Isolation and characterization of flavonols from blackcurrant by high-performance counter-current chromatography and electrospray ionization tandem mass spectrometry.

Blackcurrant is considered as a natural high-value food raw material and possesses a variety of therapeutic properties. The health benefits of blackcurrant have generally been credited to its high anthocyanin content; however, the therapeutic properties of other minor flavonoids constituents have not yet been investigated due the difficulties related to their isolation. Multiple steps of high-performance counter-current chromatography in combination with ESI tandem mass spectrometry (MS(n)) were successfully used for the preparative isolation of flavonols from blackcurrant extract, to study their electrospray ionization mass spectrometry fragmentation behavior. Seven flavonols, namely myricetin-3-O-rutinoside (145.5 mg), myricetin-3-O-hexoside (79.7 mg), myricetin-3-O-(6″-malonyl)-glucoside (17.4 mg), kaempferol-3-O-glucoside (20.5 mg), quercetin-3-O-rutinoside (55.1 mg), quercetin-3-O-hexoside (25.8 mg), and myricetin (129.1 mg) have been successfully isolated and their multistage MS(n) data were used for detailed structure characterization. The results of these experiments demonstrated that high-performance counter-current chromatography along with ESI-MS(n) is a sensitive, selective, and effective technology for isolation and characterization of minor constituents from a complex mixture.