Purpose: To identify and quantify anethole in the essential oil of fruits of Illicium verum Hook (star anise) and in vivo in rat plasma using reverse-phase liquid chromatography.

Methods: Anethole was identified in the essential oil of the fruits of Star anise and determined by gas chromatography-tandem mass spectrometry  (GC-MS), nuclear magnetic resonance (NMR), ultraviolet visible spectrophotometry (UV-VIS). A simple, sensitive and validated high performance liguid chromatography  (HPLC) technique with UV-VIS detection  method was developed for the determination of the compound in rat plasma using: methanol-water (85:15, v/v) as mobile phase at a flow rate of 0.2 ml/min Hypersil ODS Thermo (150 mm ´ 2.1 mm ´ 3.0 µM) as column with wavelength detection at 259 nm.

Results: GC determination showed that anethole in the essential oil of star anise exhibited a retention time of 21.02 min. The validation results for anethole in plasma were satisfactory, with coefficient of determination (R²) of 0.9945 and relative standard deviation of < 3 %. HPLC run time of 4 min with a retention time of 2.73 min was the faster method to determine anethole when compared to a previously reported method which had a run time of 15 min.

Conclusion: Anethole in the essential oil of Illicium verum Hook can be identified and determined by GC-MS, NMR and UV-VIS, and a superior HPLC method has been developed for the determination of the compound in rat plasma.