RESUMEN
A new method was established for the determination of indoles (indole (IND), 3-methylindole (3-MI), indolyl-3-acetic acid (IAA) and indolyl-3-propionic acid (IPA)) in plasma by high performance liquid chromatography-fluorescence detection (HPLC-FLD). The analytes were separated simultaneously on a Shim-pack VP-ODS column (150 mm×4.6 mm, 4.6 µm) using 15 mmol/L sodium dihydrogen phosphate solution and methanol (48:52, v/v) as the mobile phases. The column temperature was 30 â, and the flow rate was 0.8 mL/min. The calibration curves of IND, 3-MI, IPA and IAA showed good linear relationships. The intra-day and inter-day relative standard deviations (RSDs) for the analytes were both less than 6.31%. The average recoveries of the analytes in plasma were 97.5%-107.0%. The method was successfully applied to the analysis of indoles in the plasma of healthy women of reproductive age (n=25) as controls and patients with polycystic ovarian syndrome (n=61). The results showed that the concentrations of indoles in the plasma were significantly different between the two groups, and IND was found to be a risk factor and a potential diagnostic biomarker for polycystic ovarian syndrome (PCOS). The method is simple, sensitive and suitable for use in clinical testing and laboratory research.
RESUMEN
Indole is an essential metabolite in intestinal tract. The dysregulation of plasma indole concentration occurred in various diseases. In this study, the indole in plasma was determined directly using electrochemical sensor with multiwall carbon nanotubes-chitosan (MWCNTs-CS) modified screen-printed carbon electrode (SPCE). The electrochemical behavior of indole was elucidated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) on the MWCNTs-CS composites modified SPCE (MWCNTs-CS/SPCE). The results showed that the current responses of indole improved greatly due to the high catalytic activity and electron transfer reaction of nano-composites. Under the optimized conditions, the linear range of indole was from 5 to 100µgL-1 with the detection limit of 0.5µgL-1 (S/N = 3). This novel electrochemical sensor exhibited acceptable accuracies and precisions with the variations less than 7.3% and 9.0%, respectively. Furthermore, high performance liquid chromatography (HPLC) method was utilized to compare with the established electrochemical method for the determination of indole in plasma. The results showed a high correlation between the two methods. At last, the electrochemical sensor was successfully applied to detect the level of indole in plasma samples with satisfactory selectivity and sensitivity. The concentrations of plasma indole in healthy pregnant women and gestational diabetes mellitus (GDM) patients were 5.3 (4.1-7.0)µgL-1 and 7.2 (4.5-9.4)µgL-1, respectively.
