Avenanthramides and Phenolic Acids from Oats Are Bioavailable and Act Synergistically with Vitamin C to Enhance Hamster and Human LDL Resistance to Oxidation

Abstract

The intake of phenolic acids and related polyphenolic compounds has been inversely associated with the risk of heart disease, but limited information is available about their bioavailability or mechanisms of action. Polyphenolics, principally avenanthramides, and simple phenolic acids in oat bran phenol-rich powder were dissolved in HCl:H(2)O:methanol (1:19:80) and characterized by HPLC with electrochemical detection. The bioavailability of these oat phenolics was examined in BioF1B hamsters. Hamsters were gavaged with saline containing 0.25 g oat bran phenol-rich powder (40 micromol phenolics), and blood was collected between 20 and 120 min. Peak plasma concentrations of avenanthramides A and B, p-coumaric, p-hydroxybenzoic, vanillic, ferulic, sinapic, and syringic acids appeared at 40 min. Although absorbed oat phenolics did not enhance ex vivo resistance of LDL to Cu(2+)-induced oxidation, in vitro addition of ascorbic acid synergistically extended the lag time of the 60-min sample from 137 to 216 min (P < or = 0.05), unmasking the bioactivity of the oat phenolics from the oral dose. The antioxidant capability of oat phenolics to protect human LDL against oxidation induced by 10 micromol/L Cu(2+) was also determined in vitro. Oat phenolics from 0.52 to 1.95 micromol/L increased the lag time to LDL oxidation in a dose-dependent manner (P < or = 0.0001). Combining the oat phenolics with 5 micromol/L ascorbic acid extended the lag time in a synergistic fashion (P < or = 0.005). Thus, oat phenolics, including avenanthramides, are bioavailable in hamsters and interact synergistically with vitamin C to protect LDL during oxidation.

Phenolic amides (avenanthramides) in oats - a review

“…Oat phenolics may serve as potent antioxidants by scavenging reactive oxygen and nitrogen species and/or by chelating transition minerals (Chen et al 2004). AVAs are important phenolic compounds found in oats.…”

“…Both animal studies and human clinical trials confirmed that oats antioxidants have the potential of reducing cardiovascular risks by lowering serum cholesterol, inhibiting LDL cholesterol oxidation and peroxidation (Cook & Samman 1996;Ji et al 2003;Inglett & Chen 2012). Therefore, it is emphasised that the consumption of oats and oats products is extremely important to reduce the risk of cardiovascular disease (Bazzano et al 2003;Chen et al 2004Chen et al , 2007Singh et al 2013). Another study has indicated that the consumption of oats and oats bran may reduce the risk of colon cancer not only because of their high fiber contents but also due to AVAs (Guo et al 2010).…”

“…AVAs are generally determined by various chromatographic methods. For the determination of the AVAs amounts, highperformance liquid chromatography (HPLC) (Bryngelsson et al 2002;Peterson et al 2002;Chen et al 2004;Mattila et al 2005;Jastrebova et al 2006;Skoglund et al 2008;Wise et al 2011;Ortiz-Robledo et al 2013;Ishihara et al 2014;Koening et al 2014), liquid chromatography-mass spectrometry (LC-MS) (Okazaki et al 2004), liquid chromatography-mass/ mass spectrometry (LC-MS/MS) (Ishihara et al 2014), and ion-exchange chromatography (Collins 1989) have been used. HPLC currently represents the most popular technique for the analysis of AVAs.…”

Vegetable milks and their fermented derivative products

“…Dietary fiber is present in large quantities and this is rich in fructo-oligosaccharides, which are reportedly effective at stimulating the growth of Bifidobacteria and Lactobacilli in the human intestine (K. D. Kaur, Jha, Sabikhi, & Singh, 2011). Besides this prebiotic effect, their phenolic compounds have also been reported to possess gastroprotective properties, in addition to their antioxidant, cholesterol-lowering, anti-atherogenic, anti-carcinogenic and anti-inflammatory effects (C. Chen et al, 2004;Dykes & Rooney, 2006;Prior & Gu, 2005). Indeed, epidemiological studies have shown an association between increased wholegrain consumption and reduced risks of various types of chronic diseases, such as CVD, obesity, DM-2 and some cancers (Chan, Wang, & Holly, 2007;de Munter, Hu, Spiegelman, Franz, & van Dam, 2007;Esmaillzadeh, Mirmiran, & Azizi, 2005;Larsson, Giovannucci, Bergkvist, & Wolk, 2005;Mellen, Walsh, & Herrington, 2008;Murtaugh, Jacobs, Jacob, Steffen, & Marquart, 2003;Schatzkin, Park, Leitzmann, Hollenbeck, & Cross, 2008;van de Vijver, van den Bosch, van den Brandt, & Goldbohm, 2009).…”

Significance of coarse cereals in health and nutrition: a review

“…Avenanthramides are amides of cinnamoylanthranilic acids and are found exclusively in oats. They have anti-inflammatory, anti-atherogenic and antioxidant properties (Emmons et al 1999;Chen et al 2004). Alkyl resorcinol produced by various plants, bacteria and fungi are bioactive compounds possessing beneficial activities for human health such as anticancerous activity (Kozubek and Tyman 1999;Ross et al 2004).…”