Preparative isolation of highly polar free radical inhibitor from Floccularia luteovirens using hydrophilic interaction chromatography directed by on-line HPLC-DPPH assay

•On-line HPLC-DPPH coupling with hydrophilic interaction chromatography was constructed for preparative isolation of highly polar free radical inhibitor from Floccularia luteovirens.•Mid-pressure and high-pressure Click XION hydrophilic interaction chromatography were successfully used in enrichment and purification of highly polar free radical inhibitor.•One main highly polar free radical inhibitor was isolated from natural products for the first time.