Cellular effects of monohydrochloride of L-arginine, N-lauroyl ethylester (LAE) on exposure to Salmonella typhimurium and Staphylococcus aureus.

Aims: Here we study the effect of monohydrochloride of L-arginine, N(alpha)-lauroyl ethylester (LAE), a cationic preservative derived from lauric acid and arginine, on the cell envelopes of Salmonella typhimurium and Staphylococcus aureus at sub-lethal concentration such as their respective minimal inhibitory concentrations, 32 and 8 microg ml(-1), respectively.

Methods And Results: Bacterial populations were studied by using transmission electron and fluorescence microscopy (TEM and FM), flow cytometry (FC) and ion-flux across the cellular membrane. Cell integrity was altered mainly in the outer membrane of S.

Irritancy potential induced by surfactants derived from lysine.

The ocular irritancy potential of surfactants of the anionic and non-ionic type, derived from lysine has been tested by the hen's egg test-choriollantoic membrane (HET-CAM) to correlate the potential irritation with the structure of the surfactant, in order to synthesize the less irritant surfactant for their use in the pharmaceutical and cosmetics industry. The anionic compounds, independently of the counterion, showed an irritant action higher than non-ionic surfactants. Among the anionic surfactants the presence of lysine as cation reduced the degree of irritation; nevertheless, the salt of lysine of lauric acid was a severe irritant.

Hemolytic action of anionic surfactants of the diacyl lysine type.

Amphiphiles induce hemolysis at a given concentration and that would be dependent on their structure. To know this, we have synthesized anionic surfactants derived from lysine and differing in their chain length and we have studied their hemolytic action. The chain length of the surfactants affects their hemolytic behaviour.

Preliminary studies of the toxic effects of non-ionic surfactants derived from lysine.

The toxic effects of new synthetic monodisperse non-ionic long-chain N alpha, N epsilon-diacyl lysine polyoxyethylene glycol amide compounds with a structural resemblance to natural lecithin phospholipids were studied by the haemolytic method and the test of the chorioallantoic membrane of the hen's egg (HET-CAM). The following compounds were tested: symmetrical N alpha,N epsilon-diacyl lysine homologues (N alpha,N epsilon-dihexanoyl, N alpha,N epsilon-dioctanoyl and N alpha,N epsilon-didecanoyl lysine) with one methyl ether polyoxyethylene glycol chain of different oxyethylene units (dioxyethylene glycol, tetraoxyethylene glycol and hexaoxyethylene glycol) as headgroup; symmetrical N alpha,N epsilon-diacyl lysine homologues with two methyl ether dioxyethylene glycol chains and the asymmetrical N alpha-butanoyl, N epsilon-dodecyl lysine with two hydrophilic methyl ether dioxyethylene glycol chains as headgroup. A commercial (polydisperse) oleoyl polyoxyethylene glycol diethanolamide with an average of eight units of ethylene oxide was used as control.