Identification of antioxidant constituents of the aerial part of Plantago asiatica using LC-MS/MS coupled DPPH assay

Abstract

Screening of EtOAc soluble fraction of Plantago asiatica (Plantaginaceae) using HPLC-MS/MS coupled DPPH online assay suggested the presence of antioxidant compounds, which characterized as phenylethanoid glycosides. Twenty-nine compounds including three new compounds, plantalides A-C, a phenylethanoid (1), a phenolic compound (9) and an iridoid (10), were isolated from P. asiatica. Consistent with HPLC-MS/MS analysis, seven phenylethanoid glycosides (1-7) including a new phenylethanoid glycoside (1) showed antioxidant with ranging IC50 values of 22.9-88.5 mu M. These results suggested that phenylethanoid glycosides were contributed to the antioxidant activity of P. asiatica and HPLC-MS/MS coupled online assay is powerful tool for predicting active compounds with short time and limited amounts.