Dietary Genistein Inhibits Methylglyoxal-Induced Advanced Glycation End Product Formation in Mice Fed a High-Fat Diet

BACKGROUND

Methylglyoxal (MGO), an important precursor of advanced glycation end products (AGEs), circulates at high concentrations in diabetic patients' blood and plays an important role in the pathogenesis of diabetes and other chronic diseases.

OBJECTIVES

The aim of this study was to determine whether dietary genistein can prevent indicators of metabolic syndrome (MetS) induced by a very-high-fat (VHF) diet or a high-fat (HF) diet plus exogenous MGO, and the accumulation of MGO and AGEs in mice.

METHODS

Male, 6-wk-old C57BL/6J mice (n = 15) were fed a low-fat (LF) diet (10% fat energy) or a VHF diet (60% fat energy) alone or including 0.25% genistein (VHF-G) for 16 wk in study 1. In study 2, 75 similar mice were fed the LF diet (LF) or the HF diet alone (HF) or in combination with up to 0.2% MGO in water (HFM) and 0.067% (HFM-GL) or 0.2% (HFM-GH) dietary genistein for 18 wk. Anthropometric and metabolic data were obtained in both studies to determine the effects of MGO and genistein on variables indicative of MetS.

RESULTS

Body weight gain, fat deposits, dyslipidemia, hyperglycemia, and fatty liver were ameliorated by dietary genistein in both studies. The plasma MGO concentration in VHF-G mice was 52% lower than that in VHF mice. Moreover, the AGE concentrations in plasma, liver, and kidney of VHF-G mice were 73%, 52%, and 49%, respectively, lower than in the VHF group (study 1). Similarly, the concentrations of plasma MGO and AGE in plasma, liver, and kidney of HFM-GH mice were 33.5%, 49%, 69%, and 54% lower than in HFM mice (study 2). Genistein inhibited AGE formation by trapping MGO to form adducts and upregulating the expressions of glyoxalase I and II and aldose reductase in liver and kidney to detoxify MGO in both studies.

CONCLUSIONS

Our data demonstrate for the first time that genistein significantly lowers MGO and AGE concentrations in 2 mouse MetS models via multiple pathways.

The chemical disruption of human metabolism

BACKGROUND

Recent evidence highlights the reality of unprecedented human exposure to toxic chemical agents found throughout our environment - in our food and water supply, in the air we breathe, in the products we apply to our skin, in the medical and dental materials placed into our bodies, and even within the confines of the womb. With biomonitoring confirming the widespread bioaccumulation of myriad toxicants among population groups, expanding research continues to explore the pathobiological impact of these agents on human metabolism.

METHODS

This review was prepared by assessing available medical and scientific literature from Medline as well as by reviewing several books, toxicology journals, government publications, and conference proceedings. The format of a traditional integrated review was chosen.

RESULTS

Toxicant exposure and accrual has been linked to numerous biochemical and pathophysiological mechanisms of harm. Some toxicants effect metabolic disruption via multiple mechanisms.

CONCLUSIONS

As a primary causative determinant of chronic disease, toxicant exposures induce metabolic disruption in myriad ways, which consequently result in varied clinical manifestations, which are then categorized by health providers into innumerable diagnoses. Chemical disruption of human metabolism has become an etiological determinant of much illness throughout the lifecycle, from neurodevelopmental abnormalities in-utero to dementia in the elderly.

New Insights on Plant Salt Tolerance Mechanisms and Their Potential Use for Breeding

Soil salinization is a major threat to agriculture in arid and semi-arid regions, where water scarcity and inadequate drainage of irrigated lands severely reduce crop yield. Salt accumulation inhibits plant growth and reduces the ability to uptake water and nutrients, leading to osmotic or water-deficit stress. Salt is also causing injury of the young photosynthetic leaves and acceleration of their senescence, as the Na+ cation is toxic when accumulating in cell cytosol resulting in ionic imbalance and toxicity of transpiring leaves. To cope with salt stress, plants have evolved mainly two types of tolerance mechanisms based on either limiting the entry of salt by the roots, or controlling its concentration and distribution. Understanding the overall control of Na+ accumulation and functional studies of genes involved in transport processes, will provide a new opportunity to improve the salinity tolerance of plants relevant to food security in arid regions. A better understanding of these tolerance mechanisms can be used to breed crops with improved yield performance under salinity stress. Moreover, associations of cultures with nitrogen-fixing bacteria and arbuscular mycorrhizal fungi could serve as an alternative and sustainable strategy to increase crop yields in salt-affected fields.

Effects of cyanobacterial lipopolysaccharides from microcystis on glutathione-based detoxification pathways in the zebrafish (Danio rerio) embryo

Cyanobacteria ("blue-green algae") are recognized producers of a diverse array of toxic secondary metabolites. Of these, the lipopolysaccharides (LPS), produced by all cyanobacteria, remain to be well investigated. In the current study, we specifically employed the zebrafish (Danio rerio) embryo to investigate the effects of LPS from geographically diverse strains of the widespread cyanobacterial genus, Microcystis, on several detoxifying enzymes/pathways, including glutathione-S-transferase (GST), glutathione peroxidase (GPx)/glutathione reductase (GR), superoxide dismutase (SOD), and catalase (CAT), and compared observed effects to those of heterotrophic bacterial (i.e., E. coli) LPS. In agreement with previous studies, cyanobacterial LPS significantly reduced GST in embryos exposed to LPS in all treatments. In contrast, GPx moderately increased in embryos exposed to LPS, with no effect on reciprocal GR activity. Interestingly, total glutathione levels were elevated in embryos exposed to Microcystis LPS, but the relative levels of reduced and oxidized glutathione (i.e., GSH/GSSG) were, likewise, elevated suggesting that oxidative stress is not involved in the observed effects as typical of heterotrophic bacterial LPS in mammalian systems. In further support of this, no effect was observed with respect to CAT or SOD activity. These findings demonstrate that Microcystis LPS affects glutathione-based detoxification pathways in the zebrafish embryo, and more generally, that this model is well suited for investigating the apparent toxicophore of cyanobacterial LPS, including possible differences in structure-activity relationships between heterotrophic and cyanobacterial LPS, and teleost fish versus mammalian systems.