lignans and glycitein

Phytoestrogens are plant-derived polyphenols with structural and functional similarities to mammalian oestrogens. The aim of this work was to study the metabolism of phytoestrogens by children's intestinal microbiota and to compare it with previous results in adults. Faecal samples of 24 healthy children were subjected to phytoestrogen fermentation assay. Only one child produced equol, while O-desmethylangolensin was found in all. Urolithin production was detected in 14 children and enterolactone in 10. Further comparison with the metabolism of phytoestrogens by adult intestinal microbiota reflected that glycitein, dihydrogenistein, urolithins D and E, enterolactone, secoisolariciresinol and arctigenin were the most important metabolites differentiating between adult and child microbial gut metabolism. Although the child intestinal microbiota showed the ability to metabolise isoflavones, ellagitannins and lignans to a certain extent, it generally showed a reduced metabolism of phytoestrogens, with a lack of 5-hydroxy equol and enterodiol, and less urolithins and enterolactone producers.

Topics: 4-Butyrolactone; Adult; Butylene Glycols; Case-Control Studies; Child, Preschool; Coumarins; Equol; Feces; Female; Furans; Gastrointestinal Microbiome; Humans; Hydrolyzable Tannins; Infant; Isoflavones; Lignans; Male; Phytoestrogens; Polyphenols

The presence of plant lignans in 14 different soy-based health supplements is reported here for the first time together with the analysis of the isoflavone content, for which these products are commercialized. Six plant lignans, i.e., secoisolariciresinol, matairesinol, syringaresinol, lariciresinol, isolariciresinol, and pinoresinol, have been identified and quantified by gas chromatography-mass spectrometry, and a positive correlation has been found between the levels of plant lignans and the levels of isoflavones in the different products. Additional quantification of plant lignans and isoflavones in soybeans has been carried out, and results are provided to allow the comparison of the average levels in soybeans and soy-based supplements.

Topics: Dietary Supplements; Gas Chromatography-Mass Spectrometry; Genistein; Glycine max; Isoflavones; Lignans

Phytoestrogens (isoflavones and lignans) are of increasing interest due to their potential to prevent certain types of complex diseases. However, epidemiological evidence is needed on the levels of phytoestrogens and their metabolites in foods and biological fluids in relation to risk of these diseases. We report an assay for phytoestrogens which is sensitive, accurate, and uses low volumes of sample. Suitable for epidemiological studies, the assay consists of a simple sample preparation procedure and has been developed for the analysis of five isoflavones (daidzein, O-desmethylangolensin, equol, genistein, and glycitein) and two lignans (enterodiol and enterolactone), which requires only 200 microl of urine and utilizes one solid-phase extraction stage for sample preparation prior to derivatization for GC/MS analysis. Limits of detection were in the region 1.2 ng/ml (enterodiol) to 5.3ng/ml (enterolactone) and the method performed well in the UK Government's Food Standards Agency-sponsored quality assurance scheme for phytoestrogens. For the first time, average levels of all the above phytoestrogens were measured in samples of urine collected from a free living population sample of women. Results show a large range in both the amount and the type of phytoestrogens excreted.

Topics: 4-Butyrolactone; Equol; Female; Gas Chromatography-Mass Spectrometry; Genistein; Humans; Isoflavones; Lignans; Molecular Structure; Phytoestrogens; Plant Preparations; Reproducibility of Results; Sensitivity and Specificity

This study was undertaken to better understand the metabolic fate of dietary isoflavones in humans. Twelve volunteers were challenged with soya flour and urinary diphenol levels were then determined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The presence of previously described urinary diphenols was confirmed, i.e. the isoflavones, daidzein and genistein; the isoflavonoid metabolites, equol, dihydrodaidzein (Int-O-D), O-desmethyl-angolensin (O-Dma); the lignan, enterolactone. Diphenols detected for the first time were the isoflavone, glycitein and five novel isoflavonoid metabolites which are tentatively identified as 6'-hydroxy-O-desmethylangolensin (6' OH-O-Dma), dihydrogenistein (Int-O-G), dehydro-O-desmethylangolensin (dehydro-O-Dma) and two isomers of tetrahydrodaidzein. Urinary excretion rates of the three isoflavones (daidzein, genistein, glycitein) over a 3-day period following soya challenge showed moderate variation (4x, 6x and 12x, respectively) between the 12 individuals suggesting some individual variabilities in ability to deconjugate and to absorb dietary isoflavones. However, urinary excretion rates of each of three major isoflavonoid metabolites (equol, O-Dma, 6' OH-O-Dma) showed more marked variation (922x, 17x, 15x, respectively); while some of this variability may reflect varying individual ability to ferment dietary isoflavones per se, an inverse relationship was found between urinary levels of equol and both O-Dma and 6' OH-O-Dma suggesting individual variability in the preferred metabolic pathways of dietary isoflavones.

Topics: Adult; Chromans; Chromatography, Gas; Equol; Female; Gas Chromatography-Mass Spectrometry; Genistein; Glycine max; Humans; Isoflavones; Lignans; Male; Middle Aged