Isolation, identification and antioxidative capacity of water-soluble phenylpropanoid compounds from Rhodiola crenulata

Six water-soluble phenylpropanoid compounds obtained from Rhodiola crenulata (R. crenulata) were fractionated by high-speed counter-current chromatography (HSCCC), and purified by semi-preparative high-performance liquid chromatography (Semi-prep HPLC). The purities of the six compounds were all above 98.0% and their structures were identified by spectroscopic methods. Among them, a new compound, 2-(4-hydroxyphenyl)-ethyl-O-β-d-glucopyranosyl-6-O-β-d-glucopyranoside (1), together with two known phenylpropanoids, p-hydroxyphenacyl-β-d-glucopyranoside (3) and picein (4) were isolated from R. crenulata for the first time. Meanwhile, the contents of six isolated ingredients from the crude extract of R. crenulata had been simultaneously detected, with satisfactory results. Furthermore, the antioxidant activities of the six compounds were accessed by measuring the radical scavenging activity against 2,2-diphenyl-1-picrylhydrazy (DPPH), and four compounds exhibited potent antioxidative activity.