity, and molecular modeling studies of 48 compounds as o- and p-(3-substitutedethoxyphenyl)-1H-benzimidazole derivatives. According to the ChE inhibitor activity results, generally, para series are more active against acetylcholinesterase (AChE) whereas ortho series are more active against butyrylcholinesterase (BuChE). The most active compounds against AChE and BuChE are compounds A12 and B14 with IC50 values of 0.14 and 0.22 µM, respectively. Additionally, the most active 16 compounds against AChE/BuChE were chosen to investigate the neuroprotective effects, and the results indicated that most of the compounds have free radical scavenging properties and show their effects by reducing free radical production; moreover, some of the compounds significantly increased the viability of SH-SY5Y cells exposed to H2 O2 . Overall, compounds A12 and B14 with potential AChE and BuChE inhibitory activities, high neuroprotection against H2 O2 -induced toxicity, free radical scavenging properties, and metal chelating abilities may be considered as lead molecules for the development of multi-target-directed ligands against Alzheimer's disease.

Design, synthesis, and biological evaluation of some novel naphthoquinone-glycine/ß-alanine anilide derivatives as noncovalent proteasome inhibitors.

A series of novel noncovalent glycine/ß-alanine anilide derivatives possessing 2-chloronaphthoquinone structure as a pharmacophoric unit were designed, synthesized, and evaluated for their antiproliferative and antiproteasomal activities against MCF-7 cell line, in vitro. According to biological activity results, all the target compounds showed antiproliferative activity in the range of IC50  = 7.10 ± 0.10-41.08 ± 0.14 µM and most of them exhibited inhibitory efficacy with varying ratios against the three catalytic subunits (ß1, ß2, and ß5) presenting caspase-like (C-L), trypsin-like (T-L) and chymotrypsin-like (ChT-L) activities of proteasome. The antiproteasomal activity evaluations revealed that compounds preferentially inhibited the ß5 subunit compared with ß1 and ß2 subunits of the proteasome. Among the compounds, compounds 7 and 9 showed the highest antiproliferative activity with an IC50 value of 7.10 ± 0.10 and 7.43 ± 0.25 µM, respectively. Additionally, compound 7 displayed comparable potency to PI-083 lead compound in terms of ß5 antiproteasomal activity with an inhibition percentage of 34.67 at 10 µM. This compound showed an IC50 value of 32.30 ± 0.45 µM against ß5 subunit. Furthermore, molecular modeling studies of the most active compound 7 revealed key interactions with ß5 subunit. The results suggest that this class of compounds may be beneficial for the development of new potent proteasome inhibitors.

Exploring enzyme inhibition profiles of novel halogenated chalcone derivatives on some metabolic enzymes: Synthesis, characterization and molecular modeling studies.

Enzyme inhibition is a very active area of research in drug design and development. Chalcone derivatives have a broad enzyme inhibitory activity and function as potential molecules in the development of new drugs. In this study, the synthesized novel halogenated chalcones with bromobenzyl and methoxyphenyl moieties were evaluated toward the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes and human erythrocyte carbonic anhydrase I (hCA I), and II (hCA II) isoenzymes. They showed highly potent inhibition ability toward AChE with Ki values of 1.83 ± 0.21-11.19 ± 0.96 nM and BChE with Ki values of 3.35 ± 0.91-26.70 ± 4.26 nM; hCA I with Ki values of 29.41 ± 3.14-57.63 ± 4.95 nM, and hCA II with Ki values of 24.00 ± 5.39-54.74 ± 1.65 nM. Among the tested enzyme inhibitions, compounds 14 and 13 were the most active compounds against AChE and BChE. Docking studies were performed to the most active compounds against AChE, BChE, hCA I and hCA II to propose a binding mode in the active site and molecular dynamics simulations were studied to check the molecular interactions and the stability of the ligands in the active site. The results may contribute to the development of new drugs particularly to treat some global disorders including Alzheimer's disease (AD), glaucoma, and diabetes.

Design, synthesis and biological evaluation of novel naphthoquinone-4-aminobenzensulfonamide/carboxamide derivatives as proteasome inhibitors.

A series of novel 4-aminobenzensulfonamide/carboxamide derivatives bearing naphthoquinone pharmacophore were designed, sythesized and evaluated for their proteasome inhibitory and antiproliferative activities against human breast cancer cell line (MCF-7). The structures of the synthesized compounds were confirmed by spectral and elemental analyses. The proteasome inhibitory activity studies were carried out using cell-based assay. The antiproteasomal activity results revealed that most of the compounds exhibited inhibitory activity with different percentages against the caspase-like (C-L, ß1 subunit), trypsin-like (T-L, ß2 subunit) and chymotrypsin-like (ChT-L, ß5 subunit) activities of proteasome. Among the tested compounds, compound 14 bearing 5-chloro-2-pyridyl ring on the nitrogen atom of sulfonamide group is the most active compound in the series and displayed higher inhibition with IC50 values of 9.90 ± 0.61, 44.83 ± 4.23 and 22.27 ± 0.15 µM against ChT-L, C-L and T-L activities of proteasome compared to the lead compound PI-083 (IC50 = 12.47 ± 0.21, 53.12 ± 2.56 and 26.37 ± 0.5 µM), respectively. The antiproliferative activity was also determined by MTT (3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) assay in vitro. According to the antiproliferative activity results, all of the compounds exhibited cell growth inhibitory activity in a range of IC50 = 1.72 ± 0.14-20.8 ± 0.5 µM and compounds 13 and 28 were found to be the most active compounds with IC50 values of 1.79 ± 0.21 and 1.72 ± 0.14 µM, respectively. Furthermore, molecular modeling studies were carried out for the compounds 13, 14 and 28 to investigate the ligand-enzyme binding interactions.

Synthesis and anticonvulsant activity of some alkanamide derivatives.

A group of N-phenylacetamide, N-phenylpropanamide and N-benzylamide derivatives bearing 5-membered heterocyclic rings such as pyrazole, 1,2,4-triazole and imidazole rings at omega position were synthesized and their anticonvulsant activity was evaluated in the maximal electroshock test. The results indicated that the 1,2,4-triazole ring leads to superior activity than the pyrazole ring and inserting a CH2 group into the anilide structure leading to N-benzyl derivatives did not change the anticonvulsant activity, but caused a noticeable decrease in duration of action. The most active compound was 2-(1H-1,2,4-triazole-1-yl)-N-(2,6-dimethylphenyl)acetamide.