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Accumulation of macular xanthophylls in unsaturated membrane domains. Free Radic Biol Med 2006 May 15;40(10):1820-6

Date

05/09/2006

Pubmed ID

16678020

DOI

10.1016/j.freeradbiomed.2006.01.016

Abstract

The distribution of macular xanthophylls, lutein and zeaxanthin, between domains formed in membranes made from an equimolar ternary mixture of dioleoylphosphatidylcholine/sphingomyelin/cholesterol, called a raft-forming mixture, was investigated. In these membranes, two domains are formed: the raft domain enriched in saturated lipids and cholesterol (detergent-resistant membranes, DRM), and the bulk domain enriched in unsaturated lipids (detergent-soluble membranes, DSM). These membrane domains have been separated using cold Triton X-100 extraction from membranes containing 1 mol% of either lutein or zeaxanthin. The results indicated that xanthophylls are substantially excluded from DRM and remain concentrated in DSM. Concentrations of xanthophylls in DRM and DSM calculated as the mole ratio of either xanthophyll to phospholipid were 0.005 and 0.03, respectively, and calculated as the mole ratio of either xanthophyll to total lipid (phospholipid + cholesterol) were 0.003 and 0.025, respectively. Thus, xanthophylls are over eight times more concentrated in DSM than in DRM. No significant difference in the distribution of lutein and zeaxanthin was found. It was also demonstrated using saturation-recovery EPR that at 1 mol%, neither lutein nor zeaxanthin affect the formation of membrane domains. The location of xanthophylls in domains formed from unsaturated lipids is ideal if they are to act as a lipid antioxidant, which is the most accepted mechanism through which lutein and zeaxanthin protect the retina from age-related macular diseases.

Author List

Wisniewska A, Subczynski WK

Author

Witold K. Subczynski PhD Professor in the Biophysics department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Antioxidants
Lipid Bilayers
Liposomes
Lutein
Membrane Microdomains
Spin Trapping
Xanthophylls
Zeaxanthins