Characterisation of lupin-derived lupeol with a metabolomics study of the impact and potential neuroprotection of luepol

Pilkington, Michael (2013) Characterisation of lupin-derived lupeol with a metabolomics study of the impact and potential neuroprotection of luepol. Honours thesis, Murdoch University.

Abstract

Lupins are an agriculturally significant, dietary legume expressing multiple pharmacologically active minor components including the triterpenoid lupeol. However, there is currently a lack of knowledge regarding the abundance of lupeol in lupin seeds and the relative abundances of lupeol in seed hulls, kernels and embryos. In this work, lupeol in L. angustifolius seeds and seed fractions was characterised using GC-MS QQQ analysis of lupin seed matrix extracted using a novel application of the QuEChERS approach, a pesticide residue extraction methodology. Lupeol was significantly more abundant in isolated seed hulls than whole seeds or germ and was absent in seed kernels, indicating a potential localisation of lupeol to the hull of lupin seeds. Despite demonstrating various pharmacological activities and bioprotective functions, neuroprotective properties of lupeol have not been investigated. Cell concentration and a metabolomics approach were utilised to examine the response of rat cortical neuronal cell cultures to lupeol (10 μM) and investigate potential neuroprotection against an acute dose of the neurotoxin caffeine (1 mM). Lupeol, caffeine and co-administration of lupeol with caffeine had no significant impact on cell concentration after 24 hours despite caffeine and co-administration treatment visibly inducing a toxic response. Metabolomics investigations illustrated lupeol minimally impacted the metabolite profiles of cell cultures after 4 and 24 hours, with the exception of an intracellular reduction in tryptamine, signifying a potential neuromodulatory effect. Caffeine generally reduced intracellular metabolites including most amino acids and carbohydrates, in addition to GABA and tryptamine, whilst extracellular metabolites (notably fructose) largely increased in abundance, indicating increased catabolism of metabolites for ATP production or increased carbohydrate efflux, potentially resulting from cell membrane damage. Co-administration with lupeol and caffeine replicated these changes, with significantly greater reductions in aspartate, ribitol and ribose relative to treatment with caffeine only, while extracellular metabolite levels were not significantly different. Lupeol therefore appeared to demonstrate no toxicity in isolation but failed to provide neuroprotection against caffeine toxicity and may have potentiated the intracellular toxicity of caffeine by increasing the catabolism or utilisation of amino acids and carbohydrates.

Item Type:	Thesis (Honours)
Murdoch Affiliation(s):	School of Veterinary and Life Sciences
Supervisor(s):	Trengove, Robert, Mullaney, Ian and Maker, Garth
URI:	http://researchrepository.murdoch.edu.au/id/eprint/17653

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