Differentiating Westlake Longjing tea from the first- and second-grade producing regions using ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry-based untargeted metabolomics in combination with chemometrics.

There are numerous articles published for geographical discrimination of tea. However, few research works focused on the authentication and traceability of Westlake Longjing green tea from the first- and second-grade producing regions because the tea trees are planted in a limited growing zone with identical cultivate condition. In this work, a comprehensive analytical strategy was proposed by ultrahigh performance liquid chromatography-quadrupole time-of-flight mass spectrometry-based untargeted metabolomics coupled with chemometrics. The automatic untargeted data analysis strategy was introduced to screen metabolites that expressed significantly among different regions. Chromatographic features of metabolites can be automatically and efficiently extracted and registered. Meanwhile, those that were valuable for geographical origin discrimination were screened based on statistical analysis and contents in samples. Metabolite identification was performed based on high-resolution mass values and tandem mass spectra of screened peaks. Twenty metabolites were identified, based on which the two-way encoding partial least squares discrimination analysis was built for geographical origin prediction. Monte Caro simulation results indicated that prediction accuracy was up to 99%. Our strategy can be applicable for practical applications in the quality control of Westlake Longjing green tea.

Automatic time-shift alignment method for chromatographic data analysis.

Time shift among samples remains a significant challenge in data analysis, such as quality control of natural plant extracts and metabolic profiling analysis, because this phenomenon may lead to invalid conclusions. In this work, we propose a new time shift alignment method, namely, automatic time-shift alignment (ATSA), for complicated chromatographic data analysis. This technique comprised the following alignment stages: (1) automatic baseline correction and peak detection stage for providing useful chromatographic information; (2) preliminary alignment stage through adaptive segment partition to correct alignment for the entire chromatogram; and (3) precise alignment stage based on test chromatographic peak information to accurately align time shift. In ATSA, the chromatographic peak information of both reference and test samples can be completely employed for time-shift alignment to determine segment boundaries and avoid loss of information. ATSA was used to analyze a complicated chromatographic dataset. The obtained correlation coefficients among samples and data analysis efficiency indicated that the influences of time shift can be considerably reduced by ATSA; thus accurate conclusion could be obtained.

Characterization of aromatic glycosides in the extracts of Trollius species by ultra high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry.

Ultra high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UHPLC/ESI-Q-TOF MS/MS) was used to investigate the MS fragmentation behaviors of flavone C-glycosides present in the extracts of five Trollius species. In this study, the primary MS fragmentation pathways and key diagnostic fragment ions of flavone C-glycosides were systematically investigated and summarized to distinguish different types of derivatives and to trace other analogs in Trollius species. This method was useful, rapid, efficient and sensitive and allowed the simultaneous identification of different types of flavone C-glycosides present in other medicinal plants. The features of the MS fragmentation of these compounds indicated that the product ions were primarily the result of cleavage in the saccharide moiety, followed by hydrogen rearrangement and dehydration. In this study, thirty-six components including thirty-two flavone C-glycosides, two flavone O-glycosides and two phenylethanoid glycosides, were identified in the extracts of five Trollius species. Eleven of the flavone C-glycosides were identified by comparison with reference standards, and twenty-one flavone C-glycosides were tentatively identified based on their retention times, exact mass information and fragment ions. Two potentially new flavone C-glycosides (2″-O-vanilloylorientin and 2″-O-feruloylvitexin) were successfully characterized based on the summarized fragmentation pathways, and six known flavone C-glycosides (2″-O-glucosylvitexin, 2″-O-acetylorientin, 2″-O-acetylvitexin, 3″-O-acetylorientin, 3″-O-acetylvitexin and 6″-O-acetylvitexin) were identified in these plant species for the first time. In conclusion, the fragmentation pathways proposed in this paper were helpful for the identification of different types of flavone C-glycosides when no reference standards were available.

Two new diterpenes, neocaesalpin MR and minaxin C, from Caesalpinia minax.

Two new cassane-type diterpenes, neocaesalpin MR and minaxin C, were isolated from Caesalpinia minax HANCE. The structures of these compounds were elucidated by means of spectroscopic analysis. Among these isolated compounds, neocaesalpin MR showed mild activities toward HeLa and colon cancer (HCT-8) human cancer cell lines.