Cleavage of 4-Nitrophenyl Diphenyl Phosphate by Isomeric Quaternary Pyridinium Ketoximes - How Can Structure and Lipophilicity of Functional Surfactants Influence Their Reactivity in Micelles and Microemulsions?

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1642-1658 ◽  
Author(s):  
Milan Kivala ◽  
Radek Cibulka ◽  
František Hampl
Keyword(s):  
Model Reaction ◽  
Head Group ◽  
Hexadecyltrimethylammonium Bromide ◽  
Polar Head Group ◽  
Cationic Micelles ◽  
Brij 35 ◽  
Ionic Micelles ◽  
Diphenyl Phosphate ◽  
Functional Surfactants ◽  
Triton X

Amphiphilic pyridinium ketoximes 4-[1-(hydroxyimino)alkyl]-1-methylpyridinium bromides (1) and 1-alkyl-4-[1-(hydroxyimino)ethyl]pyridinium bromides (2) are isomeric cationic surfactants bearing the nucleophilic hydroxyimino group. They differ in the position of the nucleophilic function relative to polar head group and hydrophobic alkyl chain. The 4-nitrophenyl diphenyl phosphate (PNPDPP) cleavage by the oximate anions generated from 1 and 2 was used as a model reaction for the investigation of the influence of the structure and lipophilicity of functional surfactants on their reactivity in micelles and microemulsions. The investigation of the model reaction in cationic micelles of hexadecyltrimethylammonium bromide (CTAB), in non-ionic micelles (Triton X-100 and Brij 35) and in o/w microemulsion (isooctane/phosphate buffer/CTAB and butan-1-ol) has revealed that it is the lipophilicity which is the most important factor influencing the localization and reactivity of functional surfactants in nanoaggregates.

The inhibitory effects of polyoxyethylene detergents on human erythrocyte acetylcholinesterase and Ca2+ + Mg2+ ATPase

1989 ◽  
Vol 67 (2-3) ◽  
pp. 137-146 ◽  
Author(s):  
R. Blaine Moore ◽  
J. F. Manery ◽  
J. Still ◽  
V. N. Mankad
Keyword(s):  
Human Erythrocyte ◽  
Acetylcholinesterase Activity ◽  
Significant Inhibition ◽  
Erythrocyte Membranes ◽  
Head Group ◽  
Polar Head Group ◽  
Detergent Concentration ◽  
Human Erythrocyte Membranes ◽  
Hydrophobic Tail ◽  
Triton X

The activities of acetylcholinesterase and Ca2+ + Mg2+ ATPase were measured following treatment of human erythrocyte membranes with nonsolubilizing and solubilizing concentrations of Triton X-100. A concentration of 0.1% (v/v) Triton X-100 caused a significant inhibition of both enzymes. The inhibition appears to be caused by perturbations in the membrane induced by Triton X-100 incorporation. No acetylcholinesterase activity and little Ca2+ + Mg2+ ATPase activity were detected in the supernatant at 0.05% Triton X-100 although this same detergent concentration induced changes in the turbidity of the membrane suspension. Also, no inhibition of soluble acetylcholinesterase was observed over the entire detergent concentration range. The inhibition of these enzymes at 0.1% Triton X-100 was present over an eightfold range of membrane protein in the assay indicating an independence of the protein/detergent ratio. The losses in activities of these two enzymes could be prevented by either including phosphatidylserine in the Triton X-100 suspension or using Brij 96 which has the same polyoxyethylene polar head group but an oleyl hydrophobic tail instead of the p-tert-octylphenol group of Triton X-100. The results are discussed in regard to the differential recovery of enzyme activities over the entire detergent concentration range.Key words: Triton X-100, erythrocyte membranes, acetylcholinesterase, Ca2+ + Mg2+ ATPase, polyoxyethylene detergents.

scholarly journals SN2 Mechanism of Cationic Micelles on the Hydrolysis of Bis-p-Methoxyphenyl Phosphate Ester

2015 ◽  
Vol 58 (3) ◽  
pp. 117-121
Author(s):  
Abanish Kumar
Keyword(s):  
Head Group ◽  
Phosphate Ester ◽  
Polar Head Group ◽  
Polar Groups ◽  
First Order Kinetics ◽  
Cationic Micelles ◽  
Pseudophase Model ◽  
Group Form ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Hydrolysis of bis-p-methoxyphenyl phosphate ester (bis-p-MPPE) was studied in micellar solutions of cityltrimethylammoniumbromide n-C16H33N+(CH3)3Br- (CTABr) at pH-9.0. The hydrolysis followed first order kinetics with respect to bis-p-MPPE concentration. At the concentration of critical micelle concentration (CMC) the rate of hydrolysis increased with increasing CTABr concentration. Surfactant with cationic or polar head group form micelles in water with hydrocarbon like interior or polar groups at the surface and bind cationic solute. The binding constant of micelle for bis-p-MPPE and the rate constant in micellar pseudo phase were determined from kinetic data using the pseudophase model. 

Intense Room-Temperature Phosphorescence of 1-Bromonaphthalene in Organized Media of Beta-Cyclodextrin and Triton X-100

1996 ◽  
Vol 50 (10) ◽  
pp. 1273-1276 ◽  
Author(s):  
Xin-Zhen Du ◽  
Yong Zhang ◽  
Xian-Zhi Huang ◽  
Yun-Bao Jiang ◽  
Yao-Qun Li ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Ternary Complex ◽  
Room Temperature ◽  
Guest Molecule ◽  
Head Group ◽  
Polar Head Group ◽  
Room Temperature Phosphorescence ◽  
Beta Cyclodextrin ◽  
Organized Media ◽  
Triton X

In aerated aqueous solution, intense room-temperature phosphorescence (RTP) of 1-bromonaphthalene (1-BrN) is observed with an host–guest inclusion complex composed of Triton X-100, 1-BrN, and beta-cyclodextrin (β-CD). Triton X-100 is incorporated into the hydrophobic cavity of β-CD as the second guest molecule, and a 1:1:1 ternary complex is formed. This complex, with a polar head group, can be well distributed in aqueous solution, and stable RTP is obtained. Ethanol further enhances the RTP of the ternary complex, whereas 1-propanol and 1-butanol greatly attenuate RTP. Spectral analyses indicate that 1-BrN in the β-CD cavity is replaced by 1-propanol and 1-butanol.

scholarly journals Inhibition of Plasmodium falciparum Choline Kinase by Hexadecyltrimethylammonium Bromide: a Possible Antimalarial Mechanism

2006 ◽  
Vol 51 (2) ◽  
pp. 696-706 ◽  
Author(s):  
Vinay Choubey ◽  
Pallab Maity ◽  
Mithu Guha ◽  
Sanjay Kumar ◽  
Kumkum Srivastava ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Parasite ◽  
Antimalarial Activity ◽  
Plasmodium Yoelii ◽  
Head Group ◽  
Hexadecyltrimethylammonium Bromide ◽  
Choline Kinase ◽  
Polar Head Group ◽  
Dependent Manner

ABSTRACT Choline kinase is the first enzyme in the Kennedy pathway (CDP-choline pathway) for the biosynthesis of the most essential phospholipid, phosphatidylcholine, in Plasmodium falciparum. In addition, choline kinase also plays a pivotal role in trapping essential polar head group choline inside the malaria parasite. Recently, Plasmodium falciparum choline kinase (PfCK) has been cloned, overexpressed, and purified. However, the function of this enzyme in parasite growth and survival has not been evaluated owing to the lack of a suitable inhibitor. Purified recombinant PfCK enabled us to identify an inhibitor of PfCK, hexadecyltrimethylammonium bromide (HDTAB), which has a very close structural resemblance to hexadecylphosphocholine (miltefosin), the well-known antiproliferative and antileishmanial drug. HDTAB inhibited PfCK in a dose-dependent manner and offered very potent antimalarial activity in vitro against Plasmodium falciparum. Moreover, HDTAB exhibited profound antimalarial activity in vivo against the rodent malaria parasite Plasmodium yoelii (N-67 strain). Interestingly, parasites at the trophozoite and schizont stages were found to be particularly sensitive to HDTAB. The stage-specific antimalarial effect of HDTAB correlated well with the expression pattern of PfCK in P. falciparum, which was observed by reverse transcription-PCR and immunofluorescence microscopy. Furthermore, the antimalarial activity of HDTAB paralleled the decrease in phosphatidylcholine content, which was found to correlate with the decreased phosphocholine generation. These results suggest that inhibition of choline kinase by HDTAB leads to decreased phosphocholine, which in turn causes a decrease in phosphatidylcholine biosynthesis, resulting in death of the parasite.

Acid-base and optical properties of neutral red in the presence of ionic and nonionic tensides

1987 ◽  
Vol 52 (10) ◽  
pp. 2401-2411 ◽  
Author(s):  
Jitka Jurasová ◽  
Vlastimil Kubáň
Keyword(s):  
Dissociation Constant ◽  
Sodium Dodecyl ◽  
Neutral Red ◽  
Hexadecyltrimethylammonium Bromide ◽  
Cationic Dye ◽  
Acid Base ◽  
Brij 35 ◽  
Ionic Associates ◽  
Triton X

Changes in the optical and acid-base characteristics of neutral red in the presence of hexadecylpyridinium bromide, hexadecyltrimethylammonium bromide, α-carbethoxypentadecyltrimethylammonium bromide (Septonex), sodium dodecyl sulphate, Triton X-100, and BRIJ 35 in submicellar and micellar concentrations were studied spectrophotometrically. The conditional dissociation constant of neutral red pKai* depends on the kind and concentration of tenside, kind and concentration of inert electrolyte, and concentration of the cationic dye. Changes in the pKai* values are described in terms of formation of ionic associates of the dye with the tenside and of the inert electrolyte ions with the tenside. The validity of equations for the dependence of pKai* on the logarithm of tenside concentration was proved experimentally over a wide region of cationic tenside concentrations. The changes in pKai* can also be partly accounted for by changes in the nature of the solvent. A titrimetric method based on the changes in the conditional dissociation constant of neutral red is suggested for the determination of tensides in aqueous solutions using photometric end point indication.

Influence of surface micellar head group neutralized in hexadecyltrimethylammonium bromide (CTAB) and hydroxide (CTAOH) on the dehydrochlorination of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD)

1985 ◽  
Vol 63 (11) ◽  
pp. 2892-2898 ◽  
Author(s):  
C. Otero ◽  
E. Rodenas
Keyword(s):  
Experimental Results ◽  
Head Group ◽  
Hexadecyltrimethylammonium Bromide ◽  
Empirical Expressions ◽  
Theoretical Approaches ◽  
Cationic Micelles

The basic dehydrohalogenation reactions of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) have been studied in cationic micelles of hexadecyltrimethylammonium bromide (CTAB) and hexadecyltrimethylammonium hydroxide (CTAOH). Different theoretical approaches are discussed, considering the fraction of micellar head group neutralized, β, as a constant, or supposing different kinds of variation in its value. The following two empirical expressions for β have been found: β = 0.8 + 0.5 ([NaOH] + [KBr]) for DDT, and β = 0.8 + 1 ([NaOH] + [KBr]) for DDD, and this is the best way to explain the experimental results.

Reactivity in Micelles - Are We Really Able to Design Micellar Catalysts?

2008 ◽  
Vol 73 (2) ◽  
pp. 127-146 ◽  
Author(s):  
Radek Jurok ◽  
Eva Svobodová ◽  
Radek Cibulka ◽  
František Hampl
Keyword(s):  
Electrostatic Interactions ◽  
Sodium Dodecyl ◽  
Kinetic Studies ◽  
Opposite Polarity ◽  
Micellar Systems ◽  
Ionic Micelles ◽  
Diphenyl Phosphate ◽  
Triton X ◽  
Hydrolysis Of ◽  
Positively Charged

Coordination of lipophilic alkyl pyridin-2-yl ketoximes 1 to Ni2+ ions, reduction of lipophilic 3-alkoxyacetophenones 2 with sodium borohydride, and alkaline hydrolysis of 4-nitrophenyl diphenyl phosphate (PNPDPP) were employed as probes in the investigation which factors may influence the reactivity of organic compounds in micellar systems. In all these reactions, a lipophilic substrate solubilized in micellar core was attacked by a hydrophilic reagent from the bulk aqueous phase. To evaluate the contribution of electrostatic interactions between the micellar surface charge and the reagent to the observed reactivity, we combined reactions involving the reagents with opposite polarity (Ni2+ cations and borohydride or hydroxide anions) with positively charged micelles of hexadecyltrimethylammonium chloride (CTAC) or bromide (CTAB) and negatively charged micelles of sodium dodecyl sulfate (SDS). Non-ionic micelles (Triton X-100 or Brij 35) served as a reference. The results of the kinetic studies give evidence that each of the investigated systems has unique properties going in particular aspects beyond the scope of the generally accepted concepts of reactivity in micelles.

Solubility and adsorption behaviors of chlorophenols in the presence of surfactant

1997 ◽  
Vol 35 (7) ◽  
pp. 123-130 ◽  
Author(s):  
J. C. Liu ◽  
P. S. Chang
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Critical Micelle Concentration ◽  
Sodium Dodecyl ◽  
Adsorption Behaviors ◽  
Brij 35 ◽  
Important Index ◽  
Dodecyl Sulfate ◽  
Triton X

The solubility of chlorophenols as affected by surfactant was investigated. Three kinds of surfactant, sodium dodecyl sulfate, Triton X-100, and Brij 35, were utilized. The solubilization of chlorophenols by surfactant follows the order of 2,4,6-trichlorophenol > 2,4-dichlorophenol > 2,6-dichlorophenol > 2-chlorophenol; and the critical micelle concentration is an important index. The adsorption reactions of 2,4-dichlorophenol and 2,4,6- trichlorophenol onto hydrous montmorillonite in the presence of surfactant were examined. The presence of surfactant decreased the adsorption of chlorophenols significantly. The roles of hydrophobicity of chlorophenols in solubilization and adsorption behaviors are discussed.

Spectrophotometric study of the complexation equilibria of cadmium ions with 5-bromo and 5-chloro derivatives of 2-(2-pyridylazo)-5-diethylaminophenol (BrPADAP, ClPADAP)

1983 ◽  
Vol 48 (1) ◽  
pp. 52-59 ◽  
Author(s):  
Vlastimil Kubáň ◽  
Miroslav Macka
Keyword(s):  
Equilibrium Constants ◽  
Spectrophotometric Study ◽  
Graphical Analysis ◽  
Optimal Conditions ◽  
Cadmium Ions ◽  
Brij 35 ◽  
Ethanol Medium ◽  
Triton X ◽  
Derivatives Of

The composition, optical characteristics, molar absorption coefficients and equilibrium constants of the reactions of formation of the ML and ML2 complexes of both reagents with cadmium(II) ions were determined by graphical analysis and numerical interpretation of the absorbance-pH curves by the modified SQUAD-G program. Optimal conditions were proposed for the spectrophotometric determination of Cd in 10% v/v ethanol medium in the presence of 0.1% w/v Triton X-100 or 1% w/v Brij 35. BrPADAP and ClPADAP are the most sensitive spectrophotometric reagents for the determination of cadmium(II) ions (ε = 1.28-1.44 . 105 mmol-1 cm2 at 560 nm and pH 8.0-9.5) with a high colour contrast in the reaction (Δλmax ~117 nm) and a selectivity similar to that of other N-heterocyclic azodyes (PAR, PAN, etc.).

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