RESUMO
Synopsis Chemical microbial inhibitors compatible with formulations of soaps and deodorant perfumes are more effective if they are substantive to the skin. However, highly effective inhibitors are toxic and their substantivity on skin may accentuate the toxicity. Natural compounds such as short to medium chain fatty acids and their derivatives, which are known to be germicidal, offer a viable alternative to chemical inhibitors. We report here the synthesis of sodium 2-lauroyloxy propionate and an in vivo method to test its substantivity on skin following its incorporation in soaps. Among several compounds tested, sodium 2-lauroyloxy propionate was found to be highly substantive in soap formulation.
RESUMO
An 8-azaguanine-resistant mutant, azg-11, derived from a guanine auxotroph, gua-1, of Salmonella typhimurium was isolated. This mutant was resistant to the analogue when grown on 2,6-diaminopurine, but showed greater susceptibility than the parent on guanine. Studies with the uptake of radioactive purines revealed that the mutant was defective in a mechanism for incorporation of guanine as well as of xanthine. Initial rates of uptake were determined for guanine at concentrations which were sufficiently low to make permeases limiting. The affinity constant K(m) for the mutant was found to be 2.5 x 10(-4)m; that of the parent was 2.3 x 10(-5)m. Examination of cell-free extracts suggested that the purine nucleotide pyrophosphorylases, responsible for the conversion of free intracellular purines to the corresponding nucleotides, were present and unaltered. The results indicate that the mutant is defective in a mechanism for the active transport for guanine and possibly xanthine.