Metabolic labeling, unnatural

Jacobs, C. L., Yarema, K. J., Mahal, L. K., Nanman, D. A., Charters, N., Bertozzi, C. R. (2000). Metabolic labeling of glycoproteins with chemical tags through unnatural sialic acid biosynthesis. Methods Enzymol., 327, 260-275. 

The metabolic pathways in plants and living organisms were studied by means of tritium-labeled morphine (508, 509). The use of unnaturally tritium-labeled codeine derivatives showed that P. somniferum is able to... 

In a pharmaceutical context, the biologically active part of a structure is of the most importance, and it is convenient to group biologically equivalent forms together. A technique which has worked for many years in GSK is the concept of a parent structure. The parent structure is derived from the version structure (as supplied by the chemist) by stripping off any salts and solvates and converting any unnatural isotopes to their normally abundant form. Isotopically labelled compounds are typically used for metabolism studies and are therefore normalised and grouped under the same parent as the nonisotope form. 

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