Design and synthesis of 4-heteroaryl 1,2,3,4-tetrahydroisoquinolines as triple reuptake inhibitors

A new paradigm shift in antidepressant therapy? From dual-action to multitarget-directed ligands

Major Depressive Disorder is a chronic, recurring, and potentially fatal disease affecting up to 20% of the global population. Since the monoamine hypothesis was proposed more than 60 years ago, only a few relevant advances have been achieved, with very little disease course changing, from a pharmacological perspective. Moreover, since negative efficacy studies with novel molecules are frequent, many pharmaceutical companies have put new studies on hold. Fortunately, relevant clinical studies are currently being performed, and extensive striving is being developed by universities, research centers, and other public and private institutions. Depression is no longer considered a simple disease but a multifactorial one. New research fields are emerging in what could be a paradigm shift: the multitarget approach beyond monoamines. In this review, we summarize the present and the past of antidepressant drug discovery, with the aim to shed some light on the current state of the art in clinical and preclinical advances to face this increasingly devastating disease.

Catalytic N-methyl amidation of carboxylic acids under cooperative conditions

The generation of N-methyl amides using simple acids with high atom economy is rare owning to the volatile nature of methyl amine. Herein, an atom economic protocol was disclosed to prepare this valuable motif under DABCO/Fe3O4 cooperative catalysis.

5-Aryloxazolidines as Reagents for Double Alkylation of Arenes: A Novel Synthesis of 4-Aryltetrahydroisoquinolines

5-Aryloxazolidines react with arenes under Lewis or Brønsted acid conditions via the Friedel-Crafts/Pictet-Spengler double alkylation sequence to give alkaloid-like 4-aryltetrahydroisoquinolines in 12-94% yields. Three approaches for the controlled insertion of substituents into the target molecules and application of oxazolidine derivatives such as 1-arylethanol-2-amines or 4-hydroxytetrahydroisoquinolines in the alkylation of arenes are also described. An unprecedented two-step easily scalable synthesis of the 4-aryltetrahydroisoquinoline core from aromatic aldehyde was achieved applying oxazolidine methodology.

Medicinal chemistry perspectives of 1,2,3,4-tetrahydroisoquinoline analogs - biological activities and SAR studies

Isoquinoline alkaloids are a large group of natural products in which 1,2,3,4-tetrahydroisoquinolines (THIQ) form an important class. THIQ based natural and synthetic compounds exert diverse biological activities against various infective pathogens and neurodegenerative disorders. Due to these reasons, the THIQ heterocyclic scaffold has garnered a lot of attention in the scientific community which has resulted in the development of novel THIQ analogs with potent biological activity. The present review provides a much-needed update on the biological potential of THIQ analogs, their structural-activity relationship (SAR), and their mechanism of action. In addition, a note on commonly used synthetic strategies for constructing the core scaffold has also been discussed.

Recent Advances and Challenges of the Drugs Acting on Monoamine Transporters

Background:

The human Monoamine Transporters (hMATs), primarily including hSERT, hNET and hDAT, are important targets for the treatment of depression and other behavioral disorders with more than the availability of 30 approved drugs.

Objective:

This paper is to review the recent progress in the binding mode and inhibitory mechanism of hMATs inhibitors with the central or allosteric binding sites, for the benefit of future hMATs inhibitor design and discovery. The Structure-Activity Relationship (SAR) and the selectivity for hit/lead compounds to hMATs that are evaluated by in vitro and in vivo experiments will be highlighted.

Methods:

PubMed and Web of Science databases were searched for protein-ligand interaction, novel inhibitors design and synthesis studies related to hMATs.

Results:

Literature data indicate that since the first crystal structure determinations of the homologous bacterial Leucine Transporter (LeuT) complexed with clomipramine, a sizable database of over 100 experimental structures or computational models has been accumulated that now defines a substantial degree of structural variability hMATs-ligands recognition. In the meanwhile, a number of novel hMATs inhibitors have been discovered by medicinal chemistry with significant help from computational models.

Conclusion:

The reported new compounds act on hMATs as well as the structures of the transporters complexed with diverse ligands by either experiment or computational modeling have shed light on the poly-pharmacology, multimodal and allosteric regulation of the drugs to transporters. All of the studies will greatly promote the Structure-Based Drug Design (SBDD) of structurally novel scaffolds with high activity and selectivity for hMATs.

Synthesis of 4-Aryl Isoquinolinedione Derivatives by a Palladium-Catalyzed Coupling Reaction of Aryl Halides with Isoquinoline-1,3(2 H,4 H)-diones

The palladium-catalyzed cross-coupling reaction of aryl halides with isoquinoline-1,3(2 H,4 H)-diones for the synthesis of 4-aryl isoquinoline-1,3(2 H,4 H)-diones was developed. The reaction conditions exhibit remarkable compatibility with various aryl halides and isoquinoline-1,3(2 H,4 H)-diones, and the product could be conveniently transformed to 4-aryl tetrahydroisoquinolines. (±) Dichlorofensine was synthesized using this protocol in two steps with an overall yield of 71%.

Computational identification of the binding mechanism of a triple reuptake inhibitor amitifadine for the treatment of major depressive disorder

A shared binding mode involving eleven key residues at the S1 site of MATs for the binding of amitifadine is identified.

Novel serotonin transporter regulators: Natural aristolane- and nardosinane- types of sesquiterpenoids from Nardostachys chinensis Batal

Serotonin transporter (SERT) is a classic target of drug discovery for neuropsychiatric and digestive disorders, and against those disorders, plants of Nardostachys genus have been valued for centuries in the systems of Traditional Chinese Medicine, Ayurvedic and Unani. Herein, chemical investigation on the roots and rhizomes of Nardostachys chinensis Batal. led to the isolation of forty sesquiterpenoids including six new aristolane-type sesquiterpenoids and six new nardosinane-type sesquiterprenoids. Their structures were elucidated by extensive spectroscopic methods, combined with analyses of circular dichroism and single-crystal X-ray diffraction data. To explore natural product scaffolds with SERT regulating activity, a high-content assay for measurement of SERT function in vitro was conducted to evaluate the SERT regulating properties of these isolates. In conclusion, eleven compounds could be potential natural product scaffolds for developing drug candidates targeting SERT. Among which, kanshone C of aristolane-type sesquiterpenoid inhibited SERT most strongly, while desoxo-nachinol A of nardosinane-type sesquiterpenoid instead enhanced SERT potently.

Design and synthesis of dual 5-HT1A and 5-HT7 receptor ligands

5-HT1A and 5-HT7 receptors have been at the center of discussions recently due in part to their major role in the etiology of major central nervous system diseases such as depression, sleep disorders, and schizophrenia. As part of our search to identify dual targeting ligands for these receptors, we have carried out a systematic modification of a selective 5HT7 receptor ligand culminating in the identification of several dual 5-HT1A and 5-HT7 receptor ligands. Compound 16, a butyrophenone derivative of tetrahydroisoquinoline (THIQ), was identified as the most potent agent with low nanomolar binding affinities to both receptors. Interestingly, compound 16 also displayed moderate affinity to other clinically relevant dopamine receptors. Thus, it is anticipated that compound 16 may serve as a lead for further exploitation in our quest to identify new ligands with the potential to treat diseases of CNS origin.