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

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 IC 50 values of 22.9–88.5 μM. 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. [ABSTRACT FROM AUTHOR]