On the accumulation of apigenin in chamomile flowers.

By preparing and analysing extracts of fresh chamomile flowers from outdoor and greenhouse cultures, it was possible to show that apigenin does not actually occur in living chamomile flowers. Apigenin is the result of post-harvest processes converting apigenin 7-glycoside and its derivatives into the aglycone. The different apigenin/apigenin 7-glycoside ratios reported in the literature for various chamomile samples can easily be explained as the result of different post-harvest conditions. The accumulation of free apigenin in chamomile flowers must be ascribed to the enzymatic degradation of apigenin 7-glycoside and other glycosidic derivatives of apigenin. Thus, the selection of chamomile types yielding large amounts of apigenin seems to be based on a degradation product.