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United States Department of Agriculture

Agricultural Research Service

Research Project: Investigation of Biological Activities and Metabolism of Citrus Phytochemicals

Location: Citrus and Other Subtropical Products Research

2013 Annual Report


1a.Objectives (from AD-416):
1. Measure in vivo pharmacokinetics and biological actions of citrus phytonutrients in human and small-animal trials. 2. Study factors that influence the in vivo pharmacokinetics of citrus phytonutrients. 3. Characterize the beneficial actions of citrus phytonutrients in in vivo systems.


1b.Approach (from AD-416):
1. Administer citrus juices to test subjects and to monitor targeted biological actions and the presence of these compounds or their metabolites in biological sample extracts, primarily of blood and urine, over set periods of time. 2. Extract phytonutrients and main metabolites from biological tissue extracts, and analyze by high performance liquid chromatography-mass spectrometry (HPLC-MS).


3.Progress Report:

This project involves research pertaining to Objective 1 of the parent project, and most specifically to Sub-objective 1b: Discover new beneficial pharmacological actions of citrus byproduct compounds, validate these biological actions in animals, and characterize the associated modes of action, pharmacokinetics and bioavailability.

The successful development of value-added health products from citrus bioactive constituents depends on efficacy of these compounds towards influencing biochemical targets linked to human health. Efficacy is intimately linked to the levels and rates of uptake (pharmacokinetics) of these citrus compounds. In this collaborative study the pharmacokinetics of key citrus flavonoids were measured in humans. Instrumental methods were developed to achieve the detection and monitoring of seven metabolites by HPLC-mass spectrometry in blood plasma and urine of 24 volunteers at Sao Paulo University. These spectroscopic analyses showed that the main flavonoid metabolites occurred as conjugates of glucuronic acid and sulfate. The detection of metabolites of a second minor class of bioactive flavonoids known as the polymethoxylated flavones was also achieved. These studies show what chemical species occur in humans following oral administration of citrus flavonoids, thus enabling researchers to focus on the actual chemical structures involved in expressed biological actions in mammals.


Last Modified: 11/27/2014
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