Structural determinants for high 5-HT 2A receptor affinity of spiro[9,10-dihydroanthracene]-9,3 ′ -pyrrolidine (SpAMDA)

G protein-coupled receptors in neurodegenerative diseases and psychiatric disorders

Neuropsychiatric disorders are multifactorial disorders with diverse aetiological factors. Identifying treatment targets is challenging because the diseases are resulting from heterogeneous biological, genetic, and environmental factors. Nevertheless, the increasing understanding of G protein-coupled receptor (GPCR) opens a new possibility in drug discovery. Harnessing our knowledge of molecular mechanisms and structural information of GPCRs will be advantageous for developing effective drugs. This review provides an overview of the role of GPCRs in various neurodegenerative and psychiatric diseases. Besides, we highlight the emerging opportunities of novel GPCR targets and address recent progress in GPCR drug development.

Precision Medicine in Antidepressants Treatment

Precision medicine uses innovative approaches to improve disease prevention and treatment outcomes by taking into account people's genetic backgrounds, environments, and lifestyles. Treatment of depression is particularly challenging, given that 30-50% of patients do not respond adequately to antidepressants, while those who respond may experience unpleasant adverse drug reactions (ADRs) that decrease their quality of life and compliance. This chapter aims to present the available scientific data that focus on the impact of genetic variants on the efficacy and toxicity of antidepressants. We compiled data from candidate gene and genome-wide association studies that investigated associations between pharmacodynamic and pharmacokinetic genes and response to antidepressants regarding symptom improvement and ADRs. We also summarized the existing pharmacogenetic-based treatment guidelines for antidepressants, used to guide the selection of the right antidepressant and its dose based on the patient's genetic profile, aiming to achieve maximum efficacy and minimum toxicity. Finally, we reviewed the clinical implementation of pharmacogenomics studies focusing on patients on antidepressants. The available data demonstrate that precision medicine can increase the efficacy of antidepressants and reduce the occurrence of ADRs and ultimately improve patients' quality of life.

Multitargeting nature of muscarinic orthosteric agonists and antagonists

Muscarinic receptors (mAChRs) are typical members of the G protein-coupled receptor (GPCR) family and exist in five subtypes from M₁ to M₅. Muscarinic receptor subtypes do not sufficiently differ in affinity to orthosteric antagonists or agonists; therefore, the analysis of receptor subtypes is complicated, and misinterpretations can occur. Usually, when researchers mainly specialized in CNS and peripheral functions aim to study mAChR involvement in behavior, learning, spinal locomotor networks, biological rhythms, cardiovascular physiology, bronchoconstriction, gastrointestinal tract functions, schizophrenia, and Parkinson’s disease, they use orthosteric ligands and they do not use allosteric ligands. Moreover, they usually rely on manufacturers’ claims that could be misleading. This review aimed to call the attention of researchers not deeply focused on mAChR pharmacology to this fact. Importantly, limited selective binding is not only a property of mAChRs but is a general attribute of most neurotransmitter receptors. In this review, we want to give an overview of the most common off-targets for established mAChR ligands. In this context, an important point is a mention the tremendous knowledge gap on off-targets for novel compounds compared to very well-established ligands. Therefore, we will summarize reported affinities and give an outline of strategies to investigate the subtype’s function, thereby avoiding ambiguous results. Despite that, the multitargeting nature of drugs acting also on mAChR could be an advantage when treating such diseases as schizophrenia. Antipsychotics are a perfect example of a multitargeting advantage in treatment. A promising strategy is the use of allosteric ligands, although some of these ligands have also been shown to exhibit limited selectivity. Another new direction in the development of muscarinic selective ligands is functionally selective and biased agonists. The possible selective ligands, usually allosteric, will also be listed. To overcome the limited selectivity of orthosteric ligands, the recommended process is to carefully examine the presence of respective subtypes in specific tissues via knockout studies, carefully apply “specific” agonists/antagonists at appropriate concentrations and then calculate the probability of a specific subtype involvement in specific functions. This could help interested researchers aiming to study the central nervous system functions mediated by the muscarinic receptor.

Dibenzofuranylethylamines as 5-HT2A/2C Receptor Agonists

The human 5-HT₂ receptor subtypes have high sequence identity in their orthosteric ligand-binding domain, and many agonists are poorly selective between the 5-HT_2A and 5-HT_2C subtypes. Nevertheless, their activation is associated with different pharmacological outcomes. We synthesized five phenethylamine analogs in which the benzene ring is replaced by a bulky dibenzo[b,d]furan moiety and found a couple with >70-fold 5-HT_2C selectivity. Molecular docking studies of the most potent compound (5) at both receptor subtypes revealed the likely structural basis of its selectivity. Although in both cases, some crucial interactions are conserved, the change of the Ala222^5.46 residue in the 5-HT_2C receptor to the larger Ser242^5.46 in the 5-HT_2A subtype, which is the only structural difference between the orthosteric binding pockets of both receptors, weakens a π-π stacking interaction between the dibenzofuran moiety and the important Phe^6.52 residue and breaks a hydrogen bond between the dibenzofuran oxygen and Ser^5.43, explaining the selectivity of compound 5 for the 5-HT_2C receptor. We believe that this effect of the residue at position 5.46 merits further exploration in the search for selective 5-HT_2C receptor agonists that are of considerable interest in the treatment of schizophrenia and substance abuse.

Chiral Sulfide Catalysis for Desymmetrizing Enantioselective Chlorination

An unprecendented chiral sulfide catalyzed desymmetrizing enantioselective chlorination is disclosed. Various aryl-tethered diolefins and diaryl-tethered olefins afforded teralins and tricyclic hexahydrophenalene derivatives, respectively, bearing multiple stereogenic centers in high yields with excellent enantio- and diastereoselectivities. In contrast, the tertiary amine catalyst (DHQD)₂ PHAL led to a diastereomeric product. The products could be transformed into a variety of compounds, such as spiro-N-heterocycles.

Assembly of Diverse Spirocyclic Pyrrolidines via Transient Directing Group Enabled Ortho-C(sp2)-H Alkylation of Benzaldehydes

A diversity-oriented synthesis of useful spirocyclic pyrrolidines was successfully accomplished via late-stage cascade reactions of o-succinimide-substituted benzaldehydes. A catalytic amount of aniline as a transient directing group was efficient for the ruthenium-catalyzed ortho-C(sp²)-H alkylation of benzaldehyde with maleimide. The in situ formed imine overrided a series of other traditional directing groups with excellent site selectivities. More importantly, only 0.5 mol % of ruthenium catalyst was sufficient for a 100 mmol scale-up reaction without column chromatography purification.

1-Benzyl-3′-[(1H-indol-3-yl)carbonyl]-1′-methyl-2-oxo-4′-(pyridin-3-yl)spiro[indoline-3,2′-pyrrolidine]-3′-carbonitrile

In the title compound, C34H27N5O2, the central pyrrolidine ring adopts an envelope conformation, with the N atom as the flap. The mean planes of the two indoline ring systems are inclined to the mean plane of the central pyrrolidine ring by 86.26 (9) and 69.30 (9)°, respectively. The dihedral angle between the benzene and pyridine rings is 75.09 (11)°. In the crystal, molecules are linked by N—H...N and C—H...N hydrogen bonds, forming sheets parallel to theabplane.

An Expedient Regio- and Diastereoselective Synthesis of Hybrid Frameworks with Embedded Spiro[9,10]dihydroanthracene [9,3']-pyrrolidine and Spiro[oxindole-3,2'-pyrrolidine] Motifs via an Ionic Liquid-Mediated Multicomponent Reaction

A series of hitherto unreported anthracene-embedded dispirooxindoles has been synthesized via a one-pot three-component 1,3-dipolar cycloaddition reaction of an azomethine ylide, generated in situ from the reaction of isatin and sarcosine to 10-benzylideneanthracen-9(10H)-one as a dipolarophile in 1-butyl-3-methylimidazolium bromide([bmim]Br), an ionic liquid. This reaction proceeded regio- and diastereoselectively, in good to excellent yields.

Crystal structure of ethyl 2'',3-dioxo-7',7a'-di-hydro-1'H,3H,3'H-di-spiro[benzo[b]thio-phene-2,6'-pyrrolo-[1,2-c]thia-zole-5',3''-indoline]-7'-carboxyl-ate

In the title compound, C23H20N2O4S2, the central pyrrolidine ring adopts an envelope conformation with the spiro C atom, shared with the benzo-thio-phene ring system, as the flap. The thia-zole ring has a twisted conformation on the S-C bond, where the C atom is that closest to methine C atom. The mean planes of the benzo-thio-phene and indoline ring systems are inclined to the mean plane of the central pyrrolidine ring by 82.75 (8) and 80.03 (8)°, respectively, and to each other by 61.49 (6)°. In the crystal, mol-ecules are linked via pairs of N-H⋯O hydrogen bonds, forming inversion dimers with an R 2 (2)(8) ring motif. The dimers are linked via C-H⋯O and C-H⋯N hydrogen bonds, forming a three-dimensional structure. The eth-oxy-carbonyl group is disordered over two orientations, with an occupancy ratio of 0.717 (12):0.283 (12).

Methyl 3′-benzyl-4′-(2,4-dichlorophenyl)-1′-methyl-2-oxo-1-propylspiro[indoline-3,2′-pyrrolidine]-3′-carboxylate

In the title compound, C₃₀H₃₀Cl₂N₂O₃, the indole ring system is roughly planar, with a maximum deviation of 0.1039 (18) Å for the carbonyl C atom, and makes a dihedral angle of 86.61 (9)° with the mean plane of the pyrrolidine ring. This spiro pyrrolidine ring adopts an envelope conformation with the N atom at the flap position. The pyrrole ring of the indole ring system adopts a twisted conformation on the C—C(=O) bond. The mol­ecular structure is stabilized by an intra­molecular C—H⋯O hydrogen bond, which generates an S(6) ring motif, and a π–π inter­action [centroid–centroid distance = 3.6577 (12) Å] involving the 2,4-di­chloro­phenyl ring and the benzyl ring. In the crystal, mol­ecules are linked via C—H⋯O hydrogen bonds, forming C(9) chains running parallel to [10-1].

Methyl 5′′-chloro-1′,1′′-dimethyl-2,2′′-dioxodispiro[indoline-3,2′-pyrrolidine-3′,3′′-indoline]-4′-carboxylate

In the title compound, C₂₂H₂₀ClN₃O₄, the central pyrrolidine ring adopts an envelope conformation on the N atom. The indolinone systems are individually roughly planar, with maximum deviations from their mean planes of 0.130 Å for the spiro C atom of the indolinone unit and 0.172 Å for the carbonyl C atom of the 5-chloro-1-methyl­indolinone unit. They make dihedral angles of 77.7 (8) and 86.1 (8)° with the mean plane through the central pyrrolidine ring. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds supported by C—H⋯O contacts into chains along the ab diagonal. The structure also features C—H⋯O hydrogen bonds, forming R₂²(8) and R₂²(16) rings and generating a three-dimensional array.

Ethyl 27-oxo-15-oxa-2,20-diaza-hexa-cyclo-[18.6.1.0(1,8).0(2,6).0(9,14).0(21,26)]hepta-cosa-9,11,13,21,23,25-hexa-ene-7-carboxyl-ate

In the title compound, C27H30N2O4, the pyrrolidine ring adopts a twisted conformation. The indoline ring system is almost perpendicular to the mean plane of the pyrrolidine ring, making a dihedral angle of 81.7 (8)°. In the crystal, mol-ecules are linked into centrosymmetric dimers with graph-set motif R2(2)(16) via pairs of C-H⋯O hydrogen bonds. The terminal ethyl group of the ester group is disordered over two sets of sites, with a site-occupancy ratio of 0.587 (11):0.413 (11).

Methyl (3R*,3'S*)-1',1''-dimethyl-2,2''-dioxodispiro-[indoline-3,2'-pyrrolidine-3',3''-indoline]-4'-carboxyl-ate

In the title compound, C₂₂H₂₁N₃O₄, the central pyrrolidine ring adopts an envelope conformation with the N atom in the flap position. The indoline ring systems are almost perpendic­ular to the mean plane of the pyrrolidine ring, making dihedral angles of 86.4 (8) and 83.1 (8)°. The acetate group attached to the pyrrolidine ring assumes an extended conformation. In thecrystal, N—H⋯O hydrogen bonds result in the formation of a C(7) chain running along [100]. The crystal packing also features π–π inter­actions [centroid–centroid distance = 3.2032 (11) Å].

Ethyl (E)-3-[1′-ethyl-2-oxo-4′-(phenylsulfonyl)-2H-spiro[acenaphthylene-1,2′-pyrrolidine]-3′-yl]acrylate

In the title compound, C₂₈H₂₇NO₅S, the five-membered pyrrolidine ring, which exhibits an envelope conformation (the C atom at the spiral junction being the flap atom), makes dihedral angles of 57.37 (10) and 86.84 (8)°, respectively, with the phenyl ring and the acenaphthyl­ene ring system. In the crystal, mol­ecules associate via two C—H⋯O hydrogen bonds, forming R₂²(20) and R₂²(10) graph-set motifs.

Antidepressant potential of nitrogen-containing heterocyclic moieties: An updated review

Depression is currently the fourth leading cause of disease or disability worldwide. Antidepressant is approved for the treatment of major depression (including paediatric depression), obsessive-compulsive disorder (in both adult and paediatric populations), bulimia nervosa, panic disorder and premenstrual dysphoric disorder. Antidepressant is a psychiatric medication used to alleviate mood disorders, such as major depression and dysthymia and anxiety disorders such as social anxiety disorder. Many drugs produce an antidepressant effect, but restrictions on their use have caused controversy and off-label prescription a risk, despite claims of superior efficacy. Our current understanding of its pathogenesis is limited and existing treatments are inadequate, providing relief to only a subset of people suffering from depression. Reviews of literature suggest that heterocyclic moieties and their derivatives has proven success in treating depression.

1',1''-Dimethyl-4'-(naphthalen-1-yl)-1,2,3,4-tetra-hydro-naphthalene-2-spiro-3'-pyrrolidine-2'-spiro-3''-indoline-1,2''-dione

In the title compound, C₃₂H₂₈N₂O₂, the pyrrolidine ring adopts an envelope conformation, whereas the cyclo­hexa­none ring in the tetra­hydro­naphthalene fused-ring system adopts a half-chair conformation. The oxindole ring system is oriented at an angle of 48.2 (1)° with respect to the naphthyl ring system. An intra­molecular C—H⋯O close contact is observed. In the crystal, mol­ecules associate via two C—H⋯O hydrogen bonds, forming R₂²(14) and R₂²(10) dimers.