Riboflavin protection against azo dye hepatoma induction in the rat.

Abstract

In 1936 Kenosita demonstrated that feeding a diet containing 4-dimethylaminoazoben-zene (DAB) caused the production of hepatomas in the rat. Five years later, Kensler et al. (1) showed that excess riboflavin provided such experimental rats with protection against the action of this dye and this observation appears to have been the first evidence suggesting that nutrition might play a role in carcinogenesis. The in vitro activity of a liver azo reductase enzyme is enhanced by the addition of excess riboflavin (2, 3) and the administration of DAB causes a decrease in the ability of this enzyme to cleave DAB (4, 5). The evidence that this enzyme is a flavoprotein has not been convincing.Morris and Robertson (6) found that the growth rate of mammary carcinomas in C3H mice was decreased by severe riboflavin deficiency. Holly et al. (7) reported that the riboflavin analog 6,7-dichloro-9-(1′-D-sorbityl)-isoalloxazine, which has no antiriboflavin activity in rats, caused regression of established lymphosarcoma in...