Simultaneous determination of cis- and trans-palmitoleic acid in rat serum by UPLC-MS/MS

Palmitoleic acid, a monounsaturated fatty acid which could affect glucose and lipid metabolism and reduce insulin resistance has two isomers, i.e. cis-palmitoleic acid (cPOA) and trans-palmitoleic acid (tPOA). However, the pharmacokinetic, metabolic transformation and structure-activity relationship of the two isomers have not been reported. A precise and accurate ultra performance liquid chromatography-tandem mass spectroscopy (UPLC-MS/MS) method was developed to determine cPOA and tPOA simultaneously. Both the cPOA and tPOA were administered i.g. (intragastric gavage) to rats at 75 mg/kg. Serum samples were collected and analyzed for the two isomers by UPLC-MS/MS on a reverse-phase BDS C18 column equilibrated and eluted with water (A) and acetonitrile (B) at a flow rate of 0.3 mL/min. The calibration curves for cPOA and tPOA were linear over the range 0.1-12 mu g/mL. Analytes were monitored by selected-reaction monitoring in negative electrospray ionization mode. The Tmax of cPOA was 0.94 +/- 0.44 h and the Cmax 8.17 +/- 1.97 mu g/L, and the Tmax and Cmax of tPOA were 1.50 +/- 0.98 h and 14.77 +/- 11.91 mu g/L, respectively. AUC(0-24 h) of cPOA and tPOA were 59.45 +/- 29.83 and 113.88 +/- 72.25 mg/L center dot h. The method was applied in pharmacokinetic study of cPOA and tPOA in rat serum successfully. Besides, the concentrations of cPOA and tPOA in rat serums were observed fluctuating with a consistent trend, which may be due to reciprocal bio-convert in the body.

Automated summary

A new method for determining the isomers of palmitoleic acid, cPOA and tPOA, has been developed and successfully applied in pharmacokinetic studies in rat serum. Fluctuating concentrations of cPOA and tPOA in rat serum were observed, suggesting reciprocal bio-conversion in the body.