Abstract
Oral administration of a number of flavonoids to animals and humans has been shown to result in the urinary excretion of a variety of hydroxy aromatic acids (1,2,3). This finding suggested that, through the medium of their metabolites, flavonoids might influence the pituitary-adrenal axis in a manner comparable to that reported for salicylic acid and related compounds(4,5). The present report concerns an investigation of this possibility with the flavonoids quercetin, dihydroquercetin, and eriodictyol.
Methods. Albino rats from a colony maintained in this laboratory since 1931 were used. Young rats were weaned at about 21 days of age, weighed individually, and sexes segregated. Overweight and underweight rats were discarded. When selected rats were not more than 4 weeks old they were fed for 1 to 4 weeks a basal diet with or without addition of a flavonoid. The basal diet had the following percentage composition: corn meal 73, casein 10, linseed oil cake meal 10, alfalfa meal 2, cod liver oil 3, bone ash 1.5, and sodium chloride 0.5. The quercetin was prepared by acid hydrolysis of the rhamnoside quercitrin(6), and eriodictyol was prepared from dihydroquercetin‡ by the method of Pew(7). At end of feeding period all control and experimental rats were sacrificed, body weights and thymus weights determined, and all organs examined for evidence of gross changes. Comparable experiments were performed with groups of rats which had been adrenalectomized or hypophysectomized. Adrenalectomized rats were placed on the diets immediately after operation and supplied with 0.9% sodium chloride in the drinking water. Hypophysectomized rats were placed on the diets 4 days after operation.
Results. The data on fresh thymus weights, expressed as per cent of body weight for rats receiving quercetin, dihydroquercetin, or eriodictyol, and their respective controls are summarized in Table I.
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