Anthocyanins crude extract purification

Different resins have been used to clean up or prefractionate anthocyanins prior to isolation or characterization, including ion-ex-change resins, polyamide powders, and gel materials. Chromatography on Dowex or Amber-lite ion-exchange resins, as well as polyamide powders such as polyvinylpyrrolidone (PVP), have been used to isolate polar nonphenolic compounds from crude anthocyanin extracts. Column chromatography on Sephadex LH-20 can be used for fractionation of crude extracts and is also particularly useful for purification... 

The Basic Protocol describes the reversed-phase HPLC analysis of polyphenolic compounds isolated into nonanthocyanin and anthocyanin fractions by solid-phase extraction. The Alternate Protocol describes the HPLC separation of acidic and neutral polyphenolic fractions. Fractionated samples are used because significant amounts of interfering compounds are extracted along with polyphenolics from plant materials. Solid-phase extraction with C18 Sep-Pak cartridges (vnitu.2) is used to selectively eliminate undesired components from crude extracts, and may minimize the effects of sample cleanup or preparation on the integrity of polyphenolics. The isolation and purification step using solid-phase extraction of polyphenolics will make possible the efficient analysis of individual polyphenolics by reversed-phase HPLC. 

Purification of anthocyanins extracted fi om berries is not deemed necessary if measurement of UV/VlS-absorption (>500 nm) for quantification is used. Except in cases of adulteration with red or blue food colorants the measurement wave lengths are selective enough to quantify anthocyanins in crude extracts. If berry anthocyanins are extracted from complex matrices (dietary supplements or food products) removal of other ingredients extracted is advantageous [125, 126]. For structural elucidation, for the analysis of the specific glycosidation/acylation pattern or the requirement to enrich anthocyanins from low content sources, crude extracts need to be purified and eventually fractionated [63, 67, 114, 118, 127-131]. 

---