Amphiphilic Compounds Research Articles

Бактериальные поверхностно-активные вещества как агенты с антибиопленочной активностью

Биосурфагенты представляют собой гетерогенную группу биологических поверхностно-активных амфифильных соединений. Продуцентами биосурфагентов являются различные микроорганизмы: бактерии и грибы. Класс биосурфагентов состоит из двух групп: низкомолекулярных и высокомолекулярных соединений. Представителями низкомолекулярных соединений являются липопептиды, гликолипиды, жирные кислоты, фосфолипиды, которые снижают поверхностное и межфазное натяжение, а высокомолекулярных соединений — полимерные и дисперсные биосурфактанты, которые представляют собой эмульсионные стабилизаторы. Наиболее изученными биосурфагентами, обладающими потенциалом лекарственных средств, являются липопептиды и гликолипиды. Подгруппу липопептидов представляют полимиксины, псевдофактины, путисолвины, сурфактины, фенгицин и другие; а гликолипидов — рамнолипиды, трегалозные, софорозные, целлобиозные, маннозилеритритольные липиды и другие. Биосурфагенты играют ключевую роль в жизнедеятельности биопленок: они регулируют адгезию бактерий и матрикса биопленки, поддерживают функционирование каналов матрикса, обеспечивая потребности бактерий в питательных веществах. Также показано, что биосурфагенты участвуют в формировании и диспергировании сформированных биопленок. Данные вещества, прямо реагируя с компонентами матрикса, индуцируют деградацию биопленки. Биосурфагенты, обладая антимикробными, противогрибковыми и противовирусными свойствами и сочетанием антибактериального и антибиопленочного действия, открывают новые перспективы в терапии рецидивирующих, хронических инфекционных заболеваний. Полагают, что поверхностно-активные соединения — как представители липопептидов, так и гликолипидов — могут быть молекулярной основой для разработки лекарственных средств, которые будут способствовать повышению эффективности антибактериальной терапии проблемных инфекций, особенно тех, которые вызваны антибиотикорезистентными штаммами.

Gemini Lipopeptide Bearing an Ultrashort Peptide for Enhanced Transfection Efficiency and Cancer-Cell-Specific Cytotoxicity.

Cationic gemini lipopeptides are a relatively new class of amphiphilic compounds to be used for gene delivery. Through the possibility of incorporating short peptides with cell-penetrating functionalities, these lipopeptides may be advantageous over traditional cationic lipids. Herein, we report the design, synthesis, and application of a novel cationic gemini lipopeptide for gene delivery. An ultrashort peptide, containing four amino acids, arginine–cysteine–cysteine–arginine, serves as a cationic head group, and two α-tocopherol moieties act as hydrophobic anchoring groups. The new lipopeptide (ATTA) is incorporated into the conventional liposomes, containing 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and 1,2-dioleoyl-sn-glycerol-3-phosphoethanolamine (DOPE), at different molar ratios. The formulated liposomes are characterized and screened for better transfection efficiency. Transfection activity in multiple human cell lines from cancerous and noncancerous origins indicates that the inclusion of an optimal ratio of ATTA in the liposomes substantially enhances the transfection efficiency, superior to that of a traditional liposome, DOTAP–DOPE. Cytotoxicity of ATTA-containing formulations against multiple cell lines indicates potentially distinct activity between cancer and noncancer cell lines. Furthermore, lipoplexes of the ATTA-containing formulations with anticancer therapeutic gene, plasmid encoding tumor necrosis factor-related apoptosis-inducing ligand (pTRAIL), induce obviously more cytotoxicity than conventional formulations. The results indicate that arginine-rich cationic lipopeptide appears to be a promising ingredient in gene delivery vector formulations to enhance transfection efficiency and cell-selective cytotoxicity.

Determination of Optimal Application of Biosurfactant by using Linear Programming (LP) Model

Biosurfactant or amphiphilic compounds are a diverse group of molecules that contains a hydrophobic part and a hydrophilic part, division at liquid/solid, liquid/liquid, or liquid/gas interfaces. The characteristics of these biomolecules play a significant part in the formation of foam, emulsification, pharmaceutical, detergence, and biopesticide that can be admissible aspects in a few sectors. Currently, industrial biosurfactant production is still lacking, and the challenges presented in this regard are due to the high cost of microbial cultivation to biosurfactant recovery. Biosurfactants have already been applied individually or as mixed with biosurfactants in industries as commercially available using microbes and synthesis processes. In this study, linear mathematical modelling using Generalized Algebraic Modelling System (GAMS) software is being used to identify the worthwhile biosurfactant product and the pathways of biosurfactant that will provide the most significant profit to the biosurfactant application. The model consisted of the linear programming (LP) model, which utilized a diverse equation to determine the industrial application of biosurfactants that can provide profitable income to the country.

Biosurfactants: Properties and Applications in Drug Delivery, Biotechnology and Ecotoxicology.

Surfactants are amphiphilic compounds having hydrophilic and hydrophobic moieties in their structure. They can be of synthetic or of microbial origin, obtained respectively from chemical synthesis or from microorganisms’ activity. A new generation of ecofriendly surfactant molecules or biobased surfactants is increasingly growing, attributed to their versatility of applications. Surfactants can be used as drug delivery systems for a range of molecules given their capacity to create micelles which can promote the encapsulation of bioactives of pharmaceutical interest; besides, these assemblies can also show antimicrobial properties. The advantages of biosurfactants include their high biodegradability profile, low risk of toxicity, production from renewable sources, functionality under extreme pH and temperature conditions, and long-term physicochemical stability. The application potential of these types of polymers is related to their properties enabling them to be processed by emulsification, separation, solubilization, surface (interfacial) tension, and adsorption for the production of a range of drug delivery systems. Biosurfactants have been employed as a drug delivery system to improve the bioavailability of a good number of drugs that exhibit low aqueous solubility. The great potential of these molecules is related to their auto assembly and emulsification capacity. Biosurfactants produced from bacteria are of particular interest due to their antibacterial, antifungal, and antiviral properties with therapeutic and biomedical potential. In this review, we discuss recent advances and perspectives of biosurfactants with antimicrobial properties and how they can be used as structures to develop semisolid hydrogels for drug delivery, in environmental bioremediation, in biotechnology for the reduction of production costs and also their ecotoxicological impact as pesticide alternative.

Biodegradable and Dual-Responsive Polypeptide-Shelled Cyclodextrin-Containers for Intracellular Delivery of Membrane-Impermeable Cargo.

The transport of membrane impermeable compounds into cells is a prerequisite for the efficient cellular delivery of hydrophilic and amphiphilic compounds and drugs. Transport into the cell's cytosolic compartment should ideally be controllable and it should involve biologically compatible and degradable vehicles. Addressing these challenges, nanocontainers based on cyclodextrin amphiphiles that are stabilized by a biodegradable peptide shell are developed and their potential to deliver fluorescently labeled cargo into human cells is analyzed. Host–guest mediated self‐assembly of a thiol‐containing short peptide or a cystamine‐cross‐linked polypeptide shell on cyclodextrin vesicles produce short peptide‐shelled (SPSVss) or polypeptide‐shelled vesicles (PPSVss), respectively, with redox‐responsive and biodegradable features. Whereas SPSVss are permeable and less stable, PPSVss effectively encapsulate cargo and show a strictly regulated release of membrane impermeable cargo triggered by either reducing conditions or peptidase treatment. Live cell experiments reveal that the novel PPSVSS are readily internalized by primary human endothelial cells (human umbilical vein endothelial cells) and cervical cancer cells and that the reductive microenvironment of the cells’ endosomes trigger release of the hydrophilic cargo into the cytosol. Thus, PPSVSS represent a highly efficient, biodegradable, and tunable system for overcoming the plasma membrane as a natural barrier for membrane‐impermeable cargo.

Regioselective synthesis of 6’’-O-lauroyl-1-kestose and 6’’’-O-lauroylnystose by sequential enzymatic reactions of transfructosylation and acylation

Fructan fatty acid esters are amphiphilic compounds with potential applications in the food industry due to their surface-active properties on the air/water interface. In this work, the regioselective synthesis of fatty acid esters of short-chain inulin-type fructooligosaccharides (FOS) was carried out in a two-step process comprising sequential enzymatic reactions of transfructosylation and acylation. In the first step, Schedonorus arundinaceus sucrose:sucrose 1-fructosyltransferase (1-SST, EC 2.4.1.99) converted sucrose (600 g/L) into the trisaccharide 1-kestose and the tetrasaccharide nystose in a ratio 9:1 with their sum accounting for 53% (w/w) of total carbohydrates. In the second step, the FOS mixture was transesterified with vinyl laurate in 2-methyl-2-butanol by immobilized Candida antarctica lipase B (CALB) (EC.3.1.1.3). NMR analysis of the synthesized monolaurate FOS esters revealed a regioselective acylation of the 6-OH of the terminal fructosyl moiety of both 1-kestose and nystose. The hydrophilic-lipophilic balance (HLB) values of 6’’-O-lauroyl-1-kestose and 6’’’-O-lauroylnystose were 14.7 and 15.7, respectively; which suggests their use as oil in water (O/W) emulsifiers. The main compound 6’’-O-lauroyl-1-kestose with critical micelle concentration (CMC) of 0.6 mM and surface tension of 45.8 mN/m proved to be a more efficient surfactant than 6’’’-O-lauroylnystose (CMC 5.38 mM) and surface tension 36.26 mN/m). We report a regioselective method for the synthesis of lauryl-FOS using the abundant and renewable resource sucrose as the starting substrate.

Amphiphilic Distyrylbenzene Derivatives as Potential Therapeutic and Imaging Agents for Soluble and Insoluble Amyloid β Aggregates in Alzheimer's Disease.

Alzheimer's Disease (AD) is the most common neurodegenerative disease, and efficient therapeutic and early diagnostic agents for AD are still lacking. Herein, we report the development of a novel amphiphilic compound, LS-4, generated by linking a hydrophobic amyloid-binding distyrylbenzene fragment with a hydrophilic triazamacrocycle, which dramatically increases the binding affinity toward various amyloid β (Aβ) peptide aggregates, especially for soluble Aβ oligomers. Moreover, upon the administration of LS-4 to 5xFAD mice, fluorescence imaging of LS-4-treated brain sections reveals that LS-4 can penetrate the blood-brain barrier and bind to the Aβ oligomers in vivo. In addition, the treatment of 5xFAD mice with LS-4 reduces the amount of both amyloid plaques and associated phosphorylated tau aggregates vs the vehicle-treated 5xFAD mice, while microglia activation is also reduced. Molecular dynamics simulations corroborate the observation that introducing a hydrophilic moiety into the molecular structure of LS-4 can enhance the electrostatic interactions with the polar residues of the Aβ species. Finally, exploiting the Cu2+-chelating property of the triazamacrocycle, we performed a series of imaging and biodistribution studies that show the 64Cu-LS-4 complex binds to the amyloid plaques and can accumulate to a significantly larger extent in the 5xFAD mouse brains vs the wild-type controls. Overall, these results illustrate that the novel strategy, to employ an amphiphilic molecule containing a hydrophilic moiety attached to a hydrophobic amyloid-binding fragment, can increase the binding affinity for both soluble and insoluble Aβ aggregates and can thus be used to detect and regulate various Aβ species in AD.

Double-Chain Cationic Surfactants: Swelling, Structure, Phase Transitions and Additive Effects.

Double-chain amphiphilic compounds, including surfactants and lipids, have broad significance in applications like personal care and biology. A study on the phase structures and their transitions focusing on dioctadecyldimethylammonium chloride (DODAC), used inter alia in hair conditioners, is presented. The phase behaviour is dominated by two bilayer lamellar phases, Lβ and Lα, with “solid” and “melted” alkyl chains, respectively. In particular, the study is focused on the effect of additives of different polarity on the phase transitions and structures. The main techniques used for investigation were differential scanning calorimetry (DSC) and small- and wide-angle X-ray scattering (SAXS and WAXS). From the WAXS reflections, the distance between the alkyl chains in the bilayers was obtained, and from SAXS, the thicknesses of the surfactant and water layers. The Lα phase was found to have a bilayer structure, generally found for most surfactants; a Lβ phase made up of bilayers with considerable chain tilting and interdigitation was also identified. Depending mainly on the polarity of the additives, their effects on the phase stabilities and structure vary. Compounds like urea have no significant effect, while fatty acids and fatty alcohols have significant effects, but which are quite different depending on the nonpolar part. In most cases, Lβ and Lα phases exist over wide composition ranges; certain additives induce transitions to other phases, which include cubic, reversed hexagonal liquid crystals and bicontinuous liquid phases. For a system containing additives, which induce a significant lowering of the Lβ–Lα transition, we identified the possibility of a triggered phase transition via dilution with water.

Self-aggregation, Temperature-responsive Agglutination, and pH-induced Disaggregation of Amphiphilic Cyclophane Dimer Having a PEG Linkage

An amphiphilic cyclophane dimer (1), which was constructed with two cyclophane skeletons, each having three hydrophobic side-chains with Boc-protecting amino groups, and a hydrophilic polyethylene glycol (PEG) linkage, was synthesized. Amphiphilic compound 1 was found to form self-aggregate in aqueous media. In addition, 1 exhibited lowest critical solution temperature (LCST) behavior and its aqueous solution became turbid above the LCST upon heating. Moreover, pH-induced disaggregation of the self-aggregates of 1 was successfully performed upon addition of hydrochloric acid, to produce a cationic water-soluble cyclophane dimer (2) by the removal of the Boc-protecting groups of 1.

Self-Assembled H-Bonding Superstructures for Alkali Cation and Proton Transport.

Transmembrane protein channels are of significant importance for the design of biomimetic artificial ion channels. Regarding the transport principles, they may be constructed from amphiphilic compounds undergoing self-assembly that synergistically generate directional superstructures across bilayer membranes. Particularly interesting, these alignments may impose an artificial pore structure that may control the ionic conduction and translocate water and ions sharing one pathway across the cell membrane. Herein, we report that the imidazole and 3-amino-triazole amphiphiles self-assemble via multiple H-bonding to form stable artificial networks within lipid bilayers. The alignment of supramolecular assemblies influences the conduction of ions, envisioned to diffuse along the hydrophilic pathways. Compounds 1-8 present subtle variations on the ion transport activities, depending the structure of hydrophilic head and hydrophobic components. Fluorinated compounds 3, 4 and 7, 8 outperform the corresponding non-fluorinated counterparts 1, 2 and 5, 6. Under the same conditions, the R enantiomers present a higher activity vs. the S enantiomers. The present systems associating supramolecular self-assembly with ion-transport behaviors may represent very promising unexplored alternatives for ion-transport along with their transient superstructures within bilayer membranes, paralleling to that of biology.

Synergistic effect of salt ions and water‐soluble amphiphilic compounds of acidic crude oil on surface and interfacial tension

AbstractThis study investigated the effect of solubility of amphiphilic compounds of acidic crude oil in water on the surface and interfacial tension (IFT) with NaCl, MgCl2, CaCl2, and Na2SO4 salts. Accordingly, distilled water, along with the salts mentioned in zero ionic strength up to 2 mol were put in contact with crude oil to become saturated with amphiphilic compounds. The effects of these compounds were investigated on the properties of contact water by pH, total organic carbon (TOC), FTIR (Fourier transform infrared spectroscopy), water‐air surface tension (ST), and water‐n‐decane IFT tests. The results showed that some of the organic components of crude oil, especially acidic and basic compounds, are present or soluble in water, which have a significant effect on reducing the surface and IFT. The IFT reduction of water‐n‐decane was greater than the water‐air ST system. Also, the observations showed that for both NaCl and Na2SO4 salt water, with increasing ionic strength of water, there was an optimum salinity within the range of 0.1‐0.25 mol/L for both salts with the amount of surface and IFT minimized at this point. In the other two salts, this point was delayed upon elevation of ionic strength and was observed at high salinity. In this case, divalent cations reduce tension rate compared to monovalent cations. Due to solubility of acidic and basic groups in water, pH of salt water illustrates an acidic trend. Results of the FTIR test confirmed solubility of these compounds as well.

Isolation of saturated alkylresorcinols from rye grains by countercurrent chromatography.

Alkylresorcinols (5-alkyl-1,3-dihydroxybenzenes) are amphiphilic phenolic lipid compounds that are abundant in cereals with highest contents in rye. Alkylresorcinols are suspected to show a wide range of favourable biological activities. For such and further testing, highly pure alkylresorcinol standards are required. Especially, purities>>98% were partly difficult to obtain in the past. Here, we aimed to isolate the most abundant (saturated) alkylresorcinols from rye using countercurrent chromatography. To achieve very high purity, alkylresorcinol-containing extract (∼7.14g) of rye grains (cold extracts with cyclohexane/ethyl acetate (46/54, w/w)) were preparatively transesterified followed by a preparative hydrogenation. Countercurrent chromatography separation of ∼1g hydrogenated and transesterified rye grain extract using the solvent system n-hexane-ethyl acetate-methanol-water (9:1:9:1, v/v/v/v) yielded 51.8mg AR17:0, 77.4mg AR19:0, 57.2mg AR21:0, 28.8mg AR23:0 and 11.5mg AR25:0 with purities>99% in either case. The isolated alkylresorcinol homologues can be used for subsequent bioassays.

Interference-free Detection of Caffeine in Complex Matrices Using a Nanochannel Electrode Modified with Binary Hydrophilic-Hydrophobic PDMS.

In the present study, a novel electrochemical sensor for the direct detection of caffeine in the crude sample has been prepared by plasma-triggered polydimethylsiloxane (PDMS) deposition on the indium tin oxide electrodes supported with silica nanochannels. The deposited PDMS contains both the original hydrophobic and oxidized hydrophilic PDMS oligomers. Nanochannels modified with these two kinds of PDMS with opposite wettability only allow the passage of small amphiphilic molecules such as caffeine, while other molecules including hydrophilic, hydrophobic, and large ones were all rejected. With the excellent shielding properties, the modified nanochannel electrode exhibits excellent anti-interference and antifouling capability, which could be directly used for the detection of caffeine in real crude food such as tea, milk, coffee, and coke without sample pretreatments. Moreover, the modified electrode has good repeatability and stability. In contrast, severe interference was observed when conventional electrodes were used directly in these unprocessed samples. The linear ranges of caffeine were determined to be between 50 nmol/L and 700 μmol/L, with a limit of detection of 20 nmol/L. The developed sensor provides a very simple, rapid, and cost-effective way for the interference-free and fouling-free analysis of specific amphiphilic compounds and can be extended to a wide range of applications.

Effects of Moisture and Amphiphilic Compounds on the Oxidative Stability of Microwave‐Treated Corn Oil

AbstractEffects of moisture and amphiphilic compounds, including oleic acid, lecithin, and monoacylglycerols (MAGs), on the oxidative stability are evaluated in microwave‐treated corn oil. Moreover, the physical properties including critical micelle concentration (CMC) and moisture content are determined in oils treated by microwave irradiation. The CMC of lecithin and moisture content of oils decreases remarkably, whereas the temperature of the oil increases rapidly with microwave irradiation. The addition of lecithin results in increased moisture content significantly in the edible oils, whereas oleic acid and MAGs do not exhibit these effects. Primary oxidation products in all the oil samples increase, despite the type of amphiphilic compounds used. Corn oil containing oleic acid and samples with lecithin exhibits lower and higher p‐anisidine values (p‐AV), respectively. Remarkably high moisture content in corn oils containing lecithin may contribute to the formation of volatile compounds and high p‐AV. Collectively, moisture and amphiphilic compounds affect the degree of lipid oxidation in microwave‐irradiated bulk oils.Practical application: A microwave oven is an irreplaceable home appliance and is widely used in households nowadays. Effects of amphiphilic compounds and moisture on the oxidative stability are evaluated and it is found that the amphiphilic compounds in lipids affect heat transfer and oxidative stability of oils. The results of this study can provide fundamental insights into lipid oxidation in edible oils, and can provide a direction to the food industry with respect to the development of more efficient and safe methods for the preparation of microwavable foods.

Critical Amphiphilic Concentration: Effect of the Extent of Amphiphilicity on Marine Fouling-Release Performance

Amphiphilic surfaces, containing both hydrophilic and hydrophobic domains, offer desirable performance for many applications such as marine coatings or anti-icing purposes. This work explores the effect of the concentration of amphiphilic moieties on converting a polyurethane (PU) system to a coating having fouling-release properties. A novel amphiphilic compound is synthesized and added at increasing amounts to a PU system, where the amount of the additive is the only variable in the study. The additive-modified surfaces are characterized by a variety of techniques including ATR-FTIR, XPS, contact angle measurements, and AFM. Surface characterizations indicate the presence of amphiphilic domains on the surface due to the introduction of the self-stratifying amphiphilic additive. The fouling-release properties of the surfaces are assessed with three biological assays using Ulva linza, Cellulophaga lytica, and Navicula Incerta as the test organisms. A change in the fouling-release performance is observed and plateaued once a certain amount of amphiphilicity is attained in the coating system, which we call the critical amphiphilic concentration (CAC).

Biosurfactants and Their Applications in the Oil and Gas Industry: Current State of Knowledge and Future Perspectives.

Surfactants are a group of amphiphilic chemical compounds (i.e., having both hydrophobic and hydrophilic domains) that form an indispensable component in almost every sector of modern industry. Their significance is evidenced from the enormous volumes that are used and wide diversity of applications they are used in, ranging from food and beverage, agriculture, public health, healthcare/medicine, textiles, and bioremediation. A major drive in recent decades has been toward the discovery of surfactants from biological/natural sources—namely bio-surfactants—as most surfactants that are used today for industrial applications are synthetically-manufactured via organo-chemical synthesis using petrochemicals as precursors. This is problematic, not only because they are derived from non-renewable resources, but also because of their environmental incompatibility and potential toxicological effects to humans and other organisms. This is timely as one of today's key challenges is to reduce our reliance on fossil fuels (oil, coal, gas) and to move toward using renewable and sustainable sources. Considering the enormous genetic diversity that microorganisms possess, they offer considerable promise in producing novel types of biosurfactants for replacing those that are produced from organo-chemical synthesis, and the marine environment offers enormous potential in this respect. In this review, we begin with an overview of the different types of microbial-produced biosurfactants and their applications. The remainder of this review discusses the current state of knowledge and trends in the usage of biosurfactants by the Oil and Gas industry for enhancing oil recovery from exhausted oil fields and as dispersants for combatting oil spills.

Особенности солюбилизирующего действия амфифильных соединений при обессмоливании целлюлозы

The necessity to improve the existing technology of pulp deresination, in particular, to reduce the surfactants consumption and decrease the environmental load, led to a combination of existing methods of resin removal with the use of enzymatic treatment. The basis of the pulp deresination mechanism by amphiphilic compounds is the solubilization of resinous substances. Thus, the establishment of the patterns of this process and its control predetermines the success of implementation of the selected technology. The features of solubilization of triolein and rosin in the lipase-based systems of individual nonionic surfactants, the enzyme, as well as their synergistic mixtures with the determination of solubilization capacities of micelles and the possible mechanism of solubilizate incorporation into them were studied using spectrophotometry, pH measurement and dynamic light scattering. It was found that synthamide-5 has a low deresination capability in spite of the high solubilization capacity of its micelles and the production of aggregates with a hydrodynamic radius up to 98 nm after diffusion of rosin into them. It is likely that compact micellar structures with a developed surface, which are implemented in mixed systems of amphiphilic compounds, including the presence of synthamide-5 in them, are more preferable for successful deresination of pulp semi-finished products. The addition of lipase leads to an increased solubilization capacity of mixed aggregates and an increase in the intensity of solubilizate molecules incorporation. Thus, depending on the nature of the amphiphilic compound, there is a different mechanism for solubilizate incorporation into micelles. Determination of the size of associates in mixed systems showed the absence of enzyme denaturation, which predicts the successful application of such cooperative systems for deresination of fiber semi-finished products. It is found that the solubilizing capability of the studied systems on resin modeling objects correlates with their deresination capability with respect to different fiber semi-finished products.

Thio-ether functionalized glycolipid amphiphilic compounds reveal a potent activator of SK3 channel with vasorelaxation effect.

The modulation of SK3 ion channels can be efficiently and selectively achieved by using the amphiphilic compound Ohmline (a glyco-glycero-ether-lipid). We report herein a series of Ohmline analogues featuring the replacement of one ether function by a thioether function located at the same position or shifted close to its initial position. The variation of the lipid chain length and the preparation of two analogues featuring either one sulfoxide or one sulfone moiety complete this series. Patch clamp measurements indicate that the presence of the thioether function (compounds 7 and 17a) produces strong activators of SK3 channels, whereas the introduction of a sulfoxide or a sulfone function at the same place produces amphiphiles devoid of an effect on SK3 channels. Compounds 7 and 17a are the first amphiphilic compounds featuring strong activation of SK3 channels (close to 200% activation). The cytosolic calcium concentration determined from fluorescence at 3 different times for compound 7b (13 min, 1 h, 24 h) revealed that the effect is different suggesting that the compound could be metabolized over time. This compound could be used as a strong SK3 activator for a short time. The capacity of 7b to activate SK3 was then used to induce vasorelaxation via an endothelium-derived hyperpolarization (EDH) pathway. For the first time, we report that an amphiphilic compound can affect the endothelium dependent vasorelaxation.

Antimicrobial activity and cytotoxicity of transition metal carboxylates derived from agaric acid

Abstract Carboxylato-type transition metal complexes with agaric acid, a bioactive natural compound derived from citric acid, were prepared, and tested in vitro for their antimicrobial activity and cytotoxicity. The products as well as agaric acid itself are amphiphilic compounds containing a hydrophilic head (citric acid moiety) and a hydrophobic tail (non-polar alkyl chain). The putative composition of the carboxylates was assigned on grounds of elemental analysis, infrared (IR) and high-resolution mass spectra (HR-MS), as well as in analogy with known complexes containing the citrate moiety. The metal carboxylates showed interesting activity in several microbial strains, especially against S. aureus (vanadium complex; MIC = 0.05 mg/ml). They were also tested for their cytotoxic activity in hepatocytes, the highest activity having been found in the copper(II) and manganese(II) complexes. Further research based on these preliminary results is needed in order to evaluate the influence of parameters like stability of the metal complexes in solution on the bioactivity of the complexes.

Synthesis and Properties of Cleavable Quaternary Ammonium Compounds.

Quaternary ammonium compounds are widely used as antiseptic and disinfectant. It is been a concern that their widespread use will lead to an increase of environmental problems, therefore the development of biodegradable surfactants is necessary. The present research is aimed at the design of novel amphiphilic molecules with similar properties to those already known but more biodegradable. Based on benzalkonium chloride (BAC), novel carbonate cleavable surfactants (CBAC) were synthesized. The breakable carbonate sites make CBAC compounds more degradable and potentially more biodegradable than their non-cleavable BAC analogues. Natural products such as fatty alcohols (C8-C16) and N,N-dimethyl-2-aminoethanol were used as reagents for the synthesis of CBAC8-16. These amphiphilic compounds were characterized in terms of surface properties and antimicrobial activity against Gram-positive and Gram-negative bacteria, yeasts and moulds. The novel surfactants showed similar surface activities in aqueous solutions when compared to BAC. Also, the surface activity/structure relationship revealed that carbonate cleavable surfactants with n-decyl group (CBAC10) showed the same behaviour as non-cleavable BAC. Furthermore, compounds containing n-octyl (CBAC8), n-decyl (CBAC10) and n-dodecyl (CBAC12) group showed strong antimicrobial activities.