Chemical standardization of kava (Piper methysticum) extract using UHPLC-MS/MS and the method of standard addition

Kava (Piper methysticum G.Forst.) is used traditionally in the South Pacific for ceremonial and medicinal purposes and as a dietary supplement for its anxiolytic effects. The pharmacological activity of kava is attributed to kavalactones and flavokavains, including desmethoxyyangonin, 7,8-dihydrokavain, kavain, methysticin, 7,8-dihydromethysticin, and yangonin. The safe and effective use of kava dietary supplements depends on botanical authentication and standardization to these active constituents.

To support safety studies being carried out by the Botanical Safety Consortium, the chemical profile of a botanically authenticated kava extract was obtained using ultrahigh-pressure liquid chromatography-high resolution tandem mass spectrometry (UHPLC-HRMS/MS), and kavalactones and flavokavains were identified by comparison with standards.

The kava extract was chemically standardized using two analytical methods based on UHPLC-MS/MS with selected reaction monitoring on a triple quadrupole mass spectrometer. One method used external calibration with standards dissolved in neat solvent due to the absence of blank kava matrix, while the second used the method of standard addition to evaluate kava extract matrix effects that might affect the accuracy of the external calibration method.

Matrix-induced ion suppression was observed for desmethoxyyangonin (23.2%) while signal enhancement was observed for 7,8-dihydrokavain (30.1%) and flavokavain A (43.2%).

The method of standard addition is ideal for correcting for botanical matrix effects that can interfere with quantitative assays based on electrospray (U)HPLC-MS/MS. Chemical authentication and standardization are essential for quality control of kava dietary supplements and to support research on their safety and efficacy.