Hydroxylated bisabolol oxides: evidence for secondary oxidative metabolism in Matricaria chamomilla.

German chamomile (Matricaria chamomilla) is one of the most popular medicinal plants used in Western herbal medicine. Among the various phytochemicals present in the essential oil of the flowers of German chamomile, bisabolol and its oxidized metabolites are considered as marker compounds for distinguishing different chemotypes. These compounds are influential in mediating the aroma of the essential oil of M. chamomilla and contribute to the therapeutic properties (anti-inflammatory, antibacterial, insecticidal, and antiulcer) of this species. In order to find other possible bisabolol derivatives as marker compounds for authentication of German chamomile in botanical and commercial products, an in-depth investigation using a GC-assisted fractionation procedure was performed on nonpolar fractions. As a result of this approach, three new hydroxylated derivatives of bisabolol oxides A and B (1-3) have been isolated from M. chamomilla. Plausible biogenetic pathways are presented.