Showing papers on "Campesterol published in 2000"

Plant sterols: biosynthesis, biological function and their importance to human nutrition.

Abstract: Plant sterols are an essential component of the membranes of all eukaryotic organisms. They are either synthesised de novo or taken up from the environment. Their function appears to be to control membrane fluidity and permeability, although some plant sterols have a specific function in signal transduction. The phytosterols are products of the isoprenoid pathway. The dedicated pathway to sterol synthesis in photosynthetic plants occurs at the squalene stage through the activity of squalene synthetase. Although the activity of 3-hydroxymethyl-3-glutaryl coenzyme A (HGMR) is rate-limiting in the synthesis of cholesterol, this does not appear to be the case with the plant sterols. Up-regulation of HGMR appears to increase the biosynthesis of cycloartenol but not the Δ5-sterols. A decline in sterol synthesis is associated with a suppression of squalene synthetase activity, which is probably a critical point in controlling carbon flow and end-product formation. The major post-squalene biosynthetic pathway is regulated by critical rate-limiting steps such as the methylation of cycloartenol into cycloeucalenol. Little is known about the factors controlling the biosynthesis of the end-point sterol esters or stanols. The commonly consumed plant sterols are sitosterol, stigmasterol and campesterol which are predominantly supplied by vegetable oils. The oils are a rich source of the steryl esters. Less important sources of sterols are cereals, nuts and vegetables. The nutritional interest derives from the fact that the sterols have a similar structure to cholesterol, and have the capacity to lower plasma cholesterol and LDL cholesterol. Since the morbidity and mortality from cardiovascular disease have been dramatically reduced using cholesterol-lowering drugs (statins), the interest in plant sterols lies in their potential to act as a natural preventive dietary product. Stanols (saturated at C-5) occur in low amounts in the diet and are equally effective in lowering plasma cholesterol and do not cause an increase in plasma levels, unlike the sterols which can be detected in plasma. © 2000 Society of Chemical Industry

Noncholesterol Sterols and Cholesterol Lowering by Long-Term Simvastatin Treatment in Coronary Patients Relation to Basal Serum Cholestanol

Abstract: Coronary patients with low baseline ratios of serum cholestanol and plant sterols to cholesterol (indicating low cholesterol absorption) but not those with high ratios (high absorption) experienced reduced recurrences of coronary events during simvastatin treatment in the Scandinavian Simvastatin Survival Study. Thus, in the present study, serum cholesterol, its precursor sterols (reflecting cholesterol synthesis), plant sterols (campesterol and sitosterol), and cholestanol were measured before and during a 5-year period of placebo treatment (n=433) and simvastatin treatment (n=434) in patients from a subgroup of the Scandinavian Simvastatin Survival Study to determine whether changes in cholesterol synthesis and serum levels were related to cholesterol absorption. Serum cholesterol level was unchanged, the ratios of cholesterol precursor sterols to cholesterol were decreased, and the ratios of plant sterols to cholesterol were increased in relation to increasing baseline ratios of cholestanol quartiles. The latter predicted 5-year ratios and simvastatin-induced reductions of the precursor sterols, with the lowering of the ratios (cholesterol synthesis reduction) being almost twice higher in the lowest versus the highest quartile. The ratios of plant sterols, especially campesterol, to cholesterol were markedly increased during simvastatin treatment, mostly in subjects with the highest baseline cholestanol quartiles. Simvastatin reduced serum cholesterol more (P=0.003) in the lowest versus the highest cholestanol quartile during the 5-year treatment period. The results show for the first time that baseline cholesterol metabolism, measured by serum noncholesterol sterols, predicts the effectiveness of simvastatin in reducing cholesterol synthesis and serum levels of cholesterol. The drug suppresses the synthesis of cholesterol markedly more effectively in subjects with high than with low baseline synthesis but reduces respective serum cholesterol levels less markedly than synthesis. Subjects with high cholesterol absorption and low synthesis may need a combination therapy to lower more effectively their serum cholesterol levels and prevent an increase in the levels of plant sterols.

Phytosterol accumulation in canola, sunflower, and soybean oils: Effects of genetics, planting location, and temperature

Abstract: To assess the potential of traditional selection breeding to develop varieties with increased phytosterol content, we determined concentrations of those sterols in canola, sunflower, and soybean seed oils produced from breeding lines of diverse genetic backgrounds. Seed oils were extracted and saponified, and the nonsaponifiable fractions were subjected to silylation. The major phytosterols brassicasterol, campesterol, stigmasterol and β-sitosterol, were quantified by capillary gas chromatography with flame-ionization detection. Canola contained approximately twice the amount of total phytosterols (4590–8070 μg g−1) as sunflower (2100–4540 μg g−1) or soybean (2340–4660 μg g−1) oils. Phytosterol composition varied among crops as expected, as well as within a crop. Both genetic background and planting location significantly affected total phytosterol concentrations. Soybean plants were maintained from flower initiation to seed maturity under three temperature regimes in growth chambers to determine the effect of temperature during this period on seed oil phytosterol levels. A 2.5-fold variability in total phytosterol content was measured in these oils (3210–7920 μg g−1). Total phytosterol levels increased with higher temperatures. Composition also changed, with greater percent campesterol and lower percent stigmasterol and β-sitosterol at higher temperatures. In these soybean oils, total phytosterol accumulation was correlated inversely with total tocopherol levels. Owing to the relatively limited variability in phytosterol levels in seed oils produced under field conditions, it is unlikely that a traditional breeding approach would lead to a dramatic increase in phytosterol content or modified phytosterol composition.

Dietary phytosterol inhibits the growth and metastasis of MDA-MB-231 human breast cancer cells grown in SCID mice.

Abstract: The objective of the present study was to investigate the effect of dietary phytosterols on the growth and metastasis of the human breast cancer MDA-MB-231 cell line xenografted in SCID mice. Two groups of animals were fed AIN-93G diet supplemented with 0.2% cholic acid and 2% sterol (cholesterol or phytosterol mixture) for 15 days before inoculation of the tumor into the right inguinal mammary fat pad. Tumor growth and food consumption were recorded weekly throughout the 8 weeks of the experiment. At the end of the experiment, the animals fed phytosterol had a 40% lower serum cholesterol and 20 and 30 fold higher serum beta-sitosterol and campesterol, respectively as compared to those fed cholesterol. There was no difference between the two groups in body weight and food consumption. However, the tumor size in animals fed phytosterols was 33% smaller (P < 0.03) and had 20% fewer metastases to lymph nodes and lungs than the cholesterol group. At termination, the tumor weight of the animals fed the phytosterol diet was also less (P < 0.07) than that of the cholesterol group. It is concluded that dietary phytosterols retard the growth and spread of breast cancer cells.

Transgenic plants containing altered levels of sterol compounds and tocopherols

Abstract: Provided are recombinant constructs comprising DNA sequences encoding enzymes effective in altering the biosynthesis and accumulation of sterol compounds and tocopherols in transgenic plants. Also provided are methods of using such constructs to produce transgenic plants, seeds of which contain elevated levels of sitostanol and/or sitostanol esters, and α-tocopherol, as well as reduced levels of campesterol and campestanol and their corresponding esters. These seeds also contain the novel sterol brassicastanol. Oil obtained from seeds of such transgenic plants is also provided. This oil can be used to prepare food and pharmaceutical compositions effective in lowering the level of low density lipoprotein cholesterol in blood serum. In addition, novel DNA sequences encoding plant steroid 5α-reductases are also disclosed.

Identification of metabolites of phytosterols in rat feces using GC/MS.

Abstract: β-Sitosterol, campesterol and stigmasterol have been known to the phytosterols the most frequently found in plants. Metabolism of phytosterols was investigated using rat feces and liver microsomes. Feces were collected after phytosterols (a well characterized mixture of β-sitosterol 40%, campesterol 30% and dihydrobrasicasterol) were administered orally (0.5 g/kg) to rats. Metabolites of phytosterols were identified using GC/MS. Three peaks were eluted at 12.47, 12.65, 12.87 min and had characteristic molecular ionsm/z 428, 430, 432, respectively. Three fecal metabolites were identified as androstadienedione, androstenedione, and androstanedione. No metabolites could be detected in the rat liver microsomal reaction mixture. The results suggest that the metabolites of phytosterols in rat feces are formed by oxidation at 3- position, saturation at 5- and 6- position, and 17- side chain cleavage in the rat large intestine.

Does increased crypt cell proliferation impair cholesterol absorption after proximal gut resection

Abstract: Background: The effects of proximal small-bowel resection on absorption and synthesis of cholesterol are unclear. Methods: To study cholesterol absorption and synthesis after proximal gut resections of variable length, plasma plant sterols, cholestanol, and cholesterol precursors were measured 1 and 2 months after 50% and 75% proximal small-bowel resection or transection. To examine the effect of increased crypt cell proliferation and brush border development on cholesterol absorption, the results were related to the mucosal morphology, crypt cell proliferation, and disaccharidase activities of the remaining small bowel. Results: Campesterol levels in proportion to cholesterol decreased markedly more, and those of cholestanol markedly less, than would be expected simply due to the amount of proximal small intestine removed, whereas sitosterol proportions decreased in proportion to the length of gut resection. Campesterol proportions markedly (P = 0.06) increased between 1 and 2 months after 50% resection ...

A Methylenedioxyflavonol from Aerial Parts of Blutaparon portulacoides.

Abstract: The aerial parts from Blutaparon portulacoides yielded a flavonol whose structure was established as 3,5,3′-trihydroxy-4′-methoxy-6,7-methylenedioxyflavone. In addition, the aerial parts yielded the isoflavone irisone B and the steroids stigmasterol, sitosterol and campesterol. The roots of B. portucaloides furnished sitosteryl, stigmast-7-enyl and spinasteryl β- D -glucopyranosides as well as vanillic acid.

Phytosterol-containing composition

Abstract: PROBLEM TO BE SOLVED: To obtain the subject composition increased in the solubility of the phytosterol to oils and fats, excellent in fluidity even at low temperature, and also excellent in function as an emulsifier, by including a phytosterol, a lecithin and a medium-chain fatty acid triglyceride. SOLUTION: This composition is obtained by incorporating (A) 5-20 wt.% of a phytosterol, (B) 15-70 wt.% of a lecithin and (C) the rest of a medium-chain fatty acid triglyceride. The component A is a phytosterol in sterols widely distributed in the biological world, being a mixture of β-sitosterol, stigmasterol, campesterol, brassicasterol and/or the like, or may be in the form of ester. The component B is preferably a high-purity lecithin containing >=20 wt.% of phosphatidylcholine. It is desirable that the medium-chain fatty acid in the component C is a 8-10C saturated fatty acid.

Quantitation of Sterols in Some Setaria Plants by Gas Chromatography

Abstract: The present sterol quantitation was carried out for four Setaria plants by gas chromatography. In S. italica, sitosterol was most abundant in all components and sitostanol accumulated in the seeds much more than other tissues. Stigmasterol accumulation was limited to leaves and stems. Sterol content of S. viridis, S. X pycnocoma and S. glauca were determined. Sitostanol was found present in these plants in less amounts than in S. italica. Major phytosterol content (campesterol, stigmasterol and sitosterol) of S. X pycnocoma was essentially the same as that of S. italica, while S. viridis and S. glauca content differed considerably from S. italica, major sterol content in leaves and stems being much less compared to seeds. These differences in the four Setaria plants are of interest from a chemotaxonomical standpoint.

Process for preparing a phytosterol composition

Abstract: A universal process for purifying phytosterols from a wood or plant derived source comprises extracting from the source a concentrated extract comprising phytosterols and a hydrocarbon; complexing the extract so formed with a metal salt; separating the phytosterol/metal salt complex from the hydrocarbon; washing the complex with a solvent mixture comprising one or both of a hydrocarbon and a ketone; hydrolysing the washed complex so formed and finally separating the phytosterols therefrom. A novel composition comprises beta-sitosterol, campesterol, campestanol, sitostanol and optionally brassicasterol and brassicastanol.

Oil comprising brassicastanol

Abstract: Provided are recombinant constructs comprising DNA sequences encoding enzymes effective in altering the biosynthesis and accumulation of sterol compounds and tocopherols in transgenic plants. Also provided are methods of using such constructs to produce transgenic plants, seeds of which contain elevated levels of sitostanol and/or sitostanol esters, and α-tocopherol, as well as reduced levels of campesterol and campestanol and their corresponding esters. These seeds also contain the novel sterol brassicastanol. Oil obtained from seeds of such transgenic plants is also provided. This oil can be used to prepare food and pharmaceutical compositions effective in lowering the level of low density lipoprotein cholesterol in blood serum. In addition, novel DNA sequences encoding plant steroid 5α-reductases are also disclosed.