Microwave-assisted synthesis of new pyrimido[4′,5′:4,5]thiazolo[3,2-a]benzimidazol-4(3H)-one derivatives in solvent-free condition

Microwave-assisted synthesis of new 2-arylpyrimido[4′,5′:4,5]thiazolo[3,2-α]benzimidazol-4(3H)-ones from 3-aminothia- zolo[3,2-α]benzimidazol-2-carboxamide and aroyl halides in solvent-free condition is described.In comparison with classical conditions the reactions are faster and the yields are higher under microwave irradiation.     

Flow injection potentiometric determination of paraquat in formulations and biological samples

A flow injection potentiometric method for the rapid determination of paraquat in herbicide formulations and biological samples is described. It is based on the utilization of a flow-through potentiometric detector containing polyvinyl chloride-immobilised octamethylcyclotetrasiloxane, a lipophilic plasticizer (tetra-n-undecyl 3,3′,4,4′-benzophenone tetracarboxylate) and membrane additive potassium tetrakis(4-chlorophenyl)borate. The detector was minimally interfered by the presence of constituents such as Na⁺, K⁺, Ca²⁺, Mg²⁺, glucose, urea, lactic and citric acids at physiological levels, respectively. Good correlation between results of the proposed method and HPLC for the formulation samples was found, while results for the determination of paraquat in biological samples such as urine, vomitus and stomach washout was less satisfactory.     

Evaluation of antibacterial and antioxidant activities of Artemisia campestris (Astraceae) and Ziziphus lotus (Rhamnacea)

The present work quantitatively evaluates the antimicrobial and antioxidant potentials of two Libyan folk medicinal plants [Artemisia campestris (Astraceae) and Ziziphus lotus (Rhamnacea)] that commonly grow in the south of Libya. The crude methanolic leaves extracts of both plants are appreciably active against Gram-positive species, associated with week anti-Gram-negative activity. These two plant extracts also showed reasonably high contents of polyphenolics and alkaloids, with minimal inhibitory concentrations between 12.5–25 and 250–1000 μg/ml for Gram-positive and Gram-negative species, respectively. Results collectively suggest that A. campestris and Z. lotus are not only reliable natural sources of antimicrobials but also potential sources of phenolic antioxidants and hence could be nominated for future intensive studies.     

Ion-exchange chromatography using citrate buffer,EDTA and α-HIBA for improving the separation of no-carrier-added <Superscript>139</Superscript>Ce from La<Subscript>2</Subscript>O<Subscript>3</Subscript> target irradiated with 14.5 MeV protons

The adsorption behaviour of La/Ce system on Dowex 50W-X8 in different media, namely, nitric acid, acetate buffer and citrate buffer was studied as a function of the concentration of nitric acid and buffer pH. In addition, in cation-exchange column chromatography experiments, three different eluants, namely, citrate buffer of pH 5.5, 0.1 M EDTA and 0.2 M α-HIBA, were employed for separation of Ce(III) from La(III). The optimum conditions for improvement of radiochemical separation of no-carrier-added ¹³⁹Ce from proton irradiated lanthanum were applied using the most suitable chelating agent 0.2 M α-HIBA. The purification of ¹³⁹Ce from macro amount of La(III) was done using two columns in a sequence. The target was prepared by pressing. The production of high radionuclidic and chemical purity ¹³⁹Ce via irradiation of lanthanum oxide target at MGC-20 cyclotron of proton energy 14.5 MeV was described. The experimental yield was found to be 200 kBq/μA h.