Abstract

Naringin and its aglycone naringenin, widely distributed in traditional Chinese medicines, had received extensive studies on their bioactivities. However, the plasma protein binding ratio, which played a very important role on pharmacokinetic and pharmacodynamic studies, remained unclear. In this present study, the protein binding of naringin and naringenin in rat, dog and human plasma was investigated using equilibrium dialysis and a liquid chromatography with electrospray ionization tandem mass/mass spectrometry (LC-ESI-MS/MS). The analytical time was less than 5 min without sacrificing resolution using ZORBAX Eclipse Plus-C18 (2.1 × 100 mm, 1.8 μm) column and MS/MS mode performed for multiple reaction monitoring. The plasma protein binding ratios of naringin were 83.30 to 84.56%, 72.14 to 74.06% and 48.17 to 51.33% in rat, human and dog plasma, respectively. No obvious concentration dependence was observed across the entire concentration range. On the other hand, the binding ratios for aglycone naringenin in three species plasma exceed 94% over all concentration studied, which suggested that naringenin existed predominantly in the bound form in the circulation blood at a wide range of naringenin concentration. The results may be speculated and make further impacts on their pharmacokinetic study.

Key words: Plasma protein binding, naringin, naringenin.