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.
Highlights
Natural products have always benefited the health care of people worldwide and are used as herbal medicines commonly (He et al, 2020)
Distribution of phytochemicals in the dried root of Isatis tinctoria was revealed by microscopic mass spectrometry imaging, using atmospheric pressure–matrixassisted laser desorption/ionization (AP-MALDI) combined with ion trap–time-of-flight mass spectrometry (IT-TOF/MS)
All samples were authenticated by Associate Professor Shuai Kang, who is in charge of the Traditional Chinese Medicine Herbarium, National Institutes for Food and Drug Control
Summary
Natural products have always benefited the health care of people worldwide and are used as herbal medicines commonly (He et al, 2020). (Isatis indigotica Fortune ex Lindl.) (Isatidis Radix in Latin, Isatis root in English, and Banlangen in Chinese) has been widely used as the remedy for fever and infection in China and other countries (Zhou and Zhang, 2013). It is well recognized for prevention and treatment effects against a variety of viral infections, such as seasonal flu (Speranza et al, 2020), severe acute respiratory syndrome (Lin et al, 2005), and H1N1 flu epidemic (Li and Tao, 2013; Luo et al, 2019). As the important ingredient in the so-called Three Drugs and Three Prescriptions, the dried root of Isatis tinctoria has been playing an active role in fighting against the novel corona virus disease 2019 (COVID-19) (Li et al, 2020b; Li and Xu, 2021).
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