Chemical Profiling and Antioxidant Evaluation of Paeonia lactiflora Pall. "Zhongjiang" by HPLC-ESI-MS Combined with DPPH Assay.

Paeonia lactiflora Pall. "Zhongjiang" is one of the four major medicinal P. lactiflora plants in China. In this research, a high-performance liquid chromatography (HPLC)-diode array detector (DAD)-electrospray ionization-mass spectrometry method was established to identify various components in the extracts of P. lactiflora "Zhongjiang" (root extract or RE, stem and leaf extract or SLE and flower extract or FE). A total of 40 compounds, including 19 monoterpenoid glycosides, five tannins, 10 phenolic acids and their esters, and six other compounds, were determined or temporarily inferred from RE (35 species), SLE (20 species) and FE (15 species). Antioxidant evaluation indicates among the monomer compounds, catechin, gallic acid and ethyl gallate showed strong antioxidant activity close to vitamin C, ascorbic acid (Vc). Paeoniflorin, albiflorin, benzoylpaeoniflorin and 6'-O-benzoylalbiflorin had certain antioxidant activities, which were much lower than Vc. Furthermore, 19, 15 and 15 antioxidant-reactive components were screened from RE, SLE and FE by using the 1,1-diphenyl-2- picrylhydrazyl (DPPH)-HPLC test results. Results indicated that the ethanol extracts of P. lactiflora "Zhongjiang" had strong antioxidant activity, and the antioxidant active material basis was mainly composed of phenolic acids and gallic acid tannins. The main components of P. lactiflora "Zhongjiang", monoterpenoid glycosides, had weak antioxidant capacity. Paeonia lactiflora stems, leaves and flowers were good sources of antioxidants.