Magic angle spinning NMR and ¹H-³¹P heteronuclear statistical total correlation spectroscopy of intact human gut biopsies

Previously we have demonstrated the use of ¹H magic angle spinning (MAS) NMR spectroscopy for the topographical variations in functional metabolic signatures of intact human intestinal biopsy samples. Here we have analyzed a series of MAS ¹H NMR spectra (spin-echo, one-dimensional, and diffusion-edited) and ³¹P-{¹H} spectra and focused on analyzing the enhancement of information recovery by use of the statistical total correlation spectroscopy (STOCSY) method. We have applied a heterospectroscopic cross-examination performed on the same samples and between ¹H and ³¹P-{¹H} spectra (heteronuclear STOCSY) to recover latent metabolic information. We show that heterospectroscopic correlation can give new information on the molecular compartmentation of metabolites in intact tissues, including the statistical "isolation" of a phosphlipid/triglyceride vesicle pool in intact tissue. The application of ³¹P-¹H HET-STOCSY allowed the cross-assignment of major ³¹P signals to their equivalent ¹H NMR spectra, e.g., for phosphorylcholine and phosphorylethanolamine. We also show pathway correlations, e.g., the ascorbate-glutathione pathway, in the STOCSY analysis of intact tissue spectra. These ³¹P-¹H HET-STOCSY spectra also showed different topographical regions, particular for minor signals in different tissue microenvironments. This approach could be extended to allow the detection of altered distributions within metabolic subcompartments as well as conventional metabonomics concentration-based diagnostics.