ABSTRACT
A pharmacophore model for butyrylcholinesterase (BChE) inhibitors was applied to a human cannabinoid subtypeâ 2 receptor (hCB2 R) agonist and verified it as a first-generation lead for respective dual-acting compounds. The design, synthesis, and pharmacological evaluation of various derivatives led to the identification of aminobenzimidazoles as second-generation leads with micro- or sub-micromolar activities at both targets and excellent selectivity over hCB1 and AChE, respectively. Computational studies of the first- and second-generation lead structures by applying molecular dynamics (MD) on the active hCB2 R model, along with docking and MD on hBChE, has enabled an explanation of their binding profiles at the protein levels and opened the way for further optimization. Dual-acting compounds with "balanced" affinities and excellent selectivities could be obtained that represent leads for treatment of both cognitive and pathophysiological impairment occurring in neurodegenerative disorders.
Subject(s)
Benzimidazoles/chemistry , Butyrylcholinesterase/chemistry , Cholinesterase Inhibitors/therapeutic use , Neurodegenerative Diseases/drug therapy , Receptor, Cannabinoid, CB2/antagonists & inhibitors , Amino Acid Sequence , Benzimidazoles/metabolism , Benzimidazoles/therapeutic use , Binding Sites , Butyrylcholinesterase/metabolism , Cholinesterase Inhibitors/chemical synthesis , Cholinesterase Inhibitors/metabolism , Drug Design , Humans , Ligands , Molecular Docking Simulation , Molecular Dynamics Simulation , Molecular Sequence Data , Protein Structure, Tertiary , Receptor, Cannabinoid, CB1/chemistry , Receptor, Cannabinoid, CB1/metabolism , Receptor, Cannabinoid, CB2/metabolism , Sequence Alignment , Stereoisomerism , Structure-Activity RelationshipABSTRACT
Using rimonabant, a potent inverse agonist for cannabinoid receptor type 1 (CB1R), as parent ligand, a series of novel univalent and bivalent ligands were designed by variation of spacer length and its chemical structure. The ligands synthesized were evaluated for affinity and selectivity by radioligand displacement and a functional steady-state GTPase assay. The results showed the nature of the spacer influences the biological readout. Albeit all compounds show significantly lower affinities than rimonabant, this fact could be used to demonstrate that affinities and selectivity are influenced by the chemical structure and length of the spacer and might be helpful for designing bivalent probes for other GPCR receptors.
Subject(s)
Amides/pharmacology , Amines/pharmacology , Cannabinoid Receptor Agonists/chemistry , Cannabinoid Receptor Agonists/pharmacology , Carboxylic Acids/pharmacology , Drug Design , Receptor, Cannabinoid, CB1/agonists , Receptor, Cannabinoid, CB1/metabolism , Amides/chemical synthesis , Amides/chemistry , Amines/chemical synthesis , Amines/chemistry , Cannabinoid Receptor Agonists/chemical synthesis , Carboxylic Acids/chemical synthesis , Carboxylic Acids/chemistry , Dose-Response Relationship, Drug , Humans , Ligands , Molecular Structure , Structure-Activity RelationshipABSTRACT
Protein citrullination results from enzymatic deimination of peptidylarginine and plays an important role in health and disease. Despite increasing scientific interest, the identity and function of citrullinated proteins in vivo remain widely unknown. Thorough proteomic studies could contribute to a better understanding of the role of this posttranslational modification but will require tools for enrichment of citrullinated polypeptides. This study presents a simple technique for a highly specific enrichment of citrullinated peptides that is based on the specific reaction of glyoxal derivatives with the citrulline ureido group under acidic conditions. Beads were functionalized with 4-hydroxyphenylglyoxal attached via a base-labile linker. Incubation of these "citrulline reactive beads" with peptide mixtures at low pH resulted in selective immobilization of citrullinated peptides. Unbound noncitrullinated peptides were removed by extensive washing. Finally, citrullinated peptides carrying a modified ureido group were cleaved off at high pH and were analyzed by mass spectrometry. The procedure was validated by enrichment of synthetic citrulline-containing peptides from a tryptic digest of bovine serum albumin and from an endoproteinase LysC digest of a cytosolic fraction of a cell line. The technique was further applied to enrich citrullinated peptides from a digest of deiminated myelin basic protein.
