Spectrum–effect relationship between ultra‐high‐performance liquid chromatography fingerprints and antioxidant activities of Lophatherum gracile Brongn

Lophatherum gracile Brongn. is a medicinal and edible plant resource as well as a natural additive in the functional food market. To better understand its characteristics and efficacy, a method combining chromatographic fingerprints and antioxidant activity was proposed. A total of 21 common peaks were confirmed from liquid chromatography fingerprints and were identified as 14 flavonoids and 7 phenolic acids by ultra‐high‐performance liquid chromatography (UHPLC) coupled with quadrupole Orbitrap mass spectrometry (Q‐Orbitrap/MS). Their antioxidant activities were evaluated by 1,1‐diphenyl‐2‐trinitrophenylhydrazine (DPPH), 2,2'‐diazide‐bis (3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS), and ferric reducing antioxidant power (FRAP) assay. The results showed that all of the test samples had moderate to high antioxidant effects, with IC50 values ranging from 5.2 to 16.1 mg/ml and 1.2 to 2.8 mg/ml for DPPH and ABTS assays, and the FeSO(4) concentrations of 1.84–4.20 mmol/L for the FRAP assay. The spectrum–effect relationship between UHPLC fingerprints and antioxidant activity was investigated through Pearson correlation analysis and Grey relational analysis (GRA) to identify the antioxidant constitutes in Lophatherum gracile Brongn. The results showed that 11 compounds were greatly associated with the antioxidant activity with a correlation degree >0.80, which can be used as the quality marker of Lophatherum gracile Brongn.