Metabolic analysis of the rabbit cornea by proton nuclear magnetic resonance spectroscopy

Perchloric acid extracts of the rabbit cornea were analyzed by high-resolution 1H NMR spectroscopy, including the two-dimensional shift-correlated (COSY) technique. Numerous metabolites including leucine/isoleucine, 3-hydroxybutyrate, valine, lactate, alanine, lysine, acetate, glutamate, creatine/phosphocreatine, taurine, glycine, inositol, glucose, tyrosine, phenylalanine, histidine, adenosine and formate have been simultaneously detected and identified in the NMR spectra. Concentrations of some of these were also determined. Of particular importance are the detection and identification of hypotaurine in the corneal tissue. Hypotaurine is a precursor of the synthesis of taurine and may act as an antioxidant. Moreover, the presence of choline, a precursor for acetylcholine, was established. This novel metabolite profile of the cornea obtained by high-resolution 1H NMR spectroscopy may be of value in the study of pathologic and toxic disorders.