Strategy of Cr detoxification by Callitriche cophocarpa

The present work focused on the qualitative and quantitative analysis of Cr detoxification strategy of aquatic cosmopolitan plant Callitriche cophocarpa. This plant species has just been described in the context of its unusual accumulation potential of Cr. The emphasis of the work was placed on the redox reaction Cr(VI)→Cr(III) which is considered to be remediation mechanism of highly reactive and mobile Cr(VI) ions. Plants were immersed for 5 days in 1 mM of Cr(VI) (potassium dichromate) or 1 mM of Cr(III) (chromium sulphate) solutions in semi-natural conditions. Cr was effectively removed from the solution up to the extent of ca.58% or 35% of the starting amount, in the case of Cr(III) and Cr(VI), respectively. No plant-induced Cr(VI) reduction accompanying Cr accumulation was observed in Cr(VI) solutions except from the apparent one, noticed at the fourth day of incubation. On the contrary to these results, according to the method of electron paramagnetic resonance spectroscopy (L-band EPR), biphasic signal of Cr(V) attending Cr(VI) to Cr(III) reduction was detected inside the plant tissue every day of investigations. Our results show that phytoextraction but not phytostabilization is the main strategy of Cr detoxification by C. cophocarpa in aquatic systems.      

Micro-TLC Approach for Fast Screening of Environmental Samples Derived from Surface and Sewage Waters

In this work we demonstrated analytical capability of micro-planar (micro-TLC) technique comprising one and two-dimensional (2D) separation modes to generate fingerprints of environmental samples originated from sewage and ecosystems waters. We showed that elaborated separation and detection protocols are complementary to previously invented HPLC method based on temperature-dependent inclusion chromatography and UV-DAD detection. Presented 1D and 2D micro-TLC chromatograms of SPE (solid-phase extraction) extracts were optimized for fast and low-cost screening of water samples collected from lakes and rivers located in the area of Middle Pomerania in northern part of Poland. Moreover, we studied highly organic compounds loaded in the treated and untreated sewage waters obtained from municipal wastewater treatment plant “Jamno” near Koszalin City (Poland). Analyzed environmental samples contained number of substances characterized by polarity range from estetrol to progesterone as well as chlorophyll-related dyes previously isolated and pre-purified by simple SPE protocol involving C18 cartridges. Optimization of micro-TLC separation and quantification protocols of such samples were discussed from the practical point of view using simple separation efficiency criteria including total peaks number, log(product ΔhR _F), signal intensity and peak asymmetry. Outcomes of the presented analytical approach, especially using detection involving direct fluorescence (UV366/Vis) and phosphomolybdic acid (PMA) visualization are compared with UV-DAD HPLC-generated data reported previously. Chemometric investigation based on principal components analysis revealed that SPE extracts separated by micro-TLC and detected under fluorescence and PMA visualization modes can be used for robust sample fingerprinting even after long-term storage of the extracts (up to 4 years) at subambient temperature (?20 °C). Such approach allows characterization of wide range of sample components that are present in given extract in high and middle concentration range. Due to protocol simplicity and low cost of analysis this method can be useful for preliminary sample screening.     

An Unusual Reaction of Dimethyl Sulfonium Methylide with Fhenyl Alkyl Ketones Having p-Electron Donating Substituents

A recent report by El Feraly et. al ³ describing the direct conversion of 5, 7-dimethoxy - 2, 3 - dihydro - 1H-benzcyclopenten- 1 -one(1) to the homologated aldehyde (3) by dimethyl sulfonium 4 methylide⁴ (2), prompted us to present results obtained from our investigation of the reaction of various aromatic aldehydes and ketones, possessing electron releasing p-substituent, with (2). Our interest in examining this particular reaction arose from a need to prepare the oxirane (5) and the aldehyde (6), required in connection with the synthesis and biological evaluation of semi-rigid analogues of catecholamines as probes for the study 5 of adrenergic and dopaminergic receptors.⁵     

Allylic Hydroxylation Through Acid Catalysed Epoxy Ring Opening of Betulinic Acid Derivatives

Acid catalysed epoxy ring opening of several lupane type triterpenoids leads to unusual allylic hydroxylation. The reaction involves the formation of epoxide by m‐chloroperbenzoic acid followed by the treatment of mineral acid. The simple methodology finds utility to introduce a hydroxyl function at the allylic position in these triterpenoids, which is otherwise quite difficult.     

Kinetic Studies on Interaction of Platinum(II) Complexes with an ‘S’ Containing Ligand in Aqueous Medium

The kinetics of the substitution reactions of [Pt(dach)(H₂O)₂]²⁺ and [Pt(en)(H₂O)₂]²⁺ (where ‘dach’ and ‘en’ are cis-1,2-diaminocyclohexane and ethylenediamine, respectively) with excess N,N′-diethylthiourea have been studied in aqueous solution by UV–Vis spectrophotometry. The effect of different N–N spectator ligands on the reactivity of platinum(II) complexes was investigated by studying the water lability of the reactant complexes. The kinetic study has been substantiated by product isolation, IR, NMR and ESI-MS spectral analysis and DFT calculations. The reactions follow normal square-planar substitution mainly in an associative way. Rate parameters have been evaluated under different conditions. The substitution rates of the complexes studied can be tuned through the nature of the N–N chelates, which is important in the development of new active compounds for cancer therapy.     

Strategies for Enhancing the Production of Penicillin G Acylase from Bacillus badius: Influence of Phenyl Acetic Acid Dosage

Bacillus badius isolated from soil has been identified as potential producer of penicillin G acylase (PGA). In the present study, batch experiments performed at optimized inoculum size, temperature, pH, and agitation yielded a maximum PGA of 9.5 U/ml in shake flask. The experiments conducted in bioreactor with different oxygen flow rates revealed that 0.66 vvm oxygen flow rate could be sufficient for the maximum PGA activity of 12.7 U/ml. From a detailed investigation on the strategies of the addition of phenyl acetic acid (PAA) for increasing the production of PGA, it was found that the controlled addition of 10 ml of 0.1 % (w/v) PAA once in every 2 h from 6th hour of growth showed the maximum PGA activity of 32 U/ml. Thus, our studies for the first time showed that at concentration above 0.1 % (w/v) PAA, the PGA production decreased. This selective condition paves the way for less costly bioprocess for the production of PGA.     

Dielectric and ac impedance studies of nanostructured CaCu3Ti3.90Ce0.10O12 electro-ceramic synthesized by citrate-gel route

Effect of doping at Ti⁴⁺ site by Ce³⁺ has been examined in CaCu₃Ti_3.90Ce_0.10O₁₂ synthesized by citrate-gel route. DTA/TG analysis of dry powder gives pre-information about formation of final product around 850 °C. X ray diffraction analysis confirmed the formation of CaCu₃Ti_3.90Ce_0.10O₁₂ phase of the ceramic sintered at 950 °C for 12 h. Microstructure has been studied using scanning electron microscopy and confirmed the average grain size found in nano range 200–400 nm in system CaCu₃Ti_3.90Ce_0.10O₁₂.The nature of relaxation behavior of ceramic was also rationalized by using the impedance and modulus spectroscopy. The bulk conductivity indicates an Arrhenius-type thermally activated process. The ac conductivity spectrum obeyed the Jonscher power law. The complex impedance diagrams of the ceramic exhibited a significant contribution from the grains, grain boundaries and electrode. The activation energies calculated from the grain-boundary relaxation time constant was found to be 0.49 eV which confirmed the Maxwell–Wagner type of relaxation present in the ceramic.     

Simple Sulfinate Synthesis Enables C?H Trifluoromethylcyclopropanation

A simple method to convert readily available carboxylic acids into sulfinate salts by employing an interrupted Barton decarboxylation reaction is reported. A medicinally oriented panel of ten new sulfinate reagents was created using this method, including a key trifluoromethylcyclopropanation reagent, TFCS‐Na. The reactivity of six of these salts towards C H functionalization was field‐tested using several different classes of heterocycles.