ABSTRACT
Sphingosine-1-phosphate (S1P) receptor agonists have shown promise as therapeutic agents for multiple sclerosis (MS) due to their regulatory roles within the immune, central nervous system, and cardiovascular system. Here, the design and optimization of novel [1,2,4]oxadiazole derivatives as selective S1P receptor agonists are described. The structure-activity relationship exploration was carried out on the three dominant segments of the series: modification of the polar head group (P), replacement of the oxadiazole linker (L) with different five-membered heterocycles, and the use of diverse 2,2'-disubstituted biphenyl moieties as the hydrophobic tail (H). All three segments have a significant impact on potency, S1P receptor subtype selectivity, physicochemical properties, and in vitro absorption, distribution, metabolism, excretion and toxicity (ADMET) profile of the compounds. From these optimization studies, a selective S1P1 agonist, N-methyl-N-(4-{5-[2-methyl-2'-(trifluoromethyl)biphenyl-4-yl]-1,2,4-oxadiazol-3-yl}benzyl)glycine (45), and a dual S1P1,5 agonist, N-methyl-N-(3-{5-[2'-methyl-2-(trifluoromethyl)biphenyl-4-yl]-1,2,4-oxadiazol-3-yl}benzyl)glycine (49), emerged as frontrunners. These compounds distribute predominantly in lymph nodes and brain over plasma and induce long lasting decreases in lymphocyte count after oral administration. When evaluated head-to-head in an experimental autoimmune encephalomyelitis mouse model, together with the marketed drug fingolimod, a pan-S1P receptor agonist, S1P1,5 agonist 49 demonstrated comparable efficacy while S1P1 -selective agonist 45 was less potent. Compound 49 is not a prodrug, and its improved property profile should translate into a safer treatment of relapsing forms of MS.
Subject(s)
Drug Design , Encephalomyelitis, Autoimmune, Experimental/drug therapy , Immunologic Factors/chemistry , Immunologic Factors/therapeutic use , Oxadiazoles/chemistry , Oxadiazoles/therapeutic use , Receptors, Lysosphingolipid/agonists , Animals , Encephalomyelitis, Autoimmune, Experimental/immunology , Female , Humans , Immunologic Factors/pharmacokinetics , Mice , Mice, Inbred C57BL , Models, Molecular , Multiple Sclerosis/drug therapy , Oxadiazoles/pharmacokinetics , Receptors, Lysosphingolipid/immunology , Structure-Activity RelationshipABSTRACT
The discovery of a novel series of S1P1 agonists is described. Starting from a micromolar HTS positive, iterative optimization gave rise to several single-digit nanomolar S1P1 agonists. The compounds were able to induce internalization of the S1P1 receptor, and a selected compound was shown to be able to induce lymphopenia in mice after oral dosing.
Subject(s)
Antineoplastic Agents/chemistry , Receptors, Lysosphingolipid/agonists , Administration, Oral , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacokinetics , Cell Line, Tumor , Drug Discovery , Fingolimod Hydrochloride , High-Throughput Screening Assays , Humans , Mice , Microsomes, Liver/metabolism , Propylene Glycols/chemistry , Propylene Glycols/pharmacology , Rats , Receptors, Lysosphingolipid/metabolism , Sphingosine/analogs & derivatives , Sphingosine/chemistry , Sphingosine/pharmacology , Structure-Activity RelationshipABSTRACT
Glycogen synthase kinase-3 (GSK3) is a serine-threonine protein kinase that exists as two isozymes, GSK3alpha and GSK3beta. It plays important roles in regulating cell structure, function, and survival, and dysregulation of its function is linked to disorders such as Alzheimer's disease and type II diabetes. In resting cells, GSK3 is active and regulates the function of many downstream targets, including beta-catenin. We describe the development of a cell-based assay designed to measure the activity of GSK3 by directly measuring the accumulation of beta-catenin in Chinese hamster ovary clone K1 (CHOK1) cells. Beta-catenin levels were assessed using an antibody-based staining protocol with a luminometric readout. The assay is set up in a 96-well format. The use of GSK3 inhibitors demonstrated that this assay could be used to compare the effects of various small molecules on GSK3 inhibition in CHOK1 cells.
