A novel and simple spectrophotometric method for the determination of tiopronin with sodium 1,2-naphthoquinone-4-sulfonate (NQS) is established in this paper. The detailed mechanism is proposed and discussed. It is based on the fact that tiopronin can catalyze the reaction between sodium 1,2-naphthoquinone-4-sulfonate and hydroxyl ion to form 2-hydroxy-1,4-naphthoquinone in a buffer solution of...

The use of the dye calcon (1-(2 hydroxy-1-naphthylazo)-2-naphthol-4 sulphonic acid) for the estimation of calcium using E.D.T.A. and a commercial photoelectric titrimeter is described. The interfering effects of magnesium and phosphate have been overcome. The method has been extended to estimations on biological materials. Results on 55 sera show that the E.D.T.A./calcon method gave slightly lo...

IN THE TITLE COMPOUND [SYSTEMATIC NAME: 5-(5,7-dihydr-oxy-4-oxo-4H-chromen-yl)-2-hydroxy-benzene-sulfonic acid dihydrate], C(15)H(10)O(8)S·2H(2)O, the benzopyran-one ring is not coplanar with the phenyl ring, the dihedral angle between them being 41.35 (3)°. No H atom was placed on the sulphonic acid group because it was not possible to distinguish between the two S=O bonds and the S-O bond. In...

DT-diaphorase catalysed the reduction of 1,4-naphthoquinones with hydroxy, methyl, methoxy and glutathionyl substituents at the expense of reducing equivalents from NADPH. The initial rates of quinone reduction did not correlate with either the half-wave reduction potential (E1/2) value (determined by h.p.l.c. with electrochemical detection against an Ag/AgCl reference electrode) or the partiti...

The objective of this study was to characterize the antioxidant properties of ethanol extracted from leaves of Jatropha curcas and to determinate the compounds. The IC50 values of DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt) were found to be 7.47 and 6.6 μg/ml, respectively, for the extracts. The reducing power of the ex...