Bioactive compounds extraction from different lemongrass species: Strategies and deep eutectic solvents evaluation

Lemongrasses are known and used worldwide due to several benefits conferred to them regarding the high content of essential oils and other phenolic compounds, which are essential and nonessential compounds that occur in nature, are part of the food chain and present several benefits on human health. The obtaining of phenolic compounds from natural matrices requires the development of effective processes with minor impacts on the environment and target compounds. In this work, green solvents entitled deep eutectic solvents (DES) were evaluated against conventional solvents, as acetone, ethanol, and methanol, to obtain phenolic compounds from three different species of lemongrasses (Cymbopogon flexuosus, Cymbopogon citratus, and Elyonurus muticus). The best extraction conditions were determined into three completely random designs (CRD). The first CRD aimed at solvent selection, for this the extraction conditions were fixed in 45°C/2 hr. The second CRD was to determine the optimum process temperature. And finally, the last CRD compared different methods of extraction: magnetic stirring, Ultra‐Turrax, and ultrasound assisted extraction. The extraction kinetics were also obtained. The experimental results indicated that the extract from lemongrass C. citratus presented higher content of phenolic compounds using the DES composed of cholinium chloride and acetic acid as solvent, employing magnetic stirring at 60°C by 180 min. Moreover, all the DES‐based extracts presented higher antioxidant, iron chelating, and antimicrobial capacities than the traditional solvents. Therefore, the DES showed suitable capacity for extraction, and maintenance of phenolic compounds from lemongrasses, superior to those traditional solvents, being a promising alternative for use in medical, pharmaceutical, and food industries. PRACTICAL APPLICATIONS: The research uses different solvents and mechanisms to extract biocompounds, as essential oils and phenolic compounds from lemongrass species. The higher extraction conditions, in terms of solvent, time and extraction method, showed higher antioxidant activity, antimicrobial potential, and iron chelating capacity, which in interest to enrich food, improve cosmetics, clean waste water and residues. Also, there were identified several bioactive compounds from lemongrass, as citral. DES employment is an innovative extraction solvent, and can present low cost and nontoxic approach enhancing extraction efficiency of bioactive compounds.