The Importance of Molecular Parameters of Quaternary Ammonium Salts in Their Antigibberellin (Retardant) Activity

The importance of six theoretically calculated molecular parameters in the antigibberellin (retardant) activity of quaternary ammonium salts is studied using a regression analysis. A bioassay system based on cell culture of fungus Gibberella fujikuroi is used to determine the activity. In the case of N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium chloride (choline) and N,N,N-triethyl-N-(2-hydroxyethyl)ammonium chloride (N,N,N-triethylcholine) derivatives with linear structure, the polarizability, proton acceptor activity, and lipophilicity of these compounds exert the largest effect on the antigibberellin activity. The antigibberellin activity of more sterically hindered N,N-dialkylpiperidinium salts was mainly defined by the steric parameter, while the polarizability, proton acceptor activity, and (through them) lipophilicity exert a lesser effect. Other parameters are of minor importance for the three groups of compounds studied.     

Effects of some cyclic elements containing amphiphilic compounds on stability and transport properties of model lecithin membranes

The paper presents results of studies on changes in model membrane properties induced by some single-chain amphiphilic quaternary ammonium salts with fungicidal activity, N-dodecyl-N-methylmorpholinium chloride (IVC), N-dodecyloxymethylene-N-methylmorpholinium chloride (IVD), N-dodecyl-N-methylpiperidinium chloride (VIC), N-dodecyloxymethylene-N-methylpiperidinium chloride (VID) and N-dodecyl-N,N-dimethyl-N-benzy-lammonium chloride (IB). Two different lipid systems were used, namely, unilamellar liposomes and black planar membranes (BLM). All the compounds studied interfered with sulphate ion transport across liposomal membranes as well as with calcium ion desorption from the membranes. The compounds were found also to change the stability of black lecithin membranes. Generally the sequence of effectiveness of the salts studied on both models used was: IB greater than VID greater than IVD greater than VIC greater than IVC, although there were some differences for particular processes. The results obtained are discussed in view of a possible mechanism of the interaction between the salts studied and the lipid model including the role the salt head group structure and charge distribution can play in this interaction.     

A structure-activity study of spermicidal and anti-HIV properties of hydroxylated cationic surfactants

The syntheses of 2-hydroxy-N-(2-hydroxyethyl)-N,N-dimethylhexadecan-1-aminium chloride [1(16)Cl] and iodide [1(16)I], 2-hydroxy-N,N,N-trimethylhexadecan-1-aminium chloride (6), N-(2-hydroxyethyl)-N,N-dimethylhexadecan-1-aminium chloride (8), N,N-bis(2-hydroxyethyl)-N-methylhexadecan-1-aminium chloride (11), and 2-hydroxy-N-(2-hydroxyethyl)-N,N-dimethyl-4-oxahexadecan-1-aminium chloride (14) are reported along with the critical micelle concentrations (cmcs), as measured by conductivity at 25 degrees C, of 1(16)Cl, 1(16)I, 6, 8, 11, and N,N,N-trimethylhexadecan-1-aminium chloride (12). All compounds display spermicidal and virucidal activity. A plot of minimum effective concentration (MEC) in the Sander-Cramer spermicidal assay and cmc shows that 1(16)Cl and 6 have the best spermicidal activity and highest cmcs. Compounds 8, 11, and 1(16)Cl are the most active at 0.05 mg mL(-1) against cell-free and cell-associated virus. In conclusion, 1(16)Cl shows the best combination of dual activity against sperm and HIV; it is a promising candidate for further preclinical studies as a topical, contraceptive microbicide.     

Lysosomotropic N,N- dimethyl alpha-aminoacid N-alkyl esters and their quaternary ammonium salts as plasma membrane and mitochondrial ATPases inhibitors

A set of n-alkyl esters of N,N-dimethylglycine (DMG-n) and their methobromides (DMGM-n) was synthesized, and their activities on yeast Saccharomyces cerevisiae were compared. The compounds differ in the number of carbon atoms in the aliphatic chain. Aminoesters with 12 carbon atoms appeared to be most active. Unlike quaternary ammonium salts previously tested, the activities of the compounds were not pH-dependent; the minimal inhibitory concentrations (MIC) were identical at pH 8 and at pH 6. In contrast to quaternary ammonium salts, aminoesters showed similar effects on respiratory sufficient (rho+) and respiratory deficient (rho0) mutants. When tested on glucose stimulated proton extrusion, aminoesters applied at MIC increased external pH. Aminoesters inhibited the plasma membrane H+-ATPase, whereas they were less inhibitory on the mitochondrial ATPase. In order to further compare the aminoesters and their corresponding quaternary ammonium salts, derivatives of N,N-dimethylalanine (DMAL-n and DMALM-n, respectively) were synthesized. The quaternary ammonium salts appeared to have a higher inhibitory potency than aminoesters, especially at pH 8, and alanine derivatives inhibited growth at a lower concentration than glycine derivatives. Both alanine derivatives of the aminoester and the quaternary ammonium salt inhibited the plasma membrane H+- ATPase at lower concentrations than glycine derivatives, but the alanine aminoester was without a detectable effect on the mitochondrial ATPase.     

Nanoheterogeneous catalytic hydrogenation of N-, O- or S-heteroaromatic compounds by re-usable aqueous colloidal suspensions of rhodium(0)

The hydrogenation of various nitrogen-, oxygen- or sulfur-heterocyclic aromatic compounds by various surfactant-stabilized aqueous rhodium(0) colloidal suspensions was investigated. The nanocatalysts in the size range of 2.1-2.4 nm have been synthesized by reducing RhCl₃ · 3H₂O with sodium borohydride and were stabilized by highly water soluble N,N-dimethyl-N-cetyl-N-(2-hydroxyethyl)ammonium bromide or chloride salts. The catalytic reactions were performed under mild reaction conditions, namely room temperature and under atmospheric hydrogen pressure. The influence of the bromide or chloride nature of the surfactant counter-ion on the recycling of the aqueous phase containing the Rh(0) particles was studied.     

Purification and properties of the trimethylamine dehydrogenase of Bacterium 4B6

1. The trimethylamine dehydrogenase of bacterium 4B6 was purified to homogeneity as judged by analytical polyacrylamide-gel electrophoresis. The specific activity of the purified enzyme is 30-fold higher than that of crude sonic extracts. 2. The molecular weight of the enzyme is 161000. 3. The kinetic properties of the purified enzyme were studied by using an anaerobic spectrophotometric assay method allowing the determination of trimethylamine dehydrogenase activity at pH8.5, the optimum pH. The apparent K(m) for trimethylamine is 2.0+/-0.3mum and the apparent K(m) for the primary hydrogen acceptor, phenazine methosulphate, is 1.25mm. 4. Of 13 hydrogen acceptors tested, only Brilliant Cresyl Blue and Methylene Blue replace phenazine methosulphate. 5. A number of secondary and tertiary amines with N-methyl and/or N-ethyl groups are oxidized by the purified enzyme; primary amines and quaternary ammonium salts are not oxidized. Of the compounds that are oxidized by the purified enzyme, only trimethylamine and ethyldimethylamine support the growth of bacterium 4B6. 6. Trimethylamine dehydrogenase catalyses the anaerobic oxidative N-demethylation of trimethylamine with the formation of stoicheiometric amounts of dimethylamine and formaldehyde. Ethyldimethylamine is also oxidatively N-demethylated yielding ethylmethylamine and formaldehyde; diethylamine is oxidatively N-de-ethylated. 7. The activity of the purified enzyme is unaffected by chelating agents and carbonyl reagents, but is inhibited by some thiol-binding reagents and by Cu(2+), Co(2+), Ni(2+), Ag(+) and Hg(2+). Trimethylamine dehydrogenase activity is potently inhibited by trimethylsulphonium chloride, by tetramethylammonium chloride and other quaternary ammonium salts, and by monoamine oxidase inhibitors of the substituted hydrazine and the non-hydrazine types. 8. Inhibition by the substituted hydrazines is time-dependent, is prevented by the presence of trimethylamine or trimethylamine analogues and in some cases requires the presence of the hydrogen acceptor phenazine methosulphate. The inhibition was irreversible with the four substituted hydrazines that were tested.     

4-Biphenyl and 2-naphthyl substituted 6,7-dimethoxytetrahydroisoquinoline derivatives as potent P-gp modulators

Starting from lead compound 1 (EC(50)=1.64 microM), its non-basic nucleus has been conformationally restricted by 4-biphenyl and 2-naphthyl moieties. In each series we investigated if the presence of H-bond donor or acceptor substituents, the basicity and the lipophilicity (clogP) were correlated with the P-gp inhibiting activity of tested compounds. In the biphenyl series, derivative 4d displayed the best results (EC(50)=0.05 microM). The corresponding amide 3d was found less active (EC(50)=3.5 microM) ascertaining the importance of basicity in this series whilst the presence of hydroxy or methoxy substituents seems to be negligible. In the naphthyl series, both the basicity and the presence of H-bond donor or acceptor groups seem to be negligible. Moreover, the lipophilicity did not influence the P-gp inhibition activity of each series. Specific biological assays have been carried out to establish the P-gp interacting mechanism of tested compounds discriminating between substrates and inhibitors. Moreover, compound 4d displayed a potent P-gp inhibition activity with good selectivity towards BCRP pump.     

(Aminoethanol)dichloroplatinum(II) complexes: influence of the hydroxyethyl moiety on 5'-GMP and DNA binding, intramolecular stability, the partition coefficient and anticancer activity

The influence of tethered hydroxyl groups on the binding behavior of the three (aminoethanol)dichloroplatinum complexes, dichloro(N,N'-bis(2-hydroxyethyl)ethylenediamine)-platinum(II) (1), dichloro(N-(2-hydroxyethyl)ethylenediamine)platinum(II) (2) and cis-dichlorobis(2-hydroxyethylamine)platinum(II) (3) towards 5'-GMP and DNA was investigated by 1H NMR and r(b) measurements, respectively. At pH 7.2, the sequence of reactivity with 5'-GMP is 1>2>3. Complex 3 reacts very slowly with 5'-GMP and DNA and the amount and lifetime of the intermediate 5'-GMP monoadduct are much larger than for 1 and 2. At pH 5.5, the reaction of 3 with 5'-GMP is markedly accelerated and very small amounts of monoadduct are observed, indicating a pH-dependent ability of the pendant hydroxyl group to interact with the platinum moiety. In addition, the effect of the hydroxyethyl functionality on octanol/water partitioning and in vitro anticancer activity was studied. No correlation between lipophilicity and anticancer activity was detected. Furthermore, the lipophilicity and anticancer activity could not be directly correlated to 5'-GMP or DNA binding activity.     

Interaction between model membranes and a new class of surfactants with antioxidant function.

The effect of two series of amphiphilic quaternary ammonium salts on some properties of phospholipid membranes was studied. The compounds of one series, N-benzyl-N,N-dimethyl-N-alkyl ammonium bromides, exert a destructive effect on membranes and are treated as reference compounds. The compounds of the other series, N-(3,5-di-t-butyl-4-hydroxy)benzyl-N,N-dimethyl-N-alkyl ammonium bromides, are derivatives of the former ones, exhibit antioxidant properties, and do only relatively slight damage to the membranes. The aim of the work was to explain the difference in molecular interaction with membranes between the two kinds of hydrophobic compounds. Thermodynamic methods, a new mixing technique, and monolayer and quantum calculation methods were used. It has been shown that the antioxidant molecules are less hydrophobic than those of the reference compounds and disturb the membrane organization to a lesser extent. On the basis of monolayer data, we suggest that the studied antioxidant behaves like a substitutional impurity, whereas the reference behaves like an interstitial one.     

Synthesis and biological applications of ionic triphenyltin(IV) chloride carboxylate complexes with exceptionally high cytotoxicity

The reaction of N-phthaloylglycine (P-GlyH), N-phthaloyl-l-alanine (P-AlaH), and 1,2,4-benzenetricarboxylic 1,2-anhydride (BTCH) with triethylamine led to the formation of the corresponding ammonium salts [NHEt(3)][P-Gly] (1), [NHEt(3)][P-Ala] (2) and [NHEt(3)][BTC] (3) in very high yields. The subsequent reaction of 1-3 with triphenyltin(iv) chloride (1?:?1) yielded the compounds [NHEt(3)][SnPh(3)Cl(P-Gly)] (4), [NHEt(3)][SnPh(3)Cl(P-Ala)] (5), and [NHEt(3)][SnPh(3)Cl(BTC)] (6), respectively. The molecular structure of 4 was determined by X-ray diffraction studies. The cytotoxic activity of the ammonium salts (1-3) and the triphenyltin(iv) chloride derivatives (4-6) were tested against human tumor cell lines from five different histogenic origins: 8505C (anaplastic thyroid cancer), A253 (head and neck cancer), A549 (lung carcinoma), A2780 (ovarian cancer) and DLD-1 (colon cancer). Triphenyltin(iv) chloride derivatives (4-6) show very high activity against these cell lines while the ammonium salts of the corresponding carboxylic acids (1-3) are totally inactive. The most active compound is 4 which is 50 times more active than cisplatin. Compound 4 is found to induce apoptosis via extrinsic pathways on DLD-1 cell lines, probably by accumulation of caspases 2, 3 and 8. Furthermore, compound 4 seems to cause disturbances in G1 and G2/M phases in cell cycle of DLD-1 cell line.     

Quantitative relationships between structure and antimicrobial activity of new “Soft” bisquaternary ammonium salts

New surface-active bisquaternary ammonium salts derived from bis-(2-dimethylaminoethyl) ester of glutaric acid are highly effective against representatives of Gram-positive, Gram-negative bacteria and yeasts. Relationships between structure, lipophilicity and antimicrobial effectiveness were demonstrated by quantitative structure-activity methodology. The nonlinear dependence of biological activity on the structure as well as lipophilicity (expressed as critical micelle concentration—CMC) was shown using Kubinyi’s bilinear model. The most effective compounds were those with the alkyl chain of 11–12 carbon atoms and with the CMC values around 0.7−1.0 mmol/L. These derivatives possessed higher antimicrobial activity particularly to Gram-negative bacteria. Part 45 of the seriesQuaternary Ammonium Salts; part 44: Brádlerová A.et al., Pharmazie, in press.     

Pre- and post-synaptic modulation of neuromuscular transmission in smooth muscles by thiazole analogs of vitamin B1

The effects of structural analogs of vitamin B₁, thiazole derivatives with alkyloxycarbonylmethyl substituents at position 3, on neuromuscular transmission were studied in the smooth muscles of the guinea pig gastrointestinal tract. In the smooth muscles of the stomach, the studied compounds depressed excitatory cholinergic neuromuscular transmission. In the case of 3-hexyl-, 3-decyl-, and 3-dodecyloxycarbonylmethyl-4-methyl-5-(2-hydroxyethyl)-thiazole chlorides this effect was due to their presynaptic action, while in the case of 3-menthyloxycarbonylmethyl-4-methyl-5-(2-hydroxyethyl)thiazole chloride it was due to the block of muscarinic acetylcholine receptors in smooth muscle fibers. In the circular smooth muscles of the distal colon, 3-decyloxycarbonylmethyl-4-methyl-5-(2-hydroxyethyl)thiazole chloride blocked non-adrenergic inhibitory synaptic potentials (ISP) apparently through interaction with the ATP-sensitive acetylcholine receptors. In contrast, 3-hexyloxycarbonylmethyl-4-methyl-5-(2-hydroxyethyl)thlazole chloride enhanced postinhibitory excitation, without changing the ISP amplitude. Possible ways of pre- and post-synaptic modulations of neuromuscular transmission by thiazole derivatives are discussed. It has been suggested that the effects of these compounds are due to similarity of their structures to the structure of vitamin B₁.Neirofiziologiya/Neurophysiology, Vol. 27, No. 5/6, pp. 375–386, September–December, 1995.     

Use of a D-optimal design with constrains to quantify the effects of the mixture of sodium,potassium, calcium and magnesium chloride salts on the growth parameters of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

The combined effect of NaCl, KCl, CaCl(2), and MgCl(2) on the water activity (a (w)) and the growth parameters of Saccharomyces cerevisiae was studied by means of a D-optimal mixture design with constrains (total salt concentrations < or = 9.0%, w/v). The a (w) was linearly related to the concentrations of the diverse salts; its decrease, by similar concentrations of salts, followed the order NaCl > CaCl(2) > KCl > MgCl(2), regardless of the reference concentrations used (total absence of salts or 5% NaCl). The equations that expressed the maximum specific growth (mu (max)), lag phase duration (lambda), and maximum population reached (N (max)) showed that the values of these parameters depended on linear effects and two-way interactions of the studied chloride salts. The mu (max) decreased as NaCl and CaCl(2) increased (regardless of the presence or not of previous NaCl); however, in the presence of a 5% NaCl, a further addition of KCl and MgCl(2) markedly increased mu (max). The lambda was mainly affected by MgCl(2) and the interactions NaCl x CaCl(2) and CaCl(2) x MgCl(2). The further addition of NaCl and CaCl(2) to a 5% NaCl medium increased the lag phase while KCl and MgCl(2) had negligible or slightly negative effect, respectively. N (max) was mainly affected by MgCl(2) and its interactions with NaCl, KCl, and CaCl(2); MgCl(2) stimulated N (max) in the presence of 5% NaCl while KCl, NaCl, and CaCl(2) had a progressive decreasing effect. These results can be of interest for the fermentation and preservation of vegetable products, and foods in general, in which this yeast could be present.     

Reversed-phase thin-layer chromatography used to study the simultaneous effect of pH and ion strength on the lipophilicity of chlorhexidine

The effect of ion strength and pH value of the eluent on the determination of the lipophilicity of chlorhexidine was studied by reversed-phase thin-layer chromatography. The method has been improved by using various buffers: aqueous solutions of formic, acetic and propionic acids and their sodium salts in different ratios and in various concentrations. Stepwise regression analysis separated the effect of pH value, ion strength and acid type on the lipophilicity of chlorhexidine and proved that the ion strength exerted a higher impact than the pH value did. The effect of alkyl chain length of the acids was of secondary importance.     

Quantitative Studies on Fabrics as Disseminators of Viruses: III. Persistence of Vaccinia Virus on Fabrics Impregnated with a Virucidal Agent

Eight compounds were tested in vitro for virucidal and antiviral activity against poliovirus and vaccinia virus. These compounds included five quaternary ammonium salts, two bromosalicylanilides, and neomycin sulfate, an antibiotic. None of the compounds was active against poliovirus, but virucidal activity was demonstrated against vaccinia virus with three of the quarternary ammonium compounds: n-alkyl (C14, C12, C16) dimethyl benzyl ammonium chloride, di-isobutyl cresoxy ethoxy ethyl dimethyl benzyl ammonium chloride monohydrate, and n-alkyl (60% C14, 30% C16, 5% C12, 5% C18) dimethyl benzyl ammonium chlorides plus n-alkyl (50% C12, 30% C14, 17% C16, 3% C18) dimethyl ethylbenzyl ammonium chlorides. Wool blanketing, wool gabardine, and cotton sheeting materials were impregnated with the first of the above virucidal compounds, and the persistence of vaccinia virus on these fabrics was compared with the persistence of the agent on nonimpregnated fabrics of the same type held at 25 C in 35 and 78% relative humidity. No virus could be recovered from the chemically treated fabrics at any time after virus exposure, whereas the virus persisted as long as 4 weeks on nonimpregnated materials. Viable vaccinia virus was also found to persist less than 1 day on a cotton fabric finished with a wash-and-wear modified triazone resin. Poliovirus persisted less than 5 days on this wash-and-wear fabric.     

The synthesis and biological activity of lipophilic derivatives of bicine conjugated with N³-(4-methoxyfumaroyl)-L-2,3-diaminopropanoic acid (FMDP)-an inhibitor of glucosamine-6-phosphate synthase

A series of bis-N,N-(2-hydroxyethyl)glycine (bicine) derivatives, conjugated with an inhibitor of glucosamine-6-phosphate synthase, have been synthesized and their lipophilic and antifungal properties have been tested. The obtained compounds demonstrated higher lipophilicity than free inhibitor (FMDP) and, in consequence, an increased potential to cross the cytoplasmic membrane. All the tested compounds show better antifungal activity than parent compound.     

Effect of different nitrogen sources on the biosynthesis of lipase by Oospora lactis

The effect of inorganic and organic nitrogen compounds on the synthesis of biomass and extracellular lipase by Oospora lactis was studied. Among the inorganic nitrogen sources ammonium sulphate and ammonium secondary phosphate and among the organic nitrogen sources yeast autolysate proved to be most beneficial for the lipase synthesis. Lipase activity and biomass accumulation in the medium containing yeast autolysate were greater than in the media containing the above ammonium salts. Lipase synthesis reached maximum in the nutrient medium containing yeast autolysate (0.7%) and ammonium sulphate (0.3%).     

Effects of quaternary ammonium salts on membrane potential and electric conductance in internodal cells of Nitettopsis obtusa

Effects of amphiphilic derivatives of glycine esters of the general formula (CH₃)₃N⁺CH₂COOC_nH_2n+1Cl- (n = 10, 12, 14, 16) on membrane potential and conductance in internodal cells of the alga Nitellopsis obtusa were studied. The compounds decreased the potential difference between vacuole and external medium and increased the electric conductance. The effects depended on the length of the alkyl chain (n) and the concentration of these quaternary ammonium salts. Light-induced hyperpolarization was suppressed by the salts. We suggest that the ammonium salts inhibit the electrogenic proton pump in the plasmalemma and enhance the passive efflux of Cl- from the algal cell.     

Evaluation of lipophilicity and antitumour activity of parallel carboxamide libraries

Searching for molecules possessing antitumour activity, a parallel molecule library of aromatic carboxamides has been designed and synthesised. This work resulted in a "thiophene" sub-library containing a thiophene core and of a "furoyl" sub-library with a furoyl core, respectively. In both sub-libraries substitutions were carried out with six different groups resulting in six pairs of compounds differing in only the heteroatom of aromatic ring of the cores. To study the importance of the type of cores and the specific substitutions in relation to their lipophilicity and antitumour activity, lipophilicity of carboxamides was determined by chromatographical data (log k') and by software calculated parameters (CLOGP). Pairs of compounds were tested for their ability to inhibit the proliferation of the A431 cells by MTT assay. The isosteric molecule pairs were successfully separated. Our results showed that the experimentally determined (log k') and the calculated (CLOGP) lipophilicity parameters correlated well with each other. Furthermore, lipophilicity values of the thiophene sub-library were always higher than those in the furoyl sub-library. Moreover, compounds of the thiophene sub-library were more active than their respective furoyl pairs in our MTT antiproliferative assay. From these observations we can conclude that the higher the lipophilicity values the higher the antitumour activity of the carboxamides synthesised. Therefore, determination of lipophilicity by measuring the log k' or by calculating the CLOGP values of the carboxamide sub-libraries may help to predict their biological activities.