Sterols in blood of normal and Smith-Lemli-Opitz subjects

Abstract

Smith-Lemli-Opitz syndrome (SLOS) is a hereditary disorder in which a defective gene encoding 7-dehydrocholesterol reductase causes the accumulation of noncholesterol sterols, such as 7-and 8-dehydrocholesterol. Using rigorous analytical methods in conjunction with a large collection of authentic standards, we unequivocally identified numerous noncholesterol sterols in 6 normal and 17 SLOS blood samples. Plasma or erythrocytes were saponified under oxygen-free conditions, followed by multiple chromatographic separations. Individual sterols were identified and quantitated by high performance liquid chromatography (HPLC), Ag ؉ -HPLC, gas chromatography (GC), GC-mass spectrometry, and nuclear magnetic resonance. As a percentage of total sterol content, the major C 27 sterols observed in the SLOS blood samples were cholesterol (12-98%), 7-dehydrocholesterol (0.4-44%), 8-dehydrocholesterol (0.5-22%), and cholesta-5,7,9(11)-trien-3 ␤ -ol (0.02-5%), whereas the normal blood samples contained Ͻ 0.03% each of the three noncholesterol sterols. SLOS and normal blood contained similar amounts of lathosterol (0.05-0.6%) and cholestanol (0.1-0.4%) and ϳ 0.003-0.1% each of the ⌬ 8 , ⌬ 8(14) , ⌬ 5,8(14) , ⌬ 5,24 , ⌬ 6,8 , ⌬ 6,8(14) , and ⌬ 7,24 sterols. The results are consistent with the hypothesis that the ⌬ 8(14) sterol is an intermediate of cholesterol synthesis and indicate the existence of undescribed aberrant pathways that may explain the formation of the ⌬ 5,7,9(11) sterol. 19-Norcholesta-5,7,9-trien-3 ␤ -ol was absent in both SLOS and normal blood, although it was routinely observed as a GC artifact in fractions containing 8-dehydrocholesterol. The overall findings advance the understanding of SLOS and provide a methodological model for studying other metabolic disorders of cholesterol synthesis.-Ruan, B.

Gas Chromatography–Mass Spectrometry and Molecular Genetic Studies in Families with the Conradi–Hünermann–Happle Syndrome

“…They are not affected by everyday diet; however, after institution of strongly cholesterol-enriched diet for several months, effects on sterol metabolism have been shown. It should be noted that variation in sterol levels stems from differences in genotype, age, diet, rate of growth, and other factors (Ruan et al, 2001). For example, in the SLO syndrome, the elevation of 7-DHC ranged from 100-fold in mild cases to about 10,000-fold in a severely affected subject (Ruan et al, 2001).…”

“…It should be noted that variation in sterol levels stems from differences in genotype, age, diet, rate of growth, and other factors (Ruan et al, 2001). For example, in the SLO syndrome, the elevation of 7-DHC ranged from 100-fold in mild cases to about 10,000-fold in a severely affected subject (Ruan et al, 2001). In their study on 84 patients with SLO syndrome, Witsch-Baumgartner et al (2000) found also a positive correlation between clinical severity and elevated relative 7-DHC concentration.…”

Photochemistry and photophysics of cholesta-5,7,9(11)-trien-3β-ol: a fluorescent analogue of cholesterol

“…Analysis of product compositions was done by GC, by 1 H NMR, by UV-Vis, by fluorescence, by MS, and by GC/ MS. We used a Bruker/Varian CP-3800 gas chromatograph equipped with an electronic integrator for CTL and for stilbene actinometry. Semi-preparative HPLC was performed using a Beckman Coulter System Gold 125 solvent module with a System Gold 168 detector.…”

“…The natural products cholesta-5,7,9(11)-trien-3β-ol (CTL) and its close relative 9(11)-dehydroergosterol (DHE) differ from provitamin D 3 (Pro) and ergosterol (E), respectively, by the additional C 9 -C 11 double bond [1][2][3][4][5][6]. The cholestane skeleton lends rigidity to their embedded conjugated triene moieties increasing S 1 lifetimes by diminishing torsional relaxation, thereby rendering them fluorescent [7].…”

“…The accepted structure of the photooxidation product (DHEP, 5α,8α-epidioxy-22-Eergosta-6,9 (11),22-trien-3β-ol) was proposed by Fieser [16], before the role of 1 Δ g singlet oxygen ( 1 O 2 *) in such reactions was known. 1 O 2 * luminescence observed on irradiation of an air-saturated solution of CTL in CCl 4 established formation of CTL triplets that transfer energy to 3 O 2 [15]. It was suggested that CTL, naturally present in skin, may contribute to skin photoaging and UV-induced skin cancer by sensitizing the formation of 1 O 2 * [17].…”