Application · Mass Spectrometry Imaging

Imaging of Active Ingredients of TCM: Revealing the Spatial Origin of 'Effective Substances' in Herbal Materials

The efficacy of TCM often comes from the synergistic distribution of multiple active ingredients in specific parts rather than from uniform mixing. Traditional extraction-quantification methods grind the material for measurement, failing to answer exactly where this ingredient is found—in which tissue, secretory cavity, or colored spot. Mass spectrometry imaging (MSI) acquires point by point directly on sections, reconstructing the types and contents of active ingredients into spatial images, moving TCM research from 'measuring total amount' to 'seeing distribution'.
Table of Contents
1. Why TCM Is Suitable for MSI of Active Ingredients2. Typical Samples and Observable Ingredient Types3. Value in Quality Control and Authentication4. Integration with Metabolomics and Molecular Biology
Schematic principle: ion source ionizes the sample spot-by-spot Tissue section Sample Ionization beam Imaging of Active Ingredients of TCM: Revealing the Spatial Origin of 'Effective Substances' in Herbal Materials Ions MS analyzer
Imaging of Active Ingredients of TCM: Revealing the Spatial Origin of 'Effective Substances' in Herbal Materials — schematic diagram

1. Why TCM Is Suitable for MSI of Active Ingredients

TCM components are extremely complex: a single herb may simultaneously contain dozens to hundreds of compounds such as flavonoids, terpenoids, alkaloids, organic acids, glycosides and volatile oils, with a wide polarity span. Matrix-assisted imaging often faces matrix background interference and the low-mass region being 'covered'; by contrast, the Neo-Source MSI DPI adopts desorption electrospray ionization combined with photochemical post-ionization, with no polarity bias, and in both positive and negative ion modes can newly detect more than a hundred lipids, terpenoids, flavonoids, amino acids, glycosides, and other secondary metabolites, with overall metabolite signal intensity enhanced by 1–3 orders of magnitude, exactly fitting the 'full-polarity coverage' need of TCM.

Collaborative cases between Neo-Source and research teams have applied this method to real herbal materials. For example, a study published with the China Academy of Chinese Medical Sciences used DESI/PI-MSI to reveal the cause of Zhusha spots in Baizhu (Atractylodes macrocephala), finding that m/z 183.0807 and m/z 301.2164 were strongly correlated with colored structures (SCs), suggesting that accumulation of certain polyynes and sesquiterpenes may be the source of the Zhusha spots (Molecular Horticulture, 2025).

2. Typical Samples and Observable Ingredient Types

In imprint imaging of plants and herbal materials, DPI has demonstrated high detection sensitivity for various samples: theanine signal in tea leaf increased by 14.5x and caffeine by 61x; in Ginkgo, besides choline, disaccharides, glycosides and pheophytin detectable by DESI, the DESI/PI mode added flavonoids, ginkgolic acid and cardanol; in sage, monoterpenes, diterpenes and triterpenes were newly detected. These are exactly the typical families of TCM 'active ingredients'.

Methodologically, MSI imprinting (pressing plant tissue onto a carrier before imaging) can characterize the chemical spatial heterogeneity of different leaf regions (vein vs blade, tip vs base) non-destructively and rapidly, providing molecular-level evidence for genuine-region herbs, organ-specific use and harvest-time selection.

3. Value in Quality Control and Authentication

One of the pain points of TCM quality control is 'same material with different effects, different materials with same appearance'. The spatial chemical fingerprint provided by MSI can distinguish component distribution differences among herbs of different origins, parts and processing methods, helping to establish more refined quality-control standards. For samples with colored spots, abnormal textures or suspected adulteration, imaging can locate abnormal ingredient enrichment regions, providing a visualized basis for traceability and identification.

The Neo-Source MSI DPI supports high-throughput rapid analysis and screening, explicitly listing 'Chinese medicinal materials, blood, natural products and drugs' as typical applicable objects; the matrix-free, measure-on-demand feature allows pharmaceutical QC staff and food inspectors to get started relatively quickly without first becoming 'matrix-spraying experts'.

4. Integration with Metabolomics and Molecular Biology

A single image gives a spatial map of ingredients; to explain 'why the distribution is so', transcriptomics, metabolic pathways and histology must be combined. For example, if an ingredient enriches at the leaf margin, transcriptomics can be used to examine gene-expression differences in the corresponding region, forming an 'ingredient–gene–phenotype' closed loop.

At the engineering level, the two Neo-Source imaging sources are compatible with mainstream mass spectrometers from Agilent, AB SCIEX and Thermo; the tissue sections remain intact after imaging and can continue with H&E pathological testing, leaving room for multi-omics integration.

Frequently Asked Questions (FAQ)

Is matrix spraying necessary for TCM active ingredient imaging?
Traditional MALDI-type routes usually require spraying matrix and optimizing uniformity, and matrix peaks interfere with the low-mass region; Neo-Source MSI DPI and MSI LDPI are both matrix-free, allowing complex TCM samples to be analyzed directly, lowering the sample-preparation barrier.
Can MSI distinguish structurally and chemically similar ingredients in TCM?
MSI distinguishes compounds based on mass-to-charge ratio (m/z) and can simultaneously present the spatial distribution of multiple families such as flavonoids, terpenoids, alkaloids and glycosides on sections; DPI's photochemical post-ionization further improves detection of weakly polar and non-polar ingredients.
What does the Baizhu Zhusha-spot case illustrate?
This collaborative study used DESI/PI-MSI to lock onto characteristic ions strongly correlated with Zhusha spots, suggesting that accumulation of specific polyynes and sesquiterpenes may be the cause, demonstrating the capability of imaging to explain abnormal appearance in TCM.
How to interpret the signal enhancement data in tea leaf?
In the Neo-Source DPI case, theanine signal increased by about 14.5x and caffeine by 61x, reflecting the significant sensitivity enhancement of photoionization for specific polar/non-polar metabolites, not a true fold change in concentration.

Get Specifications & Quotation

To obtain detailed specifications, compatible models, or a quotation for the MSI LDPI / DPI full series imaging ion sources, visit the Neo-Source official website, or contact the official team for compatibility advice tailored to your mass spectrometer (Agilent / SCIEX / Thermo and other mainstream MS).

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