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1999 (1)
1982 (1)
1Author    SeymourSteven BrodyRequires cookie*
 Title    Absorption and Picosecond Fluorescence Characteristics o f Chlorophyll Vesicles as a Function o f Temperature  
 Abstract    With chlorophyll a-dipalmitoylphosphatidylcholine-liposomes, the absorption increases at 706 and 450 nm, and decreases at 660 and 420 nm, as the temperature is lowered. As the temperature is increased opposite changes are observed. A lipid phase change occurs at 34°. The pigment to lipid ratio is 1 to 5 in the liposome. With chlorophyll a-soy bean lecithin-liposomes the absorption increases at 706, 680 and 440 nm, and decreases at 650 and 430 nm, as the temperature is lowered. As the temperature is increased, opposite changes are observed. A lipid phase change occurs at 26-27 °C. The pigment to lipid ratio is 1 to 13. The spectral change at 706 nm is identified with aggregated chlorophyll. The concentration o f chlorophyll aggregate increases as the temperature is lowered, and decreases as the temperature is raised. Fluorescence decay from chlorophyll a-soy bean lecithin-liposomes is biphasic. The lifetimes o f freshly prepared liposomes are 121 ± 4 ps and 1400 + 200 ps. The relative contribution o f the fast and slow fluorescence components are modified by temperature. Heating results in an increase in both lifetimes, and an increase in fluorescence from the long lived component. These changes are interpreted as resulting from a decrease in energy transfer and concentration quenching. The origin o f the biphasic fluorescence and spectral transformations in liposomes, and the possible re­ lation between in vitro and in vivo picosecond fluorescence is discussed. 
  Reference    Z. Naturforsch. 37c, 260—267 (1982); received October 161981 
  Published    1982 
  Keywords    Liposome, Chlorophyll, Photosynthesis, Fluorescence Lifetime, Lipid Phase Change 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0260.pdf 
 Identifier    ZNC-1982-37c-0260 
 Volume    37 
2Author    Janina Gabrielska3, Jan Oszmiańskib, Małgorzata Komorowskac, Marek Langner3Requires cookie*
 Title    Anthocyanin Extracts with Antioxidant and Radical Scavenging Effect  
 Abstract    The antioxidative activity of three anthocyanin pigments, extracted from the fruits of chokeberry, honeysuckle and sloe, were studied. Lipid oxidation in the liposome membrane, induced by UV radiation, was evaluated with a thiobarbituric acid-reactive substances assay. The antioxidant efficiency of the studied compounds follows this sequence: chokeberry > sloe > honeysuckle. The extract concentrations at which a 50% reduction of phosphatidylcho­ line oxidation was observed, were respectively: 48, 54 and 60 mg/1. The end products of lipid membrane oxidation were evaluated using HPLC. It was found that the antioxidative potency of anthocyanin extracts is concentration-dependent. As shown by E P R technique the effi­ ciency of the extracts to eliminate free radicals from the solution follows the order of the antioxidant activity. 
  Reference    Z. Naturforsch. 54c, 319 (1999); received December 2 1998/January 22 1999 
  Published    1999 
  Keywords    Antioxidant, Anthocyanin, Liposome, TBA -Reactive Product 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0319.pdf 
 Identifier    ZNC-1999-54c-0319 
 Volume    54