Abstract The antioxidant properties of coumestans have been investigated previously using inappropriate methods, which has resulted in misleading and inaccurate mechanisms being reported to account for their antioxidant behavior. In this study, the phenolic coumestan wedelolactone increased the viability of OH -treated mesenchymal stem cells (MSCs) in a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl assay. Mechanistic analysis in vitro suggested that wedelolactone could scavenge various radicals, including OH , O 2 - , 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and 1,1-diphenyl-2-picrylhydrazyl ( DPPH ) radicals, as well as reducing Cu2+ and chelating Fe2+. Configuration analysis based on a ball and stick model indicated that the 3′,4′-catechol moiety of wedelolactone was acting as an Fe2+-chelating site. The main product of the reaction between wedelolactone and DPPH was analyzed by ultra-performance liquid chromatography electrospray ionization quadrupole time-of-flight tandem mass spectrometry, which gave a mass ion with an m/z value of 709. This peak yielded several fragments with m/z values of 663, 543, 501 and 483. Quantitative evaluation revealed that the antioxidant activity of wedelolactone was 1.62 times higher than that of Trolox. Based on these results, we concluded that (i) wedelolactone can efficiently protect MSCs against OH -induced damage and that this protective effect provides preliminary evidence for the application of wedelolactone in transplantation of MSCs (especially for osteoporosis); (ii) the main antioxidant mechanism of wedelolactone involves direct radical-scavenging via a single electron transfer (SET) → radical adduct formation (RAF) pathway, whereas the Fe2+-chelating activity of wedelolactone represents a minor pathway; and (iii) the direct radical-scavenging and Fe2+-chelating pathways can both be attributed to the catechol moiety rather than the coumestan skeleton.

中文翻译：

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威地洛内酯作为抗氧化剂-香豆素对OH处理的间充质干细胞的影响和机制

摘要 香豆素的抗氧化特性以前曾使用不适当的方法进行过研究，这导致据报道其抗氧化行为具有误导性和不准确的机制。在这项研究中，酚类香豆素内酯在 3-(4,5-二甲基噻唑-2-基)-2,5-二苯基试验中提高了 OH 处理的间充质干细胞 (MSC) 的活力。体外机理分析表明，韦德内酯可以清除多种自由基，包括 OH , O 2 - , 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) 和 1,1-diphenyl-2-picrylhydrazyl ( DPPH )自由基，以及还原 Cu2+ 和螯合 Fe2+。基于球棒模型的构型分析表明，韦德内酯的 3',4'-邻苯二酚部分充当 Fe2+-螯合位点。韦德内酯与 DPPH 反应的主要产物通过超高效液相色谱电喷雾电离四极杆飞行时间串联质谱法进行分析，得到质量离子的 m/z 值为 709。该峰产生了几个碎片m/z 值分别为 663、543、501 和 483。定量评估表明，威德洛内酯的抗氧化活性是 Trolox 的 1.62 倍。基于这些结果，我们得出结论：(i) Wedelolactone 可以有效地保护 MSCs 免受 OH 诱导的损伤，这种保护作用为 Wedelolactone 在 MSCs 移植（特别是骨质疏松症）中的应用提供了初步证据；(ii) 洋地黄内酯的主要抗氧化机制涉及通过单电子转移 (SET) → 自由基加合物形成 (RAF) 途径直接清除自由基，而洋地黄内酯的 Fe2+ 螯合活性代表次要途径；(iii) 直接清除自由基和 Fe2+ 螯合途径都可以归因于儿茶酚部分而不是香豆素骨架。