Antioxidant potential of specific cereal grain fractions: in vitro and in vivo studies
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Date
2015-02-23, 2015-09-08
Authors
Masisi, Kabo
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Agricultural and Food Chemistry
Food Chemistry
Food Chemistry
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.
Description
Keywords
Oxidative stress, Antioxidant, LDL receptor knockout mice, Human intestinal cell line, Cereal grain, Aleurone, Germ, Endosperm, Atherosclerosis