Determination of the level and absolute configuration of 2-hydroxyglutaric acid in a patient's urine is a method of diagnosing two metabolic diseases. Such a determination can be done with the aid of NMR spectroscopic methods. In this paper the careful interpretation of 1 H and 13 C NMR spectra of this metabolite and its lactone measured under conditions used in biomedical assays is reported. The 1 H chemical shifts and spin-spin coupling constants were derived using the total lineshape analysis method.
The enolization degrees of succinylacetone, an important heme biosynthesis inhibitor, have been determined in CDCl(3) and water solutions using (1)H NMR. The solution structures of SA have been investigated using a combined NMR/theoretical [GIAO DFT PBE1PBE/6-311++G(2d, p) PCM] approach. The populations of both enolic forms undergoing enol-enol equilibriums for SA and a series of unsymmetrical beta-diketones have been established by a quantitative comparison of the experimental (13)C NMR chemical shifts and calculated shielding constants. Moreover, using the same method and considering various trial structures differing in conformation and/or hydration of neutral SA molecule as well as its monoanion and dianion the structures of the most abundant species being present in the investigated water solutions have been deduced.
High-resolution (1)H NMR spectroscopy of body fluids has proved to be very useful in diagnostics of inherited metabolic diseases, whereas (13)C NMR remains almost unexploited. In this paper the application of (13)C NMR spectroscopy of fivefold concentrated urine samples for diagnosis of selected metabolic diseases is reported. Various marker metabolites were identified in test urine samples from 33 patients suffering from 10 different diseases, providing information which could be crucial for their diagnoses. Spectra were accumulated for 2 h or overnight when using spectrometers operating at 9.4 or 4.7 T magnetic fields, respectively. Interpretation of the measurement results was based on a comparison of the peak positions in the measured spectrum with reference data. The paper contains a table with (13)C NMR chemical shifts of 73 standard compounds. The method can be applied individually or as an auxiliary technique to (1)H NMR or any other analytical method.
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