Environmentally Friendly Extraction of Antioxidants from Elettaria cardamomum seeds with Glucose-Citric Acid-Based Natural Deep Eutectic Solvent

Elettaria cardamomum belongs to the Zingiberaceae family. It contains components (phenolic compounds, alkaloids, terpenoids) it has antioxidant, anti-inflammatory and antimicrobial effects. The purpose of this study is to research the effect of glucose-citric acid based natural deep eutectic solvent (NADES) on the antioxidant activity of Elettaria cardamomum. In this study, glucose-citric acid was used as a NADES and methanol-water was used as a conventional solvent. The radical scavenging activities, phenolic compound and tannin amounts of the extracts obtained as a result of extraction with two different solvents were found. Antioxidant activities of extracts prepared with natural deep eutectic solvent were found to be higher. It has been shown that NADES, which are less harmful on the health and environment, have low toxicity and are environmentally friendly, can be used in extraction instead of traditional solvents such as hexane, benzene, and methanol.

Improvement of the Solubilization and Extraction of Curcumin in an Edible Ternary Solvent Mixture

A water-free, ternary solvent mixture consisting of a natural deep eutectic solvent (NADES), ethanol, and triacetin was investigated concerning its ability to dissolve and extract curcumin from Curcuma longa L. To this purpose, 11 NADES based on choline chloride, acetylcholine, and proline were screened using UV–vis measurements. A ternary phase diagram with a particularly promising NADES, based on choline chloride and levulinic acid was recorded and the solubility domains of the monophasic region were examined and correlated with the system’s structuring via light scattering experiments. At the optimum composition, close to the critical point, the solubility of curcumin could be enhanced by a factor of >1.5 with respect to acetone. In extraction experiments, conducted at the points of highest solubility and evaluated via HPLC, a total yield of ~84% curcuminoids per rhizome could be reached. Through multiple extraction cycles, reusing the extraction solvent, an enrichment of curcuminoids could be achieved while altering the solution. When counteracting the solvent change, even higher concentrated extracts can be obtained.