An Efficient Strategy Based on Liquid–Liquid Extraction With Acid Condition and HSCCC for Rapid Enrichment and Preparative Separation of Three Caffeoylquinic Acid Isomers From Mulberry Leaves

Morus alba L. is a medicinal plant that contains a high amount of caffeoylquinic acids such as 3-caffeoylquinic acid (3-CQA), 5-caffeoylquinic acid (5-CQA) and 4-caffeoylquinic acid (4-CQA). This study aimed to establish a fast and efficient method for separating caffeoylquinic acids from mulberry leaves by using high-speed countercurrent chromatography coupled with macroporous resin. D101 resin showed better adsorption and desorption capacity for three caffeoylquinic acids among six macroporous resin adsorbents. The contents of 3-CQA, 5-CQA and 4-CQA reached for 4.77%, 18.95% and 9.84% through one cycle of D101 resin, which were 3.13-fold, 4.57-fold and 4.78-fold more than those in crude extracts, respectively. With a two-phase solvent system of ethyl acetate-water (1:1, V/V), >93% purity of target compounds were obtained in one cycle during 150 min with the recovery yields of 80.59%, 99.56% and 94.21% for 3-CQA, 5-CQA and 4-CQA, respectively. The structural identification of target compounds was carried out by ESI-MS, 1H NMR and 13C NMR spectra. The present result represented an easy and efficient separation strategy for the utilization of mulberry resource.