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High-Performance Liquid Chromatography
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Joel J. Kirschbaum, Adorjan Aszalos
A trimethylsilane column was used to assay epimers in body fluids using a mobile phase of 0.005 M aqueous n-heptylamine-methanol (89:11) adjusted to pH 6 with phosphoric acid and flowing at 1.4 ml/min into a 280 nm detector [279]. Detection limits were 1.5 μg/ml of plasma and 7.5 μg/ml of urine. HPLC assays showed a negative 3% bias compared with microbiological plasma assays, but the precision is superior. A phenyl column was also used to determine R-S isomer ratios in serum and tissue using a mobile phase of acetonitrile-0.1 M ammonium acetate, adjusted to pH 5 with acetic acid (2:98), flowing at 1.5 ml/min into a detector set to 270 nm [280]. The limit of detection was 1 μg/ml for each epimer with a linear response from 5 to 20 μg/ml. Clearance of R is higher than that of S - moxalactam.
Phenyl-substituted aminomethylene-bisphosphonates inhibit human P5C reductase and show antiproliferative activity against proline-hyperproducing tumour cells
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2021
Giuseppe Forlani, Giuseppe Sabbioni, Daniele Ragno, Davide Petrollino, Monica Borgatti
3,5-Dibromoaniline (3.01 g, 12.00 mmol), triethyl orthoformate (2.40 mL, 14.40 mmol) and diethyl phosphite (6.18 mL, 48.00 mmol) were vigorously stirred and heated at 120 °C for 16 h. After cooling, volatiles were evaporated under reduced pressure. Trituration of the solid with n-hexane followed by filtration furnished the pure ester tetraethyl (3,5-dibromophenylaminomethylene) bisphosphonate (4.38 g, 68% yield) which was further dissolved in concentrated hydrochloric acid (300 mL) and refluxed for 4 h. After this period the reaction mixture was cooled and concentrated under reduced pressure affording a solid which was washed with small amounts of cold distilled water and dried under vacuum to obtain the pure bisphosphonic acid Br2PAMBPA as a whitish solid (3.31 g, 65% overall yield). For NMR analysis 1H (300 MHz), 13 C (101 MHz), 31 P (122 MHz) NMR spectra (Supplementary Figures S1 and S2) were recorded in CDCl3 or DMSO-d6 solutions at room temperature. The chemical shifts in 1H and 13 C NMR spectra were referenced to trimethylsilane (TMS), while in 31 P NMR were referenced to 85% H3PO4 in D2O. Peak assignments were aided by 1H-1H COSY and gradient-HMQC experiments.
Alloimperatorin from Ammi majus fruits mitigates Piroxicam-provoked gastric ulcer and hepatorenal toxicity in rats via suppressing oxidative stress and apoptosis
Published in Biomarkers, 2022
Howaida I. Abd-Alla, Ghadha Ibrahim Fouad, Kawkab A. Ahmed, Kamel Shaker
Melting points were determined in hot stage microscopy and were uncorrected. Shimadzu UV-240 spectrophotometer (P/N 240 − 58000) was used for the UV spectra. Mass spectra were obtained on a Varian MAT 711 MS and with Varian MAT CH7A mass spectrometer (Bremen, Germany). NMR spectra were obtained on a Varian Mercury 300 (Varian, UK), 1³C (75 MHz) and Bruker WM-400, and AM-400 NMR, 13C (100 MHz) spectrometers in CDCl3 solvent. The δ-values (ppm) were calculated relative to that of the internal standard trimethylsilane TMS. High analytical grade products of chemicals from Merck (Germany), Sigma (USA), Fluka (Switzerland), and Riedel de Hàen (Germany) were used.
Mechanical properties and performances of contemporary drug-eluting stent: focus on the metallic backbone
Published in Expert Review of Medical Devices, 2019
Ply Chichareon, Yuki Katagiri, Taku Asano, Kuniaki Takahashi, Norihiro Kogame, Rodrigo Modolo, Erhan Tenekecioglu, Chun-Chin Chang, Mariusz Tomaniak, Neville Kukreja, Joanna J. Wykrzykowska, Jan J. Piek, Patrick W. Serruys, Yoshinobu Onuma
Stainless steel has been widely used as a backbone material particularly in the earlier generation of coronary stents. From WALLSTENT, a first introduced self-expandable coronary stent, and PALMAZ-SCHATZ, the first balloon-expandable coronary stent, to CYPHER and TAXUS stent, stainless steel is a primary component in the metallic platform of these stents. Although there are a wide variety of versions of stainless steel, 316L, an extra-low carbon stainless steel, is mostly utilized in the manufacturing of the coronary stents. The composition and characteristics of 316L stainless steel are shown in Table 1 [21–30]. Despite its suitable properties in stent production, there are some caveats of stainless steel. The density of stainless steel is low, thereby its fluoroscopic visibility is poorer than other materials. Gold, a highly radiopaque material, had been used for surface coatings of the stainless steel to improve the fluoroscopic visibility. However, studies showed a reaction of gold causing inflammation leading to higher rates of restenosis [31]. A major concern of stainless steel is its poor corrosion resistance. Since nickel is a primary component of stainless steel, releasing of the free ions of nickel can cause inflammation and an allergic reaction subsequently leading to restenosis [32]. Several solutions have been proposed to overcome the hindrance of stainless steel. Nanocoatings with trimethylsilane plasma on the surface of 316L stainless steel stent prevented the corrosive release of ions potentially limiting its detrimental effect on the vessel and circulation [33]. In addition to the improvement in corrosion resistance, coating with Iridium-Titanium oxide enhanced the radiopacity of stainless steel [34]. Moreover, surface modification by nanotechnology can potentially result in better corrosion resistance, mechanical stability, and biocompatibility [35].