Dalbergia odorifera T. Chen is a first-grade state protected plant in China. However, it is difficult to distinguish it from the closely related species Dalbergia tonkinensis Prain, which is less important in economic value, by wood anatomical features. In this study, three potential DNA barcode sequences, namely rpoC1, trnH-psbA and internal transcribed spacer (ITS), were used to differentiate wood of D. odorifera from D. tonkinensis. The average quantities of DNA extracts from twigs, sapwood and heartwood were 16.3, 11.5 and 6.0 ng mg-1, respectively. The success rates for polymerase chain reaction (PCR) amplification for three loci, namely ITS, trnH-psbA and rpoC1, were 62.5, 100 and 81.25%, respectively. The success rate for bidirectional sequencing of amplified products was 100% for all the three loci. The identification power of the three proposed DNA barcodes has been calculated by the BLAST, tree-based method and the TAXONDNA method. The interspecific differences of the trnH-psbA region were greater than intraspecific variations. Moreover, the identification power of trnH-psbA was higher than that of ITS and rpoC1 regions at the species level. Finally, the trnH-psbA region is proposed as a DNA barcode for wood identification between D. odorifera and D. tonkinensis.

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Tigecycline, a novel intravenously administered glycylcycline antibiotic, currently plays a key role in the management of complicated multiorganism infections. However, current liquid chromatography with tandem mass spectrometry methods briefly describe parameters and the only reported internal standard was sometimes difficult to obtain. In our study, an updated liquid chromatography with tandem mass spectrometry method for the quantitative analysis of tigecycline in human serum was developed. Sample preparation involved precipitation with 20% trichloroacetic acid. Chromatographic separation of tigecycline and tetracycline (internal standard) was achieved on a Hypersil GOLD C18 column using gradient elution. The selected reaction monitoring transitions were performed at m/z 586.1→513.2 for tigecycline and m/z 445.1→410.2 for tetracycline. The assay was linear over the concentration range of 5-2000 ng/mL. The intra- and interday precisions at three concentration levels (10, 100, and 1600 ng/mL) were <15% and their accuracies were within the range of 95.1-106.1%. The mean recovery ranged from 94.3 to 105.6% and the matrix effect from 92.1 to 97.6%. Tigecycline was stable under all tested conditions. This validated method was successfully applied to a pharmacokinetic study in critically ill patients. The data demonstrated that our method allows quantification of tigecycline in serum in a quick and reliable manner for widespread application.

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