The present study was conducted to evaluate the potential carcinogenicity of enzymatically modified
isoquercitrin, administered in the diet at doses of 0.5% or 1.5% to groups of 50 male and female F344/DuCrj rats. Control males and females (50 rats each) were maintained on basal diet. Animals were observed for 104 weeks. There were no treatment-related clinical signs of toxicity in the treated groups.
Body weights, feed consumption, survival rates and hematological findings for exposed rats of both sexes showed no variations among the groups. There was a slight but significant dose-dependent decrease in relative spleen weights in all treated groups, albeit with no histopathological variation. Overall histopathological evaluation of
neoplasms and all tissues after 2 years showed that
tumors developed in all groups including the controls. There was a non-significant tendency for increase in the incidence of pituitary gland
adenomas in the high dose-treated females (45.5%) as compared to controls (27.7%), with a slight increase in
hemorrhage incidences, but values for males were low and similar in both control and treated rats. There were no apparent effects of
isoquercitrin on development of
kidney neoplasms,
hyperplasias or chronic nephropathy.
Parathyroid adenomas or
hyperplasias were found not affected by
isoquercitrin treatment, and there were no differences in mammary gland
fibroadenomas or
hyperplasias between treated and control rats. Various
tumors were found in other organs with no significant differences between the groups. In conclusion, under the conditions of this 2-year feeding experiment, no evidence was obtained of carcinogenicity of enzymatically modified
isoquercitrin in male or female F344 rats.