Fig. 1

The structure of aloe-emodin-8-O-β-d-glucoside (1), rhein-8-O-β-d-glucoside (2), chrysophanol-8-O-β-d-glucoside (3), emodin-8-O-β-d-glucoside (4), and physcion-8-O-β-d-glucoside (5), the HPLC chromatogram of the mixed reference substance a and purified anthraquinone glycosides from Rheum palmatum L. b