Penta-deuterium-labeled 4E, 8Z-sphingadienine for rapid analysis in sphingolipidomics study

Elucidation of physiological functions of sphingolipid-related molecules by chemical approaches

Sphingolipids (SLs), found in all animals, plants, and fungi and in certain prokaryotic organisms, exhibit essential physiological functions that cannot be replicated by other lipids. Although SLs and their related biomolecules behave as lipid mediators, skin barrier systems, and epitopes, their detailed biological functions have not yet been revealed, unlike those of proteins and nucleic acids, because the biosynthesis of SLs is not governed by the central dogma. Recently, SLs have been widely studied in relation to diseases such as obesity, dementia, and neuron agenesis and have attracted attention as molecules related to unmet medical needs. This review presents the recent applications of the SL chemical biology in unmet medical needs.

Evaluation of Plant Ceramide Species-Induced Exosome Release from Neuronal Cells and Exosome Loading Using Deuterium Chemistry

The extracellular accumulation of aggregated amyloid-β (Aβ) in the brain leads to the early pathology of Alzheimer’s disease (AD). The administration of exogenous plant-type ceramides into AD model mice can promote the release of neuronal exosomes, a subtype of extracellular vesicles, that can mediate Aβ clearance. In vitro studies showed that the length of fatty acids in mammalian-type ceramides is crucial for promoting neuronal exosome release. Therefore, investigating the structures of plant ceramides is important for evaluating the potential in releasing exosomes to remove Aβ. In this study, we assessed plant ceramide species with D-erythro-(4E,8Z)-sphingadienine and D-erythro-(8Z)-phytosphingenine as sphingoid bases that differ from mammalian-type species. Some plant ceramides were more effective than mammalian ceramides at stimulating exosome release. In addition, using deuterium chemistry-based lipidomics, most exogenous plant ceramides were confirmed to be derived from exosomes. These results suggest that the ceramide-dependent upregulation of exosome release may promote the release of exogenous ceramides from cells, and plant ceramides with long-chain fatty acids can effectively release neuronal exosomes and prevent AD pathology.