Gemini ester quat surfactants and their biological activity

Cationic gemini surfactants are an important class of surface-active compounds that exhibit much higher surface activity than their monomeric counterparts. This type of compound architecture lends itself to the compound being easily adsorbed at interfaces and interacting with the cellular membranes of microorganisms. Conventional cationic surfactants have high chemical stability but poor chemical and biological degradability. One of the main approaches to the design of readily biodegradable and environmentally friendly surfactants involves inserting a bond with limited stability into the surfactant molecule to give a cleavable surfactant. The best-known example of such a compound is the family of ester quats, which are cationic surfactants with a labile ester bond inserted into the molecule. As part of this study, a series of gemini ester quat surfactants were synthesized and assayed for their biological activity. Their hemolytic activity and changes in the fluidity and packing order of the lipid polar heads were used as the measures of their biological activity. A clear correlation between the hemolytic activity of the tested compounds and their alkyl chain length was established. It was found that the compounds with a long hydrocarbon chain showed higher activity. Moreover, the compounds with greater spacing between their alkyl chains were more active. This proves that they incorporate more easily into the lipid bilayer of the erythrocyte membrane and affect its properties to a greater extent. A better understanding of the process of cell lysis by surfactants and of their biological activity may assist in developing surfactants with enhanced selectivity and in widening their range of application.     

Eradication of the perithecial stage of apple scab with surfactants

Clone M3 apple leaves infected with scab (Venturia inaequalis) were dipped in one of a series of surface-active compounds or mixtures tested at a concentration of 5% a.i. Seven of these reduced the concentration of scab ascopores released in the spring by more than 99%.     

Comparative study of the effect of ionic and non-ionic surface-active compounds on plasmic membrane of yeast protoplasts]

Lytic effect of some cationic surface-active compounds (SAC) on yeast protoplast plasmic membrane is studied. Comparative analysis of the lytic effect of anionic, cationic and non-ionic SAC is carried out, a correlation between key physico-chemical characteristics of the agents (critical concentration of micellization, hydrophyle-lipophyle balance) and their lytic activity is investigated. A proposition is made on the presence in all biphylic compounds of a hydrophyly gradient, which is due to the effect of hydrophylic group on lipophylic properties of hydrophobic part of the molecule, and possible role of this factor in thelytic effect of biphylic compounds on biological membranes is discussed.     

Survey of Chemical Compounds Tested In Vitro against Rumen Protozoa for Possible Control of Bloat

Over 170 chemical agents were screened for antiprotozoal action in bovine ruminal fluid. Compounds were tested at 0.1 and 0.05% concentrations. Tested compounds included inorganic compounds, antibiotics, biocides, neuromuscular agents, arsenicals, plant and animal hormones, antimalarials, surface-active agents, anthelmintics, and many others. The most active compounds were cupric sulfate, nickel sulfate, nitrofurazone, hydrogen peroxide, dodecyl sodium sulfate, pelargonic acid, iodoacetic acid, 1-diethylaminoethylamino-4-methylthiaxanthrone, sodium arsanilate, sodium arsenate, bismuth glycolyl arsanilate, 1-β-hydroxyethyl-2-methyl-5-nitroimidazole, and p-nitroaniline. Copper ion was not particularly effective against entodinia; nickel ion had no effect on holotrichs. Hydrogen peroxide and iodoacetic acid were effective at a concentration of 0.005%. Anionic surface-active agents were very effective, especially long-chain sulfates and phosphates. These antiprotozoal agents warrant further in vivo studies for possible use in treating or curing bloat in ruminants.     

Low molecular weight substitutes for beef extract as eluents for poliovirus adsorbed to membrane filters.

Basic solutions of beef extract and casein were able to elute poliovirus adsorbed to four membrane filters with different chemical compositions. Hydrolyzed protein and individual amino acids were able to elute virus adsorbed to certain filters but were unable to elute virus adsorbed to other filters efficiently. A solution of 4 M urea buffered at pH 9 with 0.05 M lysine was able to elute greater than 60% of the virus adsorbed to each of the filters tested. Certain solutions of amino acids were capable of eluting virus adsorbed to one filter but permitted adsorption of virus to another filter with a different chemical composition. Acidic amino acids could interfere with elution of virus from membrane filters. Aromatic compounds with an amino group attached to the ring were good eluents for virus adsorbed to epoxy-fiberglass membrane filters. In contrast, aromatic compounds with other substituents were generally poor eluents.     

Site of Action of Certain Antibacterial Heterocyclic Quaternary Ammonium Compounds

The site of action of related mono- and bis-quinaldinium compounds was investigated in Staphylococcus aureus and Bacillus megaterium. The effects of these compounds on cell morphology and on protoplast formation and fragility were studied, and the distribution of C(14)-labeled quinaldinium compound in cell fractions was measured. The latter studies showed that a major part of the quaternary compound penetrates the cell, leaving a very small quantity associated with the cell wall. Similar antibacterial effects were seen with both the mono- and bis-quinaldinium compounds studied, and these effects were comparable with antibacterial properties of known cationic surface-active antibacterial agents.     

Synthesis of cationic beta-vinyl substituted meso-tetraphenylporphyrins and their in vitro activity against herpes simplex virus type 1

An easy route to cationic beta-vinyl substituted meso-tetraphenylporphyrin derivatives is described. Two novel compounds were tested in vitro for their antiviral photoactivity against herpes simplex virus type 1. One of these compounds exhibited a significant activity, reaching 99% of virus inactivation after 15 min of photoactivation.     

Assessment of the potential of insecticides, emulsifiers, and solvent mixtures to enhance viral infection in cultured mammalian cells.

Various insecticides, solvents, emulsifiers, and mixtures thereof were tested to determine whether these compounds are capable of enhancing the sensitivity of cultured mammalian cells to infection with vesicular stomatitis virus. None of 42 compounds tested significantly enhanced the viral infection.     

Mechanism of entry into the cytosol of poliovirus type 1: requirement for low pH

The effect of a number of drugs and culture conditions on the entry into cells of a strain of poliovirus 1 (Brunende) was tested. The cells were exposed in the dark to light-sensitive, neutral red-containing virus, in the presence of the drug to be tested. Then the cells were exposed to light, transferred to normal medium, and incubated overnight. Cytopathogenic effect was measured as inhibition of [3H]leucine incorporation. Compounds that dissipate proton gradients across membranes, like monensin, protonophores, and amines, and compounds that inhibit the acidification process, such as N,N'- dicyclohexylcarbodiimide (DCCD) and tributyltin, inhibited the entry of virus, but not virus binding. This was also the case with metabolic inhibitors that deplete cells for ATP. The same compounds also inhibited the cell-induced alteration of the virus particles. When cells with surface-bound virus were exposed to low pH, the virus entered efficiently, even in the presence of monensin and DCCD. The results indicate that acidification somehow facilitates the entry of the virus RNA into the cytosol and that under normal conditions the entry occurs from intracellular acidic vesicles.     

Tunable pH-sensitive liposomes composed of mixtures of cationic and anionic lipids

The pH-dependent fusion properties of large unilamellar vesicles (LUVs) composed of binary mixtures of anionic and cationic lipids have been investigated. It is shown that stable LUVs can be prepared from the ionizable anionic lipid cholesteryl hemisuccinate (CHEMS) and the permanently charged cationic lipid N,N-dioleoyl-N, N-dimethylammonium chloride (DODAC) at neutral pH values and that these LUVs undergo fusion as the pH is reduced. The critical pH at which fusion was observed (pH(f)) was dependent on the cationic lipid-to-anionic lipid ratio. LUVs prepared from DODAC/CHEMS mixtures at molar ratios of 0 to 0.85 resulted in vesicles with pH(f) values that ranged from pH 4.0 to 6.7, respectively. This behavior is consistent with a model in which fusion occurs at pH values such that the DODAC/CHEMS LUV surface charge is zero. Related behavior was observed for LUVs composed of the ionizable cationic lipid 3alpha-[N-(N',N'-dimethylaminoethane)-carbamoyl] cholesterol hydrochloride (DC-Chol) and the acidic lipid dioleoylphosphatidic acid (DOPA). Freeze-fracture and (31)P NMR evidence is presented which indicates that pH-dependent fusion results from a preference of mixtures of cationic and anionic lipid for "inverted" nonbilayer lipid phases under conditions where the surface charge is zero. It is concluded that tunable pH-sensitive LUVs composed of cationic and anionic lipids may be of utility for drug delivery applications. It is also suggested that the ability of cationic lipids to adopt inverted nonbilayer structures in combination with anionic lipids may be related to the ability of cationic lipids to facilitate the intracellular delivery of macromolecules.     

Synthesis and Anti-HIV Evaluation of New Acyclic Phosphonate Nucleotide Analogues and Their Bis(SATE) Derivatives

This article describes a very simple route for synthesizing novel lipophilic phosphonate bis(t-bu-SATE) prodrugs of acyclic cyclopentenylated nucleosides such as adenine 17 and cytosine 18. The key intermediate 6 was constructed via a ring-closing metathesis of compound 5, which could be readily prepared from diethylmalonate 4. The chemical stability of the bis(SATE) derivatives was tested at neutral (pH = 7.2) and slightly acid (milli-Q water, pH = 5.5) pH. The synthesized compounds were evaluated as potential antiviral agents against HIV-1 virus.     

Assessment of the potential of insecticides, emulsifiers, and solvent mixtures to enhance viral infection in cultured mammalian cells

Various insecticides, solvents, emulsifiers, and mixtures thereof were tested to determine whether these compounds are capable of enhancing the sensitivity of cultured mammalian cells to infection with vesicular stomatitis virus. None of 42 compounds tested significantly enhanced the viral infection.     

Increase in tetracycline activity by using surface-active substances]

The antimicrobial effect of cationic and anionic surface-active substances, i.e. catamine AB and sulphonol NP-3 respectively was studied in vitro with respect to gramnegative bacteria. In non-bactericidal concentrations catamine AB significantly increased the efficacy of tetracyclines, while the anionic compound had no such effect. The increase in the tetracycline activity was due to the antibiotic increased absorption (14C-oxytetracycline as an example) on the treatment of gramnegative bacteria with catamine AB and staphylococci with catamine AB and sulphonol NP-3, which was mainly associated with impairement of the cell membrane permeability by the surface-active substances.     

Modulation of anti-pathogenic activity in canine-derived Lactobacillus species by carbohydrate growth substrate

AIMS: To investigate the effect of various carbon sources on the production of extracellular antagonistic compounds against two Escherichia coli strains and Salmonella enterica serotype Typhimurium by three canine-derived lactobacilli strains. METHODS AND MATERIALS: Cell-free preparations, pH neutralized, were used in antibiotic disc experiments as an initial screening. The bacteria/carbohydrate combinations that showed inhibition of the growth of those pathogens, were further investigated in batch co-culture experiments. The cell-free supernatants of the cultures, that decreased the population number of the pathogens in the co-culture experiments to log CFU ml-1 相似文献   

Baroresistant buffer mixtures for biochemical analyses

Hydrostatic pressure is a useful tool in the study of varied fields such as protein aggregation, association, folding, ligand binding, and allostery. Application of pressure can have a significant effect on the pK(a) values of buffers commonly used for biochemical analysis. Consequently, cationic buffers, rather than neutral ones, are generally used to minimize pH effects; however, even with these buffers, the change in pH over 3 kbar may be consequential in highly pH-sensitive biochemical systems. Using fluorescence-based assays, we have systematically examined the effects of pressure on various buffers in the neutral pH range. We show that many commonly used cationic and Good's buffers increase in pH with pressure on the order of 0.1 to 0.3 pH units/kbar, in agreement with other published values. Carboxylates and phosphate decrease in pH to a similar extent. Buffer mixtures, composed of both cationic and carboxylate or phosphate components, are shown to be an order of magnitude less pressure sensitive than the individual component buffers. Using various relative concentrations of Tris and either phosphate, tricarballylate (1,2,3-propanetricarboxylate), or CDA (1,1-cyclohexane diacetate) at pH values between 7 and 8 yields baroresistant buffer mixtures. Buffer mixtures can be optimized for a specific pH, and a list of mixtures is presented for general laboratory use.     

Synergism among ternary mixtures of fourteen sweeteners

The purpose of the present study was to determine the degree of synergism of sweet taste among ternary mixtures of 14 sweeteners. A trained panel evaluated ternary mixtures of 14 sweeteners varying in chemical structure and type. The ternary mixtures that were tested were limited to those in which the compounds comprising the mixture were synergistic in binary combinations, according to an earlier study. All sweeteners in the ternary mixtures were isointense with 2% sucrose, according to a previously developed formulae. Each self-mixture was also tested (e.g. 2% sucrose + 2% sucrose + 2% sucrose). The triad with the highest mean sweetness intensity rating was alitame-neohesperidin dihydrochalcone-rebaudioside-A (10.8). This represents an increase of 99.4% when compared with the average of the self-mixtures. While this is greater than the maximum of 74% increase found for binary mixtures, more dyadic combinations of sweeteners tested previously exhibited synergism than ternary combinations tested here. However, most ternary mixtures were synergistic (significantly greater than the average of the three self-mixtures) to some degree.     

Biosurfactants of MEL-A increase gene transfection mediated by cationic liposomes.

Many microorganisms growing on water-insoluble substrates have been known to produce surface-active compounds called biosurfactants. Although biosurfactants have received increasing attention due to their special properties, there has been no information available until now of a role for them with regard to gene transfection. Thus, we studied here the effects of biosurfactants on gene transfection by cationic liposomes with a cationic cholesterol derivative. Our results showed clearly that a biosurfactant of mannosylerythritol lipid A (MEL-A) increased dramatically the efficiency of gene transfection mediated by cationic liposomes with a cationic cholesterol derivative. Among them, the liposomes with a cationic cholesterol derivative, cholesteryl-3 beta-carboxyamindoethylene-N-hydroxyethylamine (I), were much more effective for gene transfection than the liposomes with DC-Chol (cholesteryl-3 beta-oxycarboxyamidoethylenedimethylamine) or liposomes without MEL-A in various cultured cells. This demonstrates that this new finding has great potential in the experiment of gene transfection and gene therapy mediated by nonviral vectors such as cationic liposomes.     

Biocidal and anti‐corrosive activities of benzoimidazol‐3‐ium cationic Schiff base surfactants

Two series of cationic Schiff base surfactants, namely, 2‐(benzylideneamino)‐3‐(2‐oxo‐2‐alkoxyethyl)‐1,3‐benzoimidazol‐3‐ium bromide (I _A–D ) and 2‐[(4‐methoxybenzylidene) amino]‐3‐(2‐oxo‐2‐alkoxyethyl)‐1,3‐benzoimidazol‐3‐ium bromide (II _A–D ) were prepared. The chemical structures of the prepared Schiff bases were recognized by elemental analysis, FTIR, H NMR, C¹³‐NMR and GC/MS spectra. The surface activities of the synthesized Schiff base cationic surfactants showed their tendency towards adsorption at the air/water interface. The adsorption tendency was estimated from the values of surface tension and the depression of surface tension at the critical micelle concentration. The studied surfactants were evaluated as antimicrobial agents against pathogenic and sulfur‐reducing bacteria using inhibition zone diameters and minimum inhibition concentration values. The synthesized cationic benzoimidazolium Schiff base cationic surfactants showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative as well as fungi. The synthesized compounds were tested for the activity as corrosion inhibitors against carbon steel corrosion in 0.5 M HCl at 200 and 400 ppm. The promising inhibition efficiency of these compounds against the sulfur‐reducing bacteria facilitates them to be applicable in the petroleum field as new categories of Sulfur Reducing Bacteria biocides. The inhibition efficiencies of the tested compounds showed good inhibition and protection of the carbon steel. The corrosion inhibition tendency correlated to the surface activity and chemical structure of the compounds.     

Comparative Study of Surface-Active Properties and Antimicrobial Activities of Disaccharide Monoesters

The objective of this research was to determine the effect of sugar or fatty acid in sugar ester compounds on the surface-active properties and antimicrobial activities of these compounds. Disaccharides of medium-chain fatty acid monoesters were synthesized through transesterifications by immobilized lipase (Lipozyme TLIM) to yield nine monoesters for subsequent study. Their antimicrobial activities were investigated using three pathogenic microorganisms: Staphylococcus aureus, Escherichia coli O157:H7 and Candida albicans. Their surface-active properties including air–water surface tension, critical micelle concentration, and foaming and emulsion power and stability were also studied. The results showed that all of the tested monoesters were more effective against Staphylococcus aureus (Gram-positive bacterium) than against Escherichia coli O157:H7 (Gram-negative bacterium). The results demonstrated that the carbon chain length was the most important factor influencing the surface properties, whereas degree of esterification and hydrophilic groups showed little effect.     

Inhibition of herpes simplex virus-induced cytopathic effect by modified hen egg-white lysozymes

Hen egg-white lysozyme and three of its basic derivatives obtained by chemical modification were tested for their activity in vitro against a wild strain of herpes simplex virus type 1. Marked inhibition of the cytopathic effect was exhibited by the three chemical derivatives and the heat-inactivated lysozyme, whereas the native enzyme displayed only modest anticytopathic activity. Enzymatic activity did not appear to be necessary for the antiherpes activity of the lysozyme compounds. Instead, other properties such as their basic nature seemed to be relevant to their antiherpes effectiveness in vitro. At the concentrations used, all compounds but one had no significant effect on cell viability and growth. Some of the compounds tested caused formation of deposits on the surface of the cells. Some correlation between deposit formation and antiherpes cytopathic activity was found. The antiherpes efficacy in vitro and toxicity of the modified lysozymes were compared with those of known antiviral agents. The lysozymes were less toxic than the reference antiviral agents, and some of them were also more active.