UPLC-MS/MS Method for Simultaneous Determination of Three Major Metabolites of Mequindox in Holothurian.

This study developed an ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the detection of three major metabolites of mequindox, including 3-methyl-quinoxaline-2-carboxylic acid, 1-desoxymequindox, and 1,4-bisdesoxymequindox (MQCA, 1-DMEQ, and BDMEQ), in holothurian. Target analytes were simplified with ultrasound-assisted acidolysis extracted without complicated enzymolysis steps. After that, each sample was centrifuged and purified by an Oasis MAX cartridge. Then, the processed samples were separated and monitored by UPLC-MS/MS. This developed method has been validated according to FDA criteria. At fortified levels of 2, 10, and 20 µg/kg, recoveries ranged from 82.5% to 93.5% with the intraday RSD less than 7.27% and interday RSD less than 11.8%. The limit of detection (LOD) of all the three metabolites ranged from 0.21 to 0.48 µg/kg, while the limit of quantification (LOQ) ranged from 0.79 to 1.59 µg/kg. On application to commercial samples, 14 of 20 samples were detected positive for the three target analytes, with positive rate at 70 percentage. The result indicated that this method was specific, sensitive, and suitable for the quantification and conformation of the three major metabolites of MEQ in holothurian.

Carboxylicivirga sediminis sp. nov., isolated from coastal sediment.

A yellow-pigmented bacterial strain (JR1T) isolated from a sediment sample was subjected to a taxonomic study, based on phenotypic, genetic and physiological characterization. Here, we describe the cultivation and characteristics of strain JR1T, a novel member of the genus Carboxylicivirga in the family Marinilabiliaceae. Cells of strain JR1T were rod-shaped, Gram-stain-negative, non-motile and facultatively anaerobic. The temperature range for growth was 15-42 °C (optimum, 33 °C) and the pH range for growth was pH 6.0-8.5 (optimum, pH 7.0-7.5). Growth occurred in the presence of 0.0-10.0 % (w/v) NaCl (optimum 2.0-3.0 %). 16S rRNA gene sequence analysis produced results with 97.4 % similarity to Carboxylicivirga taeanensisMEBiC 08903T, 96.8 % similarity to Carboxylicivirga mesophilaMEBiC 07026T, 94.9 % similarity to Carboxylicivirga linearis FB218T and 94.6 % similarity to Carboxylicivirga flava Q15T. The DNA G+C content was 42.3 mol% and the major fatty acids were iso-C15 : 0, C15 : 0, anteiso-C15 : 0, C17 : 1ω6c and iso-C17 : 0-3OH. The major polar lipids detected were phosphatidylethanolamine and two unidentified lipids; the major respiratory quinone detected was MK-7. The results of the phenotypical, phylogenetic and biochemical analyses between the study strain and some related type strains indicated that this strain represent a novel species of the genus Carboxylicivirga within the family Marinilabiliaceae, for which the name Carboxylicivirga sediminis sp. nov. is proposed. The type strain is JR1T (=MCCC 1K03323T=KCTC 52869T).