•A two-phase hollow fiber liquid phase microextraction based on magnetofluid was developed.•The method separated and determined the four main PhGs of Cistanche salsa extract in vivo.•The method is capable to get a higher enrichment ratio in a short time.A new and fast sample preparation technique based on two-phase hollow fiber liquid phase microextraction (HF-LPME) with magnetofluid was developed to quantitate and determine the four phenylethanoid glycosides (PhGs) (Echinacoside, Tubuloside B, Acteoside and Isoacteoside) in plasma after oral administration of Cistanche salsa extract. Analysis was accomplished by reversed-phase high performance liquid chromatography (RP-HPLC) with ultraviolet detection. Parameters that affect the HF-LPME processes, such as the content of magnetic powder, the solvent type, salt content, stirring speed, extraction time and hollow fiber length, were investigated and optimized. Under the optimized conditions, the preconcentration factors for PhGs were higher than 625. The calibration curve for PhGs was linear in the range of 0.1–100 ng mL−1 with correlation coefficients greater than 0.9996. The intra-day and inter-day precision (RSD) were below 8.74% and the limits of detection (LOD) for the four PhGs were 8–15 pg mL−1 (S/N = 3). The validated method was successfully applied to separate and determine the four PhGs in rat plasma after oral administration of C. salsa extract.Basic apparatus used for hollow fiber liquid phase microextraction: (A) conventional hollow fiber liquid phase microextraction and (B) hollow fiber liquid phase microextraction based on magnetofluid.

We have developed a series of new C10 dipeptide stationary phases via a simple and effective synthetic method. The preparation of the new phases involves the synthesis of silanes and the surface modification of silica. Chromatographic evaluations of these columns were performed using the Engelhardt, Tanaka, and Neue test mixtures. The applicability of these new stationary phases was also evaluated using a series of diagnostic probes including acids, bases or neutral compounds and several generic applications. These new C10 dipeptide stationary phases showed excellent hydrolytic stability over a wide pH range. Like other existing amide-embedded columns, these new stationary phases exhibit higher retention for polar and hydrophilic compounds and different selectivity as compared to conventional C18 columns. These new phases are compatible with 100% aqueous mobile phases, and also provide high column efficiency and good peak shapes for both acidic and basic compounds.Highlights► New C10 dipeptide stationary phases were developed via an effective method. ► Chromatographic parameters were evaluated. ► The new stationary phases exhibit good properties for applications in RPLC. ► The new stationary phases are a useful complement to conventional C18 columns.

Two pairs of nitronyl nitroxide radicals with specific molecular structures in which the imidazole radical moiety was directly bound to their chiral center have been prepared in their enantiopure forms. In these specific molecular structures, chirality may directly affect the unpaired spin electronic cloud. The X-ray crystal structures of them have been solved, which reveal that supermolecule helical chains are formed by intermolecular hydrogen bond interactions in the l-NNP crystal and the l-NNNBP is a 3D supermolecule structure shaped by means of intermolecular hydrogen bond interactions to link homochiral chains. Circular dichroism spectroscopy of the two pairs of chiral α-nitronyl nitroxides shows significant Cotton effects between 200 and 400 nm. The magnetic properties of the two pairs of nitronyl nitroxide radicals in the solid state were characterized by EPR spectroscopy and magnetic susceptibility measurements, respectively. Magnetic susceptibility measurements of the solids reveal antiferromagnetic interactions in all cases. However, in the l-NNNBP, the exchange interaction abruptly changes from untiferromagnetic to a ferromagnetic interaction at 40.0 k.

A new straightforward method based on cloud-point extraction (CPE) was developed to determine osthole in rat plasma by reversed phase high-performance liquid chromatography with ultraviolet detection using a photodiode array detector. The non-ionic surfactant Triton X-114 was chosen as the extract solvent. Variable parameters affecting the CPE efficiency were evaluated and optimized. A Zorbax SB-C18 column was used for elution separation at 25 °C with detection wavelength at 322 nm. Under the optimum conditions, the method was shown to be reproducible and reliable with intra-day precision below 7.62%, inter-day precision below 6.37%, and accuracy within ±5.02% and mean extraction recovery more than 90.4%, which were all calculated using a range of spiked samples at three concentrations of 0.5, 5.0 and 15.0 μg mL−1 for osthole in plasma. The calibration curve for the analyte was linear in the range from 0.1 to 20 μg mL−1 with the correlation coefficients greater than 0.9981. Limit of detection (S/N = 3) was less than 0.03 μg mL−1and limit of quantification (S/N = 10) was less than 0.1 μg mL−1. After strict validation, the method was successfully applied to the pharmacokinetic study of osthole in rats after oral and intravenous administration, respectively.

A new straightforward method based on cloud-point extraction (CPE) has been developed, optimized and validated for the determination of venlafaxine in human plasma by reversed-phase high-performance liquid chromatography with fluorescence detection. The non-ionic surfactant Triton X-114 (polyethylene glycol tert-octylphenyl ether) was chosen as the extract solvent. Separation was obtained using a reversed-phase Diamonsil column (C18, 250 mm × 4.6 mm I.D., 5 μm) and a mobile phase composed of acetonitrile–phosphate buffer solution (pH 3.0)–triethylamine (33.5:66.5:0.4). Fluorescence detection was used (λex 276 nm, λem 598 nm). Maprotiline was used as the internal standard. Under the optimum conditions, the linear range of venlafaxine in human plasma was 10–800 ng mL−1 (r2 = 0.9995). The limit of detection (LOD) was less than 2 ng mL−1 (S/N = 3) and the limit of quantification (LOQ) was less than 10 ng mL−1 (S/N = 10). The method was successfully applied for the evaluation of pharmacokinetic profiles of venlafaxine capsules in nine healthy volunteers.

Background: The 1-methyl-4-phenylpyridinium ion (MPP+), an inhibitor of mitochondrial complex I, has been widely used as a neurotoxin because it causes a severe Parkinson's disease-like syndrome accompanied by increased levels of intracellular reactive oxygen species (ROS) and apoptotic death. In the present study, we investigated the protective effects of osthole, a coumarin compound extracted from the plant-derived medicine Cnidium monnieri, on MPP+-induced cytotoxicity in cultured rat adrenal pheochromocytoma (PC12) cells.Methods: PC12 cells were treated with MPP+ 2 h after treated with different concentrations of osthole. 24 h later, the cell viability, the release of lactate dehydrogenase, the activity of caspase-3 and cytochrome c, the expression ratio of Bax/Bcl-2 and the generation of intracellular ROS were detected.Results: We found that pretreatment with osthole on PC12 cells significantly reduced the loss of cell viability, the release of lactate dehydrogenase, the activity of caspase-3 and cytochrome c, the increase in Bax/Bcl-2 ratio and the generation of intracellular ROS induced by MPP+. Moreover, our HPLC analysis of cell extracts confirmed that extracellular osthole does penetrate the cell membrane. Thus osthole may function as an intracellular antioxidant to reduce oxidative stress induced by MPP+.Conclusions: Therefore, the present study supports the notion that osthole may be a promising neuroprotective agent for the treatment of neurodegenerative disorders such as Parkinson's disease.