Linked Life Data

9723207

Source:http://linkedlifedata.com/resource/pubmed/id/9723207

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1998-10-26
pubmed:abstractText
The spectroscopy and photophysics of the photosensitizer hypericin when in homogeneous solutions and when bound to liposomes were studied. Hypericin was found to partition efficiently into DMPC liposomes, with a binding constant of 58 (mg lipid/mL)-1. In these liposomes the singlet oxygen production quantum yield was 0.43 +/- 0.09. To determine the deactivation constant of singlet oxygen in lipid bilayers for the first time, we calculated extrapolated values from its quenching by DMPC and lecithin in homogeneous solutions and obtained decay times of 36.4 and 12.2 microseconds, respectively. We also measured the quenching of singlet oxygen, sensitized by hypericin in DMPC liposomes, by NaN3, diphenyl isobenzofuran and H2O:D2O mixtures and explained the results on the basis of singlet oxygen diffusing rapidly out of the lipid bilayer into the aqueous medium. The observed temperature effect on the lifetime of singlet oxygen of about 50% over a 15 degrees C range in liposome suspension contrasts with a 3% change in a homogeneous solution in 1-nonanol and is explained by the temperature effect on the diffusion out of the liposome. A strong pH effect was observed, indicating that the deprotonated species formed above about pH 10 is a much weaker photosensitizer of singlet oxygen than the native, protonated species.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0031-8655
pubmed:author
pubmed:issnType
Print
pubmed:volume
68
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
135-40
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Kinetics and yield of singlet oxygen photosensitized by hypericin in organic and biological media.
pubmed:affiliation
Department of Chemistry and Biochemistry, University of California, Los Angeles, USA. ehren@physnet.ph.biu.ac.il
pubmed:publicationType
Journal Article, In Vitro