Comprehensive identification of walnut polyphenols by liquid chromatography coupled to linear ion trap-Orbitrap mass spectrometry.
Epidemiologic studies and clinical trials have demonstrated consistent benefits of walnut consumption on coronary heart disease risk and other chronic diseases. Walnuts (Juglans regia L.) have been described previously as a rich source of polyphenols with a broad array of different structures. However, an accurate screening of its complete phenolic profile is still lacking. In the present work, liquid chromatography coupled with electrospray ionization hybrid linear trap quadrupole-Orbitrap mass spectrometry (LC-LTQ-Orbitrap) was applied for a comprehensive identification of phenolic compounds in walnuts. A total of 120 compounds, including hydrolysable and condensed tannins, flavonoids and phenolic acids were identified or tentatively identified on the base of their retention times, accurate mass measurements and subsequent mass fragmentation data, or by comparing with reference substances and literature. The peak area of each signal in mass chromatograms was used to provide semiquantitative information for comparison purposes. The most abundant ions were observed for ellagitannins, ellagic acid and its derivatives. Furthermore, the high-resolution MS analysis revealed the presence of eight polyphenols that have never been reported in walnuts: stenophyllanin C, malabathrin A, eucalbanin A, cornusiin B, heterophylliin E, pterocarinin B, reginin A and alienanin B.
Nutrition and Bromatology Group, Department of Analytical and Food Chemistry, Faculty of Food Science and Technology, Ourense Campus, University of Vigo, Ourense 32004, Spain.
Jorge
J
Regueiro
Department of Nutrition and Food Science, School of Pharmacy, University of Barcelona, Av. Joan XXIII s/n, Barcelona 08028, Spain.
Claudia
C
Sánchez-González
Department of Nutrition and Food Science, School of Pharmacy, University of Barcelona, Av. Joan XXIII s/n, Barcelona 08028, Spain; Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN, CB06/03), Instituto de Salud Carlos III, Spain.
Anna
A
Vallverdú-Queralt
Nutrition and Bromatology Group, Department of Analytical and Food Chemistry, Faculty of Food Science and Technology, Ourense Campus, University of Vigo, Ourense 32004, Spain.
Jesús
J
Simal-Gándara
Department of Nutrition and Food Science, School of Pharmacy, University of Barcelona, Av. Joan XXIII s/n, Barcelona 08028, Spain; Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN, CB06/03), Instituto de Salud Carlos III, Spain.
Rosa
R
Lamuela-Raventós
Department of Nutrition and Food Science, School of Pharmacy, University of Barcelona, Av. Joan XXIII s/n, Barcelona 08028, Spain; Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN, CB06/03), Instituto de Salud Carlos III, Spain. Electronic address: maria_izquierdo@ub.edu.
Maria
M
Izquierdo-Pulido
D002851:Chromatography, High Pressure Liquid; D031324:Juglans / Q000737:chemistry*; D015394:Molecular Structure; D009754:Nuts / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry*; D059808:Polyphenols / Q000737:chemistry*; D053719:Tandem Mass Spectrometry
D010936:Plant Extracts; D059808:Polyphenols
Ellagitannins; High-resolution mass spectrometry; Juglans regia L.; Orbitrap; Phenolic compounds; Walnuts