The use of xanthine oxidase for a specific and sensitive fluorimetric determination of 6-mercaptopurine in serum

Near real-time determination of metabolic parameters for unquenched 6-mercaptopurine and xanthine oxidase samples using capillary electrophoresis

The enzyme activity of xanthine oxidase (XO) is influenced by several environmental factors including solution conditions, storage conditions, inhibitors, other enzymes, and activators. For instance, the metabolic reaction involving XO and the pro-drug 6-mercaptopurine, a drug used in the treatment maintenance of acute lymphatic leukemia, Crohn's disease, and ulcerative colitis, is often modified through the use of inhibitors, which varies the kinetic parameters associated with this reaction. Methods that provide fast and accurate determination of these kinetic constants can help in understanding the mechanism of these reactions. Herein, sequential and time-delayed electrokinetic injections of unpurified and unquenched samples containing xanthine oxidase, 6-mercaptopurine, and the inhibitor allopurinol are evaluated using capillary electrophoresis (CE). Using progress curve analysis, the Michaelis constant, apparent Michaelis constant, and inhibition constant are estimated to be 43.8 ± 2.0 μM, 143.0 ± 3.7 μM and 13.2 ± 1.4 μM, respectively. In addition, a turnover number of 7.9 ± 0.2 min(-1) is quantified. These values are consistent with some previously published values but were obtained without user intervention for reaction monitoring. This unique application of CE enzyme assays offers substantial advantages over traditional methods by determining kinetic parameters for enzymatic reactions with minimal (nL) sample volumes, short (<30 min) reaction analysis times, without any sample quenching or purification, and minimal user intervention.

Spectrophotometric Determination of 6-Mercaptopurine in Pharmaceutical Sample Using Fe(III)-Potassium Ferricyanide System

In the present work,we developed a simple,fast,sensitive and inexpensive method to determine 6-mercaptopurine (6-MP) in pharmaceutical sample using Fe (III)-potassium ferricyanide system by spectrophotometry.The results show that in acid medium, Fe (Ш) can be reduced to Fe (II) by hydrosulfuryl (-SH) in 6-Mercaptopurin molecule, and then Fe (II) reacts with potassium ferricyanide to form a soluble Prussian blue (KFeIII[FeII(CN)6]),the content of 6-MP was determinated indirectly through determinating the absorbance of the soluble Prussian blue.The various effect factors on the determination of 6-MP by spectrophotometry using potassium Fe (III)-ferricyanide system were investigated in detail.The maximum absorption wavelength of chromogenic system was 755 nm, good linear relationship was obtained between the absorbance and the concentration of 6-MP in the range of 0.4120~2.884 μ g·/mL,the equation of the linear regression was A=0.0411+0.1462C (μ g·/mL),with a linear correlation coefficient was 0.9991.This proposed method had been successfully applied to determinate of 6-MP in real pharmaceutical,and the results agreed well with those obtained by pharmacopoeial method.

Chromatographic analysis of anticancer drugs

The present review on the methods for the analysis of anticancer drugs should be seen as an addition to the excellent work of Eksborg and Ehrsson published half a decade ago in this journal (Vol. 340, p.31). The style and format have been followed closely, with the focus again on chromatographic techniques. We felt it important to add a list of compound (group) structures as a service to the reader. Methods have been reviewed for alkylating agents, platinum compounds, antitumour antibiotics, antimetabolites, alkaloids, suramin, 1-hydroxy-3-amino-propylidene-1,1-bisphosphonate and tamoxifen.