Phenolic derivatives from soy flour ethanol extract are potent in vitro quinone reductase (QR) inducing agents

Phytochemical Investigation of Bioactive Compounds from White Kidney Beans (Fruits of Phaseolus multiflorus var. Albus): Identification of Denatonium with Osteogenesis-Inducing Effect

Phaseolus multiflorus var. albus (Leguminosae), commonly known as “white kidney bean”, is a twining perennial vine whose fruit has been used as a popular food worldwide owing to its high nutritional content, in terms of proteins, carbohydrates, fats, and vitamins. As part of our ongoing study to investigate novel bioactive components from various natural resources, a phytochemical investigation of the extract of P. multiflorus var. albus fruits resulted in the isolation of three phenolic compounds (1–3) and one dipeptide (4). The chemical structures of the compounds (1–4) were determined through 1D and 2D nuclear magnetic resonance spectroscopy and high-resolution-liquid chromatography–mass spectrometry; they were identified as denatonium (1), trans-ferulic acid ethyl ester (2), eugenin (3), and α-L-glutamyl-L-Leucine (4). Intriguingly, denatonium (1) is known to be the most bitter chemical compound. To the best of our knowledge, denatonium (1) was identified from natural sources for the first time, and compounds 2–4 were reported for the first time from P. multiflorus var. albus in this study; however, compound 2 turned out to be an artifact produced by an extraction with ethanol. The isolated compounds 1–4 were tested for their regulatory effects on the differentiation between osteogenesis and adipogenesis of mesenchymal stem cells (MSCs). Compound 4 slightly suppressed the adipogenic differentiation of MSCs, and compounds 1 and 4 stimulated osteogenic differentiation, unlike the negative control. These findings provide experimental evidence that compounds 1 and 4 may induce the osteogenesis of MSCs and activate bone formation.

Isoflavones-Enriched Soy Protein Prevents CCL(4)-Induced Hepatotoxicity in Rats

The burden of liver disease in Egypt is exceptionally high due to the highest prevalence of hepatitis C virus (HCV) resulting in rising rates of hepatocellular carcinoma (HCC). The aim of the current study was to determine the isoflavones in soy and to evaluate the protective role of soy against CCl₄-induced liver damage in rats. Four experimental groups were treated for 8 weeks and included the control group, soy-supplemented diet (20% w/w) group, the group treated orally with CCl₄ (100 mg/kg bw) twice a week, and the group fed soy-supplemented diet and treated with CCl₄. Blood and liver tissue samples were collected for biochemical analyses and histological examination. The results indicated that protein content was 45.8% and the total isoflavones recorded 167.3 mg/100 g soy. Treatment with CCl₄ resulted in a significant biochemical changes in serum liver tissue accompanied with severe oxidative stress and histological changes. Supplementation with soy succeeded to restore the elevation of liver enzymes activities and improved serum biochemical parameters. Moreover, soy supplementation improved the antioxidant enzymes, decreased lipid peroxidation, and improved the histological picture of the liver tissue. It could be concluded that soy-protein-enriched isoflavones may be a promising agent against liver diseases.

Soy isoflavones increase quinone reductase in hepa-1c1c7 cells via estrogen receptor beta and nuclear factor erythroid 2-related factor 2 binding to the antioxidant response element

Soy protein and isoflavones (genistein and daidzein) have been demonstrated to increase quinone reductase (QR) activity, protein, and mRNA in animal and cell culture models. However, their mechanism of action has not been completely characterized. Additionally, it has not been determined if equol, a daidzein metabolite, can modulate QR activity and expression. Estrogen receptor beta (ERβ) is thought to be involved in stimulating QR gene transcription by anti-estrogens and phytoestrogens, along with nuclear factor erythroid 2-related factor 2 (Nrf2). This study tested the hypothesis that genistein, daidzein and equol increase quinone reductase activity, protein and mRNA via ERβ and Nrf2 binding to the QR antioxidant response element (ARE). QR expression and activity were determined using TaqMan polymerase chain reaction, protein immunoblots and activity assays. Molecular events were investigated using luciferase reporter gene assays and chromatin immunoprecipitation (ChIP). Hepa-1c1c7 cells were treated with control [0.1% (v:v) dimethyl sulfoxide (DMSO)]; 1 μmol/L β-naphthoflavone (positive control); 5 μmol/L resveratrol (ChIP positive control for ERβ binding) and 1, 5 and 25 μmol/L genistein, daidzein or equol. Treatment durations were 1 h (ChIP), 24 h (mRNA and luciferase assays) and 24 and 48 h (protein and activity). Genistein, daidzein and equol increased QR activity, protein and mRNA, with daidzein and equol having more of an impact at physiologic concentrations (1 and 5 μmol/L) compared to genistein. Furthermore, the study results demonstrate that genistein, daidzein and equol interact with the QR ARE and that daidzein and equol act via both ERβ and Nrf2 binding strongly to the QR ARE.

β-carboline derivatives and diphenols from soy sauce are in vitro quinone reductase (QR) inducers

A murine hepatoma (Hepa 1c1c7) cellular bioassay was used to guide the isolation of phase II enzyme inducers from fermented soy sauce, using quinone reductase (QR) as a biomarker. A crude ethyl acetate extract, accounting for 8.7% of nonsalt soluble solids of soy sauce, was found to double relative QR specific activity at 25 μg/mL (concentration required to double was defined as a "CD value"). Further silica gel column fractionation yielded 17 fractions, 16 of which exhibited CD values for QR induction of <100 μg/mL. The four most potent fractions were subfractionated by column and preparative thin layer chromatography, leading to the isolation and identification of two phenolic compounds (catechol and daidzein) and two β-carbolines (flazin and perlolyrin), with respective CD values of 8, 35, 42, and 2 μM. Western blots confirmed that the increases in QR activity corresponded to dose-dependent increases in cellular levels of NAD[P]H:quinone oxidoreductase 1 protein by these four QR inducers. To the authors' knowledge, this is the first report on the ability of β-carboline-derived alkaloids to induce phase II enzymes.

Extraction methods determine the antioxidant capacity and induction of quinone reductase by soy products in vitro

Gastrointestinal (GI) mimic and organic solvent extracts of whole soybean powder (WSP), soy protein concentrate (SPC), and soy protein isolate (SPI) as well as soy isoflavone concentrate (SIC) were analyzed for total phenols; quinone reductase (QR) induction in hepa1c1c7 cells; antioxidant scavenging of DPPH, HOCl, ONOO(-), and O(2) (-.); and total antioxidant capacity via FRAP and ORAC assays. GI extracts of all the soy products had higher concentrations of total phenols than from acidified methanol (MeOH) but lower antioxidant potency. The MeOH extract of SPC was most potent in quenching HOCl and ONOO(-) and increasing FRAP and ORAC, but did not induce QR. Despite weak antioxidant activity, hexane (HX) extracts induced QR more than GI and MeOH extracts with WSP > SPC > SPI > IC. Soy extracts were ineffective scavengers of DPPH and O(2) (-.). Thus, extraction methods markedly affect the antioxidant profile and QR induction capacity of soy products.