The impact of humic and fulvic acids on the dynamic properties of liposome membranes: the ESR method

J Liposome Res. 2014 Jun;24(2):106-12. doi: 10.3109/08982104.2013.839998. Epub 2013 Oct 21.


This paper presents the results of research on the influence of two fractions of humic substances (HS): fulvic acids (FA) and humic acids (HA), as a function of concentration, on the liposome membranes formed from egg yolk lecithin (EYL). The concentration of HS in relation to EYL changed from 0% to 10% by weight. The influence of HS on various areas of membranes: interphase water-lipid, in the lipid layer just below the polar part of the membrane and in the middle of the lipid bilayer, was investigated by different spin labels (TEMPO, DOXYL 5, DOXYL 16). The study showed that HA slightly decreased the fluidity of the analyzed membranes on the surface layer, while FA significantly liquidated the center of the lipid bilayer. The strong effect of both fractions of HS on the concentration of free radicals as a function of time was also described.

Keywords: ESR method; EYL liposomes; humic substances.

MeSH terms

  • Benzopyrans / chemistry*
  • Electron Spin Resonance Spectroscopy / methods
  • Free Radicals / analysis
  • Humic Substances*
  • Kinetics
  • Lipid Bilayers*
  • Liposomes / chemistry*
  • Membrane Fluidity
  • Nuclear Magnetic Resonance, Biomolecular
  • Spin Labels


  • Benzopyrans
  • Free Radicals
  • Humic Substances
  • Lipid Bilayers
  • Liposomes
  • Spin Labels
  • fulvic acid