Efficient Leaching of Pinocembrin from <i>Eucalyptus</i> Leaves Using Aqueous-Based Leaching Systems

The natural flavonoid pinocembrin has potential in treating diseases such as cardiovascular diseases, cancer, cerebral ischemia, cerebral hemorrhage injury, and improving human health due to its outstanding pharmacological properties. In this study, an efficient leaching process to recover pinocembrin from Eucalyptus leaves using green aqueous-based solution has been developed. The impact of the leaching solvent (i.e., modifier/water and alkaline solutions), content of modifier (i.e., ethanol, methanol, and acetonitrile), pH of alkaline solution, solid/liquid ratio, leaching time, and technique (i.e., agitation-assisted leaching and ultrasonic-assisted leaching) on pinocembrin leaching efficiency was investigated. The results revealed that pinocembrin from eucalypt leaves was efficiently recovered when ≥60 vol % ethanol/water, ≥80 vol % methanol/water, or 40–80 vol % acetonitrile/water leaching solutions were used, particularly at a ≤10 mg/mL solid/liquid ratio. The leaching performance of pinocembrin in modifier/water solutions is comparable to the trends predicted by Hansen solubility parameters (HSPs). Finally, pinocembrin stability in leached solutions was also tracked over a period of 28 days, which offers the industry a range of options for pinocembrin storage during the manufacturing process.