Linkage and Stereochemistry Characters of Phenolic Antioxidant Product Formation

Abstract

The present study developed a smart and novel strategy to elucidate the linkage and stereochemistry characters during phenolic antioxidant product formation. A series of phenolic isomers or analogues were treated with 2-phenyl-4,4,5,5tetramethylimidazoline-1-oxyl-3-oxide radical, to create 16 antioxidant dimerization reactions in aqueous solution. The products were rapidly identified by ultraperformance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass-spectrometry. Through a systematic function−structure relationship analysis of these reactions and theoretical calculations, it is concluded that the phenolic antioxidant product is formed via linear linkage or furanocyclic linkage. The linear linkage is fulfilled via a radical coupling and controlled by the O−O linkage exclusion, meta-linkage exclusion, and catechol-activated principles. However, when an exocyclic π-bond conjugates with the phenolic core and is affixed at the −OH para-position, the furanocyclic linkage may occur via a subsequent intramolecular Michael addition. The intramolecular addition always lacks Re-attack to show "α,β diastereoselectivity." The α,β diastereoselectivity is the stereochemistry character of furanocyclic linkage during phenolic antioxidant product formation. All these novel findings can benefit not only the field food science but also other fields as well.

Detection of Adulterated Naodesheng Tablet (Naodesheng Pian) via In-Depth Chemical Analysis and Subsequent Reconstruction of Its Pharmacopoeia Q-Markers

“…Similar successful instances can also be observed in Figure 4 B,D,E. Apparently, these successes could be attributed to the high selectivity of the molecular formula extraction technology in LC-MS [ 46 ] .…”

“…Similar successful instances can also be observed in Figure 4B,D,E. Apparently, these successes could be attributed to the high selectivity of the molecular formula extraction technology in LC-MS [46]. Meanwhile, these successful experiments also showed that (1) the LC-MS technology was applicable for the analysis of these Q-markers.…”

Database-aided UHPLC-Q-orbitrap MS/MS strategy putatively identifies 52 compounds from Wushicha Granule to propose anti-counterfeiting quality-markers for pharmacopoeia

“…The anti -counterfeiting validation experiment was performed using ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UHPLC-ESI-Q-TOF–MS/MS), an analytic technology inferior to UHPLC-Q-orbitrap MS/MS. The chromatography analysis protocol was based on our previous studies [ 25 , 26 ]; while the MS spectra monitoring was achieved using a Q − TOF − MS/MS apparatus (i.e., Triple TOF 5600 plus mass spectrometer, AB SCIEX, Framingham, MA, U.S.A.) [ 27 ]. However, the analytes were 6 counterfeit Wushicha Granules, i.e., CWG 1–CWG 6.…”

Database-aided UHPLC-Q-orbitrap MS/MS Strategy Putatively Identifies 52 Compounds from Wushicha Granule to Propose Anti-counterfeiting Quality-markers for Pharmacopoeia

“…The anti-counterfeiting validation experiment was performed using ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-ight tandem mass spectrometry (UHPLC-ESI-Q-TOF-MS/MS), an analytic technology inferior to UHPLC-Q-orbitrap MS/MS. The analysis protocol was based on our previous studies [24], [25] . However, the analytes were 6 counterfeit Wushicha Granules, i.e., CWG 1 ~ CWG 6.…”