Pharmacological Research Communications, Vol. 20, No. 10, 1988 90 7 REDUCTION RATE OF 14C-CARMOISINE BY RESTING CELL BACTERIAL SUSPENSION FROM HUMAN AND RAT FAECES L.M. Flaminio, E. Tragni, A. De Giorgi, T. Brusa* and C.L. Galli+ Institute of Pharmacological Sciences, Toxicology Laboratory, University of Milan, Via Balzaretti 9, I-20133 Milan. *Department of Food Science and Microbiology, Section of Agricultural, Food and Ecological Microbiology, University of Milan, Via Celoria 2, I-20133 Milan, Italy. Received in final form’1 8 July 1988 SUMMARY 14 C-Carmoisine (250,ug; 1.25 x lo6 dpm) was incubated under strictly anaerobic conditions with resting cell suspension from stool specimens collected from male rats and human male healthy adults. The kinetics of azoreduction was determined as amount of naphthionic acid (NAI, the stable metabolite of Carmoisine produced by the activity of the anaerobic bacteria. The analytical determinations were performed by radio-HPLC technique. There were no significant qualitative differences in the radiochro- matographic profiles of samples obtained from human and rat flora suspen- sions. The calculated reduction rates were 5.03 + 0.18 nmoles of NA/250 ,ug Key words: Azodye, Carmoisine, Human flora, Rat flora, Azo reduction. +To whom the correspondence should be addressed: Dr. C.L. Galli, Inst. of Pharmacological Sciences, Lab. of Toxicology, Via Balzaretti 9, I-20133 Milan, Italy, Phone: 02/29.404.672. 0031-6989/88/l OOSOi-1 O/$03.00/0 0 1988 The Italian Pharmacological Society