Simultaneous Quantitative Analysis of Shikonin and Deoxyshikonin in Rat Plasma by Rapid LC-ESI-MS-MS

The purpose of this article was to develop a rapid and robust LC-MS-MS method for quantifying shikonin and deoxyshikonin simultaneously in rat plasma using emodin as internal standard. The LC system consisted of an Agilent ZORBAX SB-C18 (1.8 mu m, 250 x 4.6 mm, 20 A degrees C) column. Elution with an isocratic mobile phase consisted of methanol/10 mM ammonium acetate in water/acetonitrile containing 0.05% formic acid (45:10:45, v/v/v) at a flow rate of 0.8 mL min(-1) yielded sharp, high-resolved peaks within 12 min. The lower limits of quantitation were 0.5 ng mL(-1) for shikonin, and 8 ng mL(-1) for deoxyshikonin. Correlation coefficient (r) values for the linear range of two analytes were greater than 0.99. Assay precision was < 13% and accuracy was 87-99%. This newly developed method was used to the pharmacokinetic studies of the shikonin analogues in rats after intravenous administration (n = 4).