An on-line analysis method for the simultaneous detection and identification of radical scavenging compounds in plant extracts was developed by combining HPLC with hydrogen dioxide radical scavenging and HPLC-DAD-MS-CL system. The structural identification and activity characteristics of various constituents could be rapidly achieved by the on-line assay of UV, MS and CL in one run. In 4 species of Epimedium studied 32 compounds, including phenolic acids, 8-isopentenyl-flavonoid glycosides and flavonoid glycosides containing a ortho-hydroxyl group, were identified by comparison with authentic standards and published mass data. Among these compounds, phenolic acids and flavonoid glycosides containing an ortho-hydroxyl group could obviously inhibit CL, which suggested their strong radical scavenging activity. These four species each exhibited different active properties, which might correlate to their respective quality. The results indicated that the on-line HPLC-DAD-MS-CL system would be a potential method to rapidly and sensitively screen radical scavengers in herbal medicines, and could display an integrated fingerprint based on different detectors.
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