Indirect identification of antioxidants in Polygalae Radix through their reaction with 2,2-diphenyl-1-picrylhydrazyl and subsequent HPLC-ESI-Q-TOF-MS/MS.

A rapid and efficient method for the identification of antioxidants in the traditional Chinese medicine Polygalae Radix (PR) by HPLC-ESI-Q-TOF-MS/MS is described. The method is based on the hypothesis that upon reaction of antioxidants with 1,1-diphenyl-2-picrylhydrazyl (DPPH), the peak areas of compounds with potential antioxidant activities in the HPLC chromatogram will be significantly reduced in comparison to the untreated sample. The identity confirmation was achieved by Q-TOF-MS/MS technique. With this method, eight components were proposed possessing potent antioxidant activity. They were identified as sibiricose A5, sibiricose A6, sucrose monoester, polygalaxanthone III, tenuifoliside B, 3',6-disinapoylsucrose (DISS), sucrose diester, tenuifoliside C, respectively. DISS was proposed to be the most potent one. The antioxidant activity of DISS was evaluated by DPPH, ABTS radical scavenging assay and ferric-reducing antioxidant power (FRAP) assay in vitro. Vitamin C (Vc) was used as positive control substance. DISS showed moderate DPPH (DISS's IC50 value was 1024.17 μg/mL, Vc's was 294.68 μg/mL) and ABTS (IC50 324.13 μg/mL, Vc's was 117.50 μg/mL) free radical scavenging capacity and ferric-reducing antioxidant power. DISS can be used as a new source of natural antioxidant in foods and cosmetics.

Shi Q ，Chen J ，Zhou Q ，Lei H ，Luan L ，Liu X ，Wu Y ... -  《-》

Chemical profiling and antioxidant evaluation of Yangxinshi Tablet by HPLC-ESI-Q-TOF-MS/MS combined with DPPH assay.

Yangxinshi Tablet (YXST) is a Chinese patent medicine commonly used to treat cardiovascular diseases. However, its detailed chemical basis and mechanisms of action have not been clarified. In this study, high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC-ESI-Q-TOF-MS) was applied for comprehensive analysis of the chemical constituents in YXST. A total of 127 compounds, including 19 phenolic acids, 12 alkaloids, 51 flavanoids, 32 triterpenoids, 2 lignans, 2 phenylethanoid glycosides, 2 anthraquinones, 1 coumarin, and 6 other compounds, were identified or tentatively deduced by comparing their retention times and MS spectra with those of authentic standards or literature data. To further prove the antioxidant activity of YXST, its free radical scavenging capacity was assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) spectrophotometric assay and the antioxidants in YXST were rapidly screened by DPPH-HPLC experiment. Especially, salvianolic acid A and salvianolic acid B showed excellent DPPH scavenging activities with the IC50 of 151.9 and 275.6μg/mL, respectively, which were stronger than that of l-ascorbic acid (positive control) with the IC50 of 297.1μg/mL. Additionally, these two most potent antioxidants were detectable in rat plasma after oral administration. In conclusion, this study reported important clues for the further pharmacological and clinical studies of YXST. Meanwhile, it provided a practical strategy for rapid screening and identifying of in vivo antioxidant in traditional Chinese medicine preparations.

Zhu J ，Yi X ，Zhang J ，Chen S ，Wu Y ... -  《-》

Screening and characterization of natural antioxidants in four Glycyrrhiza species by liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry.

Licorice, derived from the dried roots and rhizomes of several species of genus Glycyrrhiza L. (Leguminosae family), has been traditionally used in herbal medicine for over 4000 years. In recent years, the interest in antioxidative constituents in licorice has greatly increased. In this work, a new method based on 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) spiking test combined with HPLC coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS) analysis was developed to screen and identify the antioxidants in licorice. The results of the method validation indicated that the developed method was reliable and repeatable. Compared with DPPH on-line method, the HPLC-Q-TOF MS/MS method combined with DPPH spiking test offered much higher sensitivity and resolution. Using this method, 35 radical scavengers were screened from four Glycyrrhiza species (G. inflata, G. glabra, G. pallidiflora and G. uralensis), and 21 of them were unambiguously or tentatively identified by HPLC-Q-TOF MS/MS. Among the 21 identified flavonoids, 10 compounds had been reported to possess antioxidative activities in the previous studies, and the radical scavenging activities of the other 11 compounds were reported for the first time. The effects of six purified flavonoids on DPPH radical and lipid peroxidation were evaluated for validation of the developed method. The results indicated that HPLC-Q-TOF MS/MS coupled with DPPH treatment is an efficient and powerful method to discover the potential antioxidative compounds from the complex natural product mixtures. In this study, the identified components with free radical scavenging activity, would help to explain the therapeutic benefit of licorice in the treatment of human disease associated with oxidative stress.

Li YJ ，Chen J ，Li Y ，Li Q ，Zheng YF ，Fu Y ，Li P ... -  《-》

Screening natural antioxidants in peanut shell using DPPH-HPLC-DAD-TOF/MS methods.

Peanut shell, a byproduct in oil production, is rich in natural antioxidants. Here, a rapid and efficient method using DPPH-HPLC-DAD-TOF/MS was used for the first time to screen antioxidants in peanut shell. The method is based on the hypothesis that upon reaction with 1, 1-diphenyl-2-picrylhydrazyl (DPPH), the peak areas of compounds with potential antioxidant activities in the HPLC chromatogram will be significantly reduced or disappeared, and the identity confirmation could be achieved by HPLC-DAD-TOF/MS technique. With this method, three compounds possessing potential antioxidant activities were found abundantly in the methanolic extract of peanut shell. They were identified as 5,7-dihydroxychromone, eriodictyol, and luteolin. The contents of these compounds were 0.59, 0.92, and 2.36 mg/g, respectively, and luteolin possessed the strongest radical scavenging capacity. DPPH-HPLC-DAD-TOF/MS assay facilitated rapid identification and determination of natural antioxidants in peanut shell, which may be helpful for value-added utilization of peanut processing byproducts.

Qiu J ，Chen L ，Zhu Q ，Wang D ，Wang W ，Sun X ，Liu X ，Du F ... -  《-》

In vitro antioxidant activity and phenolic content of Cedrus brevifolia bark.

Cretu E ，Salminen JP ，Karonen M ，Miron A ，Charalambous C ，Constantinou AI ，Aprotosoaie AC ... -  《-》