Synthesis and biological evaluation of a series of aminoalkyl-tetralones and tetralols as dual dopamine/serotonin ligands

The Benzoylpiperidine Fragment as a Privileged Structure in Medicinal Chemistry: A Comprehensive Review

The phenyl(piperidin-4-yl)methanone fragment (here referred to as the benzoylpiperidine fragment) is a privileged structure in the development of new drugs considering its presence in many bioactive small molecules with both therapeutic (such as anti-cancer, anti-psychotic, anti-thrombotic, anti-arrhythmic, anti-tubercular, anti-parasitic, anti-diabetic, and neuroprotective agents) and diagnostic properties. The benzoylpiperidine fragment is metabolically stable, and it is also considered a potential bioisostere of the piperazine ring, thus making it a feasible and reliable chemical frame to be exploited in drug design. Herein, we discuss the main therapeutic and diagnostic agents presenting the benzoylpiperidine motif in their structure, covering articles reported in the literature since 2000. A specific section is focused on the synthetic strategies adopted to obtain this versatile chemical portion.

Do AutoML-Based QSAR Models Fulfill OECD Principles for Regulatory Assessment? A 5-HT1A Receptor Case

The drug discovery and development process requires a lot of time, financial, and workforce resources. Any reduction in these burdens might benefit all stakeholders in the healthcare domain, including patients, government, and companies. One of the critical stages in drug discovery is a selection of molecular structures with a strong affinity to a particular molecular target. The possible solution is the development of predictive models and their application in the screening process, but due to the complexity of the problem, simple and statistical models might not be sufficient for practical application. The manuscript presents the best-in-class predictive model for the serotonin 1A receptor affinity and its validation according to the Organization for Economic Co-operation and Development guidelines for regulatory purposes. The model was developed based on a database with close to 9500 molecules by using an automatic machine learning tool (AutoML). The model selection was conducted based on the Akaike information criterion value and 10-fold cross-validation routine, and later good predictive ability was confirmed with an additional external validation dataset with over 700 molecules. Moreover, the multi-start technique was applied to test if an automatic model development procedure results in reliable results.

Research progress in pharmacological activities and structure-activity relationships of tetralone scaffolds as pharmacophore and fluorescent skeleton

The tetralone and tetralone derivatives, as crucial structural scaffolds of potential novel drugs targeted at multiple biological end-points, are normally found in several natural compounds and also, it can be used as parental scaffold and/or intermediate for the synthesis of a series of pharmacologically active compounds with a broad-spectrum of bioactivities including antibacterial, antitumor, CNS effect and so on. Meanwhile, SAR information of its analogues has drawn attentions among medicinal chemists, which could contribute to the further research related to tetralone derivatives aimed at multiple targets. This review encompasses pharmacological activities, SAR analysis and docking study of tetralone and its derivatives, expecting to provide a general retrospect and prospect on tetralone derivatives.

Synthesis of novel benzimidazole acrylonitriles for inhibition of Plasmodium falciparum growth by dual target inhibition

Antimalarial drug resistance has emerged as a threat for treating malaria, generating a need to design and develop newer, more efficient antimalarial agents. This research aimed to identify novel leads as antimalarials. Dual receptor mechanism could be a good strategy to combat developing drug resistance. A series of benzimidazole acrylonitriles containing 18 compounds were designed, synthesized and evaluated for cytotoxicity, heme binding, ferriprotoporphyrin IX biomineralisation inhibition, and falcipain-2 enzyme assay. Furthermore, in silico docking and MD simulation studies were also performed.The tests revealed quite encouraging results. Three compounds, viz. R-01 (0.69 μM), R-04 (1.60 μM), and R-08 (1.61 μM), were found to have high antimalarial activity. These compounds were found to be in bearable cytotoxicity limits and their biological assay suggested that they had inhibitory activity against falcipain-2 and hemozoin formation. The docking revealed the binding mode of benzimidazole acrylonitrile derivatives and MD simulation studies revealed that the protein-ligand complex was stable. The agents exhibit good hemozoin formation inhibition activity and, hence, may be utilized as leads to design a newer drug class to overcome the drug resistance of hemozoin formation inhibitors such as chloroquine.

Stereoselective Synthesis of Functionalized Bicyclic Scaffolds by Passerini 3-Center-2-Component Reactions of Cyclic Ketoacids

We report the use of bifunctional starting materials (ketoacids) in a diastereoselective Passerini three-center-two-component reaction. Study of the reaction scope revealed the required structural features for stereoselectivity in the isocyanide addition. In this system, an interesting isomerization of the primary Passerini product - the α-carboxamido lactone - into an atypical product, an α-hydroxy imide, was found to occur under acidic conditions. Furthermore, enantioenriched Passerini products can be generated from an enantioenriched ketoacid obtained by chemoenzymatic synthesis.

Multivalent approaches and beyond: novel tools for the investigation of dopamine D2 receptor pharmacology

The dopamine D2 receptor (D2R) has been implicated in the symptomology of disorders such as schizophrenia and Parkinson's disease. Multivalent ligands provide useful tools to investigate emerging concepts of G protein-coupled receptor drug action such as allostery, bitopic binding and receptor dimerization. This review focuses on the approaches taken toward the development of multivalent ligands for the D2R recently and highlights the challenges associated with each approach, their utility in probing D2R function and approaches to develop new D2R-targeting drugs. Furthermore, we extend our discussion to the possibility of designing multitarget ligands. The insights gained from such studies may provide the basis for improved therapeutic targeting of the D2R.

Heterocycle-to-Heterocycle Route to Quinoline-4-amines: Reductive Heterocyclization of 3-(2-Nitrophenyl)isoxazoles

A variety of quinoline-4-amines were synthesized from substituted 3-(2-nitrophenyl)isoxazoles utilizing Zn0 or Fe0 dust and HOAc via a reductive heterocyclization process. The starting isoxazoles were synthesized from readily available starting materials. A brief survey of functional groups tolerated in this reductive heterocyclization was performed and several 10-amino-3,4-dihydrobenzo[b][1,6]naphthyridin-1(2H)-one and 9-amino-3,4-dihydroacridin-1(2H)-one examples were synthesized.

Isolation of the sapogenin from defatted seeds of Camellia oleifera and its neuroprotective effects on dopaminergic neurons

Sasanqua saponin is a major active compound in the defatted seeds of Camellia oleifera but is always discarded without effective utilization. The sapogenin from hydrolysis of sasanqua saponin was purified, and its amination derivative was investigated on its neuroprotective effects, which were evaluated by animal models of Parkinson disease in mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The results showed that the sapogenin and its derivative increased dopamine content in striatum and tyrosine hydroxylase (TH) positive cells in substantia nigra and relieved inflammation and behavioral disorder, but the effect on movement was reversed by dopamine receptor antagonist haloperidol and was not intervened by adenosine receptor antagonist CGS 15943. Molecular simulation showed the interaction between dopamine receptor and the sapogenin or its derivative. It is proven that the sapogenin can protect dopamine neurons through antineuroinflammation and activation of dopamine receptor rather than adenosine receptor, and its amination improves the effects. This research provides the prospective prodrugs for Parkinson disease and a new medicinal application of sasanqua saponin.