Preparative separation and identification of the flavonoid phlorhizin from the crude extract of Lithocarpus polystachyus Rehd.

The flavonoid phlorhizin is abundant in the leaves of Sweet Tea (ST, Lithocarpus Polystachyus Rehd). Phlorhizin was preparatively separated and purified from a crude ST extract containing 40% total flavonoids by static adsorption and dynamic desorption on ADS-7 macroporous resin and neutral alumina column chromatography. Only water and ethanol were used as solvents and eluants throughout the whole separation and purification process. Using a phlorhizin standard as the reference compound, the target compound separated from the crude ST extracts was analyzed by thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and electrospray ionization mass spectrometry (EIS-MS) and identified as 99.87% pure (by HPLC-UV) phlorhizin. The results showed that 10 g of the target compound could be obtained from 40 g of the crude extracts in a single operation, indicating a 40% recovery. Therefore, this represents an efficient and environmentally-friendly technology for separating and purifying phlorhizin from ST leaves.