Sphingosine 1-phosphate (S1P) is a cellular signaling molecule that has been implicated in a variety of diseases including cancer, fibrosis, Alzheimer's, and sickle cell disease. It is formed from the phosphorylation of sphingosine (Sph) by sphingosine kinase (SphK) and SphK exists as two isoforms-"SphK1 and SphK2, which differ with respect to their cellular activity and localization. As the key mediators in the synthesis of S1P, SphKs have attracted attention as viable targets for pharmaceutical inhibition. To validate their potential as therapeutic targets, we aimed to develop potent, selective, and in vivo active inhibitors of SphK.
Herein, we describe the design, synthesis and biological evaluation of SphK2 inhibitors. We first describe the development of six SphK2 inhibitors that assess the utility of replacing lipophilic tail groups with heterocyclic rings. These six compounds demonstrate that the lipid binding pocket for SphK2 cannot accommodate compounds with tail groups that are conformationally restricted or positively charged. We then describe the development of aminothiazole-based analogues of an SphK1-selective inhibitor. A library of 37 aryl-substituted aminothiazole tail groups were synthesized, revealing a structure-activity relationship study that examines electronic effects on the aryl-substituted aminothiazoles and the effect of modifying the amino portion of the aminothiazole. These molecules show surprisingly good potency and selectivity for SphK2. In particular, we highlight 3.20dd (SLC4101431), a biphenyl aminothiazole that is the post potent and selective SphK2 inhibitor to date, with an SphK2 Ki of 90 nM and 100-fold selectivity for SphK2. This molecule's in vivo activity will also be discussed.
Mitochondrial uncouplers are small molecules that shuttle protons from the inter membrane space to the mitochondrial matrix independent of ATP synthase, which disrupts oxidative phosphorylation and promotes increased nutrient metabolism for homeostasis to be maintained. Consequently, small molecule mitochondrial uncouplers have been pursued as probes for mitochondrial function and as potential therapeutics for the treatment of obesity and type 2 diabetes.
Herein, we describe the design, synthesis, and biological evaluation of small molecule mitochondrial uncouplers. We report a library of 52 compounds that have good mitochondrial uncoupling activity over a wide therapeutic range, including 5.16t (SHC4111522) and 5.17i (SHC4091665), which have EC50 values of 0.63 uM and 1.53 uM, respectively, and achieve at least 2-fold increase in oxygen consumption rates relative to basal levels. With these molecules, we demonstrate that pKa and cLogP significantly contribute to uncoupling activity and must be accounted for when developing new generation small molecule mitochondrial uncouplers. / Ph. D. / Sphingosine kinase 1 and 2 (SphK1 and SphK2) are enzymes that facilitate the production of the biomolecule sphingosine 1-phosphate (S1P), which plays an essential role in cell growth and survival. However, overproduction of S1P has been linked to a number of diseases including cancer, Alzheimer’s, and sickle cell disease. Therefore, because S1P is involved in these diseases, the amount of available S1P must be controlled. This work describes the design, development, and biological study of over 40 compounds that could be used as potential inhibitors of SphK2 to help control S1P levels and, therefore, hopefully alleviate the effects of disease. In particular, this work describes molecules that probe the SphK2 binding pocket and demonstrates that the molecules cannot be rigid or positively charged when binding to the hydrophobic portion of the SphK2 binding pocket. Additionally, this work describes the most potent and selective reported SphK2 inhibitor to date, 3.20dd (SLC4101431).
Mitochondrial uncouplers are compounds that target our body's mitochondria and aim to make ATP production challenging, causing the mitochondria to burn extra energy in the form of glucose and fatty acids to allow normal levels of ATP to be produced. By making the mitochondria burn extra energy, mitochondrial uncouplers have the potential to be treatments for diseases such as obesity and diabetes. This works describes the design, development, and biological study of over 50 mitochondrial uncouplers that are capable of increasing mitochondrial activity over a wide concentration range, including 5.16t (SHC4111522) and 5.17i (SHC4091665), which are very potent and effective uncouplers.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/86662 |
| Date | 19 July 2017 |
| Creators | Childress, Elizabeth Saunders |
| Contributors | Chemistry, Santos, Webster L., Gandour, Richard D., Carlier, Paul R., Kingston, David G. I. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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