2-(Nitroaryl)-5-Substituted-1,3,4-Thiadiazole Derivatives with Antiprotozoal Activities: In Vitro and In Vivo Study

Nitro-containing compounds are a well-known class of anti-infective agents, especially in the field of anti-parasitic drug discovery. HAT or sleeping sickness is a neglected tropical disease caused by a protozoan parasite, Trypanosoma brucei. Following the approval of fexinidazole as the first oral treatment for both stages of T. b. gambiense HAT, there is an increased interest in developing new nitro-containing compounds against parasitic diseases. In our previous projects, we synthesized several megazole derivatives that presented high activity against Leishmania major promastigotes. Here, we screened and evaluated their trypanocidal activity. Most of the compounds showed submicromolar IC₅₀ against the BSF form of T. b. rhodesiense (STIB 900). To the best of our knowledge, compound 18c is one of the most potent nitro-containing agents reported against HAT in vitro. Compound 18g revealed an acceptable cure rate in the acute mouse model of HAT, accompanied with noteworthy in vitro activity against T. brucei, T. cruzi, and L. donovani. Taken together, these results suggest that these compounds are promising candidates to evaluate their pharmacokinetic and biological profiles in the future.     

Chelator-free radiolabeling of dextran with 68Ga for PET studies

Journal of Radioanalytical and Nuclear Chemistry - The possibility of 68Ga-dextran complex formation was analyzed in an HEPES-buffered (pH = 4.5) as well as in an alkaline...     

Limit Weierstrass points on nodal reducible curves

In the 1980s D. Eisenbud and J. Harris posed the following question: ``What are the limits of Weierstrass points in families of curves degenerating to stable curves not of compact type?' In the present article, we give a partial answer to this question. We consider the case where the limit curve has components intersecting at points in general position and where the degeneration occurs along a general direction. For this case we compute the limits of Weierstrass points of any order. However, for the usual Weierstrass points, of order one, we need to suppose that all of the components of the limit curve intersect each other.

     

Square-wave cathodic adsorptive stripping voltammetric determination of trace amounts of 2-mercaptobenzimidazole in water samples

A sensitive, simple and reproducible square-wave cathodic adsorptive stripping voltammetric method is developed for the determination of 2-mercaptobenzimidazole (MBIM) in different water samples using a static mercury drop electrode (SMDE) as a working electrode. The solution conditions and instrumental parameters were optimized for the determination of MBIM by square-wave cathodic adsorptive stripping voltammetry. This method is based on a sensitive adsorptive reduction peak of the MBIM at ?0.532 V vs. Ag/AgCl reference electrode in a Britton-Robinson buffer at pH 10.0. The linear concentration range was 20–600 ng ml^?1 when using 0.0 V as the accumulation potential. The detection limit of the method was calculated to be 8.41 ng ml^?1. The precision was excellent with relative standard deviations (n = 20) of 2.30%, 1.71%, 2.25% and 1.33% at MBIM concentrations of 40, 90, 200 and 500 ng ml^?1, respectively. The proposed voltammetric method is used for the determination of MBIM in different spiked water samples.     

Sulfur modified with 2-mercaptobenzoxazole as a new sorbent for preconcentration of silver prior to determination by flame atomic absorption spectrometry

A solid-phase extraction method for preconcentration of silver and consequent determination by atomic absorption spectrometry is described. The method is based on the retention of silver on sulfur modified with 2-mercaptobenzoxazole. The retained silver is eluted from the column with a thiourea solution and determined by flame atomic absorption spectrometry. The preconcentration conditions such as pH, amount of reagent loaded on sorbent, type of eluent and its volume, flow rate and interfering ions were investigated. The calibration graph was linear in the range of 3–200 ng mL^?1 of Ag⁺ in the initial solution with r = 0.9985. The limit of detection based on 3S_b was 1.0 ng mL^?1. The relative standard deviation for ten replicate measurements of 50 and 150 ng mL^?1 of Ag⁺ was 4.1 and 1.4 %, respectively. The method was applied to the determination of silver in radiology film and water samples.     

Oxidation of Thiols to Their Disulfides with Bis Trinitratocerium (IV)l Chromate [Ce(NO3)312 CrO4 and Pyridinum Chlorochromate

Oxidation of thiophenols, benzyl thiol, and alkyl thiols with bis [trinitratocerium (IV)] chromate and pyridinum chlorochromate are investigated. Pyridinum chlorochromate is quite ineffective for the oxidative dimerization of alkyl thiols.     

Kinematic description of wave propagation through a chemical diode

The geometry of an active medium can cause wave blocking and induce unidirectional propagation. This well established phenomenon was studied in a previous paper within the framework of the photosensitive Belousov-Zhabotinsky reaction and the associated Oregonator model. In the present paper, as an extension of that study, the main factors that influence this phenomenon are interpreted in terms of a kinematic model.     

On the mechanism of reactions of oncogenic n-acyloxypurines—III : Extent of radical participation

UV irradiation of a model “activated ester” of the oncogen 3-hydroxyxanthine induced homolytic cleavage of the N-O bond and gave products arising by reduction of as well as by recombination of the solvent caged amidyl radical intermediate. Identification of the latter product constitutes the first evidence that a distinct product associated specifically with a radical from an acyloxypurine can be formed. The absence of this product among those formed spontaneously from 3-acetoxyxanthine provides the first indication that an amidyl radical is not an intermediate in the spontaneous reactions of N-acyloxy purines.