Novel natural deep eutectic solvent for salvia officinalis extraction and antioxidative activity

Abstract

Traditional extraction of plant material with alcohols and other organic solvents can yield extracts with varying degrees of toxicity to human cells, tissues, and the environment. In that light, natural deep eutectic solvents (NADES) are considered powerful and sustainable green solvents. NADES consist mainly of two compounds: an ionic bond acceptor and an ionic bond donor. One of the first and well-known ionic bond acceptors is choline chloride (ChCl). To the best of our knowledge, the use of ascorbic acid as an ionic bond donor has not been widely reported. Numerous studies have investigated polyphenols derived from various plant materials using NADES, which exhibit better extractability and lower cytotoxicity than those extracts obtained with conventional solvents. Leaves of sage (Salvia officinalis L., family Lamiaceae) are often used in traditional medicine to treat a range of health conditions, from oral and dental pathologies to rheumatic and cognitive disorders. In this study, we used sage extracts obtained with choline chloride mixed with ascorbic acid (ChCl:AA (2:1)), whose structure was confirmed with FTIR and UV-Vis spectra. Extraction was obtained under different extraction times (60 and 90 min) at a constant temperature, and NADES was diluted with 10% water for better solubility and viscosity. The total flavonoid content (TFC) of the extracts was measured, and their antioxidant activity was determined using DPPH and ABTS assays. Based on our results, a shorter extraction time yielded a higher TFC. In both DPPH and ABTS assays, lower IC50 values and higher antioxidant potential were observed with the extract obtained at shorter extraction time. The results of this study suggest that prolonged extraction time may lead to extract degradation.