We investigated the prooxidant effects of bisphenol A (BPA) phenoxyl radicals in comparison with the phenoxyl radicals of 3-tert-butyl-4-hydroxyanisole (BHA), 2,6-di-tert-butyl-methylphenol (BHT) and 4-tert-butylphenol (TBP). The phenoxyl radicals, generated in situ by 1-electron oxidation of the corresponding phenol, were allowed to react with reduced nicotinamide adenine dinucleotide phosphate (NADPH) and rifampicin. The antioxidant activity of various phenols was examined based on the reduction of 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH). It was found that the prooxidant activity of BPA phenoxyl radicals far exceeded those of BHA and BHT of phenoxyl radicals. Unlike Trolox, BPA showed minimal DPPH scavenging activity. The strong prooxidant properties of BPA phenoxyl radicals propelled us to study the markers of cellular oxidative stress in GT1-7 hypothalamic neurons exposed to BPA. It was observed that neuronal cells exposed to BPA had increased generation of intracellular peroxides and mitochondrial superoxide ([Formula: see text]). The formation of peroxides and [Formula: see text] were time- and dose-dependent and that co-incubation with N-acetyl-l-cysteine or Trolox greatly lowered their levels. The results of the present study are consistent with emerging evidence that human populations (non-institutionalized) having higher levels of urinary BPA also have increased levels of oxidative stress markers and are prone to higher risk of cardiovascular diseases, diabetes and abnormalities in hepatic enzymes.

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The decomposition of peroxidized lipids of low-density lipoprotein (LDL) has been suggested to be involved in atherosclerosis. In this study, an in vitro system with 13-hydroperoxylinoleic acid (13-HPODE) was used to determine the effects of antioxidants on its decomposition. Decomposition of 13-HPODE was not affected by a-tocopherol, several other antioxidants, or antioxidant enzymes. Moreover, the inclusion of a-tocopherol during the decomposition of 13-HPODE resulted in an accumulation of aldehydes. Further oxidation of aldehydes to carboxylic acids by a number of oxidases was prevented by a-tocopherol. Conversely, the formation of carboxylic acids may be conducive to plaque stabilization via immunomodulation, rapid degradation, and by calcium sequestration. Thus, the inhibition of formation of carboxylic acids could be a serious deleterious effect of antioxidant treatment. In contrast, a-keto acids, like pyruvic acid, promoted the conversion of 13-HPODE to 13-hydroxylinoleic acid (13-HODE) by readily undergoing decarboxylation into acetate. These observations suggest that agents that promote the reduction of lipid peroxides into lipid hydroxides could be far more effective in treating cardiovascular diseases as opposed a-tocopherol-like antioxidants that could affect additional steps in the oxidation cascade.

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We have developed a simple, reversed-phase high-performance liquid chromatography (RP-HPLC) method for the determination of bisphenol A (BPA) in thermal paper cash register receipts (CRs). The method is suitable for analysis of other types of bisphenols and it involves an overnight extraction of CRs with acetonitrile (AN) at 50 °C followed by the HPLC analysis on a Supelcosil LC18 column (150 × 4.6 mm, particle size: 5 μ) using 50% AN in water as the mobile phase (5 min, isocratic). The composition of AN in the mobile phase changed to 100% over a 10 min period (linear gradient) and then held at 100% AN for 10 min (isocratic). The flow rate was set at 1 mL/min (injection volume: 20 μL) and the eluent was monitored at 234 nm. The authentic BPA eluted with a retention time of 5.9 min and gave a linear detector response in the concentration range of 0.23-50 mg/L. BPA in the CR extracts also eluted with the same retention and had identical absorbance properties as the standard. When CR extracts were co-injected with authentic BPA, they were resolved as a single peak. Further, GC/MS/EI analysis of authentic BPA and the HPLC-purified CR extracts have identical ion chromatograms and fragmentation of the molecular ion (m/z = 228). We have analyzed 170 CRs collected from 62 different vendors including supermarkets, fast food restaurants, gas stations and banking outlets. Almost all cash receipts (n = 168) showed the presence of BPA in the concentration range of 0.45-4.26% (M ± SD, 1.54 ± 0.73%).

A modified green approach for the synthesis of stable silver nanoparticles (AgNPs) using tea leaf extract is described. The method involves the reduction of silver salt by the polyphenols present in the green tea leaf extract and requires no additional capping/stabilising agents. Compared to other biogenic methods for the synthesis of AgNPs, the uniqueness of the approach described here lies in its simplicity, low-cost, and rapid synthesis rate; the reaction being completed within 10À15 min at room temperature. The reaction was carried out in alkaline medium without stirring and heating, and requires no special cleaning or drying of the glassware used. The synthesised AgNPs were characterised by UVÀVis spectroscopy and transmission electron microscopy (TEM). The results showed that AgNPs with a strong surface plasmon resonance peak around 410 nm and particle size in the 5À30 nm range were prepared. The synthesised AgNPs show excellent chemical stability for more than six months in aqueous solution. Additionally, we showed that the as-synthesised AgNPs can be used as highly selective colorimetric and optical sensors for the detection of cysteine. Thus, with a simple synthesis strategy, and enhanced stability, these green-tea-functionalised AgNPs have the potential for further applications as biosensors and antimicrobial agents.

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The title compound [systematic name: 2,2′-dinitro-4,4′-(propane-2,2-di­yl)diphenol], C15H14N2O6, crystallizes with two mol­ecules in the asymmetric unit. Both have a trans conformation for their OH groups, and in each, the two aromatic rings are nearly orthogonal, with dihedral angles of 88.30 (3) and 89.62 (2)°. The nitro groups are nearly in the planes of their attached benzene rings, with C—C—N—O torsion angles in the range 1.21 (17)–4.06 (17)°, and they each accept an intra­molecular O—H⋯O hydrogen bond from their adjacent OH groups. One of the OH groups also forms a weak inter­molecular O—H⋯O hydrogen bond.