Article pubs.acs.org/JAFC
Protection of Feruloylated Oligosaccharides from Corn Bran against Oxidative Stress in PC 12 Cells Sheng-wen Yao,†,∥ Xiao-xiao Wen,‡,∥ Ru-qing Huang,†,∥ Rong-rong He,# Shi-yi Ou,*,† Wei-zai Shen,*,‡ Cai-huan Huang,† and Xi-chun Peng† †
Department of Food Science and Engineering, ‡Scool of Medicine, and #College of Pharmacy, Jinan University, Guangzhou 510632, Guangdong, China S Supporting Information *
ABSTRACT: Feruloylated oligosaccharides (FOs) were prepared by autoclaving corn bran in oxalic acid (0.6%) solution, and their protection effects against oxidative stress in pheochromocytoma cells (PC 12) cells were investigated. The FOs samples, which comprised a mixture of feruloylated mono- and dipentoses with 4.88% bound ferulic acid (FA), as well as xylose, arabinose, galactose, and glucose amounting to 46.43, 40.46, 3.76, and 8.68% of the total sugars, respectively, were prepared by autoclaving the pretreated corn bran in 0.6% oxalic acid and then further separated. Antioxidant activity was tested by 1,1diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH) scavenging and oxygen radical absorbance capacity (ORAC) methods. Oxidative stress was induced by H2O2 in PC 12 neuronal cell culture model. The results showed that FOs exhibited higher antioxidant activity than free ferulic acid, with an IC50 value of 11 versus 128 μM for DPPH and an ORAC value of 4.77 versus 2.62 μmol Trolox/μmol. Tetrazolium blue assay showed that the addition of FOs with an FA concentration >50 μM significantly increased cell viability after treatment with H2O2. Flow cytometry analysis showed that the addition of FOs at concentrations of 800, 200, and 50 μM significantly decreased the apoptosis rate at the sub-G0 phase from 37.5 to 12.7, 16.2, and 20.9% (P < 0.01), respectively. FOs also significantly decreased the malonic dialdehyde content and lactate dehydrogenase (LDH) activity, but increased superoxide dismutase activity in PC 12 cells treated with H2O2 and prevented the damage of cellular membranes by decreasing the release of LDH to the cultures. The addition of FA at 800 μM showed an effect similar to that of FOs at 200 μM. Therefore, the FOs prepared from corn bran are potential functional ingredients for protection against oxidative stress. KEYWORDS: feruloylated oligosaccharides, corn bran, antioxidative stress, PC 12 cells
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INTRODUCTION Oxidative stress is caused by an imbalance between the production of reactive species (peroxides and oxygen radicals) and the scavenging ability of the organism to destroy these species.1 Oxidative stress can damage the macromolecules in cells and tissues, resulting in membrane damage, fragmentation, or random cross-linking of molecules, such as DNA, enzymes, and structural proteins, and can even lead to cell death induced by DNA fragmentation and lipid peroxidation. Thus, oxidative stress has a crucial role in the development of cancer, neurodegenerative disorders, cardiovascular diseases, Alzheimer’s disease, diabetes, and autoimmune disorders.2,3 Ferulic acid, an antioxidant ubiquitously existing in plant tissues,4 protects DNA against Cu2+/GSH-induced oxidation,5 has therapeutic effects on hydrogen peroxide-induced oxidative stress in nucleus pulposus cells,6 and restores activity at the antioxidant level in alloxan-induced mice.7 Corn (Zea mays) ranks first among the crops in the world. Corn bran, produced at a yield of 60−70 g/kg after milling, contains the highest content of ferulic acid (28−31 g/kg of ferulic acid) among fiber sources.8 However, ferulic acid in corn bran is only slightly bioavailable in rats.9 Zhao et al. fed rats a diet containing 5% refined corn bran for 10 days and found that only 0.4−0.5% of the ingested ferulic acid was recovered in rat urine, whereas 81% of the ingested ferulic acid was excreted through the rat feces within 3 days after ingestion.9 Thus, the ferulic acid of © 2013 American Chemical Society
corn bran would show very low bioavailability in humans when corn bran is eaten unprocessed. Feruloylated oligosaccharides (FOs), which comprise a bound form of ferulic acid and oligosaccharides, possess the physiological functions of both ferulic acid and oligosaccharides. The ferulic acid in FOs acts as a novel antioxidant, whereas oligosaccharides increase water solubility, and their combination may result in the synergistic antioxidant activities of FOs10,11 and may act as a new potential antioxidant for the prevention of oxidative stress. Corn bran contains a high amount of ferulic acid and hemicellulose (approximately 700 g/ kg) but
