Assay of unbound teicoplanin in human plasma by centrifugal ultrafiltration combined with ultra performance liquid chromatography-tandem mass spectrometry / 药学实践杂志

Objective To establish an assay method for unbound teicoplanin in plasma by centrifugal ultrafiltration combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods Protein was removed from plasma by a Centrifree® ultrafiltration device. The ultrafiltrate was injected to determine the unbound concentration of teicoplanin. EndeadvorsilTM C18 column (1.8 μm, 50 mm×2.1 mm) was used with gradient elution of acetonitrile and 0.02 mol/L ammonium acetate solution (containing 0.1% formic acid). The detection was performed on a triple-quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM)mode via electro spray ionization (ESI). Results The calibration curve of unbound teicoplanin in plasma was linear over the range of 0.10 to 8.00 μg/ml (r=0.999). The intra-assay precision and the inter-assay precision of samples didn't exceed 7.00%. The average relative recovery ratio was 97.9%, and the matrix effect factor was 0.97. The samples had good stability after being stored at room temperature for 10 h or at −20 ℃ for 15 days, and freeze-thawed 3 times (RSDs were all within 6.50%). Conclusion This method is convenient, fast, sensitive and accurate. It provided a basis for clinical development of teicoplanin unbound concentration monitoring.

Screening potential mitochondria-targeting compounds from traditional Chinese medicines using a mitochondria-based centrifugal ultrafiltration/liquid chromatography/mass spectrometry method / 药物分析学报

Mitochondria regulate numerous crucial cell processes, including energy production, apoptotic cell death, oxidative stress, calcium homeostasis and lipid metabolism. Here, we applied an efficient mitochondria-based centrifugal ultrafiltration/liquid chromatography/mass spectrometry (LC/MS) method,also known as screening method for mitochondria-targeted bioactive constituents (SM-MBC). This method allowed searching natural mitochondria-targeting compounds from traditional Chinese medicines(TCMs), including Puerariae Radix (PR) and Chuanxiong Radix (CR). A total of 23 active compounds were successfully discovered from the two TCMs extracts. Among these 23 hit compounds, 17 were identified by LC/MS, 12 of which were novel mitochondria-targeting compounds. Among these, 6 active compounds were analyzed in vitro for pharmacological tests and found able to affect mitochondrial functions. We also investigated the effects of the hit compounds on HepG2 cell proliferation and on loss of cardiomyocyte viability induced by hypoxia/reoxygenation injury. The results obtained are useful for in-depth understanding of mechanisms underlying TCMs therapeutic effects at mitochondria level and for developing novel potential drugs using TCMs as lead compounds. Finally, we showed that SM-MBC was an efficient protocol for the rapid screening of mitochondria-targeting constituents from complex samples such as PR and CR extracts.

Determination of α-glucosidase inhibitors from Scutellaria baicalensis using liquid chromatography with quadrupole time of flight tandem mass spectrometry coupled with centrifugal ultrafiltration / 中国天然药物

The present study aimed at identifying potential lead compounds for diabetes mellitus drug discovery. We developed a novel method involving centrifugal ultrafiltration separation subsequent liquid chromatography with quadrupole time of flight tandem mass spectrometry (LC-Q/TOF-MS/MS) determination to screen α-glucosidase inhibitors in complex Scutellaria baicalensis Georgi (SBG) extract. By adding a second filter to the screening process, the level of non-specific binding of Compounds 1, 3, 10 and 11 was significantly decreased, and the level of non-specific binding of Compounds 5 and 15 also was reduced. As a result, five flavonoids identified as baicalein, baicalein, wogonin, chrysin, and oroxylin A, were rapidly found to interact with α-glucosidase and possess potent anti-α-glucosidase activity in vitro. Specific binding of ligands to α-glucosidase was demonstrated though the proposed method and the ligands could be ranked in order of affinity for α-glucosidase, which were corresponded to the order of inhibitory activity in vitro. In conclusion, our results indicated that the developed method is a rapid and effective screening method for rat intestinal α-glucosidase inhibitors from complex herbal medicines such as SBG.

Preperation and quality evaluation of vincristine sulfate thermosensitive liposomes / 中国药学杂志

OBJECTIVE: To prepare vincristine sulfate (VCR) thermosensitive liposomes, and evaluate its particle size and release characteristics in vitro and establish the methods for determination of content, entrapment efficiency and related substances.