Antioxidants screening in Limonium aureum by optimized on-line HPLC–DPPH assay

Abstract Limonium aureum (Linn.) is a traditional Chinese medicine with strong antioxidant activity. To search for antioxidants in L. aureum , an optimized, on-line high performance liquid chromatography (HPLC) method with DPPH (1,1-diphenyl-2-picrylhydrazyl) for the detection of radical scavenging ability was developed. Response surface methodology (RSM) was used to determine the best combination of experimental conditions, such as DPPH concentration, DPPH velocity and the reaction tank length. The optimized method uses a DPPH concentration of 25.0 μg/mL, DPPH velocity of 0.45 mL/min and a 15.0 m long reaction tank. The highly sensitive, optimized method can not only be used for the detection of antioxidants in plants, but can also be coupled with mass spectrometry (MS) to obtain the mass-to-charge ratios of chemical species corresponding to the different peaks in the HPLC profiles. Seven antioxidants were identified in L. aureum using the optimized method, including myricetin-3- O -β- d -(6”- O -galloyl)-glucopyranoside, myricetin-3- O -glucoside, myricitrin, eriodictyol-7- O -glucoside, myricetin, eriodictyol and homoeridictyol.