Table 2.
Observable | Probe | References |
---|---|---|
(i) Designed probes | ||
| ||
Amino acid concentrations | acetic anhydride | [39] |
| ||
Binding | 1H, 13C and 19F in binders | [42–44] |
| ||
Drug metabolism | Carbamazepine | [46] |
| ||
Ca2+ concentration | trimethylphenylammonium ubstituted with triacetic acid |
[38] |
| ||
Contrast agent | 6LiCl | [63] |
| ||
Enzyme activity | trimethylphenylammonium substituted with methyl ester |
[38] |
| ||
Hocl | p-Anisidine | [36] |
| ||
Hydrogen peroxide | benzoylformic acid trimethylphenylammonium substituted with boronic acid ester |
[38,64] |
| ||
pH | 89Y-complexes | [28,34] |
| ||
Protein expression | N-acetyl-L-methionine | [49] |
| ||
(ii) Derivatized endogenous probes | ||
| ||
Enzyme activity | 3,5-Difluorobenzoyl-L-glutamic acid (carboxypeptidase prodrug) |
[48] |
| ||
Enzyme activity | ethyl pyruvate | [57] |
| ||
Perfusion | permethylated amino acids (betains) | [51] |
| ||
Protein expression | pyruvate derivatives as reporter groups | [37] |
| ||
(iii) Endogenous probes | ||
| ||
Cell permeability, lysis | fumarate metabolism | [65] |
pyruvate diffusion | [66] | |
| ||
Drug efficacy | pyruvate | [67–69] |
fumarate | [65] | |
| ||
Enzyme activities and reaction fluxes | ||
• Ldh | pyruvate, lactate | [70,71] |
• Alt | alanine, pyruvate | [50] |
• Bcat | ketoisocaproic acid | [72] |
• Glutaminase | glutamine | [73,74] |
• Carnitine acetyltransferase, AcetylCoA synthetase |
acetate | [75] |
• Betaine aldehyde metabolism | choline analog | [76] |
• Pyruvate decarboxylase | pyruvate | [77] |
• Pyruvate dehydrogenase | pyruvate | [78,79] |
| ||
Enzyme mechanistic studies | fructose | [61] |
alanine | [80] | |
| ||
Gene expression, gene loss | glucose | [61,81] |
| ||
Intracellular pH | acetate | [82] |
pyruvate | [83] | |
| ||
Metabolic strategies in different genomes | glucose | [61] |
| ||
Oncogene signalling | pyruvate | [84] |
ketoisocaproic acid | [72] | |
| ||
Pathway activity, bottlenecks | ||
• Glycolysis | glucose | [61,85–87] |
• Indicator of aerobic glycolysis | [1-13C]pyruvate | [71,88,89] |
• TCA cycle | [2-13C]pyruvate | [90] |
• Fatty acid and ketone body metabolism | butyrate | [91] |
| ||
Redox status | dehydroascorbic acid | [92,93] |
| ||
Sulfite cytotoxicity | glucose | [94] |
| ||
Tissue pH | bicarbonate | [95] |
| ||
Transporter level and activity | ||
•Glucose transporter | glucose | [86] |
•Monocarboxylate transporter | pyruvate | [88,96] |
•Urea carrier | urea | [97] |
| ||
Tumor grading | alanine, pyruvate, lactate | [98] |