dihydrogenistin and daidzein

1. Soybean is a common source of protein in many pet foods. Slow glucuronidation of soy-derived isoflavones in cats has been hypothesized to result in accumulation with adverse health consequences. Here, we evaluated species' differences in soy isoflavone glucuronidation using urine samples from cats and dogs fed a soy-based diet and liver microsomes from cats compared with microsomes from 12 other species. 2. Significant concentrations of conjugated (but not unconjugated) genistein, daidzein and glycitein, and the gut microbiome metabolites, dihydrogenistein and dihydrodaidzein, were found in cat and dog urine samples. Substantial amounts of conjugated equol were also found in cat urine but not in dog urine. 3. β-Glucuronidase treatment showed that all these compounds were significantly glucuronidated in dog urine while only daidzein (11%) and glycitein (37%) showed any glucuronidation in cat urine suggesting that alternate metabolic pathways including sulfation predominate in cats. 4. Glucuronidation rates of genistein, daidzein and equol by cat livers were consistently ranked within the lowest 3 out of 13 species' livers evaluated. Ferret and mongoose livers were also ranked in the lowest four species. 5. Our results demonstrate that glucuronidation is a minor pathway for soy isoflavone metabolism in cats compared with most other species.

Topics: Animals; Cats; Dogs; Equol; Estradiol; Ferrets; Genistein; Glucuronidase; Glycine max; Herpestidae; Isoflavones; Liver; Microsomes, Liver; Species Specificity

Soy isoflavone metabolites are currently receiving much attention due to the stronger and wider bioactivities than that of isoflavones. Therefore, biosynthesis of isoflavone metabolites by isolated isoflavone biotransforming bacteria is important. However, the biosynthesis process must be under obligate anaerobic conditions due to the reduction reactions catalysed by isoflavone biotransforming bacteria. In this study, we cloned the daidzein and genistein reductase gene (dgr) from Slackia sp. AUH-JLC159. The recombinant Escherichia coli (E. coli) whole-cell was used for the first time as the biocatalyst for aerobic biosynthesis of dihydrodaidzein (DHD) and dihydrogenistein (DHG) from soy isoflavones daidzein and genistein. Our results indicated that the recombinant E. coli whole-cell was able to reduce daidzein and genistein to DHD and DHG under aerobic conditions, while the maximal concentration of the substrate daidzein or genistein that the E. coli whole-cell was able to convert efficiently was only 0·4 mmol l(-1) . Under the optimized conditions, the maximal concentration of daidzein or genistein that the E. coli whole-cell was able to convert efficiently was increased to 1·4 mmol l(-1) . Our results demonstrated that E. coli whole-cell is an efficient biocatalyst for biosynthesis of isoflavone metabolites under aerobic conditions.. Soy isoflavone metabolites, which are more biologically active than their precursor isoflavones, are currently receiving much more attention. However, the non-natural isoflavone metabolites are synthesized or biosynthesized under obligate anaerobic conditions. Here, we describe a new approach to the reduction of soy isoflavones daidzein and genistein under aerobic conditions by use of the recombinant Escherichia coli whole-cell expressing isoflavone reductase. Our study provides the first evidence that isoflavone metabolites, such as dihydrodaidzein and dihydrogenistein, are able to be produced efficiently under aerobic conditions.

Topics: Actinobacteria; Escherichia coli; Genistein; Humans; Isoflavones; Oxidoreductases Acting on CH-CH Group Donors

A rod-shaped and Gram-positive anaerobic bacterium, named Niu-O16, which was isolated from bovine rumen contents, was found to be capable of anaerobically converting isoflavones daidzein and genistein to dihydrodaidzein (DHD) and dihydrogenistein (DHG), respectively. The metabolites DHD and DHG were identified using EI-MS and NMR spectrometric analyses. Stereoisomeric metabolites, which were separated on chiral stationary phase HPLC, were formed in equal amounts by the strain Niu-O16. Tautomerization reaction occurred on the B-ring of DHD and DHG seems to be attributed to the equal production of stereoisomeric metabolites. For the synthesis of DHD, the strain Niu-O16 showed an optimal pH range from 6.0 to 7.0 and completely reduced up to 800 microM of daidzein to DHD with the initial OD600nm=1.0 and pH 7.0 for 3 days incubation. The strain Niu-O16, showed relatively faster reduction activity toward daidzein to produce DHD than the previously isolated human intestinal bacterium Clostridium sp. HGH6.

Topics: Animals; Bacteria, Anaerobic; Cattle; Cell Culture Techniques; Gastrointestinal Contents; Genistein; Hydrogen-Ion Concentration; Isoflavones; Rumen

In human prostate cancer cells, the availability of the steroid hormone 1,25-dihydroxyvitamin D(3) for antimitotic action is determined through the activity of the two enzymes CYP24 and CYP27B1, viz. 25-hydroxyvitamin D-24-hydroxylase and 25-hydroxyvitamin D-1alpha-hydroxylase. High performance liquid chromatography (HPLC) analysis of [(3)H]25(OH)D(3) metabolism in human prostate cancer DU-145 cells revealed that genistein and other isoflavonoids, such as dihydrogenistein and daidzein, as well as the antiestrogenic compound ICI 182,780, inhibited Vitamin D-metabolizing enzyme activities. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed that only in case of genistein this was due to transcriptional inhibition of CYP24 and CYP27B1 gene expressions. In case of CYP27B1, reduction of gene activity involves histone deacetylation because genistein was inactive in the presence of the histone deactylase inhibitor trichostatin A. In contrast, under the same condition, CYP24 gene activity was largely suppressed. In summary, our results suggest that a combined effect of genistein and trichostatin A could increase the responsiveness of human prostate cancer cells to the antiproliferative action of 1,25-dihydroxyvitamin D(3).

Topics: 25-Hydroxyvitamin D3 1-alpha-Hydroxylase; Cell Division; Chromatography, High Pressure Liquid; Cytochrome P-450 Enzyme Inhibitors; Enzyme Inhibitors; Estradiol; Estrogen Antagonists; Estrogens, Non-Steroidal; Fulvestrant; Genistein; Histone Deacetylases; Humans; Hydroxamic Acids; Isoflavones; Male; Phytoestrogens; Plant Preparations; Prostatic Neoplasms; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Steroid Hydroxylases; Time Factors; Transcription, Genetic; Tumor Cells, Cultured; Vitamin D; Vitamin D3 24-Hydroxylase