The Action of Urea and Some of Its Derivatives on Bacteria

Summary and Discussion Propyl and isopropyl carbamate were found to possess potent bacteriostatic and bactericidal properties against a number of gram-negative and 2 gram-positive organisms. The range of anti-bacterial activity was greater than that of urea, methyl, or ethyl carbamate. Propyl urea appeared to be approximately 3 times more potent than urethane and 6 times more effective than urea in its bacteriostatic properties, and about 4 times as powerful as urethane and 8 to 10 times more potent than urea in killing bacteria. All the studies carried out to this point indicate that when one of the NH2 groups in urea is replaced by a CH3 radical the antibacterial properties are increased, and that increasing the number of carbon atoms in the alkyl chain of the substituted compound results in further augmentation of antibacterial effect. Thus, urethane was found to be more potent than urea, and propyl carbamate more effective than the ethyl compound. That the configuration of the carbonatom chain in the urea derivative plays no role in determining the antibacterial effects is shown by the fact that isopropyl carbamate was no more and no less active than the straight-chain compound. Nonbacteriostatic quantities of propyl carbamate when combined with amounts of sulfanilamide that did not in themselves inhibit bacterial growth resulted in a mixture possessing bacteriostatic properties. It was impossible to ascertain whether this effect was additive or synergistic. Propyl and isopropyl carbamate were found to resemble urea and urethane in their ability to inhibit the action of para-aminobenzoic acid on sulfonamide. The propyl compounds, however, appeared to be more potent in this respect than urea or ethyl carbamate, since the same degree of effect was observed using appreciably smaller concentrations than those necessary with the latter substances. The neutralization of PABA was found to occur only over a short range of concentration of this compound and to persist for only a relatively short time.