INHIBITION OF CARCINOGEN-INDUCED BIOLOGICAL RESPONSES WITH A COFFEE WATER-INSOLUBLE FRACTION AND A MODEL SYSTEM MELANOIDIN

Within the last 10 years, naturally-occurring inhibitors of genotoxic effects of carcinogens have been explored extensively by researchers. Some researchers have speculated that inhibitors of genotoxicity protect human bodies from cancer induction.;The water-insoluble fraction (WIF) was separated from reconstituted spray dried coffee by precipitation of particulate matter with ethanol at a 90% level and was further purified by sedimentation in water under high-speed centrifugation.; Considering the compositional data on WIF, one could presume the WIF consists of: combined amino acids such as peptides and polypeptides; polysaccharides containing mannose, galactose, glucose and arabinose; melanoidins; and phenolic compounds. Probably the polysaccharides, phenolic compounds and melanoidin portions are complexed with polypeptides which contain electrically-charged groups such as carboxyl (glutamic and aspartic acids) and imidazolyl (histidine).;The Ames Salmonella test was employed to assess the genotoxic inhibitory effect of coffee WIF and MSM on BP, aflatoxin (AFB(,1)) and N-methyl-N'-nitro-N-nigrosoguanidine (MNNG). The reverse mutation frequencies were reduced in the presence of WIF and MSM over a range of dosages.;Studies have indicated that coffee brew and other heat-treated browning reaction systems have a powerful inhibitory effect on carcinogen-induced reversion in the Ames Salmonella strains. A hypothesis to explain these observations is that carcinogens are adsorbed onto water-insoluble complexes in the coffee brew and melanoidins in the heat-treated foods. The goal of the present research was to explore the influence of these brown pigments on inhibiting mutagenicity of carcinogens and assess the mechanism of action.;WIF was very effective at binding both AFB(,1) and BP through a range of pH values in various buffers at 37(DEGREES)C. A maximum binding of 83% of BP by WIF was achieved at pH 2.0 and approximately 63% binding of BP occurred at pH values ranging from 4 to 9. The binding of AFB(,1) by WIF at pH values between 2 to 9 ranged from 47 to 55%. Binding of BP by WIF was examined by column chromatography using different eluants. Hydrophobic bonds may be involved in the binding of BP to WIF.;The BP-induced AHH activity in intestinal microsomes of rats on different diets indicated that MSM significantly reduced the AHH activity which suggested a protective effect.