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Cholesterol oxides biological activities

Researchers have reasoned that if the water-soluble peptide leu-enkephalin could be conjugated with an oxidizable hydrophobic chain, and further shielded with a hydrophobic domain provided by cholesterol via an ester linkage, the modihed leu-enkephalin could become sufficiently hydrophobic to breach the blood-brain barrier. The oxidation of one of the engineered domains in the brain would produce an ionic form that cannot redistribute back into blood, and is essentially locked in. The ester linkages could then be hydrolyzed by esterases in brain tissues to release biologically active leu-enkephalin (Figure 13.12). [Pg.362]

ABSTRACT This article describes physiological properties of two classes of natural products, namely cholesterol oxides and dehydroepiandrosterone (DHEA). The cholesterol oxides, also called oxysterols, are autoxidation products of cholesterol. Dehydroepiandrosterone and its sulfate DHEAS are formed mainly in the adrenals. The biological activities of these compounds are utilized to construct the two following hypotheses. [Pg.351]

Oxysterols are oxidized forms of cholesterol they are formed enzymatically in the first steps of cholesterol metabolism, and they may also be formed as a result of autoxidation of cholesterol [50]. The high abundance of cholesterol in biological systems means that oxysterols can easily be formed nonenzymatically during sample handling and workup unless care is taken. Oxysterols are biologically active molecules they have been shown in vitro to activate nuclear receptors, for example, liver X receptors (LXRs) [51], to interact with INSIG protein and thereby to repress cholesterol synthesis [52], and, like bile acids, to interact with G-protein coupled receptors. Oxysterols also represent transport forms of cholesterol [53] (Table 2.3). [Pg.61]

CI-976 was synthesized as a fatty acid anilide derivative designed to mimic fatty acyl-CoA, the fatty acid donor for ACAT enzymes, and it has been most extensively studied in this regard as a competitive ACAT inhibitor (Field et al., 1991 Roth et al., 1992). Various animal studies have shown that CI-976 lowers plasma low density Upoprotein (LDL)-cholester-ol and raises high density lipoprotein-cholesterol by inhibiting both hver and intestinal ACAT activities CI-976 also lowers liver cholesterol esters (CE) and decreases CE secretion (Carr et al., 1995 Krause et al., 1993). The metabolic fate of CI-976 has been studied in both whole animals and isolated hepatocytes, and it is oxidized to numerous metabolites, likely by cytochrome P450 pathways (Sinz et al., 1997). The biological activities of these metabolites are unknown. [Pg.118]

The biosynthesis of steroid hormones is a fascinating process in which the neutral lipid cholesterol, a normal constituent of lipid bilayers is transformed via a series of hydroxylation, oxidation and reduction steps into a vast array of biologically active compounds mineralocorticoids, glucocorticoids and sex hormones. The majority of these transformations occur in the adrenal, testis and ovary although other tissues, such as liver, kidney, placenta, brain and skin are also quite active. [Pg.551]

Work on conduction in materials of biological interest such as proteins and oxidized cholesterol suggests that a correlation exists between the activation energies and pre-exponential factors an of the form... [Pg.194]


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Activated oxidation

Activation oxidation

Active oxides

Activity oxidation

Cholesterol oxidation

Oxidation biological

Oxidative activation

Oxides activated

Oxidizing activators

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