Metabolomic Profiling of Obese Pig Colon Mucosa and Fecal Samples to Study the Effect of Consuming Anthocyanin-Rich Color-Fleshed Potatoes

摘要

Color-fleshed potatoes are gaining popularity in the US due to their putative health-benefits. We have previously shown that color-fleshed potatoes are rich in bioactive anthocyanins and also shown to suppress high-fat diet induced systemic inflammatory and oxidative stress markers. However, anthocyanins are poorly bioavailable and their concentration is higher in the colon than in serum. Emerging evidence supports the concept that colonic inflammation promotes systemic inflammation via mesenteric fat inflammation. Our own preliminary data indicates that color-fleshed potatoes suppress both colonic inflammatory (TNF-α and TLR-4) and oxidative stress (GSSG/GSH ratio) markers. Metabolomic profiling of colonic and fecal samples from pigs consuming color-fleshed potatoes may aid in understanding anti-inflammatory and anti-oxidant properties of color-fleshed potatoes in vivo. Methods: Male pigs (42 ± 1.0 days old), were fed high fat diet (HFD) for 84 days, and then switched to one of the three isocaloric dietary groups: 1) High-Fat Control diet, 2) Purplefleshed potato chips at 20 % of the diet and 3) White-fleshed potato chips at 20 % of the diet for 35 days. The fecal samples and the distal colon mucosa were collected, snap frozen in liquid nitrogen and stored at ～80°C. Samples (50 ± 5 mg each) were processed by modified Folch extraction, the aqueous metabolites were phase separated, resolved chromatographically by a multi-mode ODS Scherzo SM-C18 column and analyzed by high accuracy LC-MS on a quadrupole time of flight mass spectrometer. Data: The aqueous extracts were separated at a flow-rate of 0.4 mL/min by a 20-min gradient using 0.2 % acetic acid in water as solvent A and 100 mM ammonium acetate, 0.06 % ammonium hydroxide in water/methanol (5:95) as solvent B. Full scan LC-MS data (25-1700 m/z) was acquired at 2 spectra/sec scan-rate, using electrospray ionization in positive and negative mode separately. The MassHunter Qualitative Analysis software was used to extract peaks in the LC-MS data using the Molecular Feature Extraction (MFE) algorithm. Differential expression profiling and statistical analyses were performed with Mass Profiler Professional (MPP) software. The differentially expressed features were searched against Metlin database based on mass accuracy (5ppm). This work was supported by National Research Initiative Grant 2009-55200-05197 from the USDA National Institute for Food and Agriculture (2009-2012).