Identification of quinoline, carboline and glycinamide compounds in cow milk using HRMS and NMR

• Published in: Food chemistry 2013-12, Vol.141 (3), p.1888-1894
• Main Authors: Rouge, Pascal, Cornu, Agnès, Biesse-Martin, Anne-Sophie, Lyan, Bernard, Rochut, Nadège, Graulet, Benoît
• Format: Article
• Language: English
• Subjects: Agricultural sciences; Analytical chemistry; Animal biology; Animals; Biological and medical sciences; Carbolines - chemistry; Cattle; Chemical Sciences; Cow milk; Food toxicology; Glycine - analogs & derivatives; Glycine - chemistry; HPLC–DAD; HRMS; Life Sciences; Magnetic Resonance Spectroscopy - methods; Medical sciences; Milk - chemistry; Molecular Structure; Multidimensional NMR; Quinolines - chemistry; Spectrometry, Mass, Electrospray Ionization - methods; Toxicology; UV-absorbing compound
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2013.04.072

•One carboline, three quinolines and cinnamoylglycine, have been identified in milk.•They were first detected as UV-absorbing compounds.•They were purified by solvent-extraction, solid phase extraction and semi-preparative HPLC.•Their structure was elucidated using HRMS and by 1H, 13C and 1H×13C NMR. The aim of this work was to characterise new UV-absorbing compounds (UAC) in cow milk in order to gain an overview of the molecular diversity of the minor bioactive constituents, that could be used to trace animal feed or that potentially affect milk quality. UAC were extracted from lyophilized milks, partitioned using SPE C-18 cartridges, purified by semi-preparative HPLC then analysed by HPLC/DAD/HRMS in both ESI− and ESI+ ionisation mode. Compounds that remained unidentified after comparison with UV and MS databases were analysed by 1D and 2D NMR techniques. The identification and structural elucidation of N-cinnamoylglycine, 2,4-, 2,6-, 2,8-quinolinediols, and 1-methyl-3-carboxy-beta-carboline are described.