MALDI-HRMS Imaging Maps the Localization of Skyrin, the Precursor of Hypericin, and Pathway Intermediates in Leaves of Hypericum Species

Molecules

Bharadwaj Revuru¹  Souvik Kusari¹  Miroslava Bálintová²  Eva Čellárová²  Jana Henzelyová² 

[1] Center for Mass Spectrometry (CMS), Department of Chemistry and Chemical Biology (CCB), Technische Universität Dortmund, Otto-Hahn-Straße 6, 44221 Dortmund, Germany;Institute of Biology and Ecology, Faculty of Science, Pavol Jozef Šafárik University in Košice, Mánesova 23, 041 54 Košice, Slovak Republic;

关键词: Hypericum;    skyrin;    hypericin;    naphthodianthrones;    MALDI-HRMS imaging;   

DOI  :  10.3390/molecules25173964

来源: DOAJ

【 摘 要 】

Hypericum perforatum and related species (Hypericaceae) are a reservoir of pharmacologically important secondary metabolites, including the well-known naphthodianthrone hypericin. However, the exact biosynthetic steps in the hypericin biosynthetic pathway, vis-à-vis the essential precursors and their localization in plants, remain unestablished. Recently, we proposed a novel biosynthetic pathway of hypericin, not through emodin and emodin anthrone, but skyrin. However, the localization of skyrin and its precursors in Hypericum plants, as well as the correlation between their spatial distribution with the hypericin pathway intermediates and the produced naphthodianthrones, are not known. Herein, we report the spatial distribution of skyrin and its precursors in leaves of five in vitro cultivated Hypericum plant species concomitant to hypericin, its analogs, as well as its previously proposed precursors emodin and emodin anthrone, using MALDI-HRMS imaging. Firstly, we employed HPLC-HRMS to confirm the presence of skyrin in all analyzed species, namely H. humifusum, H. bupleuroides, H. annulatum, H. tetrapterum, and H. rumeliacum. Thereafter, MALDI-HRMS imaging of the skyrin-containing leaves revealed a species-specific distribution and localization pattern of skyrin. Skyrin is localized in the dark glands in H. humifusum and H. tetrapterum leaves together with hypericin but remains scattered throughout the leaves in H. annulatum, H. bupleuroides, and H. rumeliacum. The distribution and localization of related compounds were also mapped and are discussed concomitant to the incidence of skyrin. Taken together, our study establishes and correlates for the first time, the high spatial distribution of skyrin and its precursors, as well as of hypericin, its analogs, and previously proposed precursors emodin and emodin anthrone in the leaves of Hypericum plants.

【 授权许可】

Unknown