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At least 19 recordsLinked to original sources
PubMed2004

beta-Sitosterol, beta-Sitosterol Glucoside, and a Mixture of beta-Sitosterol and beta-Sitosterol Glucoside Modulate the Growth of Estrogen-Responsive Breast Cancer Cells In Vitro and in Ovariectomized Athymic Mice.

We hypothesized that the phytosterols beta-sitosterol (BSS), beta-sitosterol glucoside (BSSG), and Moducare (MC; BSS:BSSG = 99:1) could modulate the growth of estrogen-dependent human breast cancer cells in vitro and in vivo. The present study evaluated the estrogenic and antiestrogenic effects of BSS, BSSG, and MC (0.001 to 150 micromol/L) on the proliferation of Michigan Cancer Foundation 7 (MCF-7) cells in vitro. Both BSS (>1 micromol/L) and MC (>50 micromol/L) increased MCF-7 cell proliferation. Treatment with 150 micro mol/L of BSS and MC increased cell growth by 2.4 and 1.5 times, respectively, compared to the negative control (NC) group. However, BSSG had no effect at the concentrations tested. The effects of dietary BSS, BSSG, and MC on the growth of MCF-7 cells implanted in ovariectomized athymic mice were also evaluated. Estrogenic effects of the phytosterols were evaluated in the NC, BSS, BSSG, and MC treatment groups, and antiestrogenic effects were evaluated in the 17 beta-estradiol (E(2)), E(2) + BSS, E(2) + BSSG, and E(2) + MC treatment groups. Mice were treated with dietary BSS (9.8 g/kg AIN93G diet), BSSG (0.2 g/kg diet), or MC (10.0 g/kg diet) for 11 wk. Dietary BSS, BSSG, and MC did not stimulate MCF-7 tumor growth. However, dietary BSS, BSSG, and MC reduced E(2)-induced MCF-7 tumor growth by 38.9% (P < 0.05), 31.6% (P = 0.08), and 42.13% (P < 0.05), respectively. The dietary phytosterols lowered serum E(2) levels by 35.1, 30.2, and 36.5% in the E(2) + BSS, E(2) + BSSG, and E(2) + MC groups, respectively (P < 0.05), compared to that of the E(2) treatment group. Estrogen-responsive pS2 mRNA expression in tumors did not differ among groups, but expression of the antiapoptotic marker B-cell lymphoma/leukemia-2 (bcl-2) in tumors from the E(2) + MC group was downregulated, compared to that of the E(2) treatment group. In summary, BSS and MC stimulated MCF-7 cell growth in vitro. Although BSSG comprises only 1% of MC, BSSG made MC less estrogenic than BSS alone in vitro. However, dietary BSS and MC protected against E(2)-stimulated MCF-7 tumor growth and lowered circulating E(2) levels.

Animals↗
PubMedDate not supplied

Sluggish sitosterol turnover and hepatic failure to excrete sitosterol into bile cause expansion of body pool of sitosterol in patients with sitosterolemia and xanthomatosis.

Sitosterolemia and xanthomatosis are characterized by the development of tendon and tuberous xanthomas at an early age and premature atherosclerosis despite normal plasma cholesterol concentrations. The reason(s) for the xanthoma formation and premature atherosclerosis are not clearly understood. The accumulation of sitosterol in the tissues of these patients could be due to increased uptake of low density lipoprotein (LDL) via LDL receptors because of an expanded sitosterol pool caused by sluggish turnover and decreased excretion of sitosterol into bile and feces coupled with the hyperabsorption of sitosterol. We have studied sitosterol and cholesterol turnovers, the biliary and fecal excretion of neutral and acidic steroids, and the response of plasma sterol (sitosterol and cholesterol) levels to either a sterol-free formula or low plant sterol diet in three patients. The average half-life of the first exponential (tA1/2) for sitosterol was 9.2 +/- 3.3 (mean +/- SD) days, which was more than twice that in normal humans. The second exponential (tB1/2) was 156 +/- 108 days, which was nearly 10 times longer than that for normal humans. The average cholesterol production rate in pool A was 0.87 g/day, which is about 40% of that in normal humans. Cholesterol synthesis measured by the sterol balance technique was also found to be about 70% lower than that for normal humans. In two patients fed a sterol-free formula diet, by 25 days their plasma sitosterol and cholesterol levels had decreased by 42% and 36%, respectively. However, in one patient plasma sitosterol and cholesterol concentrations remained unchanged while on the low plant sterol-mixed food diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2005

Synthesis, isolation and characterisation of beta-sitosterol and beta-sitosterol oxide derivatives.

Beta-sitosterol is the most prevalent plant cholesterol derivative (phytosterol) and can undergo similar oxidation to cholesterol, leading to beta-sitosterol oxides. The biological impact of phytosterol oxides has only been evaluated in a phytosterol blend (usually of beta-sitosterol, campesterol, stigmasterol and dihydrobrassicasterol). The lack of pure phytosterols, including beta-sitosterol, hinders the collection of significant toxicity data on the individual beta-sitosterol oxides. An efficient synthetic route to multi-gram quantities of pure beta-sitosterol is described here, together with the first syntheses and characterisation of pure beta-sitosterol oxides.

Gas Chromatography-Mass Spectrometry↗
PubMed1995

Randomised, placebo-controlled, double-blind clinical trial of beta-sitosterol in patients with benign prostatic hyperplasia. Beta-sitosterol Study Group.

Medical treatments have become available for benign hypertrophy of the prostate, including alpha-receptor blocking agents and 5-alpha-reductase inhibitors. Drugs derived from plants, for which no precise mechanism of action has been described, are widely used for this purpose in Europe. In a randomised, double-blind, placebo-controlled multicentre study, 200 patients (recruited between April and October 1993) with symptomatic benign prostatic hyperplasia were treated with either 20 mg beta-sitosterol (which contains a mixture of phytosterols) three times per day or placebo. Primary end-point was a difference of modified Boyarsky score between treatment groups after 6 months; secondary end-points were changes in International Prostate Symptom Score (IPSS), urine flow, and prostate volume. Modified Boyarsky score decreased significantly with a mean of -6.7 (SD 4.0) points in the beta-sitosterol-treated group versus -2.1 (3.2) points in the placebo group p < 0.01. There was a decrease in IPSS (-7.4 [3.8] points in the beta-sitosterol-treated group vs -2.1 [3.8] points in the placebo group) and changes in urine flow parameters: beta-sitosterol treatment resulted in increasing peak flow (15.2 [5.7] mL/s from 9.9 [2.5] mL/s), and decrease of mean residual urinary volume (30.4 [39.9] mL from 65.8 [20.8] mL). These parameters did not change in the placebo group (p < 0.01). No relevant reduction of prostatic volume was observed in either group. Significant improvement in symptoms and urinary flow parameters show the effectiveness of beta-sitosterol in the treatment of benign prostatic hyperplasia.

Aged↗
PubMed2000

A comparative study of the effects of cholesterol, beta-sitosterol, beta-sitosterol glucoside, dehydroepiandrosterone sulphate and melatonin on in vitro lipid peroxidation.

The free radical scavenging abilities of the structurally related steroids beta-sitosterol, beta-sitosterol glucoside (plant sterols and sterolins), cholesterol, and dehydroepiandrosterone sulphate (DHEAS) were compared with melatonin (an efficient free radical scavenger) in an in vitro system which measures lipid peroxidation of platelet membranes in the presence of iron (Fe2+). Lipid peroxidation is a process whereby cellular membranes are damaged due to the oxidative deterioration of polyunsaturated lipids, which may lead to cell death and disease in living organisms. Substances such as vitamin E protect cellular membranes against oxidative damage due to their chemical structures. The steroids cholesterol, beta-sitosterol, beta-sitosterol glucoside and dehydroepiandrosterone (DHEA) are structurally related to each other. During aging, serum concentrations of DHEA, DHEAS and melatonin decrease, while the concentration of cholesterol tends to increase. The aim of the present study was to compare the role these substances play in lipid peroxidation over a wide concentration range. At concentrations lower than the free iron in the reaction mixture, all the steroids investigated decreased lipid peroxidation. At higher concentrations, cholesterol and beta-sitosterol increased lipid peroxidation, while DHEAS and melatonin continued to decrease lipid peroxidation.

Aging↗
PubMedDate not supplied

Antihyperglycemic and insulin-releasing effects of beta-sitosterol 3-beta-D-glucoside and its aglycone, beta-sitosterol.

The effect of beta-sitosterol 3-beta-glucoside (antihyperglycemic principle isolated from the aerial part of Centaurea seridis L. var. maritima Lge.) and its aglycone on plasma insulin and glucose levels in normo- and hyperglycemic rats was investigated. The results indicate that oral treatment with the glycoside or with the beta-sitosterol increased the fasting plasma insulin levels. There was a corresponding decrease in fasting glycemia when beta-sitosterol was administered orally. In addition, these compounds improved the oral glucose tolerance test with an increase in glucose-induced insulin secretion. But when these products were administered orally, the effect of glycoside, either on fasting insulinemia or on glucose-induced insulin secretion, lasted longer than that of aglycone. The present study compared these effects with those of glibenclamide. It can be assumed that beta-sitosterol 3-beta-D-glucoside acts by increasing circulating insulin levels, and that this effect is due to their aglycone: beta-sitosterol.

Animals↗
PubMed2005

Gram-scale chromatographic purification of beta-sitosterol. Synthesis and characterization of beta-sitosterol oxides.

An effective purification method for beta-sitosterol was developed starting from a commercial source of a phytosterol mixture using preparative adsorption column chromatography. beta-Sitosterol (> or = 95% purity) was obtained on a gram-scale. Thus, the synthesis of six beta-sitosterol oxides, including 7alpha-hydroxy, 7beta-hydroxy, 5,6alpha-epoxy, 5,6beta-epoxy, 7-keto, and 5alpha,6beta-dihydroxysitosterol, were successfully carried out. The spectral characteristics of all the synthetic intermediates and target compounds (approximately 95% purity) were well-documented.

Chromatography↗
PubMed1996

beta-Sitosterol and beta-sitosterol glucoside stimulate human peripheral blood lymphocyte proliferation: implications for their use as an immunomodulatory vitamin combination.

The phytosterols, beta-sitosterol (BSS), and its glucoside (BSSG) enhance the in vitro proliferative response of T-cells stimulated by sub-optimal concentrations of phytohaemagglutinin (PHA) several fold at extremely low concentrations (femtogram level). A 100:1 (mass:mass) ratio of BSS:BSSG (termed essential sterolin formulation, ESF) showed higher stimulation than the individual sterols at the same concentration. In vivo activity of ESF was also demonstrated when volunteers ingested ESF for 4 weeks. Proliferation of their T-cells, stimulated maximally with PHA, was significantly enhanced (20-920%) when compared to baseline values. In vitro, ESF (1 microgram.ml) was able to significantly enhance the expression of CD25 and HLA-Dr activation antigens on T-cells and increased the secretion, into the medium, of IL-2 and gamma interferon. NK-cell activity was also increased by BSS and BSSG alone, but with EST a higher activity was always found at different effector:target ratios (100:1 12:1).

Adjuvants, Immunologic↗
PubMed1999

The effects of B-sitosterol (BSS) and B-sitosterol glucoside (BSSG) mixture on selected immune parameters of marathon runners: inhibition of post marathon immune suppression and inflammation.

A pilot study was undertaken to investigate the effects of the intake of capsules containing the plant sterols and sterolins (BSS:BSSG mixture) on selected immune parameters of volunteers participating in an ultra-marathon in Cape Town, South Africa. Those runners having received active capsules (n=9) showed less neutrophilia, lymphopenia and leukocytosis when compared to their counterparts having received placebo capsules (n=8): the placebo treated individuals showed significant increases in their total white blood cell numbers as well as in their neutrophils (p=0.03 and 0.03 respectively). Furthermore, statistically significant increases within lymphocyte subsets were observed in the runners having received the active capsules: CD3+ cells increased (p=0.02) as did CD4+ cells (p=0.03). In parallel, the BSS:BSSG capsules decreased the plasma level of IL6 in the runners using the active capsules (p=0.08) and significantly decreased the cortisol: DHEAs ratio (p=0.03), suggesting that these volunteers had less of an inflammatory response and were less immune suppressed during the post-marathon recovery period. These findings justify further investigations into the use of the phytosterols to prevent the subtle immunosuppression associated with excessive physical stress.

Adult↗
PubMed1983

beta-sitosterol: esterification by intestinal acylcoenzyme A: cholesterol acyltransferase (ACAT) and its effect on cholesterol esterification.

Rabbits were fed either 10% coconut oil, 10% coconut oil and 1% beta-sitosterol, 10% coconut oil and 1% cholesterol, or 10% coconut oil and 1% beta-sitosterol plus 1% cholesterol for 4 weeks. Microsomal membranes from intestines of animals fed the 1% beta-sitosterol diet had 48% less cholesterol and were enriched twofold in beta-sitosterol compared to membranes from animals fed the coconut oil diet alone. Acylcoenzyme A:cholesterol acyltransferase (ACAT) activity in jejunum and ileum was decreased significantly in animals fed the plant sterol alone. In membranes from animals fed 1% beta-sitosterol and 1% cholesterol, beta-sitosterol content increased 50% whereas cholesterol was modestly decreased compared to their controls fed only cholesterol. Intestinal ACAT was unchanged in the animals fed both sterols when compared to their controls. beta-Sitosterol esterification was determined by incubating intestinal microsomal membranes with either [(14)C]beta-sitosterol-albumin emulsion or [(14)C]beta-sitosterol:dipalmitoyl phosphatidylcholine (DPPC) liposomes to radiolabel the endogenous sterol pool. Oleoyl-CoA was then added. The CoA-dependent esterification rate of beta-sitosterol was very slow compared to that of cholesterol using both techniques. An increased amount of endogenous microsomal beta-sitosterol, which occurs in animals fed 1% beta-sitosterol, did not interfere with the stimulation of ACAT activity secondary to cholesterol enrichment of the membranes. Enriching microsomal membranes three- to five-fold with beta-sitosterol did not affect ACAT activity. Freshly isolated intestinal cells were incubated for 1 hour with [(3)H]oleic acid and beta-sitosterol:DPPC or 25-hydroxycholesterol:DPPC. Incorporation of oleic acid into cholesteryl esters did not change in the presence of beta-sitosterol but increased fourfold after the addition of 25-hydroxycholesterol. We conclude that the CoA-dependent esterification rate of cholesterol is at least 60 times greater than that of beta-sitosterol. Membrane beta-sitosterol does not interfere with nor compete with cholesterol esterification. Inadequate esterification of this plant sterol may play a role in the poor absorption of beta-sitosterol by the gut.-Field, F. J., and S. N. Mathur. beta-Sitosterol: esterification by intestinal acylcoenzyme A:cholesterol acyltransferase (ACAT) and its effect on cholesterol esterification.

Acyl Coenzyme A↗
PubMed1997

Comparative effect of dietary sitosterol on plasma sterols and cholesterol and bile acid synthesis in a sitosterolemic homozygote and heterozygote subject.

OBJECTIVE: Sitosterolemia is a genetic disorder characterized by an increased plasma plant sterol concentration due to enhanced sterol absorption coupled with reduced steroid excretion. The purpose of the present investigation was two-fold; first to assess the effects of a "basal" low sitosterol metabolic diet on plasma sterols and sterol balance, and, secondly, to quantify the relative influence of graduated increase in dietary sitosterol intake on a metabolic diet in a sitosterolemic homozygote, obligate heterozygote, and controls. METHODS: Patients were studied under strict metabolic conditions and fed a "basal" 30% fat, low-sitosterol (33 mg per 2000 kcal) diet. The level of dietary sitosterol was increased by addition of oils and resulted in final dietary sitosterol intakes of 1.8 mg/kg, 2.6 mg/kg and 3.5 mg/kg/day intakes of dietary sitosterol in the homozygote. These sitosterol dosages were selected based on sitosterol intakes equivalent to 2.6 mg/kg/day in the average American diet. Plasma cholesterol, sitosterol, and apolipoprotein A were measured, and stool collections assayed for sterol balance. RESULTS: Fecal sterol excretion and cholesterol synthesis were depressed markedly by 50% in the homozygote compared to the heterozygous parent, whereas plasma sitosterol levels were increased over 50-fold. When the sitosterol content of the diet was increased three-fold and dietary cholesterol was maintained in the homozygous and hypercholesterolemic control, plasma levels did not increase in the homozygote. Plasma cholesterol and sitosterol levels were unaffected in the hypercholesterolemic control. CONCLUSIONS: Plasma sterol levels remained elevated with the dietary sitosterol changes in the sitosterolemic homozygote. These findings were associated with a low fecal sterol excretion rate and depressed endogenous cholesterol synthesis. In this sitosterolemic patient, a very low sitosterol diet to curtail sterol input was of minimal therapeutic benefit. These results have important implications regarding the selection of therapy for this patient under these experimental conditions, but cannot be generalized to other homozygotes.

Adolescent↗