Simultaneous determination of deuterium-labeled ergosterol and brassicasterol in stroke-prone spontaneously hypertensive rats by ultra-high performance liquid chromatography-electrospray ionization-tandem mass spectrometry

Abstract

A previous study has shown that brassicasterol-d₁ was detected in the serum of stroke-prone spontaneously hypertensive rats after oral administration of ergosterol-d₁. To quantitatively evaluate the serum concentration of brassicasterol-d₁, an ultra-high performance liquid chromatography-electrospray ionization-tandem mass spectrometry method was developed for the simultaneous determination of picolinyl ester-derivatized ergosterol-d₁ and brassicasterol-d₁. The separation was performed on an ODS column (Waters Acquity UPLC BEH C18) with a mobile phase consisting of methanol and water containing 0.1% acetic acid (95/5, v/v). Linear calibration curves in the presence of the serum were obtained in a concentration range of 0.04–8 μg mL⁻¹. Recovery rates of 95.6–119% were obtained with an RSD (n = 6) of less than 7.5%. The method was applied to the determination of time-concentration curves of ergosterol-d₁ and brassicasterol-d₁ in stroke-prone spontaneously hypertensive rats, showing a pharmacokinetic profile of ergosterol-d₁ where the peak serum concentration of brassicasterol-d₁ was 3-fold higher than that of ergosterol-d₁.