No abstract

A liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry method was developed and validated to investigate the pharmacokinetic properties of β-sitosterol, campesterol, and stigmasterol in rat plasma. Cholesterol-d was used as an internal standard. To avoid interference of the three phytosterols in rat plasma and minimize matrix effects, a small volume (10 μL) of 4% bovine serum albumin was used as a surrogate matrix for making calibrators and quality control samples. Rat plasma (10 μL) samples were extracted by liquid-liquid extraction with methyl tert-butyl ether and separated on a Kinetex C column. The detection was performed on a triple quadrupole tandem mass spectrometer in selected reaction monitoring mode using positive atmospheric pressure chemical ionization. This assay was linear over concentration ranges of 250-5000 ng/mL (β-sitosterol), 250-5000 ng/mL (campesterol), and 50-2000 ng/mL (stigmasterol). Additionally, a second set of quality controls made in rat plasma was also evaluated against calibration curves made using the surrogate matrix. All the validation data, including the specificity, precision, accuracy, recovery, matrix effect, stability, and incurred sample reanalysis conformed to the acceptance requirements. Our method was successfully applied to study the pharmacokinetics of three phytosterols in rats.

The proliferation and migration of vascular smooth muscle cells (VSMCs) play important roles in the formation and progression of intimal thickening in early-phase atherosclerosis and in restenosis after vascular injury. Tumor necrosis factor-α (TNF-α) is released from macrophages in atherosclerotic lesions and from neointimal vascular smooth muscle cells after balloon-injury. Obovatol, a major biphenolic component isolated from the Magnolia obovata leaf, is known to have anti-inflammatory and antitumor activities. The goal of this study was to examine the cardioprotective effects of the obovatol derivative OD 78 on the TNF-α-induced proliferation and migration of rat aortic smooth muscle cells (RASMCs). The antiproliferative effects of OD 78 on RASMCs were examined by cell counting and [(3)H]-thymidine incorporation assays. Treatment of cells with 1-4 μM OD 78 inhibited the proliferation and DNA synthesis of TNF-α-stimulated RASMCs in a concentration-dependent manner, without cytotoxicity. Treatment with OD 78 inhibited TNF-α-mediated p38 phosphorylation, but did not change the activation of extracellular signal-regulated kinase or c-Jun N-terminal kinase. Furthermore, treatment with OD 78 decreased TNF-α-induced levels of cyclin E, cyclin D1, CDK2, proliferating cell nuclear antigen, and phosphorylated retinoblastoma protein, but not the CDK4 expression level. Also, OD 78 inhibits the migration of TNF-α-induced RASMC in transwells. OD 78 treatment strongly decreased matrix metalloproteinase-9 (MMP-9) expression in a dose-dependent manner, but the MMP-2 expression was unchanged. These results show that OD 78 may be developed as a potential antiproliferative agent for the treatment of angioplasty restenosis and atherosclerosis.