Deglycosylation of flavonoid O-glucosides by human intestinal bacteria Enterococcus sp. MRG-2 and Lactococcus sp. MRG-IF-4

Abstract

Daidzin, daidzein 7-O-glucoside, is a major isoflavone in soybean and acts as a phytoestrogen. By intestinal bacteria dietary, daidzin is hydrolyzed to the aglycone daidzein and further converted to the more reduced metabolites, such as dihydrodaidzein, tetrahydrodaidzein, and equol. Human intestinal bacteria Enterococcus sp. MRG-2 and Lactococcus sp. MRG-IF-4, which convert daidzin to daidzein, were isolated under anaerobic condition, and identified by 16S rRNA gene sequence analysis. Changes of OD 600 and pH were measured during the anaerobic growth, and deglycosylation kinetics of daidzin and genistin were measured by HPLC. Both bacteria also converted other isoflavone 7-O-glucosides, glycitin, ononin, and sissotrin, to their aglycones, glycitein, formononetin, and biochanin A, respectively. Apigetrin was deglycosylated to apigenin by these bacteria too. However, rutin, hesperidin, and naringin were not converted to the aglycones. Phylogeny analysis of the isolated strains also found that bacterial species identified by 16S rRNA gene sequence was not correlated with its metabolic ability of flavonoid biotransformation.

Demethylation of Polymethoxyflavones by Human Gut Bacterium, Blautia sp. MRG-PMF1

“…MRG-PMF1, isolated from our laboratory (GenBank accession number: KJ078647), was used in these experiments. Bacterial growth and substrate conversion experiments were performed under anaerobic conditions, according to published methods. , In detail, the stock culture of Blautia sp. MRG-PMF1 (50% glycerol in GAM) stored in liquid nitrogen was thawed in an anaerobic chamber (CO 2 5%, H 2 10%, N 2 85%) at 37 °C.…”

“…Intestinal metabolism of plant secondary metabolites by human gut microbiota is of a great importance to human health. , In particular, biotransformation of polyphenolics by human microbiota has extensively been studied. , In the case of flavonoids, chemical reactions of deglycosylation of C - and O -glycosides, reduction and cleavage of the C-ring, hydrolysis of esters, and demethylation occur during the gut metabolism. − These reactions of flavonoid metabolism are well exemplified by S -equol formation from the soy isoflavone. − Recently, demethylation of methoxyflavones drew our attention, because chemical cleavage of the methyl aryl ether bond requires very rigorous reaction conditions. Until now, only two gut bacteria, Eubacterium limosum and Blautia sp.…”

Effects of nutritional enrichment on acid production from degenerated (non-solventogenic) Clostridium acetobutylicum strain M5

“…Cell density was determined by measuring the optical density at 600 nm (OD 600 ) using an Ultrospec-3000 (Pharmacia Biotech, Uppsala, Sweden) [15]. The concentrations of acetate and butyrate were estimated using a gas chromatograph (GC-7890A; Agilent Technologies, Santa Clara, USA) equipped with an 80/120-Carbopack BAW (Supelco, Bellefonte, PA, USA) [16].…”

Icariin Metabolism by Human Intestinal Microflora

“…MRG-PMF1 (GenBank accession number: KT585282, KT583836, and KJ078647, respectively) were used in this experiment. Preparation of intestinal mixed cells, bacterial growth and substrate conversion experiments were performed under the anaerobic conditions, according to the published method [15,29].…”

“…In our research group, the biotransformation of flavonoids by human intestinal bacteria has been extensively studied [14,15]. We believe the identification of intestinal metabolites of dietary flavonoids produced by human intestinal bacteria can help to explain the pharmacological effects of flavonoids that cannot be observed from the in vitro bioassay [16].…”