Category F. Drug Metabolism, Toxicity and Pharmacogenomics
F1. Separation of the heat-based degradation products of oxytocin by capillary electrophoresis
Jessica S. Creamer1,3, Shannon T. Krauss1,2, and Susan M. Lunte1,3
1Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS, USA
2Keene State College, Department of Chemistry, Keene, NH, USA
3Ralph N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, KS, USA
Oxytocin is needed around the world to prevent postpartum hemorrhage (PPH), particularly in developing countries where PPH accounts for 25% of maternal deaths annually. Oxytocin is a peptide drug and is susceptible to both chemical and physical degradation when shipped and stored inappropriately, e.g. heat and/or light exposure. Of the few reports on the determination of oxytocin degradation, the analytical methodology typically relies on instrumentation such as liquid chromatography/mass spectrometry (LCMS). However, in developing countries, neither the funding nor the proper infrastructure is available for these types of assays.
Capillary electrophoresis (CE) is a versatile analytical technique with the benefits of a relatively low startup cost. Simple, pared-down instruments used for teaching purposes have been shown to have robust analytical performance when used to separate small molecule pharmaceuticals. Additionally, CE provides a lower cost-per-analysis than HPLC through small sample volumes, less reagent use, and less waste generated.
Accelerated degradation of oxytocin (pH 2.0) was performed in both controlled (in laboratory water bath) and uncontrolled (outside summer temperatures in Lawrence, KS) environments. Conventional capillary electrophoresis with UV detection (214nm) was used to develop a separation method for the degraded samples using a background electrolyte of 50mM sodium phosphate at pH 6.0 with 12.5mM sulfobutylether-ß-cyclodextrin to enhance selectivity. Peak identification of the degradation products was confirmed by validated LCMS methods. At low pH the major degradation products found were mono-, bis-, and tris-deamidated oxytocin.
F2. Finding DNA Damage: The Physics of Nucleosome Positioning
Sarah E. LeGresley and Matthew Antonik
University of Kansas, Department of Physics and Astronomy,
1082 Malott Hall, 1251 Wescoe Dr., Lawrence, KS 66045
DNA damage can lead to cancer or acceleration of the aging process. It is commonly accepted that DNA damage occurs at a rate of ~19,000 mutations per cell per day. Researchers, however, are perplexed at how efficient the body's repair mechanisms are at finding and repairing these lesions, as the search seems to exceed the diffusion limited rate. Interestingly, damage incurred to the DNA on a nucleosome may be even harder to repair due to steric occlusion of the nucleosome itself. To date, several published reports have illustrated that DNA undergoes a breathing process in which the DNA spontaneously wraps and unwraps from the histone octamer. We believe that this process may facilitate the body's natural repair mechanisms. Therefore, in the current study, we aim to modify a previously established mathematical model of nucleosome breathing to include the possibility of damage. In doing so, we hope to identify a mechanism which helps explain the rate of DNA repair in this region.
F3. Discovery of Sultams for Probing Cellular Signaling Pathways
Thiwanka B. Samarakoon, Qin Zang and Paul R. Hanson*
Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive,Lawrence, KS 66045-7582
The University of Kansas Center for Chemical Methodologies and Library Development (KU-CMLD), 2034 Becker Drive, Shankel Structural Biology Center, West Campus, Lawrence, KS 66047
Diversity-oriented synthetic efforts in conjunction with high-throughput screening (HTS) within the NIH-MLPCN (NIH-Molecular Libraries Probe Compound Network) are reported and have revealed a number of novel sultams exhibiting potent activities against a variety of protein targets involved in cellular signaling pathways, including TGF-b, NF-kb, Schnurri-3, and glucogen-like peptide l receptor signaling. We herein present the HTS data on the aforementioned targets. Efforts are underway in launching collaborative research efforts in the design and synthesis of focused library of key sultam scaffolds aimed at the identification of lead molecules for advancing into chemical probe development.