Plasma-aminothiols status and inverse correlation of total homocysteine with B-vitamins in arsenic exposed population of West Bengal, India.

Chronic arsenic toxicity is a serious environmental health problem across the world. Bangladesh and India (particularly the state of West Bengal) are the worst affected countries with such problem. The present study reports plasma-aminothiols (p-aminothiols) like L-cysteine (L-Cys), cysteinyl glycine (Cys-gly), total homocysteine (t-Hcy) and glutathione (GSH) status, and the inverse relationship of t-Hcy with B-vitamins (B1, B6, B9 and B12) in arsenic exposed population of West Bengal, India. Reverse phase HPLC was used to measure p-aminothiols and serum B-vitamins in different arsenic exposed population. Arsenic in drinking water and urine were measured by flow injection analysis system - Atomic Absorption Spectrometry (FIAS-AAS) and Transversely heated graphite atomizer (THGA-AAS) techniques, respectively. Water arsenic exposure was >50 µg/L in 50% population, of which majority (33.58%) belong to the range of >50-500 µg/L and more than 8% were even >1000 µg/L. Urine arsenic (µg/g creatinine) levels increased with arsenic exposure. The variability among p-aminothiols was also observed with higher exposure to arsenic in drinking water. A significant difference between exposed and control population was noticed for plasma L-Cys. The difference of B-vitamins between the population exposed to <50 and >50 µg/L arsenic in drinking water was also found to be significant. B9 and B12 deficiency with increased consumption of arsenic in water corroborates the anemic conditions commonly observed among arsenic exposed population. The aminothiol status indicated oxidative stress in exposed population. This study demonstrated progressive increase in plasma t-Hcy as well as inverse relationships of serum B-vitamins with increased water arsenic concentration.

Insights into a co-precursor driven solid-state thermal reaction of ferrocene carboxaldehyde leading to hematite nanomaterial: a reaction kinetic study.

Thermal decomposition of a mixture of ferrocene carboxaldehyde and oxalic acid dihydrate in O2 atmosphere produced rod-like hematite nanomaterial. The decomposition reaction was complex as evident from the overlapped multistep reaction steps in the non-isothermal thermogravimetry (TG) profiles obtained in the 300-700 K range. A peak deconvolution method was applied to separate the overlapped reaction steps. The multistep TG profiles were successfully deconvoluted, which showed that the decomposition occurs in six individual steps. However, it was found that only the last three reaction steps were responsible for the production of hematite. To estimate the activation energy values for these thermal reactions, six model-free integral isoconversional methods were used. The activation energy value significantly depends on the extent of conversion in each step; however, the nature of its dependence significantly different for each step. The most probable stepwise reaction mechanism functions for the solid-state reactions were obtained using the master plot method. The reaction mechanism was found to be different for different steps. Utilizing the activation energy and reaction mechanism function, the reaction rates of decomposition for each step were determined. To substantiate the validity of the assumed kinetic models, the experimental conversion curves were compared with the constructed ones, and the agreement was quite reasonable. The conversion-dependent thermodynamic parameters were obtained utilising the estimated kinetic parameters. Role of the co-precursor in the thermal reaction of the precursor was plausibly revealed. The present study describes how the use of a co-precursor significantly enhances the thermal decomposition of the precursor, how hematite nanomaterials can be synthesized from a co-precursor driven solid state reaction at low temperatures, and how the kinetic calculations facilitate the understanding of the solid-state reaction process. This study proposes the use of a suitable combination of precursor and co-precursor for solid-state thermal synthesis of iron-based nanoparticles using organo-iron compounds as precursor and also illustrates the effective application of the thermal analysis technique to understand the decomposition reaction.

A Novel High-Yield Synthesis of Substituted Isoindolequinones.

The high-yield, general, one-pot synthesis of substituted isoindolequinones, a group of important radiosensitizers which sensitize hypoxic cells to the lethal effect of radiation in cancer radiotherapy, is described. Primary amines react with 2,3-bis[2-(trimethylsilyl)ethynyl]-5,6-dimethylhydroquinone (2) in methanol at room temperature under an inert atmosphere to give substituted isoindolequinones 2-alkyl-1,3,5,6-tetramethylisoindole-4,7-quinone (4) in almost quantitative yields. Moderate yields of 4 are also obtained using 2,3-diethynyl-5,6-dimethylhydroquinone (3) and amines as reactant and solvent under the similar conditions. Tris(2-aminoethyl)amine (TREN) reacts with 2 in MeOH/THF on reflux to produce the isoindolequinone derivative of TREN. Water with 2 on reflux in MeOH forms an isobenzofuranquinone. This indicates that the formation of similar heterocycles from small molecules (e.g., Group VA and VIA hydrides) and 2 is likely. Readily synthesizable starting materials, ease of chromatographic isolation of the product, reaction generality, use of no catalyst, and cost-effective environmentally benign solvents such as MeOH/EtOH make this novel reaction simple and convenient.