Design, synthesis, structure activity relationship and molecular docking studies of thiophene-2-carboxamide Schiff base derivatives of benzohydrazide as novel acetylcholinesterase and butyrylcholinesterase inhibitors

Exploring biological activities of novel Schiff bases derived from amlodipine and in silico molecular modeling studies

Aim: Calcium channel antagonists are of considerable interest in treating elevated blood pressure and its pathologies.Materials & methods: Schiff base derivatives of amlodipine were produced to check its urease inhibition potentials as well antibacterial and antioxidant activities. Structural illustration along with chemical characterization were achieved by spectral techniques (1H NMR, FTIR, 13C NMR) and docking studies also performed.Results & conclusion: 3g displayed remarkable anti-hypertensive activity compared with parent drug. 3b, 3f and 3g showed urease inhibition potentials. These compounds can aid as lead for further investigations since they exhibited comparable or superior interactions.

Development of new Alzheimer's disease drug candidates using donepezil as a key model

Alzheimer's disease (AD) is one of the most prevalent geriatric diseases and a significant cause of high mortality. This crippling disorder is becoming more prevalent at an unprecedented rate, which has led to an increase in the financial cost of caring. It is a pathologically complicated, multifactorial disease characterized by β-amyloid precipitation, β-amyloid oligomer production, decrease in cholinergic function, and dysregulation of other neurotransmitter systems. Due to the pathogenic complexity of AD, multitarget drugs that can simultaneously alternate multiple biological targets may enhance the therapeutic efficacy. Donepezil (DNP) is the most potent approved drug for the treatment of AD. It has a remarkable effect on a number of AD-related processes, including cholinesterase activity, anti-Aβ aggregation, oxidative stress, and more. DNP resembles an excellent scaffold to be hybridized with other pharmacophoric moieties having biological activity against AD pathological factors. There have been significant attempts made to modify the structure of DNP to create new bioactive chemical entities with novel structural patterns. In this review, we highlight recent advances in the development of multiple-target DNP-hybridized models for the treatment of AD that can be used in the future in the rational design of new potential AD therapeutics. The design and development of new drug candidates for the treatment of AD using DNP as a molecular scaffold have also been reviewed and summarized.

Computational design of new tacrine analogs: an in silico prediction of their cholinesterase inhibitory, antioxidant, and hepatotoxic activities

Tacrine, the first drug approved for the treatment of Alzheimer's disease (AD), is a non-competitive cholinesterase inhibitor withdrawn due to its acute hepatotoxicity. However, new non-hepatotoxic forms of tacrine have been actively researched. Moreover, several recent reports have shown that oxidative stress is the cause of damage and plays a role in the pathogenesis of several neurodegenerative diseases including AD. The aim of the present study is the design of new easily synthesized tacrine analogs with less hepatotoxicity and potent antioxidant activity. In this context, a library of 34 novel tacrine analogs bearing an antioxidant fragment was designed and evaluated for its hepatotoxicity as well as anticholinesterase and antioxidant activities using computational methods. As a result, six new tacrine analogs have been proposed as potential inhibitors of cholinesterase with antioxidant activity and low or no hepatotoxicity. Furthermore, ADME calculations suggest that these compounds are promising oral drug candidates. Communicated by Ramaswamy H. Sarma.

Design, synthesis, crystal structure, in vitro cytotoxicity evaluation, density functional theory calculations and docking studies of 2-(benzamido) benzohydrazide derivatives as potent AChE and BChE inhibitors

A series of hydrazone derivatives of 2-(benzamido) benzohydrazide was designed, synthesized, and characterized utilizing FTIR, NMR and UV spectroscopic techniques along with mass spectrometry. Compound 10 was also characterized through X-ray crystallography. These synthesized compounds were assessed for their potential as anti-Alzheimer's agents by checking their AChE and BChE inhibition properties by in vitro analysis. The synthesized derivatives were also evaluated for their antioxidant potential along with cytotoxicity studies. The results clearly indicated that dual inhibition of both the enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) was achieved by most of the compounds (03-13), showing varying IC50values. Remarkably, compound 06 (IC50 = 0.09 ± 0.05 for AChE and 0.14 ± 0.05 for BChE) and compound 13 (IC50 = 0.11 ± 0.03 for AChE and 0.10 ± 0.06 for BChE) from the series showed IC50 values comparable to the standard donepezil (IC50 = 0.10 ± 0.02 for AChE and 0.14 ± 0.03 for BChE). Moreover, the derivative 11 also exhibited selective inhibition against BChE with IC50 = 0.12 ± 0.09. Meanwhile, compounds 04 and 10 exhibited good anti-oxidant activities, showing % scavenging of 95.06% and 82.55%, respectively. Cytotoxicity studies showed that the synthesized compounds showed cell viability greater than 80%; thus, these compounds can be safely used as drugs. DFT and molecular docking studies also supported the experimental findings.

Design, synthesis, and molecular docking study of some 2-((7-chloroquinolin-4-yl) amino) benzohydrazide Schiff bases as potential Eg5 inhibitory agents

In Search of new microtubule-targeting compounds and to identify a promising Eg5 inhibitory agents, a series of 2-((7-chloroquinolin-4-yl) amino) benzohydrazide Schiff bases molecules (6 a-r) were synthesized using appropriate synthetic method. The synthesized compounds were characterized by using FTIR, Proton NMR, Carbon NMR and mass spectral analysis. All eighteen compounds were evaluated for their Eg5 inhibitory activity. Among the evaluated compounds, only seven compounds are shown inhibitory activity. The results of Steady state ATPase reveled that compounds 6b, 6l and 6p exhibited promising inhibitory activity with IC₅₀ Values of 2.720 ± 0.69, 2.676 ± 0.53 and 2.408 ± 0.46 respectively. Malachite Green Assay results reveled that 6q compound showed better inhibitory activity with IC₅₀ Value of 0.095 ± 0.27. In vitro antioxidant capacity of the synthesized compounds was investigated. A molecular docking studies were performed to evaluate interaction in to binding site of kinesin spindle protein, these interaction influencing may support Eg5 inhibitory activity. The drug like parameters of the eighteen synthesized compounds were also computed using Qikprop software. In conclusion, some of 2-((7-chloroquinolin-4-yl) amino) benzohydrazide Schiff base compounds represent promising drug like agents for discovery of effective anticancer molecules.

Synthesis of Novel N-Acylhydrazones and Their C-N/N-N Bond Conformational Characterization by NMR Spectroscopy

In this article, a synthesis of N’-(benzylidene)-2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetohydrazides and their structural interpretation by NMR experiments is described in an attempt to explain the duplication of some peaks in their ¹H- and ¹³C-NMR spectra. Twenty new 6-methyl-1H-pyrazolo[3,4-b]quinoline substituted N-acylhydrazones 6(a–t) were synthesized from 2-chloro-6-methylquinoline-3-carbaldehyde (1) in four steps. 2-Chloro-6-methylquinoline-3-carbaldehyde (1) afforded 6-methyl-1H-pyrazolo[3,4-b]quinoline (2), which upon N-alkylation yielded 2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetate (3). The hydrazinolysis of 3 followed by the condensation of resulting 2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetohydrazide (4) with aromatic aldehydes gave N-acylhydrazones 6(a–t). Structures of the synthesized compounds were established by readily available techniques such as FT-IR, NMR and mass spectral studies. The stereochemical behavior of 6(a–t) was studied in dimethyl sulfoxide-d₆ solvent by means of ¹H NMR and ¹³C NMR techniques at room temperature. NMR spectra revealed the presence of N’-(benzylidene)-2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetohydrazides as a mixture of two conformers, i.e., E_(C=N)(N-N) synperiplanar and E_(C=N)(N-N)antiperiplanar at room temperature in DMSO-d₆. The ratio of both conformers was also calculated and E_{(C=N) (N-N)} syn-periplanar conformer was established to be in higher percentage in equilibrium with the E_{(C=N) (N-N)}anti-periplanar form.