Beilstein J. Org. Chem.2017,13, 720–727, doi:10.3762/bjoc.13.71
influence on lipid chain order, membrane permeability and formation of lateral domains.
Keywords: cholesterol; fluorescence; hydroxycholesterol; membrane structure; NMR; Introduction
Cholesterol is a major component of mammalian cell membranes with various biological functions. It plays a key role in
cholesterol into metabolites, which can easily diffuse into the brain. These metabolites are primarily the oxysterols (24S)-hydroxycholesterol (24S-HC) for the transport from the brain to the bloodstream and 27-hydroxycholesterol (27-HC) for the transport in the opposite direction [4][6][8]. These molecules
. Furthermore, high exchange rates of the molecules between erythrocytes and plasma were found [7], indicating that 24S-HC and 27-HC can – contrary to cholesterol – rapidly cross plasma membranes. Also for other oxysterols, like 7-ketocholesterol and 25-hydroxycholesterol, a lower tendency to form lateral lipid
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Graphical Abstract
Figure 1:
Top: Chemical structures of cholesterol and hydroxycholesterols with selected numbering for the car...
Beilstein J. Org. Chem.2015,11, 392–402, doi:10.3762/bjoc.11.45
transformed to 25-hydroxycholesterol (2) in 13% yield (Scheme 1). The statement that the Tl(II)/HMP/O2 adduct, suggested to be a radical in nature, is responsible for cholesterol oxidation was based on the following observations. The electrolysis performed in the divided cell indicated that the oxidation of
electrochemically generated superoxide radical anion (O2·−) in acetonitrile was described in 1997 [37]. It was established that in dry solution, with water content below 4%, no products were observed. However, cholesterol was oxidized to 7-oxocholesterol (9), 7α-hydroxycholesterol (7), and 7β-hydroxycholesterol (8
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Graphical Abstract
Figure 1:
Preferential sites of cholesterol electrooxidation.