Stabilizing Kavalactone Dispersions Utilizing Common Emulsifiers

Abstract

Piper methysticum, commonly known as kava, is a medicinal herb that is commonly used in traditional ceremonies and medical practices throughout the Pacific. The main bioactive compounds within kava are the kavalactones which can be used for the treatment of insomnia and anxiety; however, they have low bioavailability due to their poor water solubility. In order to increase the water solubility of kavalactones, the common emulsifiers, polysorbate 20 and polysorbate 80, were tested at different concentrations to determine the ideal kava dispersion system. The dispersion systems (containing 5.8% w/w kava powder) were mixed using a high-shear mixer prior to centrifugation to remove the sediment. The stability for each sample was then determined by measuring the particle size, zeta potential, and polydispersity index (PDI) utilizing a Malvern Zetasizer Nano ZS. As indicated by the results, kava dispersions with a 1.5% (w/w) concentration of polysorbate 80 managed to reduce particle size the most with an average particle diameter of 41.5 nm, which is 196.7 nm smaller than the average control particle size. However, the PDI for this sample was too high to be considered stable. The sample that exhibited the most stability was the 0.5% (w/w) concentration of polysorbate 20. This sample managed to maintain a particle size of 130.4 nm and a PDI of 0.44 over time. These results are a positive indication that nonionic emulsifiers, including polysorbate 20, at lower concentrations are suitable emulsifiers for kavalactone stabilization.