The effect of choline chloride-butanediol based deep eutectic solvents on ultrasound-assisted extraction, antioxidant activity and stability of anthocyanins extracted from Perilla frutescens (L.) Britt.

Abstract

To explore the relation between anthocyanins extraction performance and physicochemical properties of choline chloride (ChCl)-butanediol deep eutectic solvents (DESs), sixty formulas consisting of ChCl with four butanediol isomers (1,3-butanediol, 1,4-butanediol, 2,3-butanediol, or 1,2-butanediol) at different molar ratios (ChCl/butanediol) and different amounts of water were examined. In this study, 1,3-butanediol was selected as the most promising hydrogen bond donor for the preparation of DESs. The highest anthocyanins content (9.97 ± 0.04 mg/g) was obtained using the DES composed of ChCl and 1,3-butanediol with 1:2 M ratio containing 50% water (DES-2 (50%)) coupled with ultrasound assisted extraction (UAE). The anthocyanins extracted by DES-2 (50%) presented highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) antioxidation activity (1.88 ± 0.01 μM TE/g DW), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) antioxidation activity (5.10 ± 0.09 μM TE/g DW), ferric reducing/antioxidant power (FRAP) antioxidation activity (28.39 ± 0.21 μM TE/g DW). Comparative investigations on stability of anthocyanins proved that DES-2 (50%) offers outstanding advantages over acidified ethanol. After storage at 4°C for 6 days, the remaining fraction of the anthocyanins extracted by DES-2 (50%) (92.01 ± 0.52%) was higher than anthocyanins extracted by ethanol (84.25 ± 0.57%).