Isolation and Modification of Plant Glucosinolates and their Role in the Prevention of Pathologies of the Central Nervous System

Abstract

The glucosinolate-myrosinase system is present in a large number of plants, mainly of the order Brassicales, including several common vegetables like broccoli, cabbage, kale, radish and rocket consumed worldwide. The knowledge about this fascinating biochemical system is still evolving and attracting the combined efforts of scientists of several disciplines. The research focused on the multigram-scale isolation of selected glucosinolates, the setting-up of their enzymatic transformation, and the in-vivo investigation of their activity in the protection of the central nervous system from neurodegenerative disorders. One of the main task was the screening of different Brassicaceae to identify the most convenient source to isolate glucoraphanin, which pointed towards Tuscan black kale seeds that resulted to be a multifunctional source to achieve several purposes. The procedure for extraction and purification was set-up by combining preparative anion exchange chromatography and gel filtration chromatography. Further, a set of other four glucosinolates, namely thiofunctionalized glucoerucin, glucoraphasatin, glucoraphenin and the atypical glycosylated glucomoringin were isolated and purified using similar experimental approach starting from suitable plant sources. An efficient protocol for the enzymatic transformation of the selected glucosinolates and isolation of the corresponding isothiocyanates and dithiocarbamates was set up and optimized using a biphasic system. The pharmacological studies focused on glucoraphanin and glucomoringin that are the precursors of dietary isothiocyanates R-sulforaphane and moringin, respectively, recognized for their chemopreventive and medicinal properties. In contrast to the well-known R-sulforaphane, little is known about the molecular pathways targeted by moringin. The neuroprotective effects of R-sulforaphane and moringin freshly prepared by the action of myrosinase on highly pure glucoraphanin and glucomoringin, was tested in in vivo pharmacological investigations. Overall, results could contribute to a better understanding of the potential neuroprotection of R-sulforaphane and moringin in several pathologies of the central nervous system.