Revealing the interaction modes of 5-HT2A receptor antagonists and the Structure-Based virtual screening from FDA and TCMNP database

Discovery and in vitro Evaluation of Novel Serotonin 5-HT2A Receptor Ligands Identified Through Virtual Screening

The 5-HT2A receptor is a molecular target of high pharmacological importance. Ligands of this protein, particularly atypical antipsychotics, are useful in the treatment of numerous mental disorders, including schizophrenia and major depressive disorder. Structure-based virtual screening using a 5-HT2A receptor complex was performed to identify novel ligands for the 5-HT2A receptor, serving as potential antidepressants. From the Enamine screening library, containing over 4 million compounds, 48 molecules were selected for subsequent experimental validation. These compounds were tested against the 5-HT2A receptor in radioligand binding assays. From the tested batch, six molecules were identified as ligands of the main molecular target and were forwarded to a more detailed in vitro profiling. This included radioligand binding assays at 5-HT1A, 5-HT7, and D2 receptors and functional studies at 5-HT2A receptors. These compounds were confirmed to show a binding affinity for at least one of the targets tested in vitro. The success rate for the inactive template-based screening reached 17 %, while it was 9 % for the active template-based screening. Similarity and fragment analysis indicated the structural novelty of the identified compounds. Pharmacokinetics for these molecules was determined using in silico approaches.

Design, Synthesis, Molecular Docking, and Biological Evaluation of Novel Pimavanserin-Based Analogues as Potential Serotonin 5-HT2A Receptor Inverse Agonists

There is concern for important adverse effects with use of second-generation antipsychotics in Parkinson's disease psychosis (PDP) and dementia-related psychosis. Pimavanserin is the only antipsychotic drug authorized for PDP and represents an inverse agonist of 5-HT_2A receptors (5-HT2AR) lacking affinity for dopamine receptors. Therefore, the development of serotonin 5-HT2AR inverse agonists without dopaminergic activity represents a challenge for different neuropsychiatric disorders. Using ligand-based drug design, we discovered a novel structure of pimavanserin analogues (2, 3, and 4). In vitro competition receptor binding and functional G protein coupling assays demonstrated that compounds 2, 3, and 4 showed higher potency than pimavanserin as 5-HT2AR inverse agonists in the human brain cortex and recombinant cells. To assess the effect of molecular substituents for selectivity and inverse agonism at 5-HT2ARs, molecular docking and in silico predicted physicochemical parameters were performed. Docking studies were in agreement with in vitro screenings and the results resembled pimavanserin.

"Selective" serotonin 5-HT2A receptor antagonists

Blockade of the serotonin 5-HT_2A G protein-coupled receptor (5-HT_2AR) is a fundamental pharmacological characteristic of numerous antipsychotic medications, which are FDA-approved to treat schizophrenia, bipolar disorder, and as adjunctive therapies in major depressive disorder. Meanwhile, activation of the 5-HT_2AR by serotonergic psychedelics may be useful in treating neuropsychiatric indications, including major depressive and substance use disorders. Serotonergic psychedelics and other 5-HT_2AR agonists, however, often bind other receptors, and standard 5-HT_2AR antagonists lack sufficient selectivity to make well-founded mechanistic conclusions about the 5-HT_2AR-dependent effects of these compounds and the general neurobiological function of 5-HT_2ARs. This review discusses the limitations and strengths of currently available "selective" 5-HT_2AR antagonists, the molecular determinants of antagonist selectivity at 5-HT_2ARs, and the utility of molecular pharmacological and computational methods in guiding the discovery of novel unambiguously selective 5-HT_2AR antagonists.

Overcoming Depression with 5-HT2A Receptor Ligands

Depression is a multifactorial disorder that affects millions of people worldwide, and none of the currently available therapeutics can completely cure it. Thus, there is a need for developing novel, potent, and safer agents. Recent medicinal chemistry findings on the structure and function of the serotonin 2A (5-HT2A) receptor facilitated design and discovery of novel compounds with antidepressant action. Eligible papers highlighting the importance of 5-HT2A receptors in the pathomechanism of the disorder were identified in the content-screening performed on the popular databases (PubMed, Google Scholar). Articles were critically assessed based on their titles and abstracts. The most accurate papers were chosen to be read and presented in the manuscript. The review summarizes current knowledge on the applicability of 5-HT2A receptor signaling modulators in the treatment of depression. It provides an insight into the structural and physiological features of this receptor. Moreover, it presents an overview of recently conducted virtual screening campaigns aiming to identify novel, potent 5-HT2A receptor ligands and additional data on currently synthesized ligands acting through this protein.