LC−UV Analysis of N-{3-(2,4-Dioxo-1,4-dihydro-2H-quinazolin-3-yl)propyl}-N-[4-{3-(2,4-dioxo-1,4-dihydro-2H-quinazolin-3-yl)propyl-amino}butyl]acetamide (SP-8203) in Rat Plasma, Urine, and Gastrointestinal Tract Samples

Identification of new fluorophores in coelomic fluid of Eisenia andrei earthworms

Coelomic fluid of Eisenia andrei contains a number of UV-fluorescent compounds. In the present study we have found that four of these compounds showed identical fluorescence excitation and emission maxima at 310 nm and 364 nm, respectively, suggesting they share the same chromophore. NMR and HR-MS spectroscopy of the most abundant fluorophore reavealed that its molecule is composed of two quinazoline-2,4-dione rings connected by spermine linker. This compound was earlier indentified in Eisenia andrei as SP-8203. Moreover, we have identified the structure of the two other fluorophores, one differing from SP-8203 by the absence of N-acetyl group, the compound not reported in any other organisms before, and the other already found in E. fetida and regarded as species specific. However, our results indicate that this metabolite is also present in E. andrei in significant amounts. The possible origin and function of these new metabolites is discussed.

Optimized liquid chromatography-tandem mass spectrometry for Otaplimastat quantification in rat plasma and brain tissue

An optimized liquid chromatography-tandem mass spectrometry method for simple and sensitive quantification of Otaplimastat in rat plasma and brain tissue was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation method based on recovery and matrix effect. The chromatographic separation of the sample was performed on a reverse-phase AQ column with an isocratic mobile phase consisting of 10 mM ammonium acetate (pH 4.0) and acetonitrile (50:50, v/v). The analyte was quantified by multiple reaction monitoring with a Waters Quattro micro™ API mass spectrometer. The lower limits of quantification were 20 ng/mL in plasma and 2 ng/g in brain, with the relative standard deviation % of 7.6 and 8.0% for plasma and brain samples, respectively. Acceptable intra-day and inter-day precisions and accuracies were obtained. Otaplimastat was sufficiently stable under all relevant analytical conditions, including a temperature of 4°C for 24 hr, room temperature 20°C for 24 hr, -80°C for 10 days and three freeze-thaw cycles (each at -80°C for 24 hr), for rat plasma and brain tissue. The validated method was successfully used to measure Otaplimastat concentrations in rat plasma and brain samples.