Comparative evaluation of the antioxidant activity of natural extracts from the salt-tolerant plant Polygonum maritimum L. prepared by using conventional solvents, and natural deep eutectic solvents (NADES)

Iva Rukavina

Natural deep eutectic solvents (NADES) are considered as a new generation of green solvents, with multiple commercial applications. In this study choline chloride - based NADES with sucrose, fructose, glucose and xylose were prepared. NADES made of choline chloride with sucrose in a molar ratio 1:2 and 40% of distilled water (w:w) and fructose (1:2, 30% of dH2O) were selected based on the stability, and used to prepare natural extracts from aerial organs of the halophyte Polygonum maritimum. Acetone and ethanol extracts were also prepared, and used for comparison. Extracts were tested for antioxidant activity by different assays, namely radical scavenging activity (RSA) on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, oxygen radical absorbance capacity (ORAC) and copper chelating activity (CCA). Choline chloride: sucrose and choline chloride: fructose extracts exhibited better results in the ORAC and CCA, comparatively to the acetone extract. Choline chloride: fructose extract was also more efficient in the DPPH assay. Ethanol extract had a similar CCA to choline chloride: sucrose extract, but was more efficient in the DPPH and ORAC assays. This study suggests that NADES can serve as an eco-friendlier replacement for acetone in the extraction of antioxidants from P. maritimum.