| Abstract: | An HPLC method for determining a flavonoid naringin and its metabolite, naringenin, in human urine is presented for application to the pharmacokinetic study of naringin. Isocratic reversed-phase HPLC was employed for the quantitative analysis by using hesperidin for naringin or hesperetin for naringenin as internal standard and solid-phase extraction using a strong anion exchanger, Sep-Pak Accell QMA cartridge. The HPLC assay was carried out using an Inertsil ODS-2 column (250×4.6 mm I.D., 5 μm particle size). The mobile phases were acetonitrile–0.1 M ammonium acetate–acetic acid (18:81:1, v/v; pH 4.7) for naringin and acetonitrile–0.1 M ammonium acetate–triethylamine (25:75:0.05; v/v; pH 8.0) for naringenin. The flow-rate was 1.0 ml min−1. The analyses were performed by monitoring the wavelength of maximum UV absorbance at 282 nm for naringin and at 324 nm for naringenin. The lower limits of quantification were ca. 25 ng/ml for naringin and naringenin with R.S.D. less than 10%. The lower limits of detection (defined as a signal-to-noise ratio of about 3) were approximately 5 ng for naringin and 1 ng for naringenin. A preliminary experiment to investigate the urinary excretion of naringin, naringenin and naringenin glucuronides after oral administration of 500 mg of naringin to a healthy volunteer demonstrated that the present method was suitable for determining naringin and naringenin in human urine. |
