Submitted to: Journal of Chromatography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 2, 1995
Publication Date: N/A
Interpretive Summary: Flavonoids are a family of organic compounds that have several biological activities that are beneficial to human health and are naturally occurring in many fruits and vegetables. Recently, Dutch scientists have associated the ingestion of several flavonoids with reduced risk of cardiovascular disease. The citrus juices, particularly orange juice, are highly consumed in the United States and contain high levels of flavonoids. However, analytical techniques for the measurement and identification of prominent flavonoids in citrus foods are not available in the scientific literature. The current research developed an extraction and chromatographic procedure for the quantification of the three prominent flavonoids in orange and grapefruit juice. The extraction and sample preparation process consisted of repeated treatment of the sample and its residue with methanol, recovery of the methanol fraction and filtration of the sample. Individual flavonoids were separated and measured with high-performance liquid chromatography. Three flavanone glycosides were identified; hesperidin and narirutin in orange juice and naringin and narirutin in grapefruit juice. This technique will be used to measure the prominent flavanones in a variety of citrus products. Analytical data will be added to an appropriate database so that epidemiologists and other health professionals can definitively elucidate the relationship between health and the intake of individual components of the flavonoid family.
Technical Abstract: A procedure has been developed for determining levels of the major flavonoids in orange and grapefruit juice concentrates. Following addition of an internal standard, commercial juice concentrates were extracted multiple times with methanol, centrifuged, then filtered. Filtrates were analyzed by high-pressure liquid chromatography employing UV-vis detection. Flavonoids present in the extracts were separated on a C18 column with an isocratic mobile phase consisting of water/acetonitrile/2-propanol/formic acid (158:23:19:0.2). By comparing UV-vis spectra and retention times with commercial standards chromatographed under identical conditions, three flavanone glycosides were identified and quantified. Orange juice concentrate was found to contain 120 mg hg(-1) hesperidin and 24 mg hg(-1) narirutin. Grapefruit juice concentrate was found to contain 200 mg hg(-1) naringin and 62 mg hg(-1) narirutin. Consistent with several previously published reports, these high levels indicate citrus can be a major source of flavonoids in a typical diet.