Determination of isofraxidin and astilbin by HPLC in rat plasma and its application after orally administration the extract of Sarcandra glabra.

Sarcandra glaber is a common traditional Chinese medicine used to treat psoriasis and other infectious diseases, isofraxidin and astilbin are the main components of it. In order to study the pharmacokinetics of Sarcandra glabra, an HPLC method for simultaneous determination of isofraxidin and astilbin in rat plasma was established. Plasma samples were prepared using solid phase extraction method. C(18) column with a guard was used, mobile phase was consisted of A (methanol) and B (0.1% aqueous acetic acid) with gradient elution as follows: 0 - 4min, A: 35%, B: 65%; 4 - 10min, A: 35% - 45%, B: 65% - 55%; 10 - 20min, A: 45%, B: 55%. The flow rate was 1.2 mL/min from 0 to 4 min, 1.0 mL/min from 4 to 20 min. The detection wavelength was 300 nm. A linear correlation between drug amount and peak area was established for isofraxidin in the range of 20-320 ng and for astilbin in the range of 19-304 ng. The recovery was over 68% for both compounds, the accuracy was within 8%, and the inter-day and intra-day precisions were all less than 8%. The pharmacokinetics of isofraxidin and astilbin was studied after orally administration the extract of Sarcandra glabra.