ABSTRACT
Allosteric modulators of ion channels typically alter the transitions rates between conformational states without changing the properties of the open pore. Here we describe a new class of positive allosteric modulators of N-methyl D-aspartate receptors (NMDARs) that mediate a calcium-permeable component of glutamatergic synaptic transmission and play essential roles in learning, memory and cognition, as well as neurological disease. EU1622-14 increases agonist potency and channel-open probability, slows receptor deactivation and decreases both single-channel conductance and calcium permeability. The unique functional selectivity of this chemical probe reveals a mechanism for enhancing NMDAR function while limiting excess calcium influx, and shows that allosteric modulators can act as biased modulators of ion-channel permeation.
Subject(s)
Pyrrolidines/pharmacology , Receptors, N-Methyl-D-Aspartate/metabolism , Allosteric Regulation/drug effects , Animals , Calcium/metabolism , Cells, Cultured , Female , Glutamic Acid/metabolism , Glutamic Acid/pharmacology , Glycine/metabolism , Glycine/pharmacology , HEK293 Cells , High-Throughput Screening Assays/methods , Humans , Ion Channel Gating/drug effects , Mice, Inbred C57BL , Neurons/drug effects , Neurons/metabolism , Oocytes/drug effects , Oocytes/physiology , Receptors, N-Methyl-D-Aspartate/agonists , Receptors, N-Methyl-D-Aspartate/genetics , Xenopus laevisABSTRACT
A series of certain benzyl/phenethyl thiazolidinone-indole hybrids were synthesized for the study of anti-proliferative activity against A549, NCI-H460 (lung cancer), MDA-MB-231 (breast cancer), HCT-29 and HCT-15 (colon cancer) cell lines by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). We found that compound G37 displayed highest cytotoxicity with IC50 value of 0.92⯱â¯0.12⯵M towards HCT-15 cancer cell line among all the synthesized compounds. Moreover, compound G37 was also tested on normal human lung epithelial cells (L132) and was found to be safe in contrast to HCT-15 cells. The lead compound G37 showed significant G2/M phase arrest in HCT-15 cells. Additionally, compound G37 significantly inhibited tubulin polymerization with IC50 value of 2.92⯱â¯0.23⯵M. Mechanistic studies such as acridine orange/ethidium bromide (AO/EB) dual staining, DAPI nuclear staining, annexinV/propidium iodide dual staining, clonogenic growth inhibition assays inferred that compound G37 induced apoptotic cell death in HCT-15 cells. Moreover, loss of mitochondrial membrane potential with elevated intracellular ROS levels was observed by compound G37. These compounds bind at the active pocket of the α/ß-tubulin with higher number of stable hydrogen bonds, hydrophobic and arene-cation interactions confirmed by molecular modeling studies.
Subject(s)
Antineoplastic Agents/chemical synthesis , Benzene/chemistry , Indoles/chemical synthesis , Thiazolidines/chemistry , Tubulin Modulators/chemical synthesis , Tubulin/metabolism , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Cell Line, Tumor , Cell Proliferation/drug effects , Drug Screening Assays, Antitumor , Humans , Hydrogen Bonding , Hydrophobic and Hydrophilic Interactions , Indoles/pharmacology , Membrane Potential, Mitochondrial/drug effects , Molecular Docking Simulation , Molecular Structure , Protein Binding , Static Electricity , Structure-Activity Relationship , Tubulin Modulators/pharmacologyABSTRACT
Secondary structural conformation of hybrid oligo-peptides comprised of 1 : 1 alternating Nucleoside Derived beta-Amino acid (NDA) and l-amino acid residues has been reported. The studies reveal that the NDA residues organize the heterogeneous backbone featuring the surface properties of both nucleic acids and peptides, to adopt a novel 11/8-helical fold.