A rapid, simple, sensitive and accurate method for the simultaneous determination of three potential cancer biomarkers [tryptophan (TRP), isoxanthopterin (ISO) and xanthopterin (XAN)] in rat urine with synchronous fluorescence spectroscopy has been developed. In order to eliminate the interference in urine samples, the synchronous fluorescence spectra were obtained with Δλ=70 nm in a KH2PO4-NaOH buffer solution (pH=8.0). The detected wavelengths of quantitative analysis were set at 275 nm for TRP, 325 nm for ISO and 400 nm for XAN, respectively. Under the optimized conditions, the limits of the detection of the three compounds were 2.73 ng/mL, 0.52 ng/mL and 0.94 ng/mL, respectively. The recoveries were in the range of 80.5-98.0%, with the coefficient of variation between 0.62% and 2.48%. The proposed method has been applied to the simultaneous determination of TRP, ISO and XAN in rat urines of bladder cancer group and control group. The determination results showed that the average level of TRP, ISO and XAN had different change trends with the growth of the tumor. The three analytes could be used as potential biomarkers for noninvasive diagnosis of different stage of bladder cancer. However, more data are needed to support this hypothesis.
Keywords: Bladder cancer; Isoxanthopterin; Rat urine; Synchronous fluorescence spectroscopy; Tryptophan; Xanthopterin.
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