Ultrasound-Assisted Water Extraction of Gentiopicroside, Isogentisin, and Polyphenols from Willow Gentian “Dust” Supported by Hydroxypropyl-β-Cyclodextrin as Cage Molecules

Abstract

The residue after sieving (“dust”) from the willow gentian underground parts is an unexploited herbal tea by-product, although it contains valuable bioactive compounds. Cyclodextrins as efficient green co-solvents, cage molecules, and multifunctional excipients could improve the extraction and contribute to the added value of the resulting extracts. The objective of this study was to determine the optimal conditions for the extraction of gentiopicroside, isogentisin, and total phenolics (TPC) from willow gentian “dust” using ultrasound-assisted water extraction coupled with hydroxypropyl-β-cyclodextrin (HPβCD). The influence of extraction temperature (X1: 20–80 °C), time (X2: 20–50 min), and HPβCD concentration (X3: 2–4% w/v) was analyzed employing the response surface methodology (RSM). The optimal extraction conditions for simultaneously maximizing the extraction yield of all monitored responses were X1: 74.89 °C, X2: 32.57 min, and X3: 3.01% w/v. The experimentally obtained response values under these conditions (46.96 mg/g DW for gentiopicroside, 0.51 mg/g DW for isogentisin, and 12.99 mg GAE/g DW for TPC) were in close agreement with those predicted, thus confirming the suitability and good predictive accuracy of the developed RSM models. Overall, the developed extraction system could be an applicable alternative strategy to improve the extraction of bioactive compounds from the underutilized “dust” of willow gentian underground parts.

Optimization of Cyclodextrin-Assisted Extraction of Phenolics from Helichrysum italicum for Preparation of Extracts with Anti-Elastase and Anti-Collagenase Properties

“…High temperature may improve the extraction process by reducing the viscosity of the solvent and increasing the kinetic energy of the molecules in solution. However, high temperature may also cause degradation of the extracted phenolic and other sensitive compounds [ 40 ]. Additionally, interaction of phenols with CDs may be an exothermic process, as exemplified in the case of interaction of (E)-piceatannol with HP-β-CD.…”

Hydroxypropyl-β-Cyclodextrin-Glycerol-Assisted Extraction of Phenolics from Satureja montana L.: Optimization, Anti-Elastase and Anti-Hyaluronidase Properties of the Extracts

“…On the one hand, it may enhance the efficiency of the extraction because it reduces the viscosity of the solvent. On the other hand, high temperatures may cause the degradation of sensitive compounds, such as flavonoids and phenolic acids [46]. Similarly, prolonged extraction increases the chance for the diffusion of phytochemicals from plant material into the solution but also increases the chance of degradation of sensitive molecules, especially during ultrasonication.…”

“…On the one hand, it may enhance the efficiency of the extraction because it reduces the viscosity of the solvent. On the other hand, high temperatures may cause the degradation of sensitive compounds, such as flavonoids and phenolic acids [46]. Previous studies on UAE of LG and RA from Origanum majorana, another aromatic plant from the Lamiaceae family, also demonstrated the importance of temperature for the extraction of those phenolics.…”