Natural abundance 13 C NMR spectra of biological extracts are recorded in a single scan provided that the samples are hyperpolarized by dissolution dynamic nuclear polarization combined with cross polarization. Heteronuclear 2D correlation spectra of hyperpolarized breast cancer cell extracts can also be obtained in a single scan. Hyperpolarized NMR of extracts opens many perspectives for metabolomics.Lying at the interface of chemistry and biology, metabolomics is one of the youngest sprouts of the sprawling tree of "omic" sciences. The last decade has witnessed a growing interest in mapping metabolic pathways, in identifying new biomarkers, and in modeling metabolic fluxes. 1,2 Nuclear Magnetic Resonance (NMR) spectroscopy is a major analytical technique in this field, offering unambiguous information about the identity of metabolites and their time-dependent concentrations in complex samples such as biofluids, extracts and tissues. However, proton NMR spectra have a limited range of chemical shifts and often suffer from overlapping signals. Carbon-13, which has a larger chemical shift dispersion, can benefit from sensitive detectors 3 or from isotopic enrichment, 4 albeit at the cost of an enhanced complexity of the spectra due to 13 C-13 C couplings. Heteronuclear ( 1 H→ 13 C) correlation spectroscopy can in principle offer a satisfactory dispersion. 5,6 So far, 13 C NMR is not routinely used in metabolomic studies, but hyperpolarization by dissolution dynamic nuclear polarization (D-DNP) combined with cross polarization (CP) could boost its popularity in this field.Hyperpolarization techniques are capable of generating spin polarization levels that are about 50 000 times above Boltzmann equilibrium at room temperature. 7-9 Once prepared and transferred to a solution-state NMR spectrometer, the resulting magnetization can be exploited within a limited time-span that depends on the longitudinal relaxation time T 1 of the hyperpolarized nuclei. Among various methods for hyperpolarization, dynamic nuclear polarization (DNP) is least affected by the chemical substrate and sample preparation. 10 For solution-state NMR, particularly promising results can be obtained by dissolution DNP, where the sample to be analyzed is mixed with free radicals in a glass-forming solution, frozen to liquid helium temperatures, and hyperpolarized by irradiating in the vicinity of the electron spin resonance (ESR) of the unpaired electrons of the radicals. 11 Spins of 13 C nuclei may be polarized either directly or via cross-polarization from protons to 13 C. 12 Rapid melting and shuttling of the sample from the polarizer to a routine NMR spectrometer enables conventional solution-state NMR spectroscopy with a sensitivity that can be boosted by a factor of about 50 000. Most applications of D-DNP have been restricted to the injection of pure hyperpolarized 13 C-labeled molecules such as pyruvate into living organisms. 13 D-DNP has hardly been applied to complex mixtures of metabolites, 14 but only to a few wellchosen small molecules...

We have developed new methods enabling in vivo localization and identification of metabolites through their 1H NMR signatures, in a drosophila. Metabolic profiles in localized regions were obtained using HR-MAS Slice Localized Spectroscopy and Chemical Shift Imaging at high magnetic fields. These methods enabled measurement of metabolite contents in anatomic regions of the fly, demonstrated by a decrease in β-alanine signals in the thorax of flies showing muscle degeneration.