AUTHOR=Dai Lixia , He Jian , Miao Xiaolou , Guo Xiao , Shang Xiaofei , Wang Weiwei , Li Bing , Wang Yu , Pan Hu , Zhang Jiyu 

TITLE=Multiple Biological Activities of Rhododendron przewalskii Maxim. Extracts and UPLC-ESI-Q-TOF/MS Characterization of Their Phytochemical Composition

JOURNAL=Frontiers in Pharmacology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2021.599778

DOI=10.3389/fphar.2021.599778

ISSN=1663-9812

ABSTRACT=<p><bold>Backgroud:</bold><italic>Rhododendron</italic> przewalskii Maxim. is an evergreen shrub that is used as a traditional medicine in China. However, the modern pharmacology and the chemical components of this plant has not been studied. In this paper, we aimed to investigate the antifungal, anti-inflammatory and antioxidant activities and underlying mechanism of its aqueous and ethanol extracts, and analyze their chemical composition and active compounds of <italic>R. przewalskii</italic>.</p><p><bold>Methods:</bold> The antifungal activity was determined <italic>in vitro</italic>, and anti-inflammatory and antioxidant activities and underlying mechanism of its aqueous and ethanol extracts were evaluated <italic>in vitro</italic> and in RAW 264.7 cells. The chemical composition were analyzed using UPLC-ESI-Q-TOF/MS, and the contents of six compounds were determined via HPLC.</p><p><bold>Results:</bold> Both extracts of <italic>R. przewalskii</italic> showed promising anti-inflammatory activity <italic>in vitro</italic>; decreased the production of four inflammatory cytokines, namely, nitric oxide, IL-1β, IL-6 and TNF-<italic>ɑ</italic>, in RAW 264.7 cells induced by lipopolysaccharide; and exhibited weak cytotoxicity. The extracts significantly scavenged DPPH radicals, superoxide radicals and hydroxyl radicals to exert antioxidant effects <italic>in vitro</italic>. The two extracts also exhibited cellular antioxidant activity by increasing superoxide dismutase and CAT activities and decreasing malondialdehyde content in RAW 264.7 cells induced by LPS. However, the antifungal activity of the two extracts was weak. Nine <ext-link ext-link-type="uri" xlink:href="http://www.baidu.com/link?url=tPCPmhvjzQTn04W8e96qv9WxwELvMC6RrW8DvDQ8z9DLqDjooL4psku7CGEhGlQYiKA04vtu2RdHaUmiuMoN-FEK3r-mrk45H5xAvNjTOf7" xmlns:xlink="http://www.w3.org/1999/xlink">flavonoid</ext-link>s were identified by UPLC-ESI-Q-TOF/MS. Of these, six compounds were analyzed quantitatively, including avicularin, quercetin, azaleatin, astragalin and kaempferol, and five compounds (myricetin 3-O-galactoside, paeoniflorin, astragalin, azaleatin and kaempferol) were found in this species for the first time. These compounds demonstrated antioxidant activities that were similar to those of the <italic>R. przewalskii</italic> extracts and were thought to be the active compounds in the extracts<italic>.</italic></p><p><bold>Conclusion:</bold><italic>R. przewalskii</italic> extracts presented promising anti-inflammatory and antioxidant activities. The extracts contained amounts of valuable flavonoids (8.98 mg/g fresh material) that were likely the active compounds in the extract contributing to the potential antioxidant activity. These results highlight the potential of <italic>R. przewalskii</italic> as a source of natural antioxidant and anti-inflammatory agents for the pharmaceutical industry.</p>