Comparative study of oxidative stress caused by anthracene and alkyl-anthracenes in Caenorhabditis elegans

Oxidative stress was evaluated for anthracene (Ant) and alkyl-Ants (9-methylanthracene [9-MA] and 9,10-dimethylanthracene [9,10-DMA]) in Caenorhabditis elegans to compare changes in toxicity due to the degree of alkylation. Worms were exposed at 1) the same external exposure concentration and 2) the maximum water-soluble concentration. Formation of reactive oxygen species, superoxide dismutase activity, total glutathione concentration, and lipid peroxidation were determined under constant exposure conditions using passive dosing. The expression of oxidative stress-related genes (daf-2, sir-2.1, daf-16, sod-1, sod-2, sod-3 and cytochrome 35A/C family genes) was also investigated to identify and compare changes in the genetic responses of C. elegans exposed to Ant and alkyl-Ant. At the same external concentration, 9,10-DMA induced the greatest oxidative stress, as evidenced by all indicators, except for lipid peroxidation, followed by 9-MA and Ant. Interestingly, 9,10-DMA led to greater oxidative stress than 9-MA and Ant when worms were exposed to the maximum water-soluble concentration, although the maximum water-soluble concentration of 9,10-DMA is the lowest. Increased oxidative stress by alkyl-Ants would be attributed to higher lipid-water partition coefficient and the π electron density in aromatic rings by alkyl substitution, although this supposition requires further confirmation.

Comparative study of oxidative stress caused by anthracene and alkyl-anthracenes in Caenorhabditis elegans

Oxidative stress was evaluated for anthracene (Ant) and alkyl-Ants (9-methylanthracene [9-MA] and 9,10-dimethylanthracene [9,10-DMA]) in Caenorhabditis elegans to compare changes in toxicity due to the degree of alkylation. Worms were exposed at 1) the same external exposure concentration and 2) the maximum water-soluble concentration. Formation of reactive oxygen species, superoxide dismutase activity, total glutathione concentration, and lipid peroxidation were determined under constant exposure conditions using passive dosing. The expression of oxidative stress-related genes (daf-2, sir-2.1, daf-16, sod-1, sod-2, sod-3 and cytochrome 35A/C family genes) was also investigated to identify and compare changes in the genetic responses of C. elegans exposed to Ant and alkyl-Ant. At the same external concentration, 9,10-DMA induced the greatest oxidative stress, as evidenced by all indicators, except for lipid peroxidation, followed by 9-MA and Ant. Interestingly, 9,10-DMA led to greater oxidative stress than 9-MA and Ant when worms were exposed to the maximum water-soluble concentration, although the maximum water-soluble concentration of 9,10-DMA is the lowest. Increased oxidative stress by alkyl-Ants would be attributed to higher lipid-water partition coefficient and the π electron density in aromatic rings by alkyl substitution, although this supposition requires further confirmation.

Evaluation of factors influencing antibody reduction for development of antibody drug conjugates

Background: Reduction/alkylation is one of the leading strategies for the development of antibody drug conjugates [ADCs]. Precise control of the reduction process would not only yield a defined number of free thiols per antibody but also result in development of more homogenous conjugates

Methods: In the present study, we investigated the effect of various dithiothreitol [DTT] concentrations, temperature conditions, and DTT exposure times on antibody reduction. After antibody reduction, the Ellman's test and SDS-PAGE analysis were used to evaluate free thiols produced and confirm the reduction process, respectively

Results: DTT concentration seems to be a potential factor in the reduction process. Concentrations of 0.1, 1, 5, 10, 20, 50, and 100 mM DTT at 37[degree]C for 30 minutes resulted in approximately 0.4, 1.2, 5.4, 7, 8, 8, and 8 thiols per antibody, respectively

Conclusion: Optimized site specific conjugation can provide better process control and reproducibility for the development of disulfide-based ADCs

A review of experimental models in colorectal carcinogenesis / Modelos experimentais de carcinogênese colorretal

Colorectal cancer is the leading cause of malignancy of the gastrointestinal tract. A better understanding of the molecular and cellular changes that lead to the disease is necessary to develop early diagnosis and optimal treatment modalities. Rodent models are rapid, reproducible and exhibit an adenoma-carcinoma sequence similar to that found in humans. The objective of this manuscript is to review the most common chemical carcinogens used to induce experimental tumors and the usual methods of evaluation.

O câncer colorretal é a principal neoplasia maligna do trato gastrointestinal. Um melhor entendimento dos processos moleculares e celulares é necessário para o desenvolvimento de estratégias que permitam um diagnóstico precoce e um tratamento mais eficaz. Modelos que utilizam roedores são rápidos, reprodutíveis e permitem o estudo da sequencia adenoma-carcinoma de forma similar a encontrada em humanos. O objetivo desse manuscrito é revisar os principais modelos de carcinogênese química e os métodos mais usuais para avaliação dos resultados.

Gene transfer enhancement by alkylcarboxylation of poly[propylenimine]

Among synthetic carriers, dendrimers with the more flexible structure have attracted a great deal of researchers' attention in the field of gene delivery. Followed by the promising results upon hydrophobic modification on polymeric structures in our laboratory, alkylated poly [propylenimine]-based carriers were synthesized by nucleophilic substitution of amines with alkyl moieties and were further characterized for their physicochemical and biological characteristics for plasmid DNA delivery. Although not noticeably effective gene transfer activity for hexanoate- and hexadecanoate- modified series was observed, but alkylation by decanoic acid significantly improved the transfection efficiency of the final constructs up to 60 fold in comparison with unmodified poly[propylenimine] [PPI]. PPI modified by 10-bromodecanoic acid at 50% grafting, showed significantly higher gene expression at c/p ratio of 2 compared to Superfect as positive control. Overall, modification of PPI with 50% primary amines grafting with 10-bromodecanoic acid could increase the transfection efficiency which is occurred at lower c/p ratio when compared to Superfect, i.e. less amount of modified vector is required to exhibit the same efficiency as Superfect. Therefore, the obtained constructs seem to be safer carriers for long-term gene therapy applications

Synthesis and cytotoxic activity of some derivatives of alkyl piperidine

Synthesis of novel phenacyl derivatives of alkyl piperidine as cytotoxic agents via simple and single step reaction procedure is going to be reported here. Twelve new compounds were successfully synthesized in moderate yield and in solid form. Their synthesis was confirmed by TLC, melting point, CHN analysis and through different spectral studies such as UV, IR, Mass and proton NMR. The advantages of this synthetic route are simple operation, mild reaction conditions and good yields. These newly synthesized derivatives were extensively explored for their cytotoxicity by brine shrimp lethality assay

Property of liposomal fusion induced by acid-sensitive polymer / 药学学报

The fusion between liposome-liposome, liposome-biomembarnes induced by acid-sensitive polymers has been systematically investigated. The polymer-liposomes were constructed by post-insertion method with the poly (2-ethylacrylic acid) (PEAA) alkylamide derivatives. The liposomal fusion was studied by use of fluorescence resonance energy transfer assay, particle size, fluorescent-photometer. The results indicated that the poly (2-ethylacrylic acid)-liposomes has very strong acidic induced fusion capability. Under acidic conditions, acid-sensitive polymer liposomes fused each other, the fusion closely related to the molecular weight of acid sensitivity polymer on the surface of liposomes. The acidic fusion of polymer-liposomes was dependent upon the lipids composition, the degree of fusion was reversely related to the cholesterol contents. Acid-en ci-nsitive polymer liposomes fused with erythrocyte ghosts. The liposomal fusion induced by acid-sensitive polymer associated with the increase of membrane permeability. The good acid-sensitivity of PEAA has been further demonstrated by membrane fusion in current experiments, and the liposomes prepared with lipid anchored-poly (2-ethylacrylic acid) were developeds s a potential pH sensitive delivery system.

Síntese de derivados diidrofurânicos, `alfa'-metilenolactonas e dos princípios ativos lidoflazina e PR-608 / Synthesis of dihydrofurans derivatives, alpha-methylene lactones and biologically actives lidoflazine and PR608

A primeira parte deste trabalho refere-se às reações de ciclofuncionalização, utilizando, como agentes eletrofílicos, indutores de ciclofuncionalização, iodo, brometo de fenilselenenila e tricloreto de p-metoxifeniltelúrio. Na primeira etapa, foram sintetizados compostos 1,3-dicarbonílicos 2,4-dialilsubstituídos, com os grupos alila, crotila e cicloexenila, respectivamente. Os compostos 1,3-dicarbonílicos 2,4-dialilsubstituídos foram submetidos a reações de monociclofuncionalização, produzindo éteres cíclicos funcionalizados, com ligação dupla endocíclica e exocíclica, conforme o esquema ilustrativo a seguir. Com a utilização de iodo em excesso, foi possível obter `alfaï-metilenolactonas ligadas a um anel tetraidrofurânico. A segunda parte deste trabalho refere-se à síntese dos princípios ativos lidoflazina, com atividade vasodilatadora coronariana, e PR-608, com atividade anti-parkinsoniana...

Alquilaçäo de DNA por radicais metila gerados a partir de hidroperóxido de tércio-butila: Estudos in vitro e in vivo / DNA alkylation by methyl radical generated from of tert-butyl hydroperoxide: study in vitro and in vivo

Estudamos a possibilidade do hidroperóxido de tércio-butila, um reconhecido agente citotóxico e promotor de tumor, metilar DNA via ataque radicalar. inicialmente realizamos estudos por EPR associada à técnica do captador de spin in vitro para comprovar que o composto é decomposto em radicais metila na presença de DNA. Posteriormente demonstramos que TBHP na presença de Fe (II) alquila DNA de timo bovino pela detecçÝo de 80metilguanina. Detectamos, entretanto, adutos esperados tanto do ataque de espécies radicalares (8-metilguanina), como de espécies catiônicas (7-metilguanina, 3-metiladenina, 6-metilguanina) cuja formaçäo näo seria esperada durante a reduçäo do hidroperóxido de tércio-butila por Fe (II). Em funçäo disto, estudamos a influência de agentes quelantes e do íon metálico (Fe (II), Fe (III) e Cu (I)) no processo de alquilaçäo...

Participaçäo de radicais livres centrados em átomos de carbono na toxicidade de hidrazina / Centered participation free radicals in carbon atoms in the hidrazone toxicity

A produçäo de radicais de carbono "in vivo" durante a biotransformaçäo da hidrazina foi demonstrada por ressonância paramagnética eletrônica, utilizando o método do captador de spin. Eritrócitos de rato também oxidaram a hidrazina, formando radicais de carbono e nitrogênio, além de espécies reativas de oxigênio. Todas estas espécies, possivelmente formadas "in vivo", säo potencialmente causadoras de dano a macromoléculas. Podem, por exemplo, iniciar reaçöes secundárias formando radicais de componentes celulares, como ocorreu com a hemoglobina que foi oxidada a radicais tiil-hemoglobina em eritrócitos tratados com hidrazina. Radicais de carbono formados durante a biotransformaçäo da hidrazina em animais expostos provêm necessariamente de substâncias endógenas e podem ser direta ou indiretamente responsáveis pela modificaçäo (alquilaçäo) de bases no DNA "in vivo"...

Isolation and characterization of NGS mutant of Saccharomyces cerevisiae that is deficient in adaptive repair

Saccharomyces cerevisiae is an ideal eukaryotic unicell system for the study of the 'damage and repair'. In order to understand the genetics and mechanism of adaptive repair to alkylation stress the isolation and characterization of ada mutants [like ngs] bear important implications. We report for an ethyl methane sulfonate [EMS] - induced ngs MR0192 mutant of S. cerevisiae. The mutant cells showed a decreased survival after nitrosoguanidine [MNNG] treatment [doses >1.5 micro g mL -1 proved lethal] compared to is its parent strain [that survived upto 5 micro g mL -1] and failed to manifest adaptive repair. This ada mutant suffered from a cumulative effect of MNNG dose and cyclohexamide protein synthesis inhibitor]. The results have helped to elucidate the role of ada gene in alkylation mediated repair in S. cerevisiae

DNA alkylation by carbon-centered radicals

1. Over the last two decades, the prevalent view in chemical carcinogenesis has been that most free radicals do not bind to DNA. Recent studies, however, are demonstrating formation of adducts between DNA and free radicals such as hydroxyl radicals and aromatic cation radicals. 2. Within this context, we discuss the recent work from our group demonstrating DNA alkylation by carbon-centered radicals formed during biotransformation of genotoxic hydrazine derivatives both in vitro and in vivo. 3. The mutagenic potential of the identified methyl radical adduct, C8-methylguanine, is discussed, and other possible biological sources of carbon-centered radicals are presented

Chemical study of the alkylation of benzimidazole-2thiol and benzothiazole-2thiol with epichlorohydrin

Three isomeric products [3a and 4b] were obtained from the alkylation of [1] with epichlorohydrin under different reaction conditions. The epoxide [3a] was found to be convertible to [4a], while [4a] and [4b] were nonconvertible to each other and proved to be stereo- isomers. Mechanisms of formation of these isomers were attempted. Alkylation of [2] with epichlorohydrin was epichlorohydrin was also investigated and shown to produce [10] or [11]. Structures of the final products were evidenced by spectroscopic data and variable routes of synthesis

Enhancement of O-dealkylation in Mouse Liver by Dietary Administrations of BHA and BHT: Studies with Isolated Perfused Livers and Hepatic Microsomes

Effects of feeding 2(3)-tert-butyl 4-hydroxyanisole (BHA) and 3, 5-di-tert-butyl 4-hydroxytoluene (BHT) on the rates of mixed function oxidation and conjugation enzyme reactions have been determined using isolated hepatic microsomal fractions and isolated perfused livers of mice. The treatments with either of the antioxidants have increased the rates of O-demethylation for p-nitroanisole and of O-deethylation for 7-ethoxycoumarin up to 2-fold, both in microsomes and in perfused liver. Analysis of the perfusate showed that the increased amounts of p-nitrophenol and 7-hydroxycoumarin produced by the elevated mixed-function oxidase activities were reflected by the increase in the amounts of glucuronide conjugates and not in the increase for the amounts of the sulfate ester conjugates. Comparison of results also indicated that in the perfused liver, the maximal rate of metabolite conjugation is limited by the maximal rates of the initial mixed function oxidase activities.

Catalytic alkylation of benzene in vapour phase

The catalytic alkylation of benzene in vapour phase was carried out over Egyptian natural aluminosilicate clay. The clay was activated with 10 percent ZnCl2 solution and the catalytic reaction was carried out at 200-350 degree. The ratio between the reactants, benzene: isobutylchloride was kept 1:1 by volume and feed rate 1 ml/min. The percentage reaction increases on increasing the reaction temperature, reaching a maximum value [42.3 percent] at 300 degree the products consisted of mono-, di- and trialkylated benzenes together with an increasing amount of liquid Cg hydrocarbons which may be produced as a result of dimerisation of the alkylating agent. The catalyst used, however, exhibited a marked selectivity for the production of monoalkylbenzene

Alkylation reaction and Michael condensation of 3 aroyl acrylic acids

It is reported that when Beta [3,4-dichloro]-benzoyl acrylic acid was treated with aromatic hydrocarbons and aluminum chloride, addition occurred alpha to carboxyl group. In this study this method has been applied to Beta [p-phenyl]-benzoyl acrylic acid la, to augment the reactivity of the aroyl acrylic acids to react as alpha, Beta-unsaturated ketones rather than alpha, Beta-unsaturated acids in which the polar factor increases. The acid la undergoes addition reaction with p-xylene under Friedel Crafts conditions to give the corresponding alpha-[2, 5-dimethyl]-phenyl-Beta-[p-phenyl]-benzoyl propionic acid [II]. The structure of the resultant acid II was derived from its spectral data. IR spectrum showed bands due to ketonic C=O [1680], carboxylic CO [1710] and OH [3300-3000]. The PMR spectrum [CDC1[3]] showed signals at 2:29 and 2:36 [6H, s, of Ar-CH[3]], 2.80-3-50 [dxd, 2H of non equivalent CH[2]], 3-95-4-3 [m, IH of >CH-] and 7-7-8 [m, 12H of Ar-H]

Alkylation of indole with Baroylacrylic acids and some studies on the alkylated products

A large number of pyridazinones are reported to exhibit insecticidal and bactericidal activities. This prompted us to synthesise a new series of pyridazinones through the alkylation of indole with Beta-aroylacrylic acids followed by cyclization with hydiazines to the corresponding pyridazinone, the synthesis of various compounds prepared are outlined in Schemes 1-6

Preparation, reduction and alkylation of 5,7-polyethylene cyclohepta- [c] and [b] furan-6-one

In continuation of our interest in the reaction of heterocyclic o-dialdehydes, we report here the reaction of furan 3,4-and 2,3-di-carbo-xaldehydes with cyclic ketones. It was previously reported that o-phthaldehyde condenses with cyclic ketones to give the 2,7-polymethylene-4,5-ben-zotropones in which the tropone ring is planar. Recently Guilard et al. [8] reported that thiophenedicarboxaldehyde behave similarly to o-phthaldehyde. The reaction of furan 3,4-dicarboxaldehyde I and 2,3 -dicarboxaldehyde II with cyclic ketones in sodium ethoxide medium gave the corresponding 5,7 -polymethylene cyclohepta -[c]- and [b]-furan-6-one III and IV. Lithium aluminum hydride [LiAlH4] reduction of the carbonyl function of compounds III and IV afforded the non-isolable alcohols V and VI. The reaction of 70 percent perchloric acid with these alcohols gave the corresponding 5,7-polymethylene-[c] and [b]- furotropylium perchlorate salts VII and VIII. The reaction of alcohols V and VI with sodium hydride followed by alky-lation with methyl iodide gave the corresponding 6-methoxy-5,7-polymethylene cyclohepta-[c] and [b]-furan IX and X [Scheme 1]