ISOLATION AND IDENTIFICATION OF A NEW MUTAGEN, YDROXYMETHYL-3,8-DIMETHYLIMIDAZO[4,5-F]QUINOXALINE (4-CH(2)0H-8-MEIQX), FROM BEEF EXTRACT

By monitoring the mutagenicity to a new Salmonella tester strain, YG10 24, which has a much higher level of O-acetyltransferase activity than S.typhimurium TA98, we found two new mutagenic compounds in bacteriol ogical-grade beef extract. One of them (compound I), which had a simil ar W spectrum to that of 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxal ine (4,8-DiMeIQx), was isolated and shown to account for similar to 2% of the total mutagenicity of the materials adsorbed to blue cotton, a nd its concentration was estimated to be 6.0 ng/g beef extract. This a mount of compound in beef extract was insufficient to allow measuremen ts of various spectra, but its level was increased similar to 9-fold b y heating beef extract with creatine and threonine at 200 degrees C fo r 5 h. From UV and mass spectra of the compound obtained from beef ext ract heated with creatine plus threonine, it was deduced to be a hydro xymethyl derivative of aminodimethylimidazo-quinoxaline. Compound I wa s isolated from the urine of rats given 4,8-DiMeIQx and identified as 2-amino-4-hydroxymethyl-3,8-dimethylimidazo[4,5-f] quinoxaline (4-CH2O H-8-MeIQx) by H-1-NMR analysis. 4-CH2OH-8-MeIQx induced 326 000 revert ants of YG1024 and 99 000 revertants of TA98 per mu g in the presence of S9 mix.