mutica have been analyzed recently by GC-MS together with the application of on-line databases.[30] Saponins Saponins are steroidal or triterpenoidal glycosides that occur widely in plant species of nearly 100 families.[31] leave a message As saponins are highly polar compounds and difficult to volatilize, the application of GC-MS is mainly restricted to the analysis of aglycones known as sapogenins or saponins. Apart from just a few, saponins do not have chromophores that are essential for UV detection. Owing to the lack of chromophores in saponins, it is not helpful to use a UV or PDA as the primary detection technique. An alternative primary detection technique, e.g., refractive index, could be used. Sometimes, precolumn derivatization of saponins can be used to attach a chromophore that facilitates UV detection at higher wavelengths.

Among the hyphenated techniques, LC-MS, LC-NMR, and CE-MS could be useful for the rapid initial screening of crude extracts or fraction for the presence of saponins. While in LC-MS analysis TSP interface is used most extensively in phytochemical analysis, saponins having more than three sugars cannot be analyzed using this interface. For larger saponins (MW > 800), CF-FAB or ES is the method of choice. A combination of matrix solid-phase dispersion extraction and LC-NMR-MS was applied in the rapid on-line identification of asterosaponins of the starfish Asterias rubens.[23,24] The LC-NMR-MS provided structural information in one single chromatographic run and was suitable for saponins in the molecular mass range 1200�C1400 amu.

This technique also allowed semiquantitative LC-NMR measurements through methyl signals (Me-18 and Me-19) of the steroidal skeleton. Dereplication The discrimination between previously tested or recovered natural product extracts and isolated single components found therein is essential to decrease the screening costs by reducing the large collections of isolates that are then subject to further detailed evaluation. Bioassay guided natural product isolation often leads to already known compounds of limited, or no chemical or pharmacological interest. Hence, appropriate methods that can distinguish at an early stage novel rather than known or already isolated natural compounds are essential for modern cost-effective natural product research.

Dereplication strategies employ a combination of separation science, Carfilzomib spectroscopic detection technologies, and on-line database searching. Thus, the combination of HPLC with structurally informative spectroscopic detection techniques, e.g., PDA, MS, and NMR, could allow crude extracts or fractions to be screened not just for biological activity but also for structural classes. To perform an efficient screening of extracts, both biological assays and HPLC analysis with various detection methods are used.