Simultaneous quantification of three iridoids in rat plasma after oral administration of Zhi-zi-chi decoction using...

A sensitive and efficient liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for the simultaneous determination of geniposide, 6α-hydroxygeniposide, and genipin gentiobioside in rat plasma. After the addition of internal standard (I.S.) salidroside and acidification (formic acid, 0.1%), plasma samples were carried out by protein precipitation with acetonitrile and separated on a Kromasil C(18) column (200 mm × 4.6 mm, 5 μm) within a runtime of 15.0 min. The linear ranges were 2-250 ng/mL for both 6α-hydroxygeniposide and genipin gentiobioside and 2-2000 ng/mL for geniposide, respectively. The lower limit of quantification (LLOQ) was 2 ng/mL for all the analytes. The validated method was successfully applied to the pharmacokinetics study of geniposide, 6α-hydroxygeniposide, and genipin gentiobioside in rats after oral administration of Zhi-zi-chi decoction.