Usage of the ultrafast intermolecular single-quantum coherence (UF iSQC) sequence for NMR spectroscopy of ex vivo tissue

• UF iSQC method not only can overcome the inhomogeneity of biological tissues, but also greatly reduce the experimental time.
• Metabolic changes of three types of fish samples during storage have been investigated.
• Some metabolites may be selected as biomarkers to indicate the decayed process.
• The similar metabolic profile variation has been found among three types of fish samples.

High-resolution nuclear magnetic resonance (NMR) spectroscopy has been considered as a powerful tool for noninvasive, rapid, and accurate composition analyses on solution samples. However, because tissues are in semisolid phase, the high-resolution spectra cannot be obtained by conventional NMR spectroscopy. In the present study, an ultrafast intermolecular single quantum coherence (UF iSQC) NMR spectroscopic method based on spatial encoding is used for direct analyses of intact salmon muscle tissues, intact eggs from shishamo smelt, and a whole zebra fish. Most of free amino acid and fatty acid signals can be directly detected within 5 min in their original state without tedious sample preparation processes. The experimental results show that not only can the UF iSQC method overcome the inhomogeneity of biological tissues, but also it can greatly reduce experimental times owing to the introduction of ultrafast acquisition schemes. Changes occurring in amino acids and fatty acids of salmon muscle tissues, eggs from shishamo smelt, and the whole zebra fish during storage are investigated. Similar variation patterns of metabolic profiles have been deduced for three fish samples, yielding good agreements with literature results.