Identification by HPLC-DAD and HPLC-MS analyses and quantification of constituents of fennel teas and decoctions

Qualitative and quantitative differences among the constituents in various fennel (Foeniculum vulgare Mill., family Apiaceae) teas prepared by classical infusion, microwave decoction, and dissolution are reported. Different commercial starting materials, such as fruit (unbroken and crushed), four herbal teas, and two instant herbal teas were evaluated. Chlorogenic acid (1), quercetin-3-O-beta-D-glucuronide (2), p-anisaldehyde (3), and trans-anethole (4) were identified by HPLC-DAD and HPLC-MS as constituents of fennel teas. No coumarins, which are characteristic constituents of plants of Apiaceae family, were found. Trans-anethole (4), the main constituent of the essential oil, was present in all teas. In addition p-anisaldehyde (3), a degradation product of trans-anethole, was also identified in all teas with the exception of two samples. Chlorogenic acid (1) and quercetin-3-O-beta-D-glucuronide (2) were also present in all teas. In addition, minor unidentified flavonol constituents were found in two teas. Quality, activity, and safety of the content of the investigated preparations are also discussed.