Mass spectrometry in natural product structure elucidation.

Abstract

Starting in the sixties of the last century mass spectrometry has steadily gained in importance in natural products chemistry. Originally limited to electron ionization of molecules that can be vaporized un-decomposed in high vacuum, the introduction of alternate ionization techniques allows today the access to compounds with masses well over one million Daltons. In this review six classes of natural products will be presented where structural information can be obtained from the fragmentation patterns, considering also historical developments. Using the example of pentacyclic triterpenoids, it is shown how structural studies with electron ionization have been developed over the years. Vertebrate alkaloids cover a field where the structural studies mainly stem from the last twenty years relying also on electron ionization but in part introducing more recent techniques. The chapters on lipids and on carbohydrates demonstrate specifically how new ionization techniques have allowed the handling of involatile compounds and have extended the area of structural research step by step. The chapters covering peptides and nucleotides show the access to very high masses and to three-dimensional information of molecules. Fast computers with almost unlimited data storage capacities have made possible automated structural studies and the analysis of complex mixtures.