A simple and sensitive HPLC-MS/MS assay for the quantitation of montelukast in cell-based systems in vitro pulmonary drug permeability study.

Montelukast is a potent and selective antagonist of the cysteinyl leukotriene receptor 1 subtype (CysLT1) and widely used in the form of oral tablets and granules for asthma prophylaxis and treatment. Recently, due to the pulmonary inhaled administration can limit montelukast distribution in the systemic circulation, avoid the first-pass metabolism and have better therapeutic effects in respiratory disease treatment, explore alternative routes of administration, like delivery of montelukast via an inhaled, is a new research trend for montelukast. The aim of the current study was to develop and validate a simple, accurate, highly sensitive and selective liquid chromatography-tandem mass spectrometry method (LC-MS/MS) for determination of montelukast in an in vitro cell-based pulmonary pharmacokinetics system model, which can be used to be a better understanding the fate of inhaled montelukast in the lungs. In this study, montelukast was extracted by protein precipitation with acetonitrile containing labeled montelukast. The chromatography was performed on an Agilent Eclipse plus C8 column (4.6 mm × 100 mm, 3.5 µm, Darmstadt, Germany) operating at 35 ◦C. The mobile phase consisted of acetonitrile: 20 mM ammonium formate buffer (80: 20, v/v), was delivered at a flow rate of 0.5 mL/min. montelukast and the internal standard were both eluted at 4.2 min. A linear (1/x2) relationship was used to perform the calibration over an analytical range from 0.5 to 600 ng/mL. The intra- and inter-batch precision expressed as CV for four QC samples including LLOQ range from 1.14 % to 6.25 %. The intra- and inter-batch accuracy for four concentrations of montelukast were in the range of 95.19%-104.1%. All the values for accuracy and precision were within the acceptance range. The method met all the bioanalytical method validation requirements by ICH and was suitable for the assay of montelukast which in the in vitro cell-based pulmonary pharmacokinetics system model.

Discovery of the possible mechanisms in kouyanqing granule for treatment of oral ulcers based on network pharmacology.

BACKGROUND: Oral ulcer diseases are complex inflammatory diseases caused by multi-factors, which severely impact patient quality of life. Kouyanqing Granule (KYQG) has been used to treat inflammatory diseases of the mouth and throat, including recurrent aphthous stomatitis (RAS), traumatic ulcers, oral leukoplakia and so on. However, the underlying molecular mechanisms of KYQG in treating these diseases are still unclear. We aimed to explore the possible mechanisms in KYQG for the treatment of oral ulcers. METHODS: An innovative network pharmacology method was established by incorporating targets searching and fishing, network analysis, and silico validation to discover the pharmacological mechanisms of action of KYQG for the treatment of oral ulcers. Then, we verified the reliability of this method by an animal experiment. RESULTS: Our data indicated that a total of 47 key targets were screened, which mainly involved in three function modules including the inhibition of inflammation, the regulation of immunological response, and the suppression of oxidative stress. The implementation of these functions relies on the complex multi-pathways network, especially TNF signaling pathway and HIF-1 signaling pathway. The results of the experimental verification indicated that KYQG significantly inhibited the serum levels of cyclooxygenase-2 (COX2), matrix metalloproteinase 9 (MMP9) and tumor necrosis factor-alpha (TNF-α) in rats with oral ulcer. CONCLUSION: KYQG exhibited the therapeutic effects on oral ulcers probably by inhibiting inflammation, regulating immunological response, and suppressing oxidative stress through a complex multi-pathways network. Particularly, TNF signaling pathway and HIF-1 signaling pathway may play crucial roles in the protection of KYQG against oral ulcers. This work not only offers a method for understanding the functional mechanisms of KYQG for treating oral ulcer diseases from a multi-scale perspective but also may provide an efficient way for research and development of complex composition formula.

Effects of Total Flavonoids from Exocarpium Citri Grandis on Air Pollution Particle-Induced Pulmonary Inflammation and Oxidative Stress in Mice.

Exocarpium Citri Grandis (ECG) is a famous traditional Chinese medicine, which has been commonly used to alleviate cough and phlegm for more than several hundred years, and total flavonoids are the main effective components of this medicine. This study investigated the effects of total flavonoids from ECG (TFECG) on pulmonary inflammation and oxidative stress induced by PM2.5 in mice. Model mice received an intratracheal instillation of PM2.5 (10 mg/mL) once at day 0. Bronchoalveolar lavage fluid (BALF) was collected after 72 hr to measure the total number of white blood cell (WBC), neutrophils (NEUT), lymphocytes (LYMPH), and monocytes (MONO). The levels of tumor necrosis factor-α (TNF-α), interleukin 1ß (IL-1ß), interleukin-6 (IL-6), and interleukin-18 (IL-18) in BALF were quantified by using enzyme-linked immunosorbent assay kits. Lung tissues were used to determine the contents of total protein (TP), malondialdehyde (MDA), nitric oxide (NO), reduced glutathione (GSH), oxidized glutathione (GSSG) and the activities of superoxide dismutase (SOD), lactate dehydrogenase (LDH), Glutathione Peroxidase (GSH-Px), and inducible nitric oxide synthase (iNOS). We found that TFECG significantly inhibited PM2.5 -stimulated overproduction of TNF-α, IL-1ß, IL-6, and IL-18 and increased the numbers of WBC, NEUT, LYMPH, and MONO in BALF. TFECG observably relieved the PM2.5 -induced increases in the contents of TP, MDA, and NO, and the activities of LDH and iNOS. TFECG also alleviated PM2.5 -induced decreases in the activities of iNOS and GSH-Px as well as GSH/GSSG ratio. The results indicate that TFECG has anti-inflammatory and antioxidant activities, which may potentially contribute to the treatment of PM2.5 -induced lung injury. PRACTICAL APPLICATION: Exocarpium Citri Grandis (ECG) is rich in flavonoids, which are beneficial to improve anti-inflammation and antioxidant capacity. We proved that total flavonoids of ECG had a positive therapeutic effect on PM2.5 -induced lung injury, which expands the potential applications of ECG in the dietary supplement industries.

NO2 gas sensor based on graphene decorated with Ge quantum dots.

We report a NO2 gas sensor based on germanium quantum dots (GeQDs)/graphene hybrids. Graphene was directly grown on germanium through chemical vapor deposition and the GeQDs were synthesized via molecular beam epitaxy. The samples were characterized by atomic force microscope, Raman spectra, scanning electron microscope, x-ray photoelectron spectroscope and transmission electron microscope with energy dispersive x-ray. By introducing GeQDs on graphene, the gas sensor sensitivity to NO2 was improved substantially. With the optimization of the growth time of GeQDs (600 s), the response sensitivity to 10 ppm NO2 can be as high as 3.88, which is 20 times higher than that of the graphene sensor without GeQDs decoration. In addition, the 600 s GeQDs/graphene hybrid sensor exhibits fast response and recovery rates as well as excellent stability. Our work may provide a new route to produce low-power consumption, portable, and room temperature gas sensor which is amenable to mass production.