Metabolic Fate of Hesperidin, Eriodictyol, Homoeriodictyol, and Diosmin

Three metabolites appearing in the urine of animals after the ingestion of the flavonol quercetin (1, 2) having been identified, our interests were next centered on similar studies of several citrus flavonoids. Here again our primary concern was to find evidence, if any, that these compounds are absorbed from the gastrointestinal tract after oral ingestion and, secondly, if absorption does take place, to identify the breakdown products. A preliminary report has already been published (3). Hesperidin and its aglycon hesperetin, eriodictyol, and homoeriodictyol are flavanones, whereas diosmin and its aglycon diosmetin are flavones (Fig. 1). Homoeriodictyol has not been isolated from citrus products but is included because of its structural similarity to the citrus flavanones. One other citrus flavanone, naringin, is currently being investigated in regard to its metabolic fate, and the results will be reported in a subsequent publication.