Effects of N,N'-bisdimethyl-1,2-ethanediamine dichloride, a double-chain surfactant, on membrane-related functions in human erythrocytes

Diacyl glycerol arginine-based surfactants: biological and physicochemical properties of catanionic formulations

In this paper, we report on a catanionic vesicles-based strategy to reduce the cytotoxicity of the diacyl glycerol arginine-based synthetic surfactants 1,2-dimyristoyl-rac-glycero-3-O-(N(α)-acetyl-L-arginine) hydrochloride (1414RAc) and 1,2-dilauroyl-rac-glycero-3-O-(N(α)-acetyl-L-arginine) hydrochloride (1212RAc). The behavior of these surfactants was studied either as pure components or after their formulation as pseudo-tetra-chain catanionic mixtures with phosphatidylglycerol (PG) and as cationic mixtures with 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) used as control. The antimicrobial activity of the negatively charged formulations against Acinetobacter baumannii was maintained with respect to the surfactant alone, while a significant improvement of the antimicrobial activity against Staphylococcus aureus was observed, together with a strong decrease of hemolytic activity. The influence of the net charge of the catanionic vesicles on membrane selectivity was studied using model membranes. The dynamics of surface tension changes induced by the addition of 1414RAc/PG aqueous dispersions into phospholipid monolayers composed of zwitterionic DPPC as model system for mammalian membranes and of negatively charged PG mimicking cytoplasmic membrane of gram-positive bacteria was followed by tensiometry. Our results constitute a proof of principle that tuning formulation can reduce the cytotoxicity of many surfactants, opening their possible biological applications.

Syntheses and antimicrobial activities of a series of new bis-quaternary ammonium compounds

A series of new bis-quaternary ammonium compounds (bis-QACs), 4,4'-(2,9-dioxadecane) bis(1-alkylpyridinium bromide)s, 3,3'-(2,9-dioxadecane)bis(1-alkylpyridinium bromide)s and 3,3'-(2,7-dioxaoctane)bis(1-decylpyridinium bromide) was synthesized. The compounds were evaluated by their activities against bacteria, molds and yeasts; the activities were expressed as the minimum inhibitory concentrations (MIC) and/or the minimum bactericidal concentrations (MBC). Compound 4,4'-(2,9-dioxadecane) bis(1-decylpyridinium bromide) had MIC values which exceeded those of benzalkoniumchloride and thiabendazole. It was in vitro active against a broad spectrum of Gram-negative and Gram-positive bacteria, against yeasts and some molds, it had high solubility and thermal decomposition temperature. The relationships between structure and biological activity of the tested bis-QACs are discussed.

Occurrence of echinocytosis in circulating RBC of black bullhead, Ictalurus melas (Rafinesque), following exposure to an anionic detergent at sublethal concentrations

The shape of the erythrocytes can be altered by a great variety of chemical agents, such as many detergents due to their amphiphilic nature. The present study examines the effect of an anionic detergent on the shape of mature, circulating catfish red blood cells. Experimental exposure to sodium dodecyl benzene sulphonate dissolved in the water of aquaria at two sublethal concentrations (1.5 and 3 ppm), for a maximum of 15 days, induced morphological changes of normal erythrocyte shape to echinocytic form. These changes were evaluated at 5, 10 and 15 days after the start of treatment, using scanning electron microscopy. The crenated erythrocytes from animals exposed to detergent appeared either with border irregularities or undulations, without distinct spicules, or with numerous short spikes. Statistical analysis, applied to the data obtained from counting altered cells in the various experimental groups, showed no significant difference between the 1.5 ppm-treated animals at the three times and the controls, whereas a significant difference was observed between 3 ppm-treated animals compared to the controls, showing significance of action of the higher dose employed at the three times. These data suggest latent erythrocyte damage. The results are discussed in the light of the extensive bibliography concerning evaginating amphiphilic compounds and the mechanisms involved in echinocyte formation, taking into account the marked differences existing between the nucleated red blood cells of fish and those biconcave, unnucleated of mammals.

Erythrocyte hemolysis and shape changes induced by new lysine-derivate surfactants

The effects of new synthetic lysine-derived anionic surfactants on human and rat erythrocytes were studied. The surfactants were salts of Nalpha,Nepsilon-dioctanoyl lysine with different counterions: lysine (77KK), tris (trishydroxymethyl amminomethane) (77KT), sodium (77KS), and lithium (77KL). 77KK and 77KT showed a biphasic hemolytic behavior in the erythrocytes. The surfactants 77KS and 77KL showed concentration-dependent hemolysis with a CH50 of about 3.4 and 2.6 mmol/l, respectively. 77KK and 77KT induced protection against hypotonic hemolysis in rat erythrocytes at the concentration which showed the least hemolytic activity under isotonic conditions. With human erythrocytes, 77KT did not show biphasic behavior in isotonic medium, but under hypotonic conditions biphasic behavior was present. Changes in shape of the erythrocyte, from discocytic to stomatocytic were observed after incubation with the anionic surfactants studied. Such shape changes occurred progressively over time, with total alteration in shape occuring after about 20 min of incubation.

The effects of palmitate on human erythrocyte membrane potential and osmotic stability

To evaluate the mechanism(s) of erythrocyte stabilization in hypotonic medium by free fatty acids, we have studied the effect of palmitic acid and its derivatives on human erythrocyte membrane electrochemical properties, osmotic stability and fluidity. Palmitic acid increased the membrane potential to the highest extent as compared with its derivatives. The membrane potential was equal to -11.0 +/- 1.7 mV in the absence and -23.3 +/- 3.2 mV in the presence of 400 mumol 1(-1) of palmitic acid, -15.3 +/- 2.2 mV in the presence of 400 mumol 1(-1) of methyl ester of palmitic acid and -14.2 +/- 1.8 mV in the presence of 400 mumol 1(-1) of lauric aldehyde. We propose that free fatty acids, containing the charged carboxylic end group, in contrast to the corresponding esters or aldehydes, can act as ionophores. At the same time, the osmotic stabilization of erythrocytes by palmitic acid and its derivatives was higher in sodium-containing as compared with potassium-containing media and did not correlate with the effect of these compounds on the membrane potential. We suggest that protective potassium leakage does not play a main role in erythrocyte osmotic stabilization by free fatty acids. Possibly this stabilization is due to the structural rearrangement of the whole membrane.