Effects of Triton X-100 nanoaggregates on dimerization and antioxidant activity of morin

Dimerization and antioxidant activity of morin in the Triton X-100 micelles were studied by electronic absorption, ATR-FTIR spectra, cyclic voltammetric, DSC, freeze-fracture TEM, molecular modeling and ab initio quantum calculations. Morin can be solubilized in the Triton X-100 micelles and show selective dimerization in Triton X-100 micelles with different structures. In Triton X-100 spherical micelles, morin always exists in the form of dimer, and in Triton X-100 rodlike micelles, it is always in the form of monomer. The solubilization of morin dimer in Triton X-100 spherical micelles changes the micelle morphology from spherical to cubelike, and the size of the single micelle is also increased, while morin monomer links the Triton X-100 rodlike micelles and forms a kind of network micelle structure with the size of the "rod" unchanged. Solubilized and concentrated in Triton X-100 micelles, morin can protect human serum albumin from the damage induced by hydroxyl radicals effectively and even can form a kind of protein complex with human serum albumin showing more thermal stability.     

Spectrophotometric determination of <Emphasis Type="Italic">p</Emphasis>-aminophenol in drugs using 5,7-dichloro-4,6-dinitrobenzofuroxan reagent in micellar medium

A new spectrophotometric method for determining p-aminophenol in micellar aqueous dimethylsulfoxide (DMSO) media with non-ionogenic surfactant Triton X-100 that makes use of 5,7-dichloro-4,6-dinitrobenzofuroxan as an indicator has been developed. Using the proposed method, it is possible to detect an admixture of p-aminophenol in paracetamol (acetaminophen) in such media on a level that is much lower than the limiting concentration. The presence of Triton X-100 in the form of micelles improves the sensitivity of spectrophotometric determination compared to that of standard techniques.     

Interactions of rat brain acetylcholinesterase with the detergent Triton X-100 and the organophosphate paraoxon.

Inhibition of the critical enzyme acetylcholinesterase (E.C. 3.1.1.7) with subsequent cholinergic crisis is the mechanism of acute toxicity of the organophosphorus insecticides (B. E. Mileson et al., 1998, Toxicol. Sci.41, 8-20). Consequently, measurement of acetylcholinesterase activity is important for evaluating the mammalian toxicity of this commonly used class of insecticides. While mammalian acetylcholinesterase activity has often been determined in tissue homogenates in the presence of the nondenaturing detergent Triton X-100 at a concentration of 1%, the potential actions of this detergent on the activity of this critical enzyme are not understood. In the current study, homogenization of rat brain in buffer containing 1% Triton X-100 slightly elevated the (app)V(max) for hydrolysis of acetylthiocholine, without affecting the (app)K(m) or the (app)K(ss). However, the presence of both 1% Triton X-100 and paraoxon (at concentrations of 5 nM-100 nM) resulted in complex kinetic interactions with acetylcholinesterase, as evidenced by a curvilinear secondary plot for determination of the (app)k(i). These results suggest that measurement of acetylcholinesterase activity in the presence of up to 1% Triton X-100, but in the absence of oxon, should pose no problems with regard to data interpretation, provided it is recognized that the detergent slightly elevates activity. However, measurement of acetylcholinesterase activity after enzyme was exposed simultaneously to Triton X-100 and oxon could be problematic. Caution is warranted when interpreting data where acetylcholinesterase activity was determined under such conditions since in the presence of 1% Triton X-100, the capacity of oxon to inhibit acetylcholinesterase might change as a function of oxon levels.     

Interaction of non-ionic surfactants with hepatic CYP in Prochilodus scrofa

Cytochromes P450 (CYP) constitute a superfamily of hemeproteins that play a vital role in the metabolism of a wide variety of endogenous and xenobiotic compounds. Xenobiotic metabolism and the role of CYP are of particular interest in studies regarding the prevention of the damage caused by chemical pollutants. We investigated, in this study, the interaction of Triton X-100 and Tween 80 with CYP and antioxidant defenses in Curimbatá, a Brazilian fish. Aiming to clarify the effects of non-ionic surfactants in the monooxigenase system of fish through in vitro study, the effects of Triton X-100 and Tween 80 were analyzed using monooxygenases and antioxidant system as experimental model. Total CYP and EROD were strongly inhibited by Triton X-100 and Tween 80 in a concentration-dependent way; the content of CYP was reduced until zero while EROD activity was completely inhibited in the presence of Triton X-100 and more than 40% inhibited in the presence of Tween 80. Each surfactant causes a different effect on each antioxidant enzyme. No effect was detected in SOD activity in the presence of even Triton X-100 or Tween 80. Triton X-100 increase catalase activity, while Tween 80 decreases this enzyme activity. The molecular structure of the surfactants causes the alteration of this system, since they are able to interact with the microsomal protein, especially with monooxigenase's components, altering their conformation and, consequently destroying their function. Our results suggest that surfactants can interact with components of the microsomal system leading to inhibition of CYP. Therefore, CYP activity, which has been used as a biomarker of xenobiotic exposure, should be used as a marker in association with other enzymes.     

Interactions of alpha-tocopherol with biomembrane models: binding to dry lecithin reversed micelles

The state of alpha-tocopherol (Vitamin E) in solutions of dry lecithin reversed micelles dispersed in an apolar medium has been investigated as a function of the Vitamin E to surfactant molar ratio (RVE) at fixed surfactant concentration by FT-IR, 1H NMR and SAXS with the aim to emphasize the role played by anisotropic intermolecular interactions and confinement effects as driving forces of its partitioning between apolar bulk solvent and polar nanodomains and of mutual Vitamin E/reversed micelle effects. It has been found that its binding strength to reversed micelles, triggered by steric and orientational constrains, is mainly regulated by specific interactions between the hydrophilic groups both of Vitamin E and surfactant. Moreover, the RVE dependence of the Vitamin E distribution constant and of the micellar size suggest that the inclusion of increasing amounts of Vitamin E in reversed micelles involves substantial changes in the structural and dynamical properties of the micellar aggregates. The occurrence of mutual effects and the partitioning of Vitamin E between hydrophilic/hydrophobic interfaces and apolar domains allow to infer some important biological implications concerning the capacity of Vitamin E to scavenge free radicals arising from hydrophilic and/or hydrophobic domains, possible variations of its local reactivity respect to that observed in bulk as well as its significant influence on the stability of biomembranes.     

DISSOCIATION,AGGREGATION OF SESAME α-GLOBULIN IN NONIONIC DETERGENT SOLUTION

Nonionic detergents Triton X-100 and Brij 36T induce dissociation and aggregation of the protein sesame α-globulin above the critical micelle concentrations (cmc) of the detergents. Spectrophotometric titration in Triton shows no change in the pK_Int value of the tyrosyl groups at 1 × 10^-3M detergent where both dissociation and aggregation of the protein are observed. Fluorescence measurement does not indicate any change in the environment of the tryptophan groups of the protein in Brij. Viscosity measurements show no major conformational change of the protein in the detergent solution. Binding measurements suggest that perhaps micelles of the detergent predominantly bind to the protein. The detergent micelles preferentially bind to the exposed hydrophobic surfaces of the protein subunits. The association of the protein detergent complex through electrostatic interaction is probably responsible for the formation of the aggregates.     

In vitro actions of some antibiotics on phospholipases

The effects of some antibiotics on activities of phospholipase A2, B and C were investigated in vitro. Tetracyclines, macrolides, chloramphenicol and carbenicillin inhibited the activity of Crotalus adamanteus phospholipase A2 towards phospholipids of egg-yolk emulsions. When the ability to inhibit the activity of Penicillium notatum phospholipase B towards mixed micelles of phosphatidylcholine and Triton X-100 was investigated, polymyxin B was found to be inhibitory while chloramphenicol and carbenicillin were found to stimulate the activity of the phospholipase. The activity of Bacillus cereus phospholipase C towards the mixed micelles was inhibited by bleomycin, oleandomycin and chloramphenicol.     

Differential effects of triton X-100 on benzodiazepine and GABA binding in a frozen-thawed synaptosomal fraction of rat brain

The effect of Triton X-100 on 3H-GABA and 3H-diazepam binding was measured in a frozen-thawed synaptosomal fraction of rat brain. Specific binding activity (amount bound per mg protein) of both ligands was increased by the treatment. Diazepam binding capacity in the pellet was progressively decreased, while GABA binding was increased, then decreased by increasing Triton X-100. Diazepam binding affinity was unchanged, while GABA binding affinity increased. Triton X-100 appears to preferentially solubilize benzodiazepine binding sites, indicating GABA and benzodiazepine binding sites are on separate macromolecules.     

Hydrolysis of short-chain phosphatidylcholines by bee venom phospholipase A2

In order to find out the aggregation state of the substrate, preferred by bee venom phospholipase A2 (EC 3.1.1.4), its action on short-chain phosphatidylcholines with two identical (C6-C10) fatty acids has been tested. The rate of hydrolysis as a function of acyl chain length showed a maximum at dioctanoylphosphatidylcholine. The effects of alcohols, NaCl and Triton X-100, which affect the aggregation state of phospholipids in water, were also studied. The addition of n-alcohol led to a significant inhibition of the hydrolysis of the substrates present in micellar form and activated the hydrolysis of substrates which form liposomes. The inhibitory effect increased with increasing length of the aliphatic carbon chain of the alcohol. Triton X-100 at low Triton/phospholipid molar ratios enhanced enzyme activity. These results do not agree with the accepted idea that bee venom phospholipase A2 hydrolyzes short-chain lecithins in their molecularly dispersed form and that micelles cannot act as substrates. The data indicate that short-chain lecithins in the aggregated state are hydrolyzed and that the requirements of bee venom phospholipase A2 for the aggregation state of the substrate are not strict.     

Quantitative estimation of gold nanoshell concentrations in whole blood using dynamic light scattering

We demonstrate a new nondestructive optical assay to estimate submicron solid particle concentrations in whole blood. We use dynamic light scattering (DLS), commonly used to estimate nanoparticle characteristics such as size, surface charge, and degree of aggregation, to quantitatively estimate concentration and thereby estimate the actual delivered dose of intravenously injected nanoparticles and the longitudinal clearance rate. Triton X-100 is added to blood samples containing gold (Au) nanoshells to act as a quantitative scattering standard and blood lysing agent. The concentration of nanoshells was determined to be linearly proportional (R(2) = 0.998) to the relative light scattering attributed to nanoshells via DLS as compared with the Triton X-100 micelles in calibration samples. This relationship was found to remain valid (R(2) = 0.9) when estimating the concentration of circulating nanoshells in 15-muL blood samples taken from a murine tumor model as confirmed by neutron activation analysis. Au nanoshells are similar in size and shape to other types of nanoparticles delivered intravascularly in biomedical applications, and given the pervasiveness of DLS in nanoscale particle manufacturing, this simple technique should have wide applicability toward estimating the circulation time of other solid nanoparticles.     

杨树芽提取物清除DPPH自由基的作用

目的对杨树芽进行初步提取分离,测定其总黄酮含量和抗氧化活性。方法通过超声辅助提取杨树芽中有效成分,以抗坏血酸、生育酚和芦丁为对照品,采用DPPH法测定其自由基清除作用。结果超声辅助提取的杨树芽提取物中总黄酮含量为14.4%,浓度为0.05 g.L-1时,清除自由基能力大于芦丁和生育酚,浓度提高后略低于生育酚,高于芦丁,且清除能力随浓度提高而提高。结论杨树芽提取物中总黄酮含量较高,并有较强的抗氧化活性。     

Histamine-releasing effect of a corticotrophin derivative. II. Mechanism of action of histamine release by C 44 680-Ba, compared with that of Cpd. 48/80, dextran and triton.

The mechanism of the histamine-liberating action of the synthetic polypeptide C 44 680-Ba, an alkyl-prolyl derivative of beta 1-19 corticotrophin, was investigated and compared with those of Compound 48/80, dextran, Melittin and Triton X-100. It was found that the release of histamine from rat peritoneal cells induced by the polypeptide is dependent on temperature, pH, calcium ions and energy-providing processes. In regard to these criteria, the mode of action of this histamine liberator resembles that of Compound 48/80 but is quite distinct from that of the unspecific substance Triton X-100.     

Mechanisms of acquired penicillin-resistance in Streptomyces cacaoi. Role of penicillin-binding proteins in penicillin resistant mutants

Several mutants isolated after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis of Streptomyces cacaoi strain KCCS-0352, were resistant to benzylpenicillin ranging in concentration from 1,000 to 5,000 micrograms/ml (4- to 20-fold more resistant than the parent). These mutants also acquired resistance to mecillinam, cephamycin C and methicillin. The affinity for beta-lactams of penicillin-binding proteins (including PBP-2--a possible lethal target of beta-lactams in Streptomyces cacaoi) in the mutants decreased. Addition of Triton X-100 or ethylenediaminetetraacetic acid, but not toluene, reduced the minimum inhibitory concentration of beta-lactams. In vitro accessibility of [14C]benzylpenicillin to whole cells and membrane fractions was lower in the mutants than in the parent. The binding of beta-lactams to penicillin-binding proteins in both the parent and mutants was increased by pretreatment with Triton X-100 or ethylenediaminetetraacetic acid. The results of this study of penicillin-binding suggest that penicillin-binding proteins play a major role in "acquired" resistance as well as "intrinsic" resistance.     

Improvement of 5-HT3 receptor binding assay: enhancement of specific [3H]quipazine binding with Triton X-100-treated membranes from rat cortex.

The 5-hydroxytryptamine (5-HT)3 receptor binding assay using [3H]quipazine was examined. It was impossible to obtain specific [3H]quipazine binding with the membrane fractions from rat cortex prepared by the usual procedure. When the membranes were pretreated with detergent Triton X-100, the ratio of specific [3H]quipazine binding markedly increased, depending upon the concentration of Triton X-100 in the range of 0.01-0.1% (w/v). At a concentration of more than 0.05%, the specific binding reached a maximum of 55 to 60% of the total binding. The specific [3H]quipazine binding to the Triton X-100-treated membranes was reversible and was potently inhibited by several 5-HT3 antagonists, while 5-HT1, 5-HT2 receptor antagonists and other receptor-specific ligands had no effect on the binding. Scatchard analysis indicated a single class of binding sites with a Kd of 0.62 nM and Bmax of 97 fmol/mg protein. Thus, the Triton X-100-treated membranes retained the characteristics of 5-HT3 binding sites, making it possible to use [3H]quipazine for a 5-HT3 receptor binding assay with a high ratio of specific binding.     

Protective mechanism of quercetin and rutin on 2,2′-azobis(2-amidinopropane)dihydrochloride or Cu-induced oxidative stress in HepG2 cells

Protective effects of quercetin and rutin against oxidative stress were evaluated using in vitro and intracellular antioxidant assay. Quercetin showed higher peroxyl and hydroxyl radical-scavenging activity in a dose-dependent manner than did rutin in oxygen-radical absorbance capacity (ORAC). At 10 and 100 μM, quercetin had higher metal-chelating activity than rutin carrying rutinose at position C-3 and was also more efficient than rutin in reducing intracellular oxidative stress caused by peroxyl radicals and Cu²⁺. The protective activities of 10 and 100 μM quercetin against Cu²⁺-induced intracellular oxidation were 13.8% and 44.8%, respectively. Rutin showed no protective activity against Cu²⁺-induced oxidative stress. Quercetin showed significantly lower intracellular Cu²⁺-chelating activity than did 1,10-phenanthroline but offered greater protection from Cu²⁺-induced oxidative stress. Thus, quercetin may diffuse through the cell membrane more efficiently than rutin because quercetin does not carry rutinose, is hydrophilic, and reduces Cu²⁺-induced oxidative stress by scavenging radicals instead of chelating with metal ions.     

高效液相色谱法测定质粒pUDKH中曲拉通X-100的含量

目的检测质粒pUDKH最终产品中去污剂曲拉通X 10 0 (TritonX 10 0 )的残留含量。方法用高效液相色谱法测定TritonX 10 0残留含量 ,色谱柱为C18柱 ,流动相为乙腈 水 (70∶30 ) ,流速为 1.0ml/min ,进样量 10 μl,检测波长 2 2 3nm。结果平均回收率为 10 0 .19% ,日内精密度为 4 .36 % ,日间精密度为 4 .17% ,TritonX 10 0在 1.2 5～2 0 μg/ml浓度范围内呈线性关系。pUDKH产品中的TritonX 10 0含量在 2 .2 7～ 3.0 0 μg/ml之间。TritonX 10 0的最低检测限可达 1.0 μg/ml。 结论此法有良好的准确度与精密度 ,供试品不需预处理 ,不受其它成分的干扰。     

2种西番莲叶中黄酮的抗氧化活性研究

目的:研究紫果和黄果西番莲叶中黄酮提取物的抗氧化作用。方法:以芦丁、Vc为对照,测定紫果和黄果西番莲叶中黄酮提取物对超氧阴离子自由基(O2-·)、羟自由基(·OH)及二苯代苦味酰基苯肼(DPPH·)自由基的清除率。结果:2种西番莲叶中黄酮提取物均具有不同程度的清除自由基能力,其中黄果西番莲提取物对·OH的清除率优于Vc和紫果西番莲提取物;2种西番莲提取物对O2-·和DPPH·自由基有清除效果,但总体偏低。结论:2种西番莲叶中黄酮均具有不同程度的抗氧化能力。     

Studies of monoamine oxidases: Effect of Triton X-100 and bile salts on monoamine oxidase in brain mitochondria

Triton X-100 and the bile salts, cholate and deoxycholate, detergents often used in the solubilization of monoamine oxidase (MAO) from mitochondria, have been found to cause an inhibition of the enzyme activity. With beef brain mitochondria, it was found that there was a differential effect of Triton X-100 on the putative MAO types A and B, with MAO-A being more susceptible to inhibition by Triton X-100. This was indicated by the greater loss of serotonin-deaminating than of phenyl ethylamine-deaminating activity in the presence of Triton X-100. Although the bile salts also caused substantial inactivation at concentrations above 0.1%, no differentiation between MAO types could be made. Kinetic studies of the inhibition by Triton X-100 indicated two different mechanisms were occurring with the two MAO types. The inhibition was competitive for MAO-A, but uncompetitive for MAO-B. Removal of Triton X-100 by co-polymer beads restored some, but not all of the activity for both MAO-A and MAO-B types. This suggests that the activity loss may have been due in part to inactivation when the enzyme was separated from the mitochondrial membrane.     

Acute toxicity of polyethylene glycol p-isooctylphenol ether in Syrian hamsters exposed by inhalation or bronchopulmonary lavage

Dose-response studies were conducted with Syrian hamsters exposed to polyethylene glycol p-isooctylphenyl ether (Triton X-100) via inhalation or bronchopulmonary lavage. Syrian hamsters were exposed to an aerosol of Triton X-100 with a mass median aerodynamic diameter of 1.5 μm and a concentration of 3.0 mg/liter. Estimated initial lung burdens of Triton X-100 ranged from 800 to 3100 μg. Hamsters were lavaged with concentrations of Triton X-100 ranging from 0.01 to 0.10% in isotonic saline resulting in initial lung burdens of Triton X-100 that ranged from 300 to 3200 μg. The $\text{LD}\text{50}\text{7}$ values were 1700 μg (1300–2100 μg, 95% confidence limits) for the inhalation study and 2100 (1900–2700) μg for the lavage study. The difference between the $\text{LD}\text{50}\text{7}$ values for the two methods of exposure was not significant. However histopathological examination revealed differences in the nature and distribution of pathologic changes observed in animals exposed by the two routes of administration. Animals exposed by inhalation died as a result of ulcerative laryngitis and laryngeal edema with only minimal pulmonary pathologic alterations. Animals exposed by lavage, where the larynx was not exposed to Triton X-100, died from pulmonary edema and acute exudative pneumonia, these results demonstrate the need for careful selection of exposure methods to meet the specific objectives of a toxicology study.     

Analysis of the effects of adenosine in skinned bovine coronary artery.

We have investigated the mechanism of adenosine-induced relaxation in relation to its effects on intracellular organelles in Triton X-100- and saponin-skinned bovine coronary arteries. In intact coronary arteries, high K+ and prostaglandin F2 alpha caused sustained contractions, whereas caffeine produced transient contractions. Triton X-100 treatment abolished these contractions. However, Triton X-100-skinned coronary arteries were responsive to added free calcium. There was no significant difference between calcium concentration-response curves obtained in the absence and presence of adenosine (50 microM). Unlike Triton X-100, in saponin-skinned arteries, caffeine produced transient contractions but high K+ and prostaglandin F2 alpha did not. Adenosine had no effect on caffeine-induced contractions in saponin-skinned coronary arteries. These data suggest that adenosine had no direct inhibitory effect on either the contractile apparatus or calcium release from sarcoplasmic reticulum in coronary arteries.