Small-molecule metabolite profiles

Drugs from natural sources can be classified in two categories small molecules metabolites and transgenetically produced biopolymers. Small molecule metabolites are extracted from their natural sources by various methods depending on their chemical properties. Often the isolated product is used as a starting material and is modified by chemical manipulations to obtain a desirable biological profile. A good example is 6-aminopeniciilanic acid that is used to prepare penicillin derivatives with a better spectrum of activities that alleviate bacterial resistance. 

In addition to MALDI, matrix-free LDI techniques have been proved to be useful in IMS studies of small molecules (62). Thus, NIMS has also been proved to be a highly sensitive matrix-free method (in which functionalized surfaces are used to absorb the laser, eliminating the need for matrices) for tissue imaging in metabolomics (75,76). It has been described that NIMS surface can be easily treated or modified with different chemical initiators. As a result, distinct metabolite profiles from the same biological sample can be obtained. For instance, coating NIMS surface with cationization agents... 

These preclinical drug metabolism studies may also include metabolite profiling in plasma, selected tissues, urine, and bile to assess the distribution and disposition of potentially important metabolites, such as those having a level 5% or greater relative to the parent compound. Metabolite profiling requires a technique to separate the parent compound from metabolites and other endogenous compounds. For small organic molecules, HPLC is usually the method of choice. For macromolecules, gel or capillary electrophoresis techniques can be defined with sufficient resolution capability to separate the... 

LC—MS in Endogenous Metabolite Profiling and Small-Molecule Biomarker Discovery... 

Zhang, H., Cha, S., Yeung, E.S., (2007) Colloidal graphite-assisted laser desorption/ionization MS and MS(n) of small molecules. 2. Direct profiling and MS imaging of small metabolites from fruits. Analytical Chemistry, 79, 6575-6584. 

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