Antioxidant potential of specific cereal grain fractions: in vitro and in vivo studies
| dc.contributor.author | Masisi, Kabo | |
| dc.contributor.examiningcommittee | Scanlon, Martin (Food Science) Diehl-Jones, William (Nursing/Biological Sciences) Kitts, David (University of British Columbia) | en_US |
| dc.contributor.supervisor | Beta,Trust (Food Science) Moghadasian, Mohammed H.(Human Nutritional Science) | en_US |
| dc.date.accessioned | 2016-11-01T14:34:03Z | |
| dc.date.available | 2016-11-01T14:34:03Z | |
| dc.date.issued | 2015-02-23 | en_US |
| dc.date.issued | 2015-09-08 | en_US |
| dc.degree.discipline | Food Science | en_US |
| dc.degree.level | Doctor of Philosophy (Ph.D.) | en_US |
| dc.description.abstract | Accumulating evidence has suggested that intake of whole grains is inversely associated with oxidative-stress disease. The mechanisms, however, are not completely clear. This study assessed the antioxidant potential of hand-separated aleurone, germ and endosperm fractions of barley (Hordeum vulgare L.), corn (Zea mays) and wheat (Triticum spp.), and anti-atherogenic benefits of hand-separated corn fractions. HPLC analysis confirmed the presence of lutein and zeaxanthin carotenoids (nd-15139 μg/kg) in extracts of cereal grain fractions. The antioxidant properties using 2,2-diphenyl-1-picrylhydrazyl (DPPH), oxygen radical absorbance capacity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) assays revealed significantly higher (P<0.001) antioxidant activity in the germ than in the aleurone and endosperm fractions. Using 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay, 2,2azobis (2-amidinopropane) dihydrochloride (AAPH)-induced cell loss was effectively reduced by pre-incubating Caco-2, HT-29 and FHs 74 Int cells with carotenoid extracts. Moreover, carotenoid extracts reduced (P<0.001) AAPH-induced intracellular oxidation in the cell lines, suggesting significant antioxidant activities. Of the 84 antioxidant pathway genes included in microarray array analysis (HT-29 cells), the expression of 28 genes was enhanced (P<0.05). In in vivo study, four groups of male low density lipoprotein receptor knockout (LDLr-KO) mice were fed with the experimental diets supplemented with (3 treated groups) or without (1 control group) 5% (w/w) of each of hand-separated corn fractions for 10 weeks. All diets were supplemented with 0.06% (w/w) dietary cholesterol. Consumption of aleurone and germ fractions significantly reduced the size and atherosclerotic lesions in the aortic roots as compared to those in the control group (P<0.003). This effect was associated with significant reductions in plasma total (P<0.02) and LDL (P<0.03) cholesterol concentrations as well as an increase in fecal cholesterol excretion (P<0.04). Furthermore, abdominal fat mass was significantly reduced by consumption of aleurone (P<0.03). Corn fractions also differentially modified antioxidant status. The study suggests cholesterol-lowering and oxidative stress-lowering effects of corn fractions may be beneficial for the prevention of atherosclerosis in LDLr-KO mice. Incorporation of corn fractions boosted the total carotenoid contents (TCC (P<0.06), lutein (P<0.004) and zeaxanthin (P<0.002)) of the diets, but not in the plasma and liver tissues. Therefore, dietary carotenoids of corn fractions do not seem to affect the development of atherosclerosis in LDLr-KO mice. Taken together, aleurone and germ fractions might have therapeutic potential for managing oxidative stress and its associated co-morbidities. | en_US |
| dc.description.note | February 2017 | en_US |
| dc.identifier.uri | http://hdl.handle.net/1993/31916 | |
| dc.language.iso | eng | en_US |
| dc.publisher | Journal of Agricultural and Food Chemistry | en_US |
| dc.publisher | Food Chemistry | en_US |
| dc.rights | open access | en_US |
| dc.subject | Oxidative stress | en_US |
| dc.subject | Antioxidant | en_US |
| dc.subject | LDL receptor knockout mice | en_US |
| dc.subject | Human intestinal cell line | en_US |
| dc.subject | Cereal grain | en_US |
| dc.subject | Aleurone | en_US |
| dc.subject | Germ | en_US |
| dc.subject | Endosperm | en_US |
| dc.subject | Atherosclerosis | en_US |
| dc.title | Antioxidant potential of specific cereal grain fractions: in vitro and in vivo studies | en_US |
| dc.type | doctoral thesis | en_US |