Phenylacetyl l glutamine

Sigma Aldrich (St Quentin Fallavier, France) provided indole-3-acetic acid, indoxyl sulfate, hippuric acid, kynurenic acid, TMAO, phenylalanine, kynurenine, indole-3-acetic acid-d5, tryptophan, tyrosine, sodium hydrogen phosphate, formic acid, and dimethylsulfoxide (DMSO). Phenylacetyl-L-glutamine, Phenylacetyl-L-glutamine-d5, PCS, kynurenine-d4, p-cresyl-sulfate-d7, p-cresyl glucuronide, hippuric acid-d5, p-cresyl glucuronide-d7, TMAO-d9, tyrosine-d4, tryptophan-d5, phenylalanine-d5, kynurenic acid-d5, and 3-carboxy-4-methyl-5-propyl-2-furan were provided by Toronto Research Chemicals (North York, Toronto, ON, Canada). VWR Chemicals (Radnor, PA, USA) supplied the sodium dihydrogen phosphate and sodium chloride. Fisher Scientific (Illkirch, France) provided the LC-MS-grade methanol, water, and acetonitrile.

Protease inhibitor cocktail tablets were purchased from Roche (Mannheim, Germany). Solvents for the sample preparation and LC-MS analysis, such as methanol, water, acetonitrile with 0.1% formic acid, and water with 0.1% formic acid, were purchased from Sigma–Aldrich (St. Louis, MO, USA). These solvents were of CHROMASOLV grade. N₂, N₂-Dimethylguanosine, 7-Ketodeoxycholic acid, and Phenylacetyl L-glutamine were purchased from Toronto Research Chemicals Inc. (North York, ON, Canada). The other chemicals were all purchased from Sigma–Aldrich (St. Louis, MO, USA). The peptide was synthesized by Kelowna International Scientific Inc. (Kaohsiung, Taiwan).