Amalendu Banerjee

Antiprotozoal activity of diospyrin towards Leishmania donovani promastigotes in vitro

Diospyrin, a bis-naphthoquinone derivative, isolated from a plant, known for its antitumour properties against Ehrlich ascites carcinoma in Swiss A mice, exhibits antiprotozoal activity towards L. donovani promastigotes in culture.

Evidence of esterification during the oxidation of some aromatic aldehydes by chromium (VI) in acid medium and the mechanism of the oxidation process

Abstract The oxidation kinetics of some aromatic aldehydes by chromium (VI) have been studied in perchloric acid medium. Kinetic and spectrophotometric results indicate the formation of a 1:1 intermediate ester between the reactive chromium (VI) species and protonated benzaldehyde. The rate is directly proportional to the square of hydrogen ion concentrations. The rate of oxidation decreases with the presence of electron donating groups and increases with electron withdrawing groups on the aromatic ring. The activation parameters associated with the rate determining step and the thermodynamic values associated with the equilibrium step have been computed. An attempt has been made to compare the results obtained with those for the oxidations of some aliphatic aldehydes which do not have enolizable hydrogen.

Pharmacological Studies on the Effect of the Treatment of Swiss A Mice with Diospyrin, a Tumour-inhibitory Plant Product, and its Synthetic Derivatives

Diospyrin, a bisnaphthoquinonoid plant product and its derivatives have shown significant inhibitory activities against murine tumours in vivo. Studies on the haematological status, serum protein and creatinine levels, activities of several serum glycolytic enzymes, and histopathology of the mice inoculated with Ehrlich ascites carcinoma were carried out after treatment with diospyrin and four synthetic derivatives. The prognostic significance of the pharmacological parameters acting as markers of the diseased state was evident from these findings. Normal mice were also studied before and after treatment with these compounds which did not cause noticeable adverse effects on the vital parameters, thereby indicating the possibility of the utilization of diospyrin and derivatives as appropriate therapeutic agents.

Kinetics and mechanism of oxidation of some aryl alcohols by acid bromate

Abstract The kinetics of oxidation of some substituted benzyl alcohols as well as the unsubstituted one by bromate ion in hydrochloric acid medium has been suggested. The results indicate that the reaction takes place by way of intermediate ester formation. Methoxy compounds react at much faster rates than the corresponding nitro substituted derivatives. The thermodynamic values associated with the equilibrium step and also for the slow step have been evaluated. A mechanism consistent with the experimental observations has been suggested.

Oxidative behaviours and relative reactivities of some α-hydroxy acids towards bromate ion in hydrochloric acid medium

Abstract The oxidation kinetics of some α-hydroxy acids by potassium bromate in dilute hydrochloric acid medium have been studied. The reactions are first order with respect to bromate ion. α-hydroxy acid and hydrogen ion concentrations. The reaction rate is governed by two factors : (i) the ease with which the protonated hydroxy acid is produced and (ii) the stability of the intermediate (1:1) bromate ester. The activation parameters of the reactions have been compared. The plausible mechanism of the oxidation process has been suggested. The reactivity of the α-hydroxy acids towards bromate ion are as follows: 9-hydroxy-9-carboxy fluorene > atrolactic acid > mandelic acid > benzilic acid > α-hydroxyisobutyric acid > lactic acid > glycolic acid.

Kinetics and mechanism of the oxidation of ethylene glycol, 2,3-butanediol and pinacol by hexachloroiridate(IV)

SummaryThe kinetics of oxidation of ethylene glycol, 2,3-butanediol and pinacol have been studied spectrophotometrically under different experimental conditions. The reactions seem to occur through the formation of an intermediate complex between each diol and iridium(IV). The complexes decompose through intermediate free radicals to form formaldehyde, acetaldehyde and acetone, respectively. Thermodynamic parameters have been calculated.

Iodimetric method for the determination of glucose with vanadium(V) in perchloric acid

Ammonium (or sodium) vanadate in dilute perchloric acid was found to be an excellent reagent for the determination of glucose. The method involves refluxing a mixture containing glucose and an excess of vanadate solution in dilute perchloric acid over a small flame for 40 min. To this reaction mixture potassium iodide was added to determine the residual vanadate iodimetrically. The amount of glucose can then be determined by standardising the vanadate solution with either sodium thiosulphate or glucose solutions of known strengths; the latter gave consistently better results.

KINETICS AND MECHANISM OF OXIDATION OF METHANOL BY ACID BROMATE

The kinetics of oxidation of methanol by bromate ion in hydrochloric acid medium has been investigated. A mechanism consistent with the experimental observations is suggested.AbstractИсследована кинетика окисления метанола броматным ионом в среде хлороводородной кислоты. Предложен механизм, согласующийся с экспериментальными результатами.

Iodimetric method for the determination of mono- and disaccharides with vanadium(V) in perchloric acid

Sodium (or ammonium) metavanadate in dilute perchloric acid was found to be a suitable reagent for the determination of fructose, mannose, galactose, arabinose, ribose, xylose, sucrose and maltose. A mixture containing the saccharide and an excess of the reagent was refluxed over a small flame for 40 min. The residual metavanadate was determined iodimetrically. The amount of saccharide was then determined by standardizing the metavanadate solution against either sodium thiosulphate solution or the respective saccharide solution of known strength; the latter procedure gave consistently better results.

Kinetics and mechanism of oxidation of aromatic aldehydes by vanadium(V) in perchloric acid medium

The oxidation kinetics of benzaldehyde and its substituted derivatives by vanadium(V) have been studied in perchloric acid medium. The reaction is first order in both [vanadium(V)] and [H+] whereas the order with respect to [substrate] is less than unity. The kinetic and spectrophotometric results indicate the formation of an intermediate 1 : 1 complex between the reactive vanadium(V) species and hydrated benzaldehyde prior to electron transfer. Thermodynamic parameters associated with the intermediate complex and activation parameters for the slow step have been evaluated. The reaction is found to have a significant deuterium isotope effect. A mechanism consistent with the experimental observations is proposed.