In situ MALDI-HRMS-imaging of Maytenus senegalensis during the germination process reveals the ecological role of the important anticancer compound maytansine

The ecological role of maytansine, an important antineoplastic and antimicrobial compound with high cytotoxicity [1,2], particularly as a chemical defense compound has remained elusive since its discovery in the 1970 s in Celastraceae plants such as Maytenus and Putterlickia species [3]. After more than four decades of discovery of this important drug used against breast cancer, we provide a proof-of-concept of ecospecific and tissue-specific production and in situ spatial/temporal distribution of maytansine in Maytenus senegalensis plants. We have used MALDI-HRMS-imaging to visualize the occurrence and spatial/temporal distribution of maytansine in the leaves, stems, and roots of M. senegalensis plants, seeds obtained from the mother plants, through the germination process, and finally to the establishment of new seedlings or daughter plants. The mother plant was devoid of maytansine in all tissues. However, maytansine was produced and distributed in the cotyledons and the endosperm of the seeds with an augmented accretion towards the seed coat. Furthermore, maytansine was always detected in the emerging seedlings, particularly the cortex encompassing the radicle, hypocotyl, and epicotyl (Figure 1).

Fig. 1

The typical pattern of production and accumulation of maytansine not only in the seeds but also during germination provides evidence that M. senegalensis is ecologically primed to trigger the production of maytansine in vulnerable tissues such as seeds during plant reproduction. By utilizing maytansine as chemical defense compound against predators and/or pathogens, the plant can ensure viability of the seeds and successful germination, thus leading to the next generation of daughter plants with an evolutionary advantage of survival [4].

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[3] Kupchan et al. J. Am. Chem. Soc. 1972; 94: 1354 – 1356

[4] Eckelmann et al. Fitoterapia 2017; 119: 51 – 56