Nuclear chemistry

Deep eutectic solvent

Metal

Choline chloride

Biology

Yield (engineering)

High-performance liquid chromatography

Metallurgy

Materials science

Chromatography

Biochemistry

Solvent

Botany

Chloride

Juglans

Extraction (chemistry)

Organic chemistry

Membrane

Alloy

Juglandaceae

Eutectic system

Antioxidant

Phospholipid

Phosphatidyl choline

Chemistry

Quercetin

Aqua regia

Industrial Crops and Products

The extraction of phenolic compounds from walnut leaves (Juglans regia L.) was optimized using heat-assisted extraction and deep eutectic solvents based on choline chloride and carboxylic acids. A preliminary solvent screening was performed using a selected group of carboxylic acids as hydrogen bond donors, showing that the highest extraction yield of phenolic compounds was obtained using choline chloride mixtures with butyric or phenylpropionic acid at a mole ratio 1:2, with 20% of water (w/w). The extraction conditions (time, temperature and water proportion) were then optimized by an experimental design, assisted by response surface methodology. To evaluate the response, the three most abundant compounds identified by HPLC (neochlorogenic acid, quercetin 3-O-glucoside and quercetin O-pentoside) were quantified. Additionally, the solid/liquid ratio effect at the optimal conditions, in dose-response format, was studied in view of its upscale, not showing any significant decrease until 140 g/L. The results here presented provide valuable information towards the design of a process in a pre-industrial form for the extraction of phenolic compounds from J. regia leaves using deep eutectic solvents.

Enhanced extraction of phenolic compounds using choline chloride based deep eutectic solvents from Juglans regia L.