EFFECTS OF RIBOFLAVIN DEFICIENCY AND RIBOFLAVIN ADMINISTRATION ON CARCINOGEN-DNA BINDING

A study was conducted to assess the effects of riboflavin deficiency a nd riboflavin supplementation on carcinogen-DNA binding. After 12 wk o n a riboflavin-sufficient or a riboflavin-deficient diet male Wistar r ats were administered H-3-labelled benzo[a]pyrene (BP) ip. [H-3]BP was given either at a uniform dose of 450 muCi/rat irrespective of body w eight or at a dose adjusted to body weight. After 17 hr the animals we re killed, various organs were dissected and the level of [H-3]BP boun d to DNA was quantified in organs that are known to be the seats of dr ug metabolism (i.e. the liver, lungs and intestinal mucosa). In a sepa rate experiment, the effect of riboflavin supplementation on BP-DNA bi nding was also investigated. When [H-3]BP was administered at 450 muCi /rat, BP-DNA binding was markedly increased in the livers and intestin al mucosae of the pair-fed and deficient groups compared with controls . With the administration of [H-3]BP adjusted to body weight, no diffe rences in BP-DNA binding between groups were observed in any tissue. H owever, on administration of riboflavin there was a decrease in the le vel of [H-3]BP bound to DNA in almost all tissues, especially in the l ungs, where the reduction was significant. The results suggest that un dernutrition/riboflavin deficiency may increase the risk of carcinogen esis by way of an increase in carcinogen binding, which however can be reversed by riboflavin supplementation.