Preparative layer chromatography methodology

Flavonols and flavones are present in many food products and medicinal plants and show relevant antioxidant activity in vitro. In this chapter, classical analytical methods sueh as thin layer ehromatography and two-dimensional paper chromatography together with modem methodologies such as HPLC-MS-MS are reported. Preparative ehromatography methods are also reviewed as well as spectroseopie methods used for flavonoid characterization and identification, including UV spectrophotometry and MS spectrometry. Chemical and enzymatic methods used in flavonoid identification are also reviewed. 

Isolation of potential anticancer compounds from bioactive extracts involves bioactivity-guided fractionation. The DNA-damaging natural products encountered in our studies were extracted by MEK and/or methanol, and the general methodology which we have employed in our bioassay-directed fractionation of these extracts is schematically presented in Fig. 7. These fractionations involved solvent-solvent partition, Sephadex LH-20 gel filtration, normal phase and reversed-phase (RP) column, preparative thin-layer and high pressure liquid chromatography (HPLC). Silica gel chromatography was employed only if bioactive compounds were found to be stable under these mildly acidic conditions. 

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