FT IR SPECTROSCOPY AND MOLECULAR MODELING OF THE VITAMIN B13 / ‑CD INCLUSION COMPLEX

I. Bratu1, A. Hernanz2, Greta Gilca3 and Pamela Horbaniuc3 

1National Institute for R&D of Isotopic and Molecular Technologies, P.O. Box 700, 400293, Cluj-Napoca, ROMANIA
2UNED, Depto de CC y TT Físico Quimicas, Senda del Rey 9, 28040 Madrid, SPAIN 
3"Babes-Bolyai" University, Faculty of Physics, 1 Kogalniceanu st., 400084, Cluj-Napoca, ROMANIA

Orotic acid (OA), also known as vitamin B13 or 4-carboxy-uracile, is a precursor of nucleic acid bases acting as an intermediate in pyrimidine synthesis, particularly the uracile base [1]. It was found in cells and body fluids of many living organisms. This compound is applied in medicine as biostimulator of the of the ionic exchange processes. There is a great interest in the orotic acid relation to food protection and nourishment research. A reliable assignment of its vibrational spectra [2] is a useful basis in the study of the interaction with other chemical species present in the biological milieu. From this point of view there are problems with the solubility in water of this molecular compound. Inclusion complexes in cyclodextrins could be a possibility due to the water solubility increase of these supramolecular compounds. The perfect compatibility of these inclusion complexes with the living organisms must be taken into account by their frequent use now as antiiflammatory [3-4], cardiovascular [5], antidepressive or ophthalmologic drugs [6]. 
The aim of the present work was to explain the supramolecular structure of these inclusion complexes based on the analysis of the vibrational spectra and on molecular modeling. 
The changes appearing in the 2000-1500 cm-1 spectral region of the inclusion complexes obtained by different methods (kneading, co precipitation and freeze-drying ones) were investigated to identify the forces implied in these inclusion processes.
A spatial geometry of the inclusion complex was obtained with the molecular modeling by using MM+ molecular mechanics calculation.

Bibliography
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