The membrane-permeabilizing effect of avenacin A-1 involves the reorganization of bilayer cholesterol

Biophys J. 1999 Jan;76(1 Pt 1):281-90. doi: 10.1016/S0006-3495(99)77196-1.


Avenacin A-1 is a member of a group of naturally occurring compounds called saponins. It is found in oat plants, where it protects against fungal pathogens. A combined electrical and optical chamber was used to determine the interaction of avenacin A-1 with Montal-Mueller planar lipid bilayers. This system allowed simultaneous measurement of the effect of avenacin A-1 on the fluorescence and lateral diffusion of a fluorescent lipid probe and permeability of the planar lipid bilayer. As expected, cholesterol was required for avenacin A-1-induced bilayer permeabilization. The planar lipid bilayers were also challenged with monodeglucosyl, bis-deglucosyl, and aglycone derivatives of avenacin A-1. The results show that the permeabilizing activity of the native avenacin A-1 was completely abolished after one, two, or all three sugar residues are hydrolyzed (monodeglucosyl, bis-deglucosyl, and aglycone derivatives, respectively). Fluorescence recovery after photobleaching (FRAP) measurements on cholesterol-containing planar lipid bilayers revealed that avenacin A-1 caused a small but significant reduction in the lateral diffusion of the phospholipid probe N-(7-nitrobenzoyl-2-oxa-1,3-diazol-4-yl)-1, 2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (NBD-PE). Similarly, with the sterol probe (22-(N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl)amino)-23,24-bisnor-5-cholen-3beta-ol (NBD-Chol), avenacin A-1, but not its derivatives, caused a more pronounced reduction in the lateral diffusion than that observed with the phospholipid probe. The data indicate that an intact sugar moiety of avenacin A-1 is required to reorganize membrane cholesterol into pores.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 4-Chloro-7-nitrobenzofurazan / analogs & derivatives
  • Biophysical Phenomena
  • Biophysics
  • Carbohydrate Sequence
  • Cholesterol / analogs & derivatives
  • Cholesterol / chemistry*
  • Diffusion
  • Fluorescent Dyes
  • In Vitro Techniques
  • Lipid Bilayers / chemistry*
  • Liposomes
  • Models, Chemical
  • Molecular Sequence Data
  • Permeability
  • Phosphatidylethanolamines
  • Saponins / chemistry
  • Saponins / pharmacology*


  • Fluorescent Dyes
  • Lipid Bilayers
  • Liposomes
  • Phosphatidylethanolamines
  • Saponins
  • N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)phosphatidylethanolamine
  • N(1)-cholesterylcarbamoyl-N(8)-(4-nitrobenzo-2-oxa-1,3-diazole)-3,6-dioxaoctyl-1,8-diamine
  • avenacin A 1
  • Cholesterol
  • 4-Chloro-7-nitrobenzofurazan