2 research outputs found
Domain Formation and Permeabilization Induced by the Saponin α‑Hederin and Its Aglycone Hederagenin in a Cholesterol-Containing Bilayer
Saponins and triterpenic acids have
been shown to be able to interact
with lipid membranes and domains enriched with cholesterol (rafts).
How saponins are able to modulate lipid phase separation in membranes
and the role of the sugar chains for this activity is unknown. We
demonstrate in a binary membrane model composed of DMPC/Chol (3:1
mol/mol) that the saponin α-hederin and its aglycone presenting
no sugar chain, the triterpenic acid hederagenin, are able to induce
the formation of lipid domains. We show on multilamellar vesicles
(MLV), giant unilamellar vesicles (GUV), and supported planar bilayers
(SPB) that the presence of sugar units on the sapogenin accelerates
domain formation and increases the proportion of sterols within these
domains. The domain shape is also influenced by the presence of sugars
because α-hederin and hederagenin induce the formation of tubular
and spherical domains, respectively. These highly curved structures
should result from the induction of membrane curvature by both compounds.
In addition to the formation of domains, α-hederin and hederagenin
permeabilize GUV. The formation of membrane holes by α-hederin
comes along with the accumulation of lipids into nonbilayer structures
in SPB. This process might be responsible for the permeabilizing activity
of both compounds. In LUV, permeabilization by α-hederin was
sterol-dependent. The biological implications of our results and the
mechanisms involved are discussed in relation to the activity of saponins
and triterpenic acids on membrane rafts, cancer cells, and hemolysis
Domain Formation and Permeabilization Induced by the Saponin α‑Hederin and Its Aglycone Hederagenin in a Cholesterol-Containing Bilayer
Saponins and triterpenic acids have
been shown to be able to interact
with lipid membranes and domains enriched with cholesterol (rafts).
How saponins are able to modulate lipid phase separation in membranes
and the role of the sugar chains for this activity is unknown. We
demonstrate in a binary membrane model composed of DMPC/Chol (3:1
mol/mol) that the saponin α-hederin and its aglycone presenting
no sugar chain, the triterpenic acid hederagenin, are able to induce
the formation of lipid domains. We show on multilamellar vesicles
(MLV), giant unilamellar vesicles (GUV), and supported planar bilayers
(SPB) that the presence of sugar units on the sapogenin accelerates
domain formation and increases the proportion of sterols within these
domains. The domain shape is also influenced by the presence of sugars
because α-hederin and hederagenin induce the formation of tubular
and spherical domains, respectively. These highly curved structures
should result from the induction of membrane curvature by both compounds.
In addition to the formation of domains, α-hederin and hederagenin
permeabilize GUV. The formation of membrane holes by α-hederin
comes along with the accumulation of lipids into nonbilayer structures
in SPB. This process might be responsible for the permeabilizing activity
of both compounds. In LUV, permeabilization by α-hederin was
sterol-dependent. The biological implications of our results and the
mechanisms involved are discussed in relation to the activity of saponins
and triterpenic acids on membrane rafts, cancer cells, and hemolysis