1. Reactions of the Agonist Clofibric Acid With Cr3+
Britney Yates, Jessica Hayes, Yahia Hamada, Chemistry department, LeMoyne-Owen College, Memphis, TN 38126; Mostafa Badr, Division of Pharmacology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, MO 64108
Chemistry
Abstract
This research is part of the Peroxisome Proliferator-Activated Receptors (PPAR) research. PPARs are a group of receptor proteins that function as transcription factors regulating the expression of genes. Articles published for the PPAR research are increasing exponentially. An American Chemical Society SciFinder library research found 38,000 papers by using PPAR as the key search term in the title of the paper. The following are two examples 1- A forum for a highly important and ever-expanding field of study, M. Badr, PPAR Research, 2006, Activation of member of steroid hormone receptor super family by PPAR, Nature, 1990, 347, (p-Chlorophenoxy)-2-Methylpropionic acid or (Clofibric acid; C10H11ClO3) is an agonist that binds to PPAR. The objectives of this work are: 1- to find whether there is a binding between Cr3+ and Clofibric acid, and 2- to find what is the binding mode if there is binding. From potentiometry, UV-Vis, and IR spectroscopy work it appeared that there is strong binding. These data will be presented.
Experimental
The potentiometric titration solutions were contained in a 250 mL beaker equipped with a magnetic stirring bar. The beaker was covered with a custom made Teflon cover. In a typical titration; Clofibric acid was added then the metal ion (Cr3+) solution followed by the addition of the appropriate amount of NaNO3 to adjust the ionic strength to 0.1 M. D. I. water was added to take the total volume to 100 mL. Details of solution preparation have been documented in references one-three.
References
[1] Hamada, Y. Z. et al. “Spectroscopic and potentiometric studies of the interaction of adenine with trivalent metal ions” J. Coord. Chem., 63 (2),
[2] Hamada, Y. Z. et al. “Equilibrium models of Cr3+ and Cu2+ with glutamate” J. Coord. Chem., 62 (5)
[3] Hamada, Y. Z. et al., “Accurate potentiometric studies of chromium-citrate and ferric-citrate complexes in aqueous solutions at physiological and alkaline pH-values” Synthesis and reactivity of inorganic and metal-organic and nano-metal chemistry 36,
[4] L. Alderighi, P. Gans, A. Ienco, D. Perters, A. Sabatini, and A. Vacca, Hyperquad simulation and speciation (Hyss): a utility program for the investigation of equilibria involving soluble and partially soluble species, Coord. Chem. Rev., 184,
[5] A. E. Martell, R. M. Smith, and R. J. Motekaitis, Critical Stability Constants Database, Version 6.0, NIST, Texas A & M University, College Station, TX, USA 2001.
Conclusion
[1] Our hypothesis that there is binding between the Cr-ion and Clofibric acid was correct.
[2] Calibration of the potentiometric titration system using H3PO4 proved its accuracy.
[3] The reaction system in aqueous solutions at 25oC of Cr3+ and Clofibric acid released four protons due to their strong binding.
[4] The IR and UV-VIS Spectroscopy independently proved the metal binding.
[5] Speciation diagrams have been constructed from the potentiometric titrations using the software program from references numbers 4 & 5 which further proved that the acid is a mono-protic acid.
Acknowledgements
NSF Grant # HRD
Division of Natural & Math. Sciences at LOC