School of Chinese Herbal Medicine, Guangzhou University of Chinese Medicine, Guangzhou 510006, China.
Innovative Research & Development Laboratory of TCM, Guangzhou University of Chinese Medicine, Guangzhou 510006, China.
Molecules. 2018 Dec 6;23(12):3225. doi: 10.3390/molecules23123225.
To explore whether and how glucuronidation affects pyrogallol-type phytophenols, scutellarein and scutellarin (scutellarein-7--glucuronide) were comparatively investigated using a set of antioxidant analyses, including spectrophotometric analysis, UV-vis spectra analysis, and ultra-performance liquid chromatography coupled with electrospray ionization-quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) analysis. In spectrophotometric analyses of the scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide radicals (PTIO) and the reduction of Cu ions, scutellarein showed lower IC values than scutellarin. However, in O₂-scavenging spectrophotometric analysis, scutellarein showed higher IC value than scutellarin. The analysis of UV-Vis spectra obtained after the Fe-chelating reaction of scutellarin showed a typical UV-Vis peak (λ = 611 nm), while scutellarein showed no typical peak. In UPLC-ESI-Q-TOF-MS/MS analysis, mixing of scutellarein with DPPH yielded MS peaks (/ 678, 632, 615, 450, 420, 381, 329, 300, 288, 227, 196, 182, 161, and 117) corresponding to the scutellarein-DPPH adduct and an MS peak (/ 570) corresponding to the scutellarein-scutellarein dimer. Scutellarin, however, generated no MS peak. On the basis of these findings, it can be concluded that glucuronidation of pyrogallol-type phytophenol antioxidants has a dual effect. On the one hand, glucuronidation can decrease the antioxidant potentials (except for O₂ scavenging) and further lower the possibility of radical adduct formation (RAF), while on the other hand, it can enhance the O₂-scavenging and Fe-chelating potentials.
为了探究葡萄糖醛酸化是否以及如何影响焦棓酚型植物酚，本研究使用一组抗氧化分析方法，包括分光光度分析、紫外可见光谱分析和超高效液相色谱-电喷雾电离-四极杆飞行时间串联质谱联用分析（UPLC-ESI-Q-TOF-MS/MS），对染料木素和染料木苷（染料木素-7-O-葡萄糖醛酸苷）进行了比较研究。在 1,1-二苯基-2-苦基肼（DPPH）、2,2'-联氮-双（3-乙基苯并噻唑啉-6-磺酸）（ABTS）和 2-苯基-4,4,5,5-四甲基咪唑啉-1-氧自由基（PTIO）清除以及 Cu 离子还原的分光光度分析中，染料木素的 IC 值均低于染料木苷。然而，在 O₂清除分光光度分析中，染料木素的 IC 值却高于染料木苷。染料木苷与 Fe 螯合反应后的紫外可见光谱分析显示出典型的紫外可见峰（λ=611nm），而染料木素则没有典型的峰。在 UPLC-ESI-Q-TOF-MS/MS 分析中，染料木素与 DPPH 混合生成的 MS 峰（/678、632、615、450、420、381、329、300、288、227、196、182、161 和 117）对应于染料木素-DPPH 加合物，以及一个 MS 峰（/570）对应于染料木素-染料木素二聚体。然而，染料木苷没有生成 MS 峰。基于这些发现，可以得出结论，焦棓酚型植物酚抗氧化剂的葡萄糖醛酸化具有双重作用。一方面，葡萄糖醛酸化可以降低抗氧化能力（除了 O₂清除），进一步降低自由基加合物形成的可能性（RAF），另一方面，它可以增强 O₂ 清除和 Fe 螯合能力。
