Mixed dissociation constants of four drug acids, i.e. silychristin, silybinin, silydianin and mycophenolate at various ionic strengths I of range 0.01 and 0.30 and at temperatures of 25 and 37 ◦C were determined using the SQUAD(84) regression analysis program applied to pH-spectrophotometric titration data. The proposed strategy of an efficient experimentation in a protonation constants determi...

Two simple methods are described for the determination of ethionamide (ETM) in bulk drug and tablets using cerium (IV) sulphate as the oxidimetric agent. In both methods, the sample solution is treated with a measured excess of cerium (IV) solution in H2SO4 medium, and after a fixed standing time, the residual oxidant is determined either by back titration with standard iron (II) solution to a ...

The experimental determination of formation constant for interaction of two water soluble phthalocyanines, Cobalt (II) 4,4',4",4'"-tetrasulpho phthalocyanine (CoTsPc ) and Manganese(II) 4,4',4",4"-tetrasulpho phthalocyanine (MnTsPc ) , with calf thymus DNA have been studied by UV-Vis spectrophotometric method at lrnM phosphate buffer , pH 7.4 and at 5 different temperatures 20,25,30,35 and 400 ...

Isothermal titration calorimetry (ITC) may be used to determine the kinetic parameters of enzyme-catalyzed reactions when neither products nor reactants are spectrophotometrically visible and when the reaction products are unknown. We report here the use of the multiple injection method of ITC to characterize the catalytic properties of oxalate oxidase (OxOx) from Ceriporiopsis subvermispora (C...

Binding of Cu(2+), Ni(2+) and Ag(+) ions to polyallylamine (PAA), polyethylenimine (PEI), poly(N-2-(2-pyridyl)ethylallylamine) (PEPAA), poly(N-2-(2-pyridyl)ethylethylenimine) (PEPEI), and N-2-(2-pyridyl)ethylchitosan (PEC) has been investigated using batch sorption experiments, spectrophotometric titration, ESR, and XPS to elucidate how the structure of polymer precursors affects the ion bindin...

Triclinic single crystals of mitochondrial aspartate aminotransferase from chicken were examined by microspectrophotometry using nonpolarized light. The crystalline enzyme shows the same protein and coenzyme absorption bands in the 250 to 500 nm region as the enzyme in solution. The spectrum of the pyridoxal form (A,,, 355 nm) changes into that of the pyridoxamine form (X,,, 333 nm) when excess...

Crystalline I,-tyrosine phenol lyase of Escherichia infermedia A-21 is inactive in the absence of added pyridoxal phosphate. Half-maximal enzymatic activity is obtained at a concentration of 1.3 x 10pB M pyridoxal phosphate. Binding of pyridoxal phosphate to the apoenzyme is accompanied by pronounced increase in absorbance at 340 and 430 rng. Holotyrosine phenol lyase requires K+ or NH4+ for it...

Two simple and accurate methods are described for the determination of piroxicam and tenoxicam in their pharmaceutical preparations. The spectrophotometric method involves the oxidation of these drugs with potassium iodate in acid medium with the liberation of iodine and subsequent extraction with cyclohexane followed by measuring the absorbance at lambda=522 nm. Beer's law is obeyed in the con...

Synthesis of a novel Combretastatin A-4 analogue using Schiff’s reaction of benzil and 4-aminoantipyrine has been achieved under solvent free conditions. The structure of compound was examined spectroscopically and confirmed from single crystal diffraction studies. The synthesized Combretastatin A-4 analogue was investigated for its DNA binding ability as the plausible mechanism for its antitum...