Impact of Glucoraphanin-Mediated Activation of Nrf2 on Non-Alcoholic Fatty Liver Disease with a Focus on Mitochondrial Dysfunction.

Non-alcoholic fatty liver disease (NAFLD) is a common disease in Western nations and ranges in severity from steatosis to steatohepatitis (NASH). NAFLD is a genetic-environmental-metabolic stress-related disease of unclear pathogenesis. NAFLD is triggered by caloric overconsumption and physical inactivity, which lead to insulin resistance and oxidative stress. A growing body of evidence indicates that mitochondrial dysfunction plays a critical role in the pathogenesis of NAFLD. Mitochondrial dysfunction not only promotes fat accumulation, but also leads to generation of reactive oxygen species (ROS) and lipid peroxidation, resulting in oxidative stress in hepatocytes. Nuclear factor erythroid 2-related factor 2 (Nrf2) is an important modulator of antioxidant signaling that serves as a primary cellular defense against the cytotoxic effects of oxidative stress. The pharmacological induction of Nrf2 ameliorates obesity-associated insulin resistance and NAFLD in a mouse model. Sulforaphane and its precursor glucoraphanin are derived from broccoli sprouts and are the most potent natural Nrf2 inducers-they may protect mitochondrial function, thus suppressing the development of NASH. In this review, we briefly describe the role of mitochondrial dysfunction in the pathogenesis of NASH and the effects of glucoraphanin on its development.

Bioavailability of Sulforaphane Following Ingestion of Glucoraphanin-Rich Broccoli Sprout and Seed Extracts with Active Myrosinase: A Pilot Study of the Effects of Proton Pump Inhibitor Administration.

We examined whether gastric acidity would affect the activity of myrosinase, co-delivered with glucoraphanin (GR), to convert GR to sulforaphane (SF). A broccoli seed and sprout extract (BSE) rich in GR and active myrosinase was delivered before and after participants began taking the anti-acid omeprazole, a potent proton pump inhibitor. Gastric acidity appears to attenuate GR bioavailability, as evidenced by more SF and its metabolites being excreted after participants started taking omeprazole. Enteric coating enhanced conversion of GR to SF, perhaps by sparing myrosinase from the acidity of the stomach. There were negligible effects of age, sex, ethnicity, BMI, vegetable consumption, and bowel movement frequency and quality. Greater body mass correlated with reduced conversion efficiency. Changes in the expression of 20 genes in peripheral blood mononuclear cells were evaluated as possible pharmacodynamic indicators. When grouped by their primary functions based on a priori knowledge, expression of genes associated with inflammation decreased non-significantly, and those genes associated with cytoprotection, detoxification and antioxidant functions increased significantly with bioavailability. Using principal components analysis, component loadings of the changes in gene expression confirmed these groupings in a sensitivity analysis.

Concentrations of thiocyanate and goitrin in human plasma, their precursor concentrations in brassica vegetables, and associated potential risk for hypothyroidism.

Brassica vegetables are common components of the diet and have beneficial as well as potentially adverse health effects. Following enzymatic breakdown, some glucosinolates in brassica vegetables produce sulforaphane, phenethyl, and indolylic isothiocyanates that possess anticarcinogenic activity. In contrast, progoitrin and indolylic glucosinolates degrade to goitrin and thiocyanate, respectively, and may decrease thyroid hormone production. Radioiodine uptake to the thyroid is inhibited by 194 µmol of goitrin, but not by 77 µmol of goitrin. Collards, Brussels sprouts, and some Russian kale (Brassica napus) contain sufficient goitrin to potentially decrease iodine uptake by the thyroid. However, turnip tops, commercial broccoli, broccoli rabe, and kale belonging to Brassica oleracae contain less than 10 µmol of goitrin per 100-g serving and can be considered of minimal risk. Using sulforaphane plasma levels following glucoraphanin ingestion as a surrogate for thiocyanate plasma concentrations after indole glucosinolate ingestion, the maximum thiocyanate contribution from indole glucosinolate degradation is estimated to be 10 µM, which is significantly lower than background plasma thiocyanate concentrations (40-69 µM). Thiocyanate generated from consumption of indole glucosinolate can be assumed to have minimal adverse risks for thyroid health.

Evaluation of the safety and bioactivity of purified and semi-purified glucoraphanin.

The anti-carcinogenic effects of broccoli have been attributed to sulforaphane, the hydrolysis product of glucoraphanin (GRP). Here we determined if purified GRP, in the absence of the plant-derived hydrolyzing enzyme myrosinase, could affect pulmonary and hepatic ethoxyresorufin O-deethylase (EROD) and/or NAD(P)H-quinone oxidoreductase 1 (NQO1) activity. Male F344 rats were administered semi-synthetic, semi-purified or purified GRP (240 mg/kg: 550 micromol/kg rat daily for 4 days) by gavage. Hepatic and pulmonary NQO1 activity increased ( approximately 20%), but not EROD. Varying doses of semi-purified GRP (30, 60, or 120 mg/kg rat daily for 4 days) again caused no change in EROD activity, although a dose-dependent increase in NQO1 was seen. Urinary excretion of mercapturic acids showed no difference between preparations, and recovery increased with decreasing dose. Histopathologic examination revealed no abnormal tissues other than cecum, where inflammation was dose dependent; mild at 120 mg/kg and severe at 240 mg/kg, a greatly supra-physiological dose. We conclude that GRP 30-60 mg/kg p.o. is safe and effectively enhances NQO1 in all tissues evaluated.

Prolongation of sickle cell survival by dimethyl adipimidate is compromised by immune sensitization.

The effect of dimethyl adipimidate (DMA), an amino-reactive crosslinking reagent with demonstrated antisickling properties in vitro, on the survival of 51Cr-labeled autologous sickle cells was evaluated in five adult males with sickle cell anemia. The survival of cells pretreated with 5 mmol/L DMA (pH 7.4), normal (t1/2 28-33 days) in four subjects and near-normal (t1/2 20 days) in the fifth, was considerably longer than that usually observed in sickle cell disease. In fact, the effect of DMA on the survival of sickle cells in vivo equals or exceeds that of any other agent tested to date. In three subjects, the survival of a second infusion of DMA-treated red cells was much shorter (t1/2 1.8, 3, 4.5 days) than in the initial study. An antibody was detected in the serum of these subjects that was directed to DMA-treated red cells. Modification of the immunogenicity of treated cells will be required before further consideration of DMA for use in the therapy of sickle cell anemia.