Identification of Five Flavonoid Compounds from the Remaining Ginger Powder Purified by Using High-Speed Counter-Current Chromatography and Their Bioactivity

HSCCC was widely used as a reliable and efficient tool for isolation of natural production. Multiple active compounds were separated and purified from ginger essential oil. But the remaining ginger powder (RGP), which was obtained from ginger without volatile oil, was discarded commonly. The crude flavonoids were extracted from RGP using ethanol at 80°C. The purification of flavonoids was performed by rotary evaporator and X-5 macroporous adsorption resin. The high-speed counter-current chromatography (HSCCC) was implemented by employing a two-phase solvent system which consist of n-hexane–ethyl acetate–methanol-water (4:5:4:5, v/v/v/v) and n-hexane–ethyl acetate–methanol-water (1:5:1:5, v/v/v/v) to separate flavonoid into five fractions. The purity of individual flavonoid in each of the fraction was analyzed by high-performance liquid chromatography (HPLC). The chemical structures of the isolated compounds were identified by liquid chromatograph mass spectrometry-ion trap-time of flight (LCMS-IT-TOF). Rutin (16.6%), tangeretin (13.1%), vitexin (18.37%), myricetin-3-O-glucopyranoside (3.3%), and isoquercitrin (15.2%) were identified in RGP at the purity of all over 90%. The HSCCC appeared to be an efficient and reliable method for the isolation of flavonoids in RGP. 3-(4,5-Dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to determine the anti-tumor abilities of five flavonoid compounds. The results showed that rutin and myricetin-3-O-glucopyranoside had better anti-tumor activities than other three flavonoid compounds from RGP. The research revealed that RGP was a bioactive product and contributed to development of ginger.