Microscopic Mass Spectrometry Imaging Reveals the Distribution of Phytochemicals in the Dried Root of Isatis tinctoria

Abstract

The dried root of Isatis tinctoria L. (Brassicaceae) is one of the most popular traditional Chinese medicines with well-recognized prevention and treatment effects against viral infections. Above 300 components have been isolated from this herb, but their spatial distribution in the root tissue remains unknown. In recent years, mass spectrometry imaging (MSI) has become a booming technology for capturing the spatial accumulation and localization of molecules in fresh plants, animal, or human tissues. However, few studies were conducted on the dried herbal materials due to the obstacles in cryosectioning. In this study, distribution of phytochemicals in the dried root of Isatis tinctoria was revealed by microscopic mass spectrometry imaging, with application of atmospheric pressure–matrix-assisted laser desorption/ionization (AP-MALDI) and ion trap–time-of-flight mass spectrometry (IT-TOF/MS). After optimization of the slice preparation and matrix application, 118 ions were identified without extraction and isolation, and the locations of some metabolites in the dried root of Isatis tinctoria were comprehensively visualized for the first time. Combining with partial least square (PLS) regression, samples collected from four habitats were differentiated unambiguously based on their mass spectrometry imaging.

Desorption Electrospray Ionization Mass Spectrometry Imaging Illustrates the Quality Characters of Isatidis Radix

“…After the optimization of the preprocess method, ions of alkaloids, sulfur-containing compounds, phenylpropanoids, nucleosides, amino acids, organic acids, flavonoids, phenols, terpenes, saccharides, peptides, and sphingolipids were detected by DESI MSI in the cross-section of the root without extraction and isolation. In comparison with our previous results obtained from MALDI MSI (Nie et al, 2021 ), the signal sensitivity of DESI under negative mode was lower. But DESI performed better for nucleosides and ( R, S )-goitrin, the assay marker of Isatidis Radix in Chinese Pharmacopeia, edition 2020 (Chinese Pharmacopoeia Commission, 2020 ).…”

“…In our previous work, a MALDI MSI-based approach was developed to reveal the distributions of phytochemicals in Isatidis Radix. In total, 118 compounds were identified, and samples from different habitats were differentiated successfully (Nie et al, 2021 ). In this study, desorption electrospray ionization combined with quadrupole-time-of-flight mass spectrometry (DESI-Q-TOF/MS) was applied for the first time to illustrate the quality-related morphological characters of Isatidis Radix, providing a deeper insight into the understanding of the quality of the herbal medicine.…”

Recent Advances of Ambient Mass Spectrometry Imaging and Its Applications in Lipid and Metabolite Analysis

“…AMSI was also used to investigate fungus-related diseases, and several phospholipids and other unidentified metabolites in fungus and oomycete pathogens, on dehydrated agar plates by Eberlin et al [126]. In 2021, Nie et al revealed the spatial distribution of phytochemicals in the dried root of isatis indigotica by using AP-MALDI [127].…”

Hydroalcoholic Leaf Extract of Isatis tinctoria L. via Antioxidative and Anti-Inflammatory Effects Reduces Stress-Induced Behavioral and Cellular Disorders in Mice

“…Numerous phytochemical studies of the root and leaves of I. tinctoria indicate differences in their chemical composition. Depending on the extraction and separation methods, particular groups of metabolites are dominant [19,20]. In in vitro and in vivo studies both the root and leaf extracts from I. tinctoria show anti-inflammatory properties by inhibiting proinflammatory cytokines [21,22] and suppression of nitric oxide (NO) production, which at least in part explain its impact on inflammatory and oxidative pathways [23][24][25].…”