Abstract
The genus Paeonia, also known as the “King of Flowers” in China, is an important source of traditional Chinese medicine (TCM). Plants of this genus have been used to treat a range of cardiovascular and gynecological diseases. However, the potential pharmacological activity of one particular species, Paeonia rockii, has not been fully investigated. In the first part of the present study, 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS), reducing power assays, and metal ion chelating assays were used to investigate the in vitro antioxidant activities of Paeonia rockii. In the second portion of the study, a mouse model of d-galactose-induced aging was used to validate the antioxidant effects of the flowers from Paeonia rockii in vivo. Lastly, potential antioxidant constituents were screened and identified by ultra-high pressure liquid chromatography and electrospray ionization coupled with high-resolution mass spectrometry (UHPLC-ESI-HRMSn) combined with the DPPH assay. Results indicated that the flowers and leaves exhibited stronger antioxidant activity than ascorbic acid in vitro. The therapeutic effect of Paeonia rockii was determined in relation to the levels of biochemical indicators, such as 8-iso-prostaglandin F2α (8-iso PGF2α) in the serum, superoxide dismutase (SOD), protein carbonyl, malondialdehyde (MDA), and glutathione (GSH) in the liver and brain, after daily intra-gastric administration of different concentrations of extracts (100, 200 and 400 mg/kg) for three weeks. The levels of 8-iso PGF2α (p < 0.01) and protein carbonyl groups (p < 0.01) were significantly reduced, whereas those of SOD (p < 0.05) had significantly increased, indicating that components of the flowers of Paeonia rockii had favorable antioxidant activities in vivo. Furthermore, UHPLC-ESI-HRMSn, combined with pre-column DPPH reaction, detected 25 potential antioxidant compounds. Of these, 18 compounds were tentatively identified, including 11 flavonoids, four phenolic acids, two tannins, and one monoterpene glycoside. This study concluded that the leaves and flowers from Paeonia rockii possess excellent antioxidant properties, highlighting their candidacy as “new” antioxidants, which can be utilized therapeutically to protect the body from diseases caused by oxidative stress.
Highlights
Oxidative stress is an excess of free radical production caused by a series of complex cellular processes, such as the accumulation of hydrogen peroxide, hydroxyl radicals, and superoxide anions during normal cellular metabolism
The results suggest that the ML and MF complexes with the ferrous ion in a dose-dependent manner [32]
This study first evaluated the antioxidant activities of leaves and flowers from Paeonia rockii and revealed the presence of antioxidant compounds
Summary
Oxidative stress is an excess of free radical production caused by a series of complex cellular processes, such as the accumulation of hydrogen peroxide, hydroxyl radicals, and superoxide anions during normal cellular metabolism. Oxidative stress is thought to be involved in the development of a range of human diseases including aging, liver damage, cardiovascular disease, and cancer [1,2,3,4]. Antioxidants are able to prevent the production of free radicals [5,6] and the chain reaction which occurs before vital molecules are damaged, protecting the body from subsequent oxidative stress and further tissue injury [7,8]. There are two basic categories of antioxidants: synthetic and natural. Due to the toxicity of synthetic antioxidants and their undesirable effects on human health [10], interest in natural antioxidants has increased considerably [11]. Natural antioxidants originating from Traditional Chinese medicinal herbs Bletilla striata, Lonicera japonica, and Paeonia have been reported to possess favorable antioxidant activity [12,13,14]
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