Differential distribution of characteristic constituents in root, stem and leaf tissues of Salvia miltiorrhiza using MALDI mass spectrometry imaging.

Segmentation-quantification is the most commonly used method for studying the tissue distribution of bioactive constituents in plant, but this method would bring uncontrollable pollution, compound migration and denaturation. Mass spectrometry imaging (MSI), as a new method developed in the past 20 years, has high sensitivity, high spatial resolution, high degree of visualization, and low risk of contamination and degeneration when studying tissue distribution of compounds. For the first time we applied matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to tissue distribution of characteristic constituents of the medicinal plant Salvia miltiorrhiza. From the collected data, we found the regional differences in root, stem, and leaf tissues, and the ion information with differential distribution characteristics. We also identified 18 bioactive constituents in S. miltiorrhiza with their spatial distribution information. In addition, the plant was divided into five parts, and the identified compounds were analyzed for differences between tissues using LC-MS, which results verified those found from the MSI. It is figured out that MALDI-MSI can be reliably applied to the differential distribution of salvianolic acids and tanshinones.