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Grant Abstract

Grant Number: 5R01GM063512-02
PI Name: Jennifer Brodbelt
Project Title: Analysis of Phenolic Phytochemical by ESI-MS

Abstract: DESCRIPTION (provided by applicant): The proposed work is aimed at the development of electrospray ionization/quadrupole ion trap mass spectrometry for the sensitive detection and characterization of phenolic phytochemicals and their metabolites in urine, tissue and food, especially soybeans, kale and citrus fruit. Many phenolic compounds are plant pigments that are known to yield health benefits as dietary phytochemicals, having antioxidant and estrogen-like properties that give antitumor activities. Three primary objectives are described. 1) Solid phase extraction and HPLC separation methods will be developed for the phenolic compounds. Samples of interest include soybeans, kale, citrus fruit, urine, plasma and tissue. 2) Novel metal complexation methods using various transition and alkaline earth metals and auxiliary ligands will be developed as an alternative to conventional protonation, which is often inefficient for the phenolic compounds. 3) The fragmentation patterns of the phenolic compounds and metabolites will be characterized by both low energy collisional activated dissociation (CAD) and infrared dissociation (IRPD). Many phenolic phytochemicals exist naturally as glycosides in plants, so the site of glycosylation and identification of the attached sugars are critical structural issues that will be probed. The diagnostic utility of, the fragmentation patterns obtained from by CAD will be compared to those obtained by IRPD. Special attention will be focused on comparing the dissociation patterns obtained for metal cationized vs. protonated vs. deprotonated complexes. Several new ways to make the IRPD method more tunable, i.e. the ability to vary the fragmentation pattern, will be examined, including implementation of tandem IRPD/CAD methods. This work will be aimed at solving specific problems from four collaborations: one involving the detection and quantitation of flavonoids in kale, soy, and urine, the second involving the identification and quantitation of coumarins in urine and tissue, the third involving the quantitation and identification of tocopherol compounds in tissue, and the fourth involving the quantitation and identification of flavonoids in citrus fruit.

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