Physiological and hemolytic toxicity of some aminophosphonates.

The effect of novel synthesized aminophosphonates on membrane potential and electrical conductance of internodal cells of Nitellopsis obtusa and hemolysis of erythrocytes (RBC) was studied. It was found that those the organophosphorous compounds, when present at 10-100 microM concentrations, caused depolarization and increased electrical conductance of alga membranes. They also influenced fluidity of erythrocyte membranes. When used at higher concentrations aminophosphonates caused hemolysis of RBC. The changes observed depended on structural features of the aminophosphonates, i.e., substituents at the carbon, phosphorus and nitrogen atoms, and, most probably, may be the result of direct interaction of the aminophosphonates with the lipid phase of the plasma membrane and the induced structural changes. Two modes of interaction are proposed.

Influence of organic and inorganic ions on organolead-induced hemolysis of erythrocytes.

The influence of some inorganic (K+, Mg2+, and Al3+) and organic CnH(2n+1)SO3-, n = 12 and 14) ions was studied on the hemolysis of erythrocytes (RBC) caused by organolead compounds (tripropyllead--TPL, tributyllead--TBL and triphenyllead--TPhL chlorides). It was found that sulfonate anions increased the hemolytic effect induced by triorganoleads, while inorganic cations protected RBC against the triorganoleads action, especially when the latter were used at small concentrations. This protection was weaker when the concentration of organoleads increased and depended on the kind of ion. The protective efficacy sequence was like that: Mg2+ > Al3+ > K+. The less hemolytic of the triorganoleads studied was TPL. TBL was slightly more effective than TPhL. The efficacy of the sulfonate ions to increase the triorganolead chloride-induced hemolysis was practically the same for TPL and TBL. A weaker efficacy of C12H25SO3+ was observed when TPhL was used as RBC membrane modifier.

The hemolytic toxicity of some new aminophosphonates.

A series of ten aminophosphonate derivatives were assayed for their hemolytic activity as a preliminary screening for the detection of herbicides. The data obtained indicate: 1. A clear correlation between the hemolytic capacity of the test compounds and their plant growth inhibition and an increase in membrane fluidity was demonstrated. 2. It was found that the most active compounds revealed at least one of the following structural features: an iso-propyl substituent at the phosphorus atom, a tert-butyl group attached to their hexane ring or a long hydrocarbon chain. 3. Ring substituents at the phosphorus (phenyl ring), carbon or nitrogen atoms (hexane) removed the hemolytic activity of compounds. 4. It may be concluded that the hemolytic toxicity of the aminophosphonates studied is related to their ability to incorporate and fuse into the lipid phase of the erythrocyte membrane. The general conclusion is that both stereochemistry and hydrophobicity are deciding factors for the efficiency of the interaction of the studied compounds studied with erythrocytes, and that the most possible location of the aminophosphonates is in the lipid phase of the RBC membrane.

The membrane-disrupting activity of alpha-aminoalkanephosphonic acids and their derivatives.

The influence of a series of acyclic and cyclic aminophosphonates on the physicochemical properties of model (planar lipid membranes-BLM) and biological (erythrocytes-RBC) membranes was studied. The results obtained were compared with the results of physiological tests performed on the aquatic plant Spirodela oligorrhiza. It was found that the inhibition of plant growth by the compounds studied correlated, although not very highly, with the observed changes in the properties of membranes used. It was also found that both the biological activity of aminophosphonates and their efficiency at modifying the physicochemical parameters of membranes depended on their structural features.

New aminophosphonates with antioxidative activity.

The antioxidative activity of some newly synthesized aminomethanephosphonic acid derivatives was studied. The compounds studied differed in their polarity and the hydrophobicity of the electronic substituents at their nitrogen and phosphorus atoms. It was found that all the aminophosphonates studied, both cyclic and acyclic, protected erythrocyte membranes against peroxidation to some extent. The effect was somewhat weaker in the case of cyclic compounds, and for erythrocytes irradiated with UV light. The cyclic compounds provided no protection of erythrocytes illuminated by natural light. The observed differences between the antioxidative activities of cyclic and acyclic compounds are probably related to differences in their ability to incorporate into the lipid phase of erythrocyte membranes. Once incorporated, they change the fluidity of the membranes. The extent of those changes was determined in fluorescence measurements. Generally, they were found to be more pronounced in the case of acyclic aminophosphonates, although as regards other structural differences between particular aminophosphonates, a clear picture of the relationship between structure and effect is more difficult to obtain. No correlation was found between the antioxidative efficiency of the compounds and the fluidity changes they induce.

Aminophosphonate-induced changes of betacyanine and ionic efflux.

Betacyanine and ionic leakage from red beet (Beta vulgaris ssp. L. rapacea) roots and lilac (Syringa vulgaris L.) leaves under the influence of new aminophosphonates were studied by spectroscopic and conductometric methods. It was found that the leakage of dye or electrolytes depended both on the concentration of the compounds used and their structural features. The results compared to those obtained for the well known herbicide Buminafos (dibutyl 1-butylamino-1-cyclohexanephosphonate) enabled to conclude that some of the compounds studied exhibited comparable or better activity than this herbicide. That makes them potentially good herbicides. It is possible that the effects observed are the result of action on cell membranes of the tissues used. The possible role of the structural features of aminophosphonates in this action is discussed.

Micellization process--temperature influence on the counterion effect.

The micellization process of dodecyltrimethylammonium chloride (DTAC) and bromide (DTAB) was studied at 313 K. Nuclear magnetic resonance and calorimetric methods were used. The calorimetric titration curves permitted determination of the critical micelle concentration (CMC) and enthalpy of the micellization process (deltaHm) of the compounds studied. The results obtained were compared to those obtained at 298 K. It was found that calorimetric curves obtained at 313 K for both compounds were similar to each other in contrast to 298 K. Especially a great difference in the shape of curves was observed for DTAC. NMR (1H NMR and 13C NMR) spectra were taken below and above the CMC values and chemical shifts (delta) analysed as a function of concentration of the compounds. Comparison of chemical shift-concentration plots with those obtained from measurements performed at lower temperature showed that chemical shifts are of very similar character in both cases for analyzed groups. However, there are some quantitative differences that indicate at smaller difference in hydration of DTAB and DTAC micelles at elevated temperature. This may be the reason of decrease of differences between micellization processes of DTAC and DTAB compounds. The smaller hydration may be, in turn, the result of diminishing differences in physicochemical properties of bromide and chloride ions with temperature.

Physiological activity of some aminophosphonates.

Influence of some new aminophosphonates on electrolyte leakage from cucumber (Cucumis sativus cv "Wisconsin") cotyledons as well as on the content of chlorophyll and activity of guaiacol and pyrogallol peroxidase were studied. Concentration of malondialdehyde (MDA), one of the end-products of lipid peroxidation, was also measured. It was found that aminophosphates influenced the parameters observed to various extents, depending on their structural features and the concentration used. Most active modifiers were those possessing sufficiently long hydrocarbon substituents at the nitrogen atom and/ or iso-propyl chain at the phosphorus atom.

Physiological activity of some organophosphorous compounds and their influence on mechanical properties of erythrocytes.

Hemolysis and fluidization of erythrocytes (RBC) membranes by some newly synthesized aminophosphonates as well as their potency to induce electrolyte efflux from cucumber (Cucumis sativus cv "Wisconsin") cotyledons were studied. Also, the chlorophyll content in aminophosphonate-treated cotyledons was affected. The compounds studied differed mainly in hydrophobicity of their substituents at the carbon, nitrogen and phosphorus atoms. It was found that aminophosphonate potency to fluidize RBC membranes depended on the combination of its overall lipophilicity and/or the kind of substituent at the P atom. Especially, iso-propyl groups enhanced that potency. The sequence of aminophosphonates that exhibited the strongest fluidization activity was paralelled by their physiological and hemolytic activities; in the latter case for these compounds that hemolyzed RBC under used concentrations. A general conclusion is that both the stereochemistry and lipophilicity determine the efficiency of the aminophosphonates studied. This efficiency is most probably related to the interaction of aminophosphonates with the lipid phase of biological objects.

Influence of triphenyllead chloride on biological and model membranes.

The physiological and hemolytic toxicities of triphenyllead chloride (TPhL) as well as its modifying influence on model lipid membranes were studied. The experiments allowed the determination of TPhL concentrations causing 50% inhibition of growth of Spirodela oligorrhiza, Lemna minor and Salvinia natans (EC50), 100% hemolysis of pig erythrocytes (C100) and destabilization of planar lipid membranes (CC). Also, fluidity of erythrocyte ghosts was measured by fluorescence technique and osmotic sensitivity of erythrocytes to the presence of TPhL. All parameters studied were found to be dependent on pH, of experimental solutions and the concentration of TPhL. Acidic conditions increased EC50 C100 and CC concentrations of TPhL. Fluorescence and osmotic measurements showed that osmotic stability and fluidity decreased with increasing trimethyllead concentration. A possible mechanism of TPhL toxicity is discussed. It is assumed that TPhL is interacting with the lipid phase of the models used. It is also assumed that there may exist various, ionic and nonionic, forms of TPhL as a result of its speciation under different experimental conditions. These species, due to their differentiated lipophilicity, may exert different effects on the model membranes studied.

Hydration of alkylammonium salt micelles--influence of bromide and chloride counterions.

The micellization process of dodecyltrimethylammonium chloride (DTAC) and bromide (DTAB) was studied. Nuclear magnetic resonance method was used. The 1H NMR and 13C NMR spectra were taken at higher and lower concentrations than the critical micelle concentrations (CMC) of the compounds studied. Chemical shifts were analysed. The studies performed were prompted by earlier calorimetric measurements which showed that there were significant qualitative and quantitative differences in the micellization process of the compounds studied. Namely, DTAB micelle dissociation was found to be an endothermic process while that of DTAC was exothermic. The differences found must be the result of differentiated influence of bromide and chloride counterions on the micellization process, including the phenomenon of micelle hydration. The objective of the work was to check whether cationic surfactant counterions can influence the micelle hydration process. Indeed, DTAB and DTAC, as monomers, exhibit similar hydrophobic hydration, but DTAB micelles are more hydrated than DTAC ones. It seems that the differences found in micellization of both salts studied may be attributed to different physicochemical properties of bromide and chloride ions, such as their mobilities and radii of their hydrated forms. Moreover, the effect of anions on the water structure must be taken into account. It is important whether the anions can be classified as water ordering kosmotropes, that hold the first hydration shell tightly, or water disordering chaotropes, that hold water molecules in that shell loosely.

Influence of amphiphilic compounds on membranes.

On the basis of Gortel & Grendel (J. Exp. Med., 1925, 41, 439-494) discovery, the importance of the lipid bilayer as an integral and indispensible component of the cell membrane is discussed. In particular, attention focuses on the interaction between membranes and amphiphilic substances. The effect on membranes of quaternary ammonium salts, both in the form of pesticides and oxidants as well as organic compounds of tin and lead are discussed in greater detail.

Antioxidative activity of some quaternary ammonium salts incorporated into erythrocyte membranes.

The antioxidative activity of two series of amphiphilic compounds from a group of quaternary ammonium salts has been investigated. They were so-called bifunctional surfactants synthesized to be used as common pesticides or as antioxidants. The latter application was to be ensured by providing the compounds studied with an antioxidant group. Studies on antioxidative possibilities of those compounds were performed on pig erythrocytes. Due to their hydrophobic parts, they anchor in the erythrocyte membrane and influence the degree of lipid oxidation in the erythrocyte membrane subjected to UV radiation. It was found that compounds of both series decreased the oxidation of the membrane lipids. The inhibition of this oxidation increased with the length of their hydrophobic chains up to fourteen carbon atoms. The compounds of the longest hydrophobic chains showed a somewhat weaker antioxidative activity. Of the two series studied compounds were more effective having bromide ions as counterions. The corresponding compounds of a second series (chlorides) protected erythrocyte significantly weaker against oxidation. The effect of the compounds on fluidity of the erythrocyte membrane has been studied in order to explain the oxidation results. Change in fluidity of the erythrocyte ghost membranes was found also dependent on length of the hydrophobic part of the compounds and was more pronounced in the case of bromide surfactants. The final conclusion is that the compounds studied can be succesfully used as antioxidant agents of good efficacy.

Physiological activity of some organophosphorus compounds and their effects on the physico-chemical properties of model membranes.

The effect of the newly synthesized phosphonic compound dibutyl 2-octylamino-2-propanephosphonate (DBOP) on the growth of the aquatic plant Spirodela oligorrhiza and stability of red blood cells (RBC) and planar lipid membranes (BLM) was studied to determine its physiological activity and, if possible, correlate this activity to compound-induced changes in the mechanical properties of the model membranes. The measure of the phytotoxicity was the DBOP concentration causing 50% plant growth retardation, while measures of stability of model membranes were 100% hemolysis of RBC and a critical concentration of DBOP causing BLM destruction in no more that 3 min. These data were compared with those for dibutyl 1-butylamino-1-cyclohexanephosphonate (DBBC) and diethyl 9-butylamino-9-fluorenephosphonate (DEBF) known for their physiological activities. Both DBBC and DEBF influenced Spirodela growth significantly less than DBOP Destabilization of the model membrane caused by DBBC and DBOP was similar whereas DEBF exerted a weak influence on RBC and BLM stability. The results indicate that the physiological activities of DBOP and DEBF are not limited to the lipid phase of biological membranes and may involve also disturbance of metabolic processes.

Protective effect of quaternary piperidinium salts on lipid oxidation in the erythrocyte membrane.

A new series of amphiphilic compounds with incorporated antioxidant functional group has been investigated. Piperidinium bromides, differing in the alkyl chain length (8, 10, 12, 14 and 16 carbon atoms in the chain) were synthesised to protect biological and/or model membranes against peroxidation and following negative consequences. Their antioxidant activity was studied with erythrocytes subjected to UV radiation. The salts used inhibited lipid oxidation in the erythrocyte membrane. The degree of this inhibition depended on the alkyl chain length of the bromide used and increased with increasing alkyl chain length. A comparison of the results obtained for piperidinium bromides with those obtained for the widely used antioxidant 3,5-di-t-butyl-4-hydroxytoluene-(BHT) revealed that only two shortest alkyl chain salts were less efficient than BHT in protecting erythrocyte membranes. A similar comparison with antioxidant efficiency of flavonoids extracted from Rosa rugosa showed that they protected the membranes studied more weakly than the least effective eight-carbon alkyl chain piperidinium bromide. The three compounds of longest alkyl chains were the most active antioxidants. Their activities did not differ significantly.

Influence of counterions on the interaction of pyridinium salts with model membranes.

The interaction of pyridinium salts (PS) with red blood cells and planar lipid membranes was studied. The aim of the work was to find whether certain cationic surfactant counterion influence its possible biological activity. The counterions studied were Cl-, Br-, I-, ClO4-, BF4- and NO3-. The model membranes used were erythrocyte and planar lipid membranes (BLM). At high concentration the salts caused 100% erythrocyte hemolysis (C100) or broke BLMs (CC). Both parameters describe mechanical properties of model membranes. It was found that the efficiency of the surfactant to destabilize model membranes depended to some degree on its counterion. In both, erythrocyte and BLM experiments, the highest efficiency was observed for Br-, the lowest for NO3-. The influence of all other anions on surfactant efficiency changed between these two extremities; that of chloride and perchlorate ions was similar. Some differences were found in the case of BF4- ion. Its influence on hemolytic possibilities of PS was significant while BLM destruction required relatively high concentration of this anion. Apparently, the influence of various anions on the destructive action of PS on the model membrane used may be attributed to different mobilities and radii of hydrated ions and hence, to different possibilities of particular anions to modify the surface potential of model membranes. This can lead to a differentiated interaction of PS with modified bilayers. Moreover, the effect of anions on the water structure must be taken into account. It is important whether the anions can be classified as water ordering kosmotropes that hold the first hydration shell tightly or water disordering chaotropes that hold water molecules in that shell loosely.

The role of counterions in the protective action of some antioxidants in the process of red cell oxidation.

A number of new surfactants with an incorporated antioxidant functional group were synthesized in order to be used as agents protecting biological and/or model membranes against lipid peroxidation. Hydrophobic parts of these amphiphilic antioxidants ensured their incorporation into the membranes studied, viz. pig erythrocytes. Proper concentrations of the antioxidants were used to avoid erythrocyte membrane destruction during the experiments. The work contains the results of studies on the protective effect of two groups of antioxidants. They differed in the chain length incorporated into the membrane hydrophobic part and in the kind of counterion (chloride and bromide). The role of these factors in the protective action of the compounds studied is discussed as well as their practical application.

The role of counterions in the interaction of bifunctional surface active compounds with model membranes.

Interaction of two series of bifunctional surfactants (bromides and chlorides) with red blood cells and planar lipid membranes was studied. The aim of the work was to determine the role of counterions in the mechanism of interaction of bifunctional cationic surfactants with model membranes. In each case bromides influenced model membranes to a greater degree than the corresponding chlorides. The possible explanation of the obtained results is presented. It seems that the greater ability of bromides to destabilize model membranes in comparison with chlorides can be attributed to the greater mobility and the smaller radius of the hydrated bromide ion. This may underlie the greater ease that this anion can modify the surface potential of the lipid bilayer, thus enhancing the interaction of the cationic surfactant with such a modified bilayer.

Role of hydrophobic and hydrophilic interactions of organotin and organolead compounds with model lipid membranes.

The present study was conducted to clarify the mechanism of toxicity of organic compounds using lipid model membranes (liposomes and planar lipid membranes). The compounds studied were trialkyltin and trialkyllead chlorides, dialkyltin dichlorides and some inorganic forms of those metals. Two different (anionic and cationic) detergents were also used in the experiments to change the surface properties of liposomes. As a measure of interaction between the compounds studied and model membranes were the release of liposome bound praseodymium and the change in stability of planar membranes under the influence of those compounds. On the basis of the results obtained it was postulated that the mechanism of interaction between tin- and leadorganics and model lipid membranes is a combination of different factors featuring interacting sides. The most important properties determining the behaviour of organic compounds in the interaction were lipophilicity and polarity of different parts of the organics and the steric arrangement they can take in the medium. On the other hand, the surface potential of the lipid bilayer and the environment of the lipid molecules, that play a significant role in the availability of the lipid bilayer to the organics, were important factors in the interaction.

Antioxidant protection of egg lecithin liposomes during sonication.

When model membranes are prepared by ultrasonic treatment of polyunsaturated phospholipids, radical production can induce a partial degradation of the polyunsaturated fatty acyl chains and the formation of lipid hydroperoxides. A suitable antioxidant employed during liposome preparation is able to protect them against lipid peroxidation. This work contains the results of studies on egg lecithin liposomes with incorporated antioxidants that were supposed to play the protective role mentioned. As it has been shown the antioxidant compounds used ensured a 40-60%, i.e., satisfactory protection of liposomes after 30 min sonication. Possible practical applications are discussed.