Development of an LC-MS/MS method for quantification of two isomeric phenylpropenes and the application to pharmacokinetic studies in rats.

Isomers β-asarone and α-asarone have recently been demonstrated to have differential pharmacological activities. Here, we report an LC-MS/MS method developed using acetonitrile to extract two isomeric phenylpropenes from rat plasma. Separation was achieved using a XDB-C18 column (100 × 2.1 mm; i.d., 1.8 μm) with a mobile phase of methanol-0.1% formic acid (55:45, v/v) at a flow rate of 0.3 mL/min. Calibration curves ranging from 5.20 to 2080 ng/mL for β-asarone and from 3.68 to 1470 ng/mL for α-asarone were linear (r2  ≥ 0.9938) with the lower limits of quantification being 5.20 and 3.68 ng/mL for both isomers. Intravenous administration of β-asarone (2.22 mg/kg) and α-asarone (2.36 mg/kg) in rats yielded half-lives of 13.40 ± 4.11 and 28.88 ± 7.82 min with clearance values of 0.196 ± 0.062 mL/min/kg and 0.112 ± 0.012 mL/min/kg for β-asarone and α-asarone, respectively.