Identification and determination of urinary acetylpolyamines in cancer patients by electrospray ionization and time-of-flight mass spectrometry

A method for the quantification of acetylpolyamines, N1,N12-diacetylspermine (DiAcSpm), monoacetylspermidine (AcSpd), and N1,N8-diacetylspermidine (DiAcSpd), identifying each compound simultaneously, was developed with the goal of evaluating these acetylpolyamines as potential biomarkers of cancer. The method consists of prepurification of acetylpolyamines in urine with commercially available cartridges and derivatization with heptafluorobutyric (HFB) anhydride. HFB derivatives of acetylpolyamines were determined simultaneously using 15N-labeled acetylpolyamines as internal standards by electrospray ionization and time-of-flight mass spectrometry (ESI–TOF MS). After the method was validated, the urinary acetylpolyamines of 38 cancer patients were quantified with this method. A comparison of the concentrations of DiAcSpm with those measured by a colloidal gold aggregation method demonstrated a correlation coefficient of 0.996, showing that the two methods were equally satisfactory. Analysis of the correlation between DiAcSpd or AcSpd and DiAcSpm, performed for the first time, indicated the usefulness of DiAcSpm as a urinary biomarker of cancer. During the course of this work, two simple methods for the preparation of α,ω-diacetylpolyamines were developed, and a possibility to separate and determine the concentrations of the two isomers, N1-acetylspermidine and N8-acetylspermidine in AcSpd, was shown by tandem mass spectrometry (MS/MS).