Isolation and Purification of Galloyl, Caffeoyl, and Hexahydroxydiphenoyl Esters of Glucoses from by High-Speed Countercurrent Chromatography and Their Antioxidant Activities In Vitro.

High-speed counter-current chromatography was used to separate and purify galloyl, caffeoyl, and hexahydroxydiphenoyl esters of glucoses from the aerial parts of the parasitic plant for the first time using -hexane-ethyl acetate-methanol-water (1:2:1:2, /) as the optimum solvent system. Accordingly, 1--()-caffeoyl-3--galloyl--d-glucopyranose (, 12.5 mg), 1--()-caffeoyl-3--galloyl-4,6-()-hexahydroxydiphenoyl--d-glucopyranose (, 27.2 mg), and 1--()-caffeoyl-4,6-()-hexahydroxydiphenoyl--d-glucopyranose (, 52.8 mg) with 98.0%, 98.5%, and 98.7% purities, respectively, were purified from 210 mg crude extract of in a one-step separation. The structures of the glucose esters were identified by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance spectra (NMR). Their antioxidant activities were evaluated by measuring their inhibition activity on liver microsomal lipid peroxidation induced by the Fe-Cys system in vitro. Compounds ⁻ showed significant antioxidant activities with IC values ranging from 2.51 to 6.68 μm, respectively.