Planta Med 2016; 82(11/12): 1058-1069
DOI: 10.1055/s-0042-107598
Natural Product Chemistry and Analytical Studies
Original Papers
Georg Thieme Verlag KG Stuttgart · New York

Liquid Chromatography-Electrospray Ionization Mass Spectrometry Analysis of Limonoids and Flavonoids in Seeds of Grapefruits, Other Citrus Species, and Dietary Supplements[*]

Bharathi Avula
1  National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, The University of Mississippi, University, MS, USA
,
Satyanarayanaraju Sagi
1  National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, The University of Mississippi, University, MS, USA
,
Yan-Hong Wang
1  National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, The University of Mississippi, University, MS, USA
,
Mei Wang
1  National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, The University of Mississippi, University, MS, USA
,
Stefan Gafner
2  American Botanical Council, Austin, TX, USA
,
John A. Manthey
3  U. S. Horticultural Research Laboratory, Agricultural Research Service, U. S. D. A., Ft. Pierce, FL, USA
,
Ikhlas A. Khan
1  National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, The University of Mississippi, University, MS, USA
4  Division of Pharmacognosy, Department of BioMolecular Sciences, School of Pharmacy, The University of Mississippi, University, MS, USA
› Author Affiliations
Further Information

Publication History

received 29 February 2016
revised 15 April 2016

accepted 15 April 2016

Publication Date:
25 May 2016 (eFirst)

Abstract

A selective UHPLC-DAD-QToF-MS method was developed to screen grapefruit seeds, and the seeds of other Citrus species for limonoid aglycones, acids, glucosides, and flavonoids. These classes of compounds were identified in positive and negative ion modes over a mass-to-charge range from 100–1500. Accurate mass values, elution times, and fragmentation patterns obtained by QToF-mass spectrometry were used to identify or tentatively characterize the compounds detected in the sample of this study. Limonin was the major limonoid in most of the seeds of Citrus species, followed by nomilin. This analytical method was successfully applied for the analysis of commercial extracts and dietary supplements claiming to contain grapefruit seed extract, or extracts made from the seed and other fruit parts such as the peel or pulp. Many commercial products contained large numbers of flavonoids, indicating the use of peel, pulp, or seed coat. This method also permitted detection of synthetic preservatives such as benzethonium chloride, methylparaben, and triclosan in commercial grapefruit seed extract products. Out of the 17 commercial products analyzed, two contained the synthetic antimicrobial agent benzethonium chloride.

* Dedicated to Professor Dr. Dr. h. c. mult. Kurt Hostettmann in recognition of his outstanding contribution to natural product research.