MALDI imaging for the localization of saponins in root tissues and rapid differentiation of three Panax herbs

Abstract

The roots of Panax genus with ginseng saponins as bioactive ingredients have been widely used as herbal medicines and food additives. Panax ginseng, Panax quinquefolius, and Panax notoginseng are three major commercial species in Panax genus, with similar morphological appearance but different pharmacological functions. Various methods have been developed and applied for the differentiation of these species. In this work, MALDI-TOF-MS imaging (MSI) was employed for the localization of saponins in root tissues and for the rapid differentiation of the three Panax species for the first time. After a simple sample preparation, MALDI-TOF-MSI analysis of root tissue allowed the detection of 51 saponins. Localization of saponins in the tissue was mapped in ion images, which were obviously related to botanical structure. The localization modes varied with Panax species, providing valuable information for the discrimination of ginseng species. Principal component analysis (PCA) of data collected from areas with abundant saponins based on ion images was applied for the differentiation. Nine characteristic saponin peaks were identified from the PCA analysis. The MALDI-TOF-MSI together with area-specific data analysis provided high potential for the rapid differentiation of Panax herbs.

MALDI-TOF MS as a Novel Tool for the Estimation of Postmortem Interval in Liver Tissue Samples

“…The amount of matrix was then applied in a defined range (minimum/maximum number) of cycles based on a given sensor signal or the defined range of spray cycles that are specified within each phase 41 . Spray time was approximately 2 s, and incubation time was 30 s. The detailed pretreatments for peptide/protein analysis, such as fresh frozen tissue sample preparation and matrix application, were prepared as reported in earlier studies 37–42 .…”

Exodermis and endodermis are the sites of xanthone biosynthesis in Hypericum perforatum roots

“…In vitro grown roots of Peritassa laevigata (Celastraceae) contained quinonemethide triterpenoids in the outer cell layers, such as cortical cells (Pina et al, 2016). In secondarily thickened roots of Panax species (P. ginseng, P. quinquefolius, and P. notoginseng), ginsenosides were primarily localized to the cork (Wang et al, 2016b). In roots of Paeonia lactiflora, gallotannins accumulated in the cork and in xylem regions (Li et al, 2016).…”

High-mass-resolution MALDI mass spectrometry imaging reveals detailed spatial distribution of metabolites and lipids in roots of barley seedlings in response to salinity stress

“…Recent MALDI–MSI analyses of roots were carried out on cross-sections with lower spatial resolution than presented in our study. For example, a 100 µm laser step size has been used to visualize saponin distribution in root cross-sections of three Panax species (Wang et al 2016 ), a 50 µm laser spot diameter was used to analyze secondary metabolites in sections of root-nodules of Medicago (Ye et al 2013 ), a 60 µm laser spot diameter was used to analyze thapsigargin in Thapsia garganica taproot cross sections (Andersen et al 2017 ). Thus, images generated as part of this study represent an improvement of 1.6-times and 3.3-times in the quality of images than previously reported by (Wang et al 2016 ) and (Ye et al 2013 ), respectively.…”

“…To date, most MALDI–MSI studies of roots have been on secondary metabolites and small molecules (Li et al 2016 ; Peukert et al 2012 ; Wang et al 2016 ; Ye et al 2013 ) and the most thorough study on lipids in roots has been carried on bulked tissue (Natera et al 2016 ). The protocol developed as part of this study allowed the tentative identification, curation and annotation of 124 lipid species and 42 metabolites by high-resolution MALDI–MSI (Tables S8, S10 and S11) in longitudinal barley root sections for the first time.…”