Estrogenic properties of six compounds derived from Eucommia ulmoides Oliv. and their differing biological activity through estrogen receptors α and ß.

Eucommia ulmoides Oliv. (Du-zhong), a well known Chinese herbal medicine, has been increasingly used as a nutraceutical supplement. The aim of this study was to identify and characterise novel estrogenic compounds in E. ulmoides. We report that six compounds, namely pinoresinol 4'-O-ß-d-glucopyranoside, pinoresinol di-O-ß-d-glucopyranoside, aucubin, wogonin, baicalein, and α-O-ß-d-glucopyranosyl-4,2',4'-trihydroxydihydrochalcone, activated estrogen receptor (ER)-dependent transcription of both transfected and endogenous target genes. Strikingly, these compounds exhibited significant difference in ER subtype (α vs. ß) selectivity. Cell proliferation and ER subcellular localisation analyses also demonstrated that they mediated the estrogenic effects by the genomic action of ERα. This study suggests that E. ulmoides is a rich source of new selective estrogen receptor modulators and evaluations of its health benefit and safety as a food additive should take into account the diverse phytoestrogen activities of the individual components.

Non-pharmacological control of plasma cholesterol levels.

The importance of non-pharmacological control of plasma cholesterol levels in the population is increasing, along with the number of subjects whose plasma lipid levels are non-optimal, or frankly elevated, according to international guidelines. In this context, a panel of experts, organized and coordinated by the Nutrition Foundation of Italy, has evaluated the nutritional and lifestyle interventions to be adopted in the control of plasma cholesterol levels (and specifically of LDL cholesterol levels). This Consensus document summarizes the view of the panel on this topic, with the aim to provide an updated support to clinicians and other health professionals involved in cardiovascular prevention.

Serum from hypercholesterolemic patients treated with atorvastatin or simvastatin inhibits cultured human smooth muscle cell proliferation.

We evaluated the pharmacological activity of whole-blood serum from atorvastatin- vs. simvastatin- (both 40 mg/day) treated hypercholesterolemic patients (n=10) on cultured smooth muscle cell (SMC) proliferation and cholesterol biosynthesis, as related to lipid-lowering effect. Patients received either single or 2-weeks repeated doses of both simvastatin and atorvastatin, following a randomised, double-blind, cross-over design. Blood samples were collected before drug administration and at the scheduled intervals after administration, and the obtained serum was separated by centrifugation, sterilized and frozen until assayed. Cultured SMC were supplemented with medium plus 15% of separate serum sampled from the patients, and grown for 72 h. Proliferation was assayed by a Coulter Counter, while cholesterol biosynthesis was measured by the incorporation of 14C-acetate into cholesterol, under the same experimental conditions. Atorvastatin was more active vs. simvastatin in reducing total- (-28.3% vs. -20.7%; p=0.045) and LDL-cholesterol (-39.8% vs. -30.1%; p=0.011) after a 2-weeks regimen. Serum from atorvastatin-treated patients inhibited SMC proliferation vs.t=0 after both single (AUC -21.6%) and repeated (AUC -26.9%) doses, while serum from simvastatin-treated patients inhibited SMC proliferation only after repeated doses (AUC -24.5%). Interestingly, in the same experimental conditions, the serum concentrations of both statins (and of their active metabolites) were constantly below the detection limits, as shown from the lack of inhibition of cholesterol biosynthesis. The absence of any significant association between the lipid-lowering effects and the inhibition of SMC proliferation, together with no detectable active statin in the serum, suggests that these effects are elicited through independent mechanisms.

The emerging link between nutrition, inflammation and atherosclerosis.

A number of dietary components modulate the inflammatory response in humans, thereby affecting cardiovascular risk. As basic research provides a better understanding of the molecular mechanisms of vascular function regulation by nutrients, clinical investigation and outcome studies demonstrate the relevance of dietary factors to the prevention and treatment of vascular disease. Benefits of dietary interventions may be attributable to weight loss or to more specialized mechanisms in which inflammation is targeted directly. Available evidence indicates that dietary intervention should be an integral part of therapeutic approaches for treating conditions such as the metabolic syndrome and, ultimately, for the prevention of cardiovascular disease.

Efficacy and safety of plant stanols and sterols in the management of blood cholesterol levels.

Foods with plant stanol or sterol esters lower serum cholesterol levels. We summarize the deliberations of 32 experts on the efficacy and safety of sterols and stanols. A meta-analysis of 41 trials showed that intake of 2 g/d of stanols or sterols reduced low-density lipoprotein (LDL) by 10%; higher intakes added little. Efficacy is similar for sterols and stanols, but the food form may substantially affect LDL reduction. Effects are additive with diet or drug interventions: eating foods low in saturated fat and cholesterol and high in stanols or sterols can reduce LDL by 20%; adding sterols or stanols to statin medication is more effective than doubling the statin dose. A meta-analysis of 10 to 15 trials per vitamin showed that plasma levels of vitamins A and D are not affected by stanols or sterols. Alpha carotene, lycopene, and vitamin E levels remained stable relative to their carrier molecule, LDL. Beta carotene levels declined, but adverse health outcomes were not expected. Sterol-enriched foods increased plasma sterol levels, and workshop participants discussed whether this would increase risk, in view of the marked increase of atherosclerosis in patients with homozygous phytosterolemia. This risk is believed to be largely hypothetical, and any increase due to the small increase in plasma plant sterols may be more than offset by the decrease in plasma LDL. There are insufficient data to suggest that plant stanols or sterols either prevent or promote colon carcinogenesis. Safety of sterols and stanols is being monitored by follow-up of samples from the general population; however, the power of such studies to pick up infrequent increases in common diseases, if any exist, is limited. A trial with clinical outcomes probably would not answer remaining questions about infrequent adverse effects. Trials with surrogate end points such as intima-media thickness might corroborate the expected efficacy in reducing atherosclerosis. However, present evidence is sufficient to promote use of sterols and stanols for lowering LDL cholesterol levels in persons at increased risk for coronary heart disease.

Ajoene, a garlic compound, inhibits protein prenylation and arterial smooth muscle cell proliferation.

(1) Ajoene is a garlic compound with anti-platelet properties and, in addition, was shown to inhibit cholesterol biosynthesis by affecting 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase and late enzymatic steps of the mevalonate (MVA) pathway. (2) MVA constitutes the precursor not only of cholesterol, but also of a number of non-sterol isoprenoids, such as farnesyl and geranylgeranyl groups. Covalent attachment of these MVA-derived isoprenoid groups (prenylation) is a required function of several proteins that regulate cell proliferation. We investigated the effect of ajoene on rat aortic smooth muscle cell proliferation as related to protein prenylation. (3) Cell counting, DNA synthesis, and cell cycle analysis showed that ajoene (1-50 micro M) interfered with the progression of the G1 phase of the cell cycle, and inhibited rat SMC proliferation. (4) Similar to the HMG-CoA reductase inhibitor simvastatin, ajoene inhibited cholesterol biosynthesis. However, in contrast to simvastatin, the antiproliferative effect of ajoene was not prevented by the addition of MVA, farnesol (FOH), and geranylgeraniol (GGOH). Labelling of smooth muscle cell cellular proteins with [3H]-FOH and [3H]-GGOH was significantly inhibited by ajoene. (5) In vitro assays for protein farnesyltransferase (PFTase) and protein geranylgeranyltransferase type I (PGGTase-I) confirmed that ajoene inhibits protein prenylation. High performance liquid chromatography (HPLC) and mass spectrometry analyses also demonstrated that ajoene causes a covalent modification of the cysteine SH group of a peptide substrate for protein PGGTase-I. (6) Altogether, our results provide evidence that ajoene interferes with the protein prenylation reaction, an effect that may contribute to its inhibition of SMC proliferation.