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Aggregation Behavior of Xanthophylls
Author(s) -
Landrum John T.,
Babino Darwin
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.539.14
Subject(s) - lutein , xanthophyll , zeaxanthin , chemistry , carotenoid , monomer , solvent , photochemistry , organic chemistry , biochemistry , polymer
Aggregation of carotenoids in biological systems influences their properties. The objective of this study is to investigate the extent to which carotenoid aggregation varies as a function of the polarity of the solvent mixture and temperature. The visible spectra of lutein, zeaxanthin and the monomethyl ether of lutein were measured in alcohol/water mixtures that favor aggregation. Over a range of temperatures in these solvent mixtures the extent of aggregation changes, in some cases dramatically. Using a two‐component, monomer/aggregate model an estimate of the enthalpy for the aggregation by these xanthophylls has been made. Our results for these systems provide insight into the energetics of xanthophyll aggregates. Lutein and zeaxanthin exhibit little difference at low concentration in their aggregation properties. Measured ΔH (kcal/mole) values for aggregation range between +5.9 and +11.5 for lutein and +3.9 and +10.3 for zeaxanthin and are sensitive to solvent composition. Methylation of the 3′‐OH group of lutein disrupts aggregate formation showing that H‐bonding at both ends of the carotenoid is a significant contributor to the stability of aggregates.