Wang Pei, Chen Huadong, Zhu Yingdong, McBride Jennifer, Fu Junsheng, Sang Shengmin
Center for Excellence in Post-Harvest Technologies, North Carolina Agricultural and Technical State University, North Carolina Research Campus, Kannapolis, NC.
Center for Excellence in Post-Harvest Technologies, North Carolina Agricultural and Technical State University, North Carolina Research Campus, Kannapolis, NC
J Nutr. 2015 Feb;145(2):239-45. doi: 10.3945/jn.114.206508. Epub 2014 Dec 17.
Avenanthramides (AVAs), which are found exclusively in oats, may play an important role in anti-inflammation and antiatherogenesis. Although the bioavailability of AVAs has been investigated previously, little is known about their metabolism.
The aim of the present study was to investigate the metabolism of avenanthramide-C (2c), one of the major AVAs, in mice and by the human microbiota, as well as to elucidate the bioactivity of its major metabolites with the goal of finding new exposure markers to precisely reflect oat consumption.
For the mouse study, 10 CF-1 female mice were divided into control (vehicle-treated) and 2c intragastrically treated (200 mg/kg) groups (5 mice/group). Twenty-four-hour urine and fecal samples were collected with use of metabolic cages. For the batch culture incubations, 2c was cultured with fecal slurries obtained from 6 human donors. Incubated samples were collected at various time points (0, 12, 24, 48, 72, 96, and 120 h). Metabolites were identified via HPLC with electrochemical detection and LC with electrospray ionization/mass spectrometry. To investigate whether 2c metabolites retain the biological effects of 2c, we compared their effects on the growth of and induction of apoptosis in HCT-116 human colon cancer cells.
Eight metabolites were detected from the 2c-treated mouse urine samples. They were identified as 5-hydroxyanthranilic acid (M1), dihydrocaffeic acid (M2), caffeic acid (M3), dihydroferulic acid (M4), ferulic acid (M5), dihydroavenanthramide-C (M6), dihydroavenanthramide-B (M7), and avenanthramide-B (M8) via analysis of their MS(n) (n = 1-3) spectra. We found that the reduction of 2c's C7'-C8' double bond and the cleavage of its amide bond were the major metabolic routes. In the human microbiota study, 2c was converted into M1-M3 and M6. Moreover, interindividual differences in 2c metabolism were observed among the 6 human subjects. Subjects B, C, E, and F could rapidly metabolize 2c to M6, whereas subject D metabolized little 2c, even up to 120 h. In addition, only subjects A, B, and F could cleave the amide bond of 2c or M6 to form the cleaved metabolites. Furthermore, we showed that 2c and its major metabolite M6 are bioactive compounds against human colon cancer cells. M6 was more active than 2c with the half-inhibitory concentration (IC50) of 158 μM and could induce apoptosis at 200 μM.
To our knowledge, the current study demonstrates for the first time that avenanthramide-C can be extensively metabolized by mice and the human microbiota to generate bioactive metabolites.
燕麦酰胺（AVAs）仅存在于燕麦中，可能在抗炎和抗动脉粥样硬化过程中发挥重要作用。尽管此前已对AVAs的生物利用度进行过研究，但对其代谢情况却知之甚少。
本研究旨在探究主要的燕麦酰胺之一——燕麦酰胺-C（2c）在小鼠体内以及人体微生物群中的代谢情况，并阐明其主要代谢产物的生物活性，以期找到能准确反映燕麦摄入量的新的暴露标志物。
在小鼠研究中，将10只CF-1雌性小鼠分为对照组（给予赋形剂）和2c灌胃处理组（200 mg/kg）（每组5只小鼠）。使用代谢笼收集24小时的尿液和粪便样本。在分批培养实验中，将2c与从6名人类供体获取的粪便悬液共同培养。在不同时间点（0、12、24、48、72、96和120小时）收集培养样本。通过高效液相色谱-电化学检测法以及液相色谱-电喷雾电离/质谱法鉴定代谢产物。为研究2c代谢产物是否保留2c的生物学效应，我们比较了它们对HCT-116人结肠癌细胞生长和凋亡诱导的影响。
在2c处理的小鼠尿液样本中检测到8种代谢产物。通过分析它们的质谱（n）（n = 1 - 3）光谱，将其鉴定为5-羟基邻氨基苯甲酸（M1）、二氢咖啡酸（M2）、咖啡酸（M3）、二氢阿魏酸（M4）、阿魏酸（M5）、二氢燕麦酰胺-C（M6）、二氢燕麦酰胺-B（M7）和燕麦酰胺-B（M8）。我们发现2c的C7'-C8'双键还原及其酰胺键断裂是主要代谢途径。在人体微生物群研究中，2c转化为M1 - M3和M6。此外，在6名人类受试者中观察到2c代谢存在个体差异。受试者B、C、E和F可迅速将2c代谢为M6，而受试者D即使在120小时后也很少代谢2c。此外，只有受试者A、B和F能裂解2c或M6的酰胺键形成裂解代谢产物。此外，我们表明2c及其主要代谢产物M6是针对人结肠癌细胞的生物活性化合物。M6比2c更具活性，其半数抑制浓度（IC50）为158 μM，在200 μM时可诱导凋亡。
据我们所知，当前研究首次证明燕麦酰胺-C可被小鼠和人体微生物群广泛代谢以生成生物活性代谢产物。
