Selenium methylselenocysteine protects human hepatoma HepG2 cells against oxidative stress induced by tert-butyl hydroperoxide

Selenium methylselenocysteine (Se-MeSeCys) is a common selenocompound in the diet with a tested chemopreventive effect. This study investigated the potential protective effect of Se-MeSeCys against a chemical oxidative stress induced by tert-butyl hydroperoxide (t-BOOH) on human hepatoma HepG2 cells. Speciation of selenium derivatives by liquid chromatography–inductively coupled plasma mass spectrometry depicts Se-MeSeCys as the only selenocompound in the cell culture. Cell viability (lactate dehydrogenase) and markers of oxidative status—concentration of reduced glutathione (GSH) and malondialdehyde (MDA), generation of reactive oxygen species (ROS) and activity of the antioxidant enzymes glutathione peroxidase (GPx) and glutathione reductase (GR)—were evaluated. Pretreatment of cells with Se-MeSeCys for 20 h completely prevented the enhanced cell damage, MDA concentration and GR and GPx activity and the decreased GSH induced by t-BOOH but did not prevent increased ROS generation. The results show that treatment of HepG2 cells with concentrations of Se-MeSeCys in the nanomolar to micromolar range confers a significant protection against an oxidative insult.     

Hydrothermal Preparation of Ni3S4/CoS2 Composite Electrocatalytic Materials for High Performance Counter Electrodes of Dye-Sensitized Solar Cells

Journal of Cluster Science - A facile one step synthetic hydrothermal route was used to fabricate the Pt free Ni3S4/CoS2 heterostructure counter electrode and study the photovoltaic characteristics...     

Crude peroxidase from onion solid waste as a tool for organic synthesis. Part I: Cyclization of 2′,3,4,4′,6′-pentahydroxy-chalcone into aureusidin

The potential of a crude peroxidase (POD) from onion solid waste as a biocatalyst for the synthesis of a naturally occurring aurone is described. The crude enzyme preparation effectively promotes the cyclization of 2′,3,4,4′,6′-pentahydroxy-chalcone (which is not a natural substrate of onion POD) into aureusidin.     

The Isoscalar Monopole Resonance of 4He

The transition form factor to the 0⁺ resonance of ⁴He at 20.10 MeV is studied using different realistic potential models. A large dependence on these models is found. The results are compared to experimental data. The Lorentz integral transform (LIT) approach has allowed the separation of resonance and background contributions.     

Investigating the structure–property relationship of aromatic–aliphatic polyamide/layered silicate hybrid films

Surface treated montmorillonite was used to prepare nanocomposites with aromatic–aliphatic polyamide by solution intercalation technique. The polyamide chains were produced through polycondensation of 4-aminophenyl sulfone with sebacoyl chloride in dimethyl acetamide. Compatibility between the polymer and organoclay was achieved through carbonyl chloride end-capped amide chains prepared by adding extra sebacoyl chloride near the end of polymerization reaction. The nanocomposites morphology and clay dispersion were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Delaminated and intercalated morphologies were observed for different loading of organoclay. Tensile strength and modulus improved for nanocomposites with optimum organoclay content (10-wt.%). Thermal stability and glass transition temperature of nanocomposites increased relative to pristine polyamide with augmenting organoclay content. Water uptake of these materials decreased as compared to the neat polyamide indicating reduced permeability.     

Quantitative Analysis of Caffeoylquinic Acids and Styrylpyrones in Sweetia panamensis Bark by UPLC

Six secondary metabolites from the methanolic extract of Sweetia panamensis (Fabaceae) bark were isolated and characterised. Along with the pyrones desmethylangonine β-d-O-glucopyranoside and desmethylangonine β-d-O-glucopyranosyl-(1→6)-O-β-d-glucopyranoside, already reported in this species, 5-O-caffeoylquinic acid (chlorogenic acid), 4-O-caffeoylquinic acid, 3-O-caffeoylquinic acid and the isoflavonoid 5-O-methylgenistein 7-O-β-d-glucopyranoside were isolated for the first time from S. panamensis. Additionally, an LC-ESI-MS qualitative analysis was performed and an ultra performance liquid chromatography (UPLC) method was developed and validated for the determination of these compounds. The UPLC method was applied to the quantitative analysis of plant samples. Pyrones and caffeoylquinic acids resulted to be the main compounds in the extract; in particular desmethylangonine β-d-O-glucopyranosyl-(1→6)-O-β-d-glucopyranoside was the most abundant compound.

     

Quantitative Analysis of Caffeoylquinic Acids and Styrylpyrones in Sweetia panamensis Bark by UPLC

Six secondary metabolites from the methanolic extract of Sweetia panamensis (Fabaceae) bark were isolated and characterised. Along with the pyrones desmethylangonine β-d-O-glucopyranoside and desmethylangonine β-d-O-glucopyranosyl-(1→6)-O-β-d-glucopyranoside, already reported in this species, 5-O-caffeoylquinic acid (chlorogenic acid), 4-O-caffeoylquinic acid, 3-O-caffeoylquinic acid and the isoflavonoid 5-O-methylgenistein 7-O-β-d-glucopyranoside were isolated for the first time from S. panamensis. Additionally, an LC-ESI-MS qualitative analysis was performed and an ultra performance liquid chromatography (UPLC) method was developed and validated for the determination of these compounds. The UPLC method was applied to the quantitative analysis of plant samples. Pyrones and caffeoylquinic acids resulted to be the main compounds in the extract; in particular desmethylangonine β-d-O-glucopyranosyl-(1→6)-O-β-d-glucopyranoside was the most abundant compound.     

DABCO-mediated substitution of vinylic iodides: synthesis of β-cyano Baylis-Hillman acetates

Nucleophilic substitution of vinyl β-iodo Baylis-Hillman acetates using 1,4-diazabicyclo[2.2.2] octane (DABCO) and then KCN, provides a stereoselective method for the synthesis of the corresponding β-cyano Baylis-Hillman acetates in high yields.