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Title: The potential application of rapeseed pomace extracts in the prevention and treatment of neurodegenerative diseases
Author: Pohl, Franziska
ISNI:       0000 0004 7971 2173
Awarding Body: Robert Gordon University
Current Institution: Robert Gordon University
Date of Award: 2019
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Rapeseed pomace (RSP) is the waste/by-product obtained after edible oil production from Brassica napus and is currently used as animal feed. In an attempt to revalorize this by-product as a potential nutraceutical for the treatment or prevention of neurodegenerative disease, this project aimed to determine (i) a suitable extraction technique, (ii) the phytochemical composition and in vitro activity of the extract, in relation to neuroprotective properties, (iii) the neuroprotective potential of the extract in a cellular model (SH-SY5Y neuroblastoma cells) and (iv) the extract's potential to prevent/treat neurodegenerative disease in one Machado-Joseph disease (MJD) and three Parkinson's disease (PD) C. elegans (nematode) models. To achieve this aim at the start of the project, three extraction techniques (i.e. Soxhlet, ultrasonic assisted and accelerated solvent extraction) were employed, using a solvent mixture of ethanol and water (95:5) on the RSP samples obtained from the north east of Scotland. Based on the chemical composition of the extracts and their antioxidant properties, Soxhlet extraction was revealed as the most promising and practical extraction technique. Bulk extraction was carried out, to obtain enough RSP extract for the duration of the project. Thereafter, the composition of the extract was further investigated, to show sinapine to be the most abundant secondary metabolite, together with other phenolic acids, such as sinapic, ferulic, caffeic and syringic acid. The final extract showed in vitro antioxidant and acetylcholinesterase inhibition activity, the potential to protect plasmid DNA from oxidative damage, copper ion chelating potential and the inhibition of self-mediated β-amyloid (1-42) aggregation. The latter in vitro characteristics and properties could be beneficial for the protection of neurons from oxidative stress induced degeneration. In the SH-SY5Y neuroblastoma cell line, the RSP extract was found to be non-toxic up to a concentration of 1.5 mg/mL. Subsequent cellular studies using 1 mg/mL or less of the RSP extract, showed its ability to protect the cells from reactive oxygen species (ROS) and oxidative DNA strand breakage induced by hydrogen peroxide. In addition, using protein array technology, the RSP extract was able to down regulate cell stress associated proteins SIRT2 and SOD2. In the C. elegans nematode model, the RSP extract showed no toxicity up to 5 mg/mL. The RSP extract was able to improve the disease phenotype in the MJD model (motility deficiency) as well as in all three PD models (dopaminergic neuronal loss). This improvement was at least partially dependent on the activation of the antioxidant gene glutathione-s-transferase (gst-4) in C. elegans. Overall, the RSP extract showed very positive in vitro characteristics and valuable in vivo effects in 4 disease C. elegans models, thus warranting further detailed studies on the use of RSP extract to help prevent and/or treat neurodegenerative diseases.
Supervisor: Kong, Thoo Lin (Paul) ; Goua, Marie ; Bermano, Giovanna Sponsor: Tenovus Scotland ; ERASMUS +
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Rapeseed extract ; Neurodegenerative diseases ; Biochemical analysis