Synthesis and bacterial metabolism of cis- and trans-2-alkyl analogues of sodium cyclamate.

Sodium cyclamate is an effective artificial sweetner, which has been banned from the U.SD. market because of alleged carcinogenic properties. It appears that cyclohexylamine, liberated from cyclamate as a result of bacterial mtabolism, is the proximate carcinogen. In an effort to elucidate the extent to which analogues of cyclamate would enter into the bacterial metabolic pathway, as well as any stereochemical requirements which might exist, several 2-alkaly analogues of sodium cyclamate were prepared. It was found that trans-N-(2-methylcyclohexyl)sulfamate (trans-2a) and trans-N-(2-ethylcyclohexyl)sulfamate were hydrolyzed by freshly collected fecal suspensions from rats fed cyclamate, but not from control rats, at the same rate as cyclamate itself. trans-N-(2-Isopropylcyclohexyl)sulfamate (trans-2c) was not hydrolyzed at all. Surprisingly, two of the analogous cis compounds (cis-2a and cis-2c, respectively) were hydrolyzed by fecal suspensions from control, as well as from cyclamate-fed, rats. Moreover, cis-2a was hydrolyzed by incubating it in medium only. Thus, it is apparent that stereochemical influences on the chemical properties of these compounds are substantial. These results do not appear to point the way toward a safe, nonmetabolizable sweetening agent.

The effect of dioctyl sodium sulphosuccinate on tartrazine azo reduction by intestinal bacteria.

1. Washed whole-cell suspensions of Proteus vulgaris and micro-organisms from rat faeces, reductively cleave the azo bond of the food dye tartrazine under anaerobic conditions. 2. Dioctyl sodium sulphosuccinate, a common faecal softening laxative, when added to incubations in vitro at concentrations greater than 0.005%, increases tartrazine azo reduction in P. vulgaris whole-cell suspensions. 3. By contrast, concentrations of dioctyl sodium sulphosuccinate greater than 0.005% when added to incubations in vitro of rat faecal preparations, resulted in an inhibition of tartrazine azo reduction.

[35S]Cyclamate metabolism: incorporation of 35S into proteins of intestinal bacteria in vitro and production of volatile 35S-containing compounds.

1. A washed whole-cell suspension of bacteria prepared from the faeces of rats regularly fed oral cyclamate incorporated 35S into bacterial protein when challenged with [35s]cyclamate. Control preparations showed low-level incorporation of label. 2. Radioactivity was also accounted for as volatile 35S-containing compounds (s), soluble in sodium hydroxide. 3. Addition of cysteine to incubation mixtures inhibited incorporation of 35S into proteins. 4. The results suggest that the bacterial conversion of cyclamate to the suspected bladder carcinogen, cyclohexylamine, is controlled by the prevailing sulphur metabolism of the intestinal bacteria.

An incubation flask to study metabolism of foreign compounds by intestinal microflora.

1. The design and procedure for use of an all-glass incubation flask which facilitates the production and maintenance of an anaerobic environment suitable for the study of drug metabolism by intestinal microflora is described. 2. Evaluation was based on monitoring available oxygen with an oxygen electrode. 3. Removal of air by the combination of replacement with hydrogen, a room temperature catalyst and a fluching technique, produced low oxygen levels comparable to vacuum systems without the need for adverse pressure changes.