Abstract

Background: Methoxyflavones are isolated from Kaempferia parviflora, a Thai herb used in traditional medicine. The method of quantification of low level of methoxyflavones in biological samples needs to be optimized.

Objectives: To develop and validate a sensitive liquid chromatography-tandem mass spectrometry (LC-MS) for the determination of methoxyflavones in rat plasma and apply for pharmacokinetic study.

Method: Chromatographic separation was achieved on a reverse phase C18 column, using acetonitrile and 0.5% formic acid in water in a ratio of 10:90 v/v to 50:50 v/v as the mobile phase, and a flow-rate of 0.2 ml/min at 25°C. LC–MS detection was performed under positive ionization with selective ion monitoring using target ions.

Results: The calibration curve showed good linearity in the concentration range of 10–3000 ng/ml. The limits of detection (LOD) and quantification (LOQ) were 0.43-0.78 ng/ml and 0.93-2.35 ng/ml, respectively. The intra-day and the inter-day variances were less than 6.41% and 12.96%. The mean recovery of methoxyflavones was 73.73- 99.76%. The assay was successfully applied to a pharmacokinetics study in rats that used a topical application of 15% K. parviflora extract in IPM-based vehicle. After topical administration, the plasma concentration of methoxyflavones continuously increased up to 48 h, indicating prolonged absorption of methoxyflavones into systemic circulation, with the maximum concentration (C_max) of methoxyflavones being 401.94 ng/ml at 1 h.

Conclusion: The current method has been successfully applied to the determination of methoxyflavones in rat plasma and was used to study its pharmacokinetics under topical administration.

Keywords: Kaempferia parviflora, methoxyflavones, LC-MS, pharmacokinetics, topical, validation.

Graphical Abstract