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SCREENING AND IDENTIFICATION OF RADICAL SCAVENGERS FROM NEO-TARAXACUM SIPHONANTHUM BY ONLINE RAPID SCREENING METHOD AND NUCLEAR MAGNETIC RESONANCE EXPERIMENTS

An online rapid screening method, the high-performance liquid chromatography (HPLC)–diode array detector (DAD)–radical scavenging detection (RSD)–electrospray ionization (ESI)–mass spectroscopy (MS)/MS system, was developed for the screening and identification of radical scavengers from Neo-Taraxacum siphonanthum, a new species found in China in 1989. For further characterization, the target compounds were isolated by silica column chromatography, preparative high-performance liquid chromatography (HPLC), HSCCC, and Sephadex LH-20 column chromatography and elucidated on the basis of ultraviolet (UV), ESI-MS/MS, and nuclear magnetic resonance (NMR) spectroscopy, as well as the chemical analysis. Eighteen antioxidative polyphenols (5 caffeic acid derivatives and 13 flavonoid derivatives) were characterized from Neo-T. siphonanthum. The distribution of all compounds was discussed in a chemosystematic context, which suggested that the genera Neo-Taraxacum and Taraxacum might relate chemosystematically.