Metabolite identification and quantitation of RBD1016 siRNA: a direct comparison of hybridization-based LC-FD and LC-HRAM assays.

Aim: RBD1016 is an N-acetylgalactosamine-conjugated siRNA drug currently in a phase II trial for treatment of chronic hepatitis B virus. To evaluate its absorption, distribution, metabolism and excretion (ADME) and pharmacokinetic/pharmacodynamic (PK/PD) properties, two LC-based bioanalytical methods, LC-high-resolution/accuracy MS and LC-fluorescence detection, were developed and qualified. Materials & methods: The LC-high-resolution/accuracy MS method was used for metabolite identification and simultaneous quantitation of the antisense and sense strands as well as their respective metabolites. The LC-fluorescence detection assay was primarily used for analyzing the antisense strand and its metabolites in low-concentration plasma samples. The two methods were successfully bridged by analyzing the same sets of study samples. Results & conclusion: Both methods were found to have excellent accuracy/precision, specificity and reproducibility to support ADME and PK/PD studies of RBD1016 siRNA.

[Serum metabonomics in mice infected with mycoplasma pneumoniae by UPLC-Q-TOF-MS].

Ultra high performance liquid chromatography coupled with tandem quadrupole time of flight mass spectrometry(UPLC-Q-TOF-MS) was applied to metabonomics study in BALB/c mice infected with mycoplasma pneumoniae(MP) to analyze the changes in serum endogenous metabolites, identify potential biomarkers associated with mycoplasma pneumoniae pneumonia(MPP), analyze the metabolic pathway and explore the pathogenic mechanism of MPP. The BALB/c mice were inoculated with MP by repeated intranasal infectious routes to establish MPP models, and the results of the lung tissue biopsy, IgM and mycoplasma nucleic acid content determination showed that the models of MP in BALB/c mice were successfully established. UPLC-Q-TOF-MS was used to analyze the serum metabolic profiling of BALB/c mice infected with MP, and then principal component analysis(PCA) was combined with orthogonal partial least squares discriminant analysis(OPLS-DA) for data processing. The results showed that there were significant differences in serum metabolic profile between the MP infected mice and the normal mice. Forty-seven potential biomarkers such as ornithine, cortisol, vitamin A and tryptophan were screened out by database searching and MS information matching. These potential biomarkers related to 17 metabolic pathways including retinol metabolism, arginine and proline metabolism, steroid hormone synthesis and so on. The metabonomic research method for serum of mice infected with mycoplasma pneumoniae based on UPLC-Q-TOF-MS was established in this study. The metabolic changes of endogenous small molecules in mice infected with MP were reflected in the overall level, laying the foundation for the selection and evaluation of MPP drugs.