Aim:Antioxidant activity is one of the important indexes for estimating medicinal value for the traditional Chinese medicine. The aim of this study is to investigate the antioxidant activity of 11 flavonoids mainly revealing luteolin as mother nucleus isolated from Pyrethrum tatsienense.Materials and Methods:The antioxidant activity of 11 flavonoids was measured in vitro using the classical 1,1-diphenyl-2-picrylhydrazyl removal method. The percentages of scavenging activity of 11 flavonoids were analyzed by taking the choice of a-tocopherol as positive drugs, and the scavenging activity was plotted against the sample concentration to obtain the IC50 values.Results:Ten flavonoids containing phenolic hydroxyl groups have different levels of antioxidant activity. Antioxidant activity mainly depends on the numbers and the substitutional positions of phenolic hydroxyls in B ring. When C-3', 4' positions in B ring of flavonoids are replaced by hydroxyl groups, the antioxidant activity improved remarkably. Phenolic hydroxyl groups in A ring contribute some to antioxidant activity because of the electrophilic effect of C ring, and the numbers and substitutional positions of methoxyl and glycosyl have a little effect on the antioxidant activity.Conclusion:Structure-activity relationships of antioxidant activity about flavonoids isolated from P. tatsienense are concluded, which will be beneficial to deep understanding the pharmacological functions of this Tibetan medicine in vivo from the point of antioxidation.

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Rationale: Paris polyphylla var. yunnanensis (Franch) Hand Mazz (PPY) is a traditionalChinese medicine with antitumor, antibacterial, hemostatic, and anthelmintic activities. Identification of the chemical composition in PPY is helpful to discover its active ingredients and can be used to establish its quality control protocols.Methods: The composition of PPY was identified using ultra-high-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry (UHPLC/QTOF-MS/MS) coupled with a molecular networking strategy. First, the UHPLC/QTOF-MS/MS approach was optimized for chemical compound profiling.Then, the MS data were processed using PeakView™ combined with an in-house database to quickly characterize the secondary metabolites. Finally, molecular networking excavated new molecular weights to discover unknown or trace natural products based on the characteristics of each cluster. Results:A total of 222 compounds, including 77 isospirostanols, 2 spirostanols, 19 furostanols, 10 pseudospirostanols, 6 cholesterols, 10 C 21 steroids, 5 insect metamorphosis hormones, 3 plant sterols, 6 five-ring triterpenoids, 4 flavonoids, 8 fatty acids, 2 phenylpropanoids, and 8 other compounds, were characterized in PPY by comparing their main fragmentation characteristics and pathways with the literature data, and 62 of them, 54 steroidals and 8 phenylpropanoids, were discovered or tentatively identified for the first time. Conclusions:This study extended the application of a molecular networking strategy to traditional herbal medicines and developed a molecular networking based screening approach with a significant increase in efficiency for the discovery and identification of trace novel natural products.Yumei Wang and Qian Fan contributed equally to this work as first authors. Paris polyphylla var. yunnanensis (Franch) Hand Mazz (PPY), calledChong Lou, is a well-known, valuable traditional Chinese medicine (TCM) that has been used to treat fractures, hemorrhages, snake bites, and abscess for many years. 1,2 PPY has been used as a main ingredient for the preparation of many TCMs, such as Yunnan Baiyao, Gongxuening capsules, and Jidesheng Sheyao tablets. 3 Phytochemistry studies have indicated that the dried rhizomes of Paris species contain steroidal saponins, triterpenoid saponins, flavonoids, phenylpropanoids, ecdysteroids, phenolic glycosides, and so on. 4-6 The glucosyl groups of steroidal saponins are normally attached to the steroidal aglycones through the hydroxyl groups at the C-3 and/or C-26 positions (and sometimes the C-1, C-21, C-23, and C-24 positions). Four types of steroidal sapogenins 6 (spirostanol, isospirostanol, furostanol, and pseudospirostanol) are considered major aglycones, and typical sugars are arabinose, xylose, apiose, fucose, rhamnose, glucose, and galactose. Comprehensive identification of ingredients in PPY is critical to understanding its biological mechanism and establishing quality control protocols. Because of the complexity of these components, their comprehensive...

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