Choline chloride-based deep eutectic solvents (NADES): Potential use as green extraction media for polyphenols from Mentha pulegium, antioxidant activity, and antifungal activity

Abstract

With the introduction of the concept of green chemistry, eco-friendly extraction processes are moving from an option to a must. Combined with ultrasound-assisted extraction (UAE), 9 choline chloride deep eutectic solvents were screened for the extraction of antioxidant polyphenolic compounds from Mentha pulegium (Lamiaceae). Data indicated that among the 9 types of choline chloride-based solvents tested, Choline Chloride: Lactic acid (1:2) and Choline Chloride: Glycerol (1:2) were selected as the most promising solvent compared to 80 % methanol. The extraction conditions were statistically investigated using Response surface methodology conducted by Boc-Behnken design (BBD). The optimal operational conditions were: temperature of extraction 80 °C, extraction time of 30 and 51 min with 44 and 20 % water content in Choline Chloride: Glycerol (1:2) and Choline Chloride: Lactic acid (1:2), respectively. The selected NADES extracts recorded excellent scavenging activity at a concentration of 1,9 mg/ml higher than 93 %. HPLC–MS/MS analysis revealed that Phenolic acids mainly hydroxycinnamic acids, such as rosmarinic acid, chlorogenic acid, salvianolic acid, caffeoyl glucose, lithospermic acid, and its derivatives, dominated the extracts tested. Otherwise, our results support that the proposed eutectic solvents are able to provide a higher selectivity toward flavonoids such as apigenin derivative, kaempferol coumaroyl hexoside, epi gallocatechin and quercetin o glucopyranoside gallate. The antifungal activity of the optimized extracts revealed inhibition of over than 88 % against the postharvest citrus fungal: Phytophthora citrophthora. In light of the presented results and considering the nature of components constituting Natural deep eutectic solvents (NADES), make these green, novel, sustainable, and low-cost extracts fresh samples for further investigation.