Characterization of phenolic compounds in rooibos tea.
Polyphenols present in rooibos, a popular herbal tea from Aspalathus linearis, were isolated in two steps. First, phenolic ingredients were separated by multilayer countercurrent chromatography (MLCCC). Preparative high-performance liquid chromatography (HPLC) was then applied to obtain pure flavonoids. The purity and identity of isolated compounds was confirmed by different NMR experiments, HPLC-diode array detector (DAD), or gas chromatography-mass spectrometry (GC-MS) analysis. This strategy proved to be valid to isolate material in up to gram quantities and to verify known and previously not published polyphenol structures. In addition the chemistry of dihydrochalcones and related intermediates was studied. The dihydrochalcone aspalathin was oxidized to the corresponding flavanone- C-glycosides (( R)/( S)-eriodictyol-6- C-beta- D-glucopyranoside and ( R)/( S)-eriodictyol-8- C-beta- D-glucopyranoside). Flavanone-6- C-beta- D-glucopyranosides were further degraded to flavones isoorientin and orientin.
Krafczyk
Nicole
N
Institute of Chemistry, Food Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Strasse 2, 06120 Halle, Germany.
Glomb
Marcus A
MA
D036903:Aspalathus / Q000737:chemistry*; D001628:Beverages / Q000032:analysis*; D047188:Chalcones / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D003377:Countercurrent Distribution; D005285:Fermentation; D005419:Flavonoids / Q000032:analysis* / Q000302:isolation & purification; D008401:Gas Chromatography-Mass Spectrometry; D009682:Magnetic Resonance Spectroscopy; D010636:Phenols / Q000032:analysis* / Q000302:isolation & purification; D059808:Polyphenols
D047188:Chalcones; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; C015812:dihydrochalcone