Natural product libraries elucidation

Classical natural products chemistry involved the isolation and purification of major natural product compounds from specific representatives of flora or fauna for structure determination. The terpenoids are the compounds of interest in this chapter and their initial structure elucidations were carried out in the 1930s—1970s. There are numerous compilations and encyclopaedia on terpenoids listing the physicochemical properties and literature background of the pure natural products. Many of the mass spectra of the underivatized terpenoid compounds are in the standard mass spectrum libraries of modern computerized data systems. 

Today, selected targets of interest are transferred to the HTS aiming at discovering a hit , and subsequently a lead structure within one to two months. After that time, the target concerned is replaced by a new one. Thus, rapid characterization and structure elucidation of the active principles of interest from natural sources are critical with reference to competition with synthetic libraries of pure and structurally defined compounds. Elaboration of LC-MS and LC-NMR techniques to accelerate structure elucidation of bioactive principles from natural sources is currently underway. Combination of these techniques with databases comprising a maximum of known natural compounds will probably contribute substantially to more interest in natural products for application in drug discovery. 

Curran et alls work informs us that construction of stereoisomer libraries followed by thorough studies on their NMR and enantioselective HPLC behaviors is an especially reliable way of elucidating the stereostructure of natural products. This type of thorough stereochemical analysis is likely to become more popular in the future in connection with the advances in parallel synthesis. 

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