Effect of
Thermozeaxanthins on Liposome Membranes in Acidic and Basic Conditions
YUAN Hui-Qing1*, CONG Li-Hong2, HARA
Masayuki3, HOSHINO Takayuki4, YOKOYAMA Akihiro5,
MIYAKE Jun3
(1Department of Biochemistry, Medical College of Shandong
University, Jinan 250012, China； 2Hospital of Shandong University, Jinan 250061, China； 3National Institute for Advanced
Interdisciplinary Research(NAIR), Agency of Industrial Science
and Technology(AIST), Ministry of International Trade and Industry(MITI),
Tsukuba 305-8562,
Japan； 4Institute of Applied Biochemistry,
University of Tsukuba, Ibaraki 305-8537, Japan； 5Marine Biotechnology Institute, Shimizu
Laboratories,Shimizu 424-0037,
Japan )
Abstract
Thermozeaxanthins (TZS), a group of carotenoid-glucoside esters extracted from
the lipids fraction of thermophilic bacterium, are amphiphilic compounds. The
effects of TZS on membrane permeability were examined on large unilamellar
liposomes (LUVs) in different pH buffers. The LUVs were composed of 0.01 molar
of TZS and phosphatidylcholine (PC) of various lengths and saturation degrees
of hydrocarbon chains. The results showed that the LUVs containing TZS were
more stable than that liposomes without TZS in pH 5.0, and no significant
effects in pH 8.2 and 9.0 buffer solutions. The liposomes composed of TZS and
egg PC or E.coli PE were better than those DPPC or DOPC LUVs
containing TZS at same experimental conditions. There was no observed
difference in stability between the liposomes with or without TZS in pH 6.5
solution. Conclusions： (1) Matching of rigid TZS in the lipid
bilayer was important in stabilization effects on liposomes, (2)The TZS showed
some stabilization effects on liposome membranes in acidic conditions and no
significant effects in basic environment.
Key words thermozeaxanthins； liposomes； stabilization； pH variation； fluorescence
*Corrseponding author： Tel, 86-531-2942373； Fax, 86-531-2942373； e-mail,
hxlou@jn public.sd.cninfo.net