Flavonols with a Catechol or Pyrogallol Substitution Pattern on ring B Readily form Stable Dimers in Phosphate-buffered Saline at four degrees Celsius

Abstract

Flavonols with a catechol or pyrogallol substitution pattern on ring B readily form stable dimers in phosphate buffered saline at four degrees Celsius.

Recent advances on the stability of dietary polyphenols

“…High‐resolution MS is a pronouncedly convenient and advanced method to analyze the polyphenol and its unstable products in complex matrices. The UPLC‐Q‐TOF‐MS n and UPLC‐LTQ‐Orbitrap‐MS n are widely applied to screen and structure predict the degraded/oxidized products of polyphenols (Cao et al, 2020; Lin et al, 2022; M. L. Wang et al, 2022; H. L. Zhang et al, 2022). Moreover, NMR spectroscopy is important tool for qualitative and quantitative analysis of polyphenols, especially in structural elucidation and stereochemistry determination.…”

“…the unstable products of quercetin in boiling water are identified as 3,5‐dihydroxyphenylglyoxylic acid, 1,3,5‐trihydroxybenzene, 3,4,5‐trihydroxybenzoic acid, 2,4,6‐trihydroxybenzoic acid, 2,3‐dihydro‐2,3′,4′,5,7‐pentahydroxy‐3‐oxoflavone, quercetin dimers, and quinones (Figure 4). Flavonols with a catechol or pyrogallol substitution pattern on ring B readily formed stable dimers and oxidized products in phosphate‐buffered saline (pH = 7.4) at 4°C within 5 s (Figure 4) (Cao et al, 2020). Epimerization of tea catechins always happened in high temperature and pH value (Xu et al, 2019).…”