Natural Deep Eutectic Solvents as Alternatives for Extracting Phlorotannins from Brown Algae

Abstract

Natural deep eutectic solvents (NADES) are promising green solvents for extracting biologically active compounds from plant raw material. This is the first study in which NADES were used to extract phlorotannins from brown algae Fucus vesiculosus L. and Ascophyllum nodosum (L.) Le Jolis. The extraction efficiency of polyphenols was evaluated using 10 NADES based on choline chloride, lactic acid, betaine, and glucose in various mole ratios. The effect of H₂O in aqueous solutions of NADES on extraction of phlorotannins was studied. Algae were extracted by maceration for 120 min at 50°C with a 1:5 raw-material:extractant ratio. Phlorotannins were quantified by spectrophotometry using the Folin–Ciocalteu method. The maximum extraction of phlorotannins (60 – 72%) was achieved using aqueous NADES solutions (50 – 70%) based on choline chloride with added lactic or malic acid and also on malic acid and betaine. The NADES had efficiencies comparable to Me₂CO and EtOH.