The overlooked rotational isomerism of C-glycosyl flavonoids

  • Guohong Zhou
  • Renliang Yan
  • Xiaogen Wang
  • Shaolin Li
  • Jin Lin
  • Jia Liu
  • Zhendong ZhaoEmail author


C-glycosyl flavonoids are important secondary plant metabolites with a wide range of biological activities. Rotational isomerism, arising from restricted bond rotation, has been observed on a portion of C-glycosyl flavonoids. NMR technique contributes most to the observation and research of this phenomenon. Signal duplication in NMR spectra may be the key characteristic of C-glycosyl flavonoids existing as rotamers. Bulky steric hindrance from the substituents at position 7 and sugar moieties are responsible for the restricted bond rotation. There are other influence factors including temperature, solvents, H-bonds and π-stacking, but these are of lesser importance. Difference exists between 8-C-glycosyl flavonoids and their 6-C-glycosyl isomers despite sharing the same flavonoid aglycone and sugar moiety. 8-C-glycosyl flavonoids are more likely to suffer from restricted rotation. The energy barriers between rotamers of C-glycosyl flavonoids seem not high enough for atropisomerism to be realized and the isolation of rotamers should be difficult.


Rotational isomerism Rotamer Atropisomerism C-glycosyl flavonoids Restricted rotation 



High performance liquid chromatography


Nuclear magnetic resonance spectroscopy



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Copyright information

© Springer Nature B.V. 2019

Authors and Affiliations

  • Guohong Zhou
    • 1
  • Renliang Yan
    • 1
  • Xiaogen Wang
    • 1
  • Shaolin Li
    • 1
  • Jin Lin
    • 1
  • Jia Liu
    • 1
  • Zhendong Zhao
    • 1
    Email author
  1. 1.Guangdong Food and Drug Vocational CollegeGuangzhouChina

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