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PubMed2005

Margarine phytosterols decrease the secretion of atherogenic lipoproteins from HepG2 liver and Caco2 intestinal cells.

Several studies in humans have demonstrated the hypocholesterolemic effect of plant sterol consumption. It is unclear whether plant sterols regulate lipoprotein metabolism in the liver and intestines, thereby decreasing the levels of circulating atherogenic lipoproteins. We investigated the effect of the three main phytosterols: stigmasterol, campesterol, and beta-sitosterol on lipoprotein production in HepG2 human liver cells and Caco2 human intestinal cells and the mechanisms involved. Cells were incubated for 24h with 50 micromol/L of the different phytosterols or 10 micromol/L of atorvastatin. Very low-density lipoprotein levels (measured by apolipoprotein (apo) B100) in HepG2 cells and chylomicron levels (measured by apoB48) in Caco2 cells were measured using western blotting. Intracellular cholesterol levels were measured using gas chromatography. Analysis was carried out using Student's t-test and ANOVA. Secretion levels of apoB100 significantly decreased by approximately 30% after incubation with all phytosterols compared to control. In addition, cholesterol ester (CE) concentrations significantly decreased when HepG2 cells were incubated with the phytosterols compared to control cells. Secretion of apoB48 from intestinal cells significantly decreased by 15% with stigmasterol, 16% with campesterol and 19% beta-sitosterol compared to control. Collectively the data suggests that plant sterols limit lipid (CE) availability in cells. Decreases in circulating levels of LDL and chylomicron remnants seen in humans with the consumption of margarine phytosterols are possibly due to their effect on lipid production in cells and would therefore reduce the risk of developing cardiovascular disease.

Anticholesteremic Agents↗
PubMed2000

The safety evaluation of phytosterol esters. Part 6. The comparative absorption and tissue distribution of phytosterols in the rat.

As part of an extensive safety evaluation programme, a series of studies has been conducted to determine the fate of phytosterols in the rat. Rats were dosed by oral gavage with 14C-labelled samples of cholesterol, beta-sitosterol or beta-sitostanol or (3)H-labelled samples of beta-sitostanol, campesterol, campestanol or stigmasterol dissolved in sunflower seed oil. Urine and faeces were collected for up to 96 hours after dosing. There was no quantification of biliary excreted material in these studies. Animals were sacrificed and either prepared for whole body autoradiography or tissues and carcass remains were assayed for 14C or (3)H. The overall absorption of phytosterols was low as judged by tissue and carcass levels of radioactivity. Elimination from the body was mainly in the faeces and was initially very rapid, but traces of material were still being excreted at 4 days after dosing. While total absorption of the phytosterols could not be fully quantified without biliary excretion data, it was clear that cholesterol was absorbed to the greatest extent (27% of the dose in females at 24 hours). Campesterol (13%) was absorbed more than beta-sitosterol and stigmasterol (both 4%) which were absorbed more than beta-sitostanol and campestanol (1-2%). The absorption of phytosterols was slightly greater in females than males. For each test material, the overall pattern of tissue distribution of radioactivity was similar, with the adrenal glands, ovaries and intestinal epithelia showing the highest levels and the longest retention of radioactivity.

Animals↗
PubMed2002

Phytosterol content in American ginseng seed oil.

North American ginseng (Panax quinquefolium L.) oil was saponifed and the unsaponifiable matter trimethylsilylated. The phytosterol fraction of hexane-extracted, air-dried seed was quantified and identified by GC and GC-MS. Phytosterol contents (milligrams per 100 g of oil) were as follows: squalene (514-569), oxidosqualene (8.97-48.2), campesterol (9.96-12.4), stigmasterol (93.2-113), clerosterol (1.91-2.14), beta-sitosterol (153-186), beta-amyrin (11.7-19.5), delta(5)-avenasterol (12.4-20.5), delta(5,24(25))-stigmasterol (3.70-.76), lupeol (14.4-15.2), delta(7)-sitosterol (12.5-14.6), delta(7)-avenasterol (4.11-8.09), 24-methylenecycloartanol (1.94-4.76), and citrostadienol (2.50-3.81). Seed stratification lowered the phytosterol levels. Oven-drying gave mixed results, and phytosterols varied slightly between the 1999 and 2000 harvests.

Cholesterol↗
PubMed2002

Inhibition of cholesterol biosynthesis by Delta22-unsaturated phytosterols via competitive inhibition of sterol Delta24-reductase in mammalian cells.

Dietary phytosterols are cholesterol-lowering agents that interfere with the intestinal absorption of cholesterol. In the present study, we have studied their effects on cholesterol biosynthesis in human cells, particularly in the sterol-conversion pathway. For this, both Caco-2 (intestinal mucosa) and HL-60 (promyelocytic) human cell lines were incubated with [(14)C]acetate, and the incorporation of radioactivity into sterols was determined using HPLC and radioactivity detection online. Sterols containing a double bond at C-22 in the side chain (stigmasterol, brassicasterol and ergosterol) dramatically inhibited the activity of sterol Delta(24)-reductase, as indicated by the decrease in radioactivity incorporation into cholesterol and the accumulation of its precursors (mainly desmosterol). Phytosterols with the saturated side chain (beta-sitosterol and campesterol) were inactive in this regard. The inhibition of sterol (24)-reductase was confirmed in rat liver microsomes by using (14)C-labelled desmosterol as the substrate. The (22)-unsaturated phytosterols acted as competitive inhibitors of sterol (24)-reductase, with K(i) values (41.1, 42.7 and 36.8 microM for stigmasterol, brassicasterol and ergosterol respectively) similar to the estimated K(m) for desmosterol (26.3 microM). The sterol 5,22-cholestedien-3beta-ol, an unusual desmosterol isomer that lacks the alkyl groups characteristic of phytosterols, acted as a much stronger inhibitor of (24)-reductase (K(i)=3.34 microM). The usually low intracellular concentrations of the physiological substrates of (24)-reductase explains the strong inhibition of cholesterol biosynthesis that these compounds exert in cells. Given that inhibition of sterol (24)-reductase was achieved at physiologically relevant concentrations, it may represent an additional mechanism for the cholesterol-lowering action of phytosterols, and opens up the possibility of using certain (22)-unsaturated sterols as effective hypocholesterolaemic agents.

Animals↗
PubMed2006

Sterol intermediates from cholesterol biosynthetic pathway as liver X receptor ligands.

The liver X receptors (LXRs) are ligand-activated transcription factors that regulate the expression of genes controlling lipid metabolism. Oxysterols bind LXRs with high affinity in vitro and are implicated as ligands for the receptor. We showed previously that accumulation of selected dietary sterols, in particular stigmasterol, is associated with activation of LXR in vivo. In the course of the defining of structural features of stigmasterol that confer LXR agonist activity, we determined that the presence of an unsaturated bond in the side chain of the sterol was necessary and sufficient for activity, with the C-24 unsaturated cholesterol precursor sterols desmosterol and zymosterol exerting the largest effects. Desmosterol failed to increase expression of the LXR target gene, ABCA1, in LXRalpha/beta-deficient mouse fibroblasts, but was fully active in cells lacking cholesterol 24-, 25-, and 27-hydroxylase; thus, the effect of desmosterol was LXR-dependent and did not require conversion to a side chain oxysterol. Desmosterol bound to purified LXRalpha and LXRbeta in vitro and supported the recruitment of steroid receptor coactivator 1. Desmosterol also inhibited processing of the sterol response element-binding protein-2 and reduced expression of hydroxymethylglutaryl-CoA reductase. These observations are consistent with specific intermediates in the cholesterol biosynthetic pathway regulating lipid homeostasis through both the LXR and sterol response element-binding protein pathways.

ATP Binding Cassette Transporter 1↗
PubMed1999

Phytoestrogen intake and prostate cancer: a case-control study using a new database.

In the last several years, attention has been focused on comparing the Western diet, which is rich in fat, protein, and refined carbohydrates, with the Asian diet, which is rich in phytoestrogens, as a possible explanation for the contrasting rates of clinically relevant prostate cancer. Phytoestrogens, plant-derived nutrients, include several isoflavones, flavonoids, lignans, phytosterols, and coumestans, some of which have been postulated as having anticarcinogenic properties. Using a new database, we examined the role of phytoestrogen intake and prostate cancer risk in 83 Caucasian cases and 107 controls. Controls reported consuming higher amounts of foods containing genistein, daidzein, and coumestrol and lower amounts of foods containing campesterol and stigmasterol. Multivariate analysis, after adjustment for age, family history of prostate cancer, alcohol consumption, and total calorie intake, showed an inverse association between coumestrol (p = 0.03) and daidzein (p = 0.07) and prostate cancer risk. Genistein, the most studied phytoestrogen, showed a slight protective effect (p = 0.26). However, a positive association was found between campesterol (p = 0.08) and stigmasterol (p = 0.03) and risk of prostate cancer. These results are suggestive of a possible relationship between phytoestrogen intake and prostate cancer risk. Larger comprehensive studies are needed to further refine the role of phytoestrogen intake in prostate cancer risk.

Anticarcinogenic Agents↗
PubMed2001

Plant sterol intakes and colorectal cancer risk in the Netherlands Cohort Study on Diet and Cancer.

BACKGROUND: Plant sterols in vegetable foods might prevent colorectal cancer. OBJECTIVE: The objective was to study plant sterol intakes in relation to colorectal cancer risk in an epidemiologic study. DESIGN: The study was performed within the framework of the Netherlands Cohort Study on Diet and Cancer in 120852 subjects who completed a baseline questionnaire in 1986. After 6.3 y of follow-up, 620 colon and 344 rectal cancer cases were detected. A case-cohort approach was used to calculate confounder-adjusted rate ratios (RRs) and their 95% CIs for quintiles of plant sterol intake. RESULTS: The total mean (+/-SD) intake of campesterol, stigmasterol, beta-sitosterol, campestanol, and beta-sitostanol was 285 +/- 97 mg/d. Major contributors to plant sterol intake were bread (38%), vegetable fats (26%), and fruit and vegetables (21%). For men, there was no clear association between intake of any of the plant sterols and colon cancer risk when age, smoking, alcohol use, family history of colorectal cancer, education level, and cholecystectomy were controlled for. Adjustment for energy did not alter the result. For rectal cancer, adjustment for energy resulted in positive associations between risk and campesterol and stigmasterol intakes. For women, there was no clear association between intake of any of the plant sterols and colorectal cancer risk. CONCLUSION: A high dietary intake of plant sterols was not associated with a lower risk of colon and rectal cancers in the Netherlands Cohort Study on Diet and Cancer.

Aged↗
PubMed1997

[Chemical constituents of Begonia evansiana Andr].

Six compounds were isolated from Begonia evansiana. By means of TLC, mp, 1H and 13CNMR, they were idenified as beta-sitosterol, beta-amyrin, daucosterol, stigmasterol, stigmasterol-3-O-beta-D-glucopyranoside and 4', 5', 7-trihydroxy-flavone-6-O-beta-D-glucopyranoside. All the compounds were isolated from this plant for the first time.

Drugs, Chinese Herbal↗
PubMed2005

[Study on sterols and triterpenes from the stems of Akebia quinata].

The ethanol extract from Akebia quinata was seperated by dichloromethane, n-butanol in sequence. Six compounds were isolated and identified as beta-sitosterol (I), delta(5,22) stigmasterol (II), oleanolic acid (III), hederagenin (IV), daucosterol (V), delta(5,22) stigmasterol-3-O-beta-D-glycopyranoside (VI). Compound VI was isolated from Akebia plants for the first time.

Glucosides↗
PubMed1997

Effect of micellar beta-sitosterol on cholesterol metabolism in CaCo-2 cells.

CaCo-2 cells were used to address the effect of the plant sterol, beta-sitosterol, on cholesterol trafficking, cholesterol metabolism, and apoB secretion. Compared to cells incubated with micelles (5 mM taurocholate and 250 microM oleic acid) containing cholesterol, which caused an increase in the influx of plasma membrane cholesterol to the endoplasmic reticulum and increased the secretion of cholesteryl esters derived from the plasma membrane, beta-sitosterol did not alter cholesterol trafficking or cholesteryl ester secretion. Including beta-sitosterol in the micelle together with cholesterol attenuated the influx of plasma membrane cholesterol and prevented the secretion of cholesteryl esters derived from the plasma membrane. Stigmasterol and campesterol had effects similar to beta-sitosterol, although campesterol did not promote a modest influx of plasma membrane cholesterol. Including beta-sitosterol in the micelle with cholesterol decreased the uptake of cholesterol. Compared to cholesterol, 60% less beta-sitosterol was taken up by CaCo-2 cells. No observable esterification of beta-sitosterol was appreciated and the transport of the plant sterol to the basolateral medium was negligible. Cholesterol synthesis and HMG-CoA reductase activities were decreased in cells incubated with beta-sitosterol. This was associated with a decrease in reductase mass and mRNA levels. Cholesteryl ester synthesis and ACAT activities were unaltered by beta-sitosterol. Both stigmasterol and campesterol decreased reductase activity, but only campesterol increased ACAT activity. beta-sitosterol did not affect the secretion of apoB mass. The results suggest that beta-sitosterol does not promote cholesterol trafficking from the plasma membrane to the endoplasmic reticulum. beta-sitosterol interferes with the uptake of micellar cholesterol causing less plasma membrane cholesterol to influx and less cholesteryl ester to be secreted. Despite its lack of effect on cholesterol trafficking, beta-sitosterol decreases cholesterol synthesis at the level of HMG-CoA reductase gene expression.

Caco-2 Cells↗
PubMed1977

Gas-liquid chromatographic determination of cholesterol and other sterols in foods.

A gas-liquid chromatographic (GLC) method, using the butyryl esters of sterols, has been developed for the measurement of cholesterol, stigmasterol, sitosterol, and campesterol in foods. An immobile phase of 1% SE-30 coated on 100-120 mesh Gas-Chrom Q packed in a 6 inch X 4 mm id glass column operated at 255 degrees C was the most satisfactory of 7 column packings evaluated. Extraction with chloroform-methanol gave 98.7% recovery with a coefficient of variation of 1.8% for cholesterol added to a variety of foods. When cholesteryl palmitate was added to vegetable oil and the butyryl derivative was prepared, followed by GLC analysis, the recovery was 99.3% with a coefficient of variation of 0.9%. Amounts as low as 1 mg/100 g food can be detected with a precision of 2.5%. The results of the analysis of a variety of foods for cholesterol, campesterol, sitosterol, and stigmasterol are given.

Cholesterol↗
PubMed1977

Study on the chemical nature of sterols contained in Bulgarian sunflower oil.

The free sterols, the sterol esters and the sterol glycosides of the crude sunflower oil as well as those of the technical lecithin, the pitch and the deodorizer distillate of the latter oil were isolated by preparative TLC. The nature of sterols contained in the isolated sterol derivatives was elucidated by GLC and combinded GLC-MS. Major sterols of all examined sterol fractions are sitosterol, campesterol and stigmasterol, the amount of sitosterol being prevalent. Unknown sterol with a molecular weight of 428 is present in sterols of the crude oil and the deodorizer distillate. Sterols of the deodorizer distillate contain an unknown sterol with a molecular weight of 430. Stigmasterol is present in the sterol fraction of the deodorizer distillate in high amounts. It was established that delta7-sterols of the crude oil occur only in esterified form. The hydrolysis of the sterol derivatives in acid medium leads to dehydration products known as steroid dienes and disteroid ethers. Hydrolysis without dehydration was achieved by enzyme preparations. Some sterols of the crude oil were esterified with the same higher fatty acids contained in the glycerides of the sunflower oil.

Chromatography, Gas↗
PubMed1977

Sterol composition of Bulgarian soya and corn oils.

The free sterols, the sterol esters and the sterol glycosides of the raw soya and corn oils as well as those of the technical lecithin and the deodorizer distillated of the latter oils were isolated by preparative TLC. The composition of each of the isolated sterol derivatives was determined by GLC and MS. Sitosterol, campesterol, stigmasterol and an unknown sterol with a molecular weight of 428 are contained in almost all of the examined fractions of the soya oil and its refinement byproducts. Dehydrocampesterol is present in the free sterols of the raw soya oil and the soya lecithin. Stigmasterol is contained in the soya deodorizer distillate in high amounts. It was established that cholesterol was present in the sterol esters of the raw soya oil high amounts. Delta7-stigmastenol occurs only in the sterol esters of the latter oil. Sitosterol, campesterol and stimgasterol are the main components of all sterol fractions of the corn oil and its refinement products. Dehydrocampesterol and unknown sterols with molecular weights of 428 are present in the free sterols of the raw corn oil. Some sterol glycosides of the soya and corn lecithin are esterified with the same major fatty acid components of the glycerides, palmitic acid being the main one. The fatty acid compositon of sterol esters of the raw soya and corn oil roughly corresponds to the fatty acid composition of oils.

Chromatography, Gas↗
PubMed1988

Studies on zoapatle. VIII: Novel cytotoxic sesquiterpene lactones from Montanoa tomentosa ssp. microcephala.

Investigation of the leaves of Montanoa tomentosa Cerv. ssp. microcephala (Sch.-Bip.) Funk (Compositae) resulted in the isolation of three novel guaianolide sesquiterpenes, montacephalin (1), tomencephalin (2), and 5-hydroxytomencephalin (3), which were shown to be cytotoxic (P-388). The structures of these sesquiterpenes were elucidated through analysis of their spectroscopic characteristics, and complete proton and carbon-13 assignments were made for the new compounds. Also isolated were the known terpenes, beta-amyrin, beta-amyrin acetate, stigmasterol, stigmasterol-3 beta-D-glucoside, (-)-kaur-16-en-19-oic acid, and monoginoic acid.

Animals↗
PubMed1979

In vitro esterification of plant sterols by the esterifying enzyme of the small intestine of rat.

The in vitro esterification of plant sterols, beta-sitosterol, campesterol and stigmasterol, by the esterifying enzyme of the small intestine of rat was studied in the presence of saturated and unsaturated fatty acids. Campesterol esterification was highest, followed by sitosterol and stigmasterol irrespective of the type of fatty acid. Both campesterol and sitosterol esterification was greater with unsaturated fatty acids than with saturated fatty acids.

Animals↗
PubMed1981

Composition of cocoa shell fat as related to cocoa butter.

The physical and chemical constants of cocoa shell fat (a by-product resulted during the production of cocoa butter at chocolate factories) were almost identical with those of cocoa butter obtained from the same cocoa beans except for their high acid value. Shell fat contained more amount of phospholipid content (as cephalin) than cocoa butter. The lipid classes were almost the same in cocoa butter and shell fat, however, the latter contained an unidentified constituent which was not found in cocoa butter. The fatty acids were determined quantitatively by GLC, and the results showed that the predominant acids in cocoa butter were palmitic, and oleic. Less amounts of capric, myristic, palmitoleic and linoleic were found in cocoa butter, whereas more amounts of these acids were found in shell fat. Cocoa butter gave higher values of stearic and myristic acids than those of shell fat. Seventeen compounds were detected by GLC in the unsaponifiable matter of both cocoa butter and shell fat from which eight were identified as C30 hydrocarbon, C32 hydrocarbon, squalene, alpha-tocopherol, cholesterol, campsterol, stigmasterol and beta-sitosterol in the two samples. The sterols were determined quantitatively, and it was found that the predominant sterol in cocoa butter and shell fat was B-sitosterol. Cocoa butter contained higher values of stigmasterol than that of shell fat, which contained increasing values of campsterol, low values of cholesterol were found in both samples. Stability of cocoa butter and shell fat towards oxidative rancidity at 100 degrees C was the same (10.5 hrs).

Cacao↗
PubMed1987

Bioconversion and binding of sterols by thermophilic moulds.

None of the fourteen thermophilic moulds was able to break down the aliphatic side chain of sterols, viz. cholesterol, lanosterol, sitosterol, and stigmasterol so as to yield 4-androstene-3,17-dione, 1,4-androstadiene-3,17-dione and progesterone. In Acremonium alabamensis and Talaromyces emersonii, cholestenone was detected as a product of fermentation of cholesterol whereas the former yielded stigmastadienone from stigmasterol and sitosterol. Lanosterol appeared to be resistant to fungal bioconversion. All the thermophilic moulds exhibited avidity for binding sterols to the mycelium, but the ability to bind sterol seemed to depend upon the nature of the organism and the sterol.

Fungi↗
PubMed2005

Changes in the composition of phospholipid fatty acids and sterols of maize root in response to monoterpenes.

Terpenes are thought to be important in plant plant interactions because of their phytotoxic action on seed germination and growth. Herein, the effects of five volatile monoterpenes on root sterols and phospholipid fatty acid (PLFA) composition have been studied during maize seedling germination. The investigated monoterpenes (camphor, 1-8 cineole, geraniol, menthol, and thymol) were applied at their respective IC80 (concentration causing 80% inhibition). They quantitatively affected free sterols and PLFA composition, thus producing an increase in the percentage of unsaturated PLFAs, stigmasterol of the free sterol fraction, and saturated steryl ester fatty acids. Alcoholic and nonalcoholic monoterpenes appeared to have different modes of action. The former affected unsaturated fatty acid and stigmasterol to a greater extent, and accordingly they could interfere in seedling growth by changes in the membrane lipids.

Cell Membrane↗