Isolation, identification and stability of acylated derivatives of apigenin 7-O-glucoside from chamomile (Chamomilla recutita [L.] Rauschert).

The major flavonoids in the white florets of chamomile (Chamomilla recutita [L.] Rauschert) were rapidly purified using a combination of polyamide solid-phase extraction and preparative HPLC. From the combined LC/MS, LC/MS/MS, and NMR data the apigenin glucosides were identified as apigenin 7-O-glucoside (Ap-7-Glc), Ap-7-(6''-malonyl-Glc), Ap-7-(6''-acetyl-Glc), Ap-7-(6''- caffeoyl-Glc), Ap-7-(4-''acetyl-Glc), Ap-7-(4''-acetyl,6-''malonyl-Glc), and a partially characterised apigenin-7-(mono-acetyl/monomalonylglucoside) isomer. Malonyl and caffeoyl derivatives of Ap-7-Glc have not previously been identified in chamomile. The two mono-acetyl/mono-malonyl flavonoids have not previously been reported in any plant species. These acylated glucosides are unstable and degrade to form acetylated compounds or Ap-7-Glc. The degradation products formed are dependent on the extraction and storage conditions, i.e. temperature, pH and solvent.