Mapping alkaloids with mass spectrometry imaging: Application of spatial distribution in medicinal plants and animal tissues.

Alkaloids, as natural bioactive compounds, exhibit significant pharmacological activities and broad applications, holding considerable research value in botany, drug metabolism, and toxicology. In the field of mass spectrometry detection, alkaloids are extensively studied due to their favorable response in positive ion mode. As a mature and rapidly evolving molecular imaging technology, mass spectrometry imaging (MSI) can intuitively visualize the spatial distribution of alkaloids in tissues without the need for labeling. Currently, the most commonly used MSI techniques for alkaloids include secondary ion mass spectrometry imaging (SIMS-MSI), matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), and desorption electrospray ionization mass spectrometry imaging (DESI-MSI). These techniques play an irreplaceable role in revealing the micro-regional distribution and accumulation of alkaloids in medicinal plant tissues (such as roots, stems, leaves, and specific organs) as well as in biological tissues of animals. Therefore, the principles of MSI techniques are outlined in this paper, followed by a comprehensive review of MSI applications in alkaloid-related research. This review focuses on case applications of MSI techniques in visualizing alkaloids within the productive parts of medicinal plants and spatial distribution dynamics of alkaloids in animal tissues. These promising technologies are conducive to the in-depth research of alkaloid drugs.