Consumption of both low and high (-)-epicatechin apple puree attenuates platelet reactivity and increases plasma concentrations of nitric oxide metabolites: a randomized controlled trial.

We hypothesised that consumption of flavanol-containing apple puree would modulate platelet activity and increase nitric oxide metabolite status, and that high flavanol apple puree would exert a greater effect than low flavanol apple puree. 25 subjects consumed 230 g of apple puree containing 25 and 100mg epicatechin (low and high flavanol apple puree, respectively) and aspirin (75 mg) in random order. Measurements were made at baseline, acutely after treatment (2, 6 and 24 h), and after 14 d of treatment. Low flavanol apple puree significantly attenuated ADP and epinephrine-induced integrin-ß3 expression 2 h and 6 h after consumption and ADP and epinephrine-induced P-selectin expression within 2h of consumption. High flavanol apple puree attenuated epinephrine and ADP-induced integrin-ß3 expression after 2 and 6h. ADP and epinephrine-induced integrin-ß3 expression was significantly attenuated 2, 6 and 24 h after consumption of aspirin, whilst 14 d aspirin consumption attenuated collagen-induced P-selectin expression only. The plasma total nitric oxide metabolite conc. was significantly increased 6h after consumption of both low and high flavanol apple purees. In conclusion, consumption of apple purees containing ⩾25 or 100 mg flavanols transiently attenuated ex vivo integrin-ß3 and P-selectin expression and increased plasma nitric oxide metabolite conc. in healthy subjects, but the effect was not enhanced for the high flavanol apple puree.

Some phenolic compounds increase the nitric oxide level in endothelial cells in vitro.

The vasorelaxing properties of chocolate and wine might relate to the presence of phenolic compounds. One of the potential mechanisms involved is stimulation of endothelial nitric oxide (NO) production, as NO is a major regulator of vasodilatation. This study aimed to develop an in vitro assay using the hybrid human endothelial cell line EA.hy926 to rapidly screen phenolic compounds for their NO-stimulating potential. The assay was optimized, and a selection of 33 phenolics, namely, procyanidins, monomeric flavan-3-ols, flavonols, a flavone, a flavanone, a chalcone, a stilbene, and phenolic acids, was tested for their ability to enhance endothelial NO level. Resveratrol, a well-known enhancer of NO level, was included as a positive control. Of the 33 phenolics tested, only resveratrol (285% increase in NO level), quercetin (110% increase), epicatechingallate (ECg) (85% increase), and epigallocatechingallate (EGCg) (60% increase) were significant (P

Human intestinal and lung cell lines exposed to beta-carotene show a large variation in intracellular levels of beta-carotene and its metabolites.

Although in vitro models are often used in beta-carotene research, knowledge about the uptake and metabolism of beta-carotene in cell lines is lacking. We measured by HPLC the intracellular levels of beta-carotene and its metabolites in 9 human intestinal and lung cell lines after exposure to 1 microM beta-carotene during 2, 6, 30, 54 h, and 3 weeks. In three colorectal carcinoma cell lines only low levels of beta-carotene could be detected and an apparent linear increase in intracellular beta-carotene was observed during the whole exposure period of 3 weeks. The remaining cell lines (an SV40 transformed colon cell line, a small intestinal carcinoma cell line and several lung cell lines) had medium or high intracellular beta-carotene levels. In these cell lines intracellular beta-carotene quickly increased during the first 54 h of exposure and after 3 weeks no further increase was observed, suggesting a stable level of beta-carotene after 54 h. Estimated intracellular concentrations at steady-state levels varied between 2 and 5 microM (low) or 9 and 55 microM (medium/high). Our results seem to indicate that an active uptake mechanism of beta-carotene exists in at least a subset of cell lines. Seven different beta-carotene metabolites were detected in the various cell lines (cis-carotene, retinol, three epoxy-carotenes, and two retinyl esters). Metabolite levels were the highest in cells with medium or high beta-carotene levels. Each cell line appeared to have a distinct metabolite profile. No intestinal or lung specific pattern could be found, but two epoxy-carotene metabolites were not detectable in the colon cell lines.

Lignan contents of Dutch plant foods: a database including lariciresinol, pinoresinol, secoisolariciresinol and matairesinol.

Enterolignans (enterodiol and enterolactone) can potentially reduce the risk of certain cancers and cardiovascular diseases. Enterolignans are formed by the intestinal microflora after the consumption of plant lignans. Until recently, only secoisolariciresinol and matairesinol were considered enterolignan precursors, but now several new precursors have been identified, of which lariciresinol and pinoresinol have a high degree of conversion. Quantitative data on the contents in foods of these new enterolignan precursors are not available. Thus, the aim of this study was to compile a lignan database including all four major enterolignan precursors. Liquid chromatography-tandem mass spectrometry was used to quantify lariciresinol, pinoresinol, secoisolariciresinol and matairesinol in eighty-three solid foods and twenty-six beverages commonly consumed in The Netherlands. The richest source of lignans was flaxseed (301,129 microg/100 g), which contained mainly secoisolariciresinol. Also, lignan concentrations in sesame seeds (29,331 microg/100 g, mainly pinoresinol and lariciresinol) were relatively high. For grain products, which are known to be important sources of lignan, lignan concentrations ranged from 7 to 764 microg/100 g. However, many vegetables and fruits had similar concentrations, because of the contribution of lariciresinol and pinoresinol. Brassica vegetables contained unexpectedly high levels of lignans (185-2321 microg/100 g), mainly pinoresinol and lariciresinol. Lignan levels in beverages varied from 0 (cola) to 91 microg/100 ml (red wine). Only four of the 109 foods did not contain a measurable amount of lignans, and in most cases the amount of lariciresinol and pinoresinol was larger than that of secoisolariciresinol and matairesinol. Thus, available databases largely underestimate the amount of enterolignan precursors in foods.

Optimization of a liquid chromatography-tandem mass spectrometry method for quantification of the plant lignans secoisolariciresinol, matairesinol, lariciresinol, and pinoresinol in foods.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the quantification of the four major enterolignan precursors [secoisolariciresinol, matairesinol, lariciresinol, and pinoresinol] in foods. The method consists of alkaline methanolic extraction, followed by enzymatic hydrolysis using Helix pomatia (H. pomatia) beta-glucuronidase/sulfatase. H. pomatia was selected from several enzymes based on its ability to hydrolyze isolated lignan glucosides. After ether extraction samples were analyzed and quantified against secoisolariciresinol-d8 and matairesinol-d6. The method was optimized using model products: broccoli, bread, flaxseed, and tea. The yield of methanolic extraction increased up to 81%, when it was combined with alkaline hydrolysis. Detection limits were 4-10 microg/(100 g dry weight) for solid foods and 0.2-0.4 microg/(100 mL) for beverages. Within- and between-run coefficients of variation were 6-21 and 6-33%, respectively. Recovery of lignans added to model products was satisfactory (73-123%), except for matairesinol added to bread (51-55%).