Determination of hyperoside in rat plasma after intravenous administration by UPLC-MS

Hyperoside is one of the major components of Hypericum perforatum L. and also present in many plant species such as Abelmoschus manihot （L.） Medik., Ribes nigrum L. and Rosa agrestis Savi （Rosaceae）. Because hyperoside exhibits many biological activities, the pharmacokinetics profile of hyperoside needs to be studied for further elucidating its mechanism of action. A simple method for the determination of hyperoside in rat plasma was developed by using ultra-high performance liquid chromatography coupled with mass spectrometry （UPLC-MS）. Only 50 ~tL plasma samples were required for sample preparation. The quantitative detection of hyperoside was accomplished by selected ion monitoring （SIM） in negative ion mode. Hyperoside was analyzed in less than 10 rain. Good linearity was obtained （r2〉0.999） and the intra- and inter-day precision of the method were lower than 15%. Lower limit of quantification （LLOQ） was 4 ng/mL for hyperoside in rat plasma. Our method showed advantage in the lower LLOQ compared with the reported method; furthermore, smaller amount of plasma was needed. The method was successfully applied for the pharmacokinetics study of hyperoside in rat after intravenous administration of hyperoside.

Molecular characterization of root exudates using Fourier transform ion cyclotron resonance mass spectrometry

The release of root exudates(REs) provides an important source of soil organic carbon. This work revealed the molecular composition of REs of different plant species including alfalfa( Medicago sativa L.), bean( Phaseolus vulgaris L.), barley( Hordeum vulgare L.), maize( Zea mays), wheat( Triticum aestivum L.), ryegrass( Lolium perenne L.) and pumpkin( Cucurbita maxima) using electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry(ESI FT-ICR MS). The combination of positive ion mode( + ESI) and negative ion mode(-ESI) increased the number of the molecules detected by ESI FT-ICR MS, and a total of 8758 molecules were identified across all the samples. In detail, lipids and proteins and unsaturated hydrocarbons were more easily detected in + ESI mode, while aromatic compounds with high O/C were readily ionized in-ESI mode, and only 38% of the total assigned formulas were shared by -ESI and + ESI modes. Multivariate statistical analysis of the formulas indicated that the close related plants species secreted REs with similar molecular components. Moreover, the unsaturation degree and nitrogen content were the two key parameters able to distinguish the similarities and differences of molecular components of REs between plant species. The results provided a feasible analysis method for characterization of the molecular components of REs and for the first time characterized the molecular components of REs of a variety of plant species using ESI FT-ICR MS.