Dimethylmaleic Anhydride Research Articles

Ultrasound assisted copolymerization of acrylonitrile with N-amino phenyl maleimides and N-amino phenyl 2,3 dimethyl maleimides

The N-amino phenyl maleimide (N-APhM) and N-amino phenyl 2,3 dimethyl maleimide (N-APhDiMeM) derivatives were prepared by the condensation of phenyl hydrazine with maleic anhydride and 2,3 dimethyl maleic anhydride respectively. 13C NMR spectroscopy proved the formation of the symmetric amino maleimide structure and not the pyridazinone or aminoisomaleimides.The copolymerization of acrylonitrile with the (N-APhM) and (N-APhDiMeM) were prepared using ultrasound. The thermal behavior of the prepared copolymers, under nitrogen atmosphere, was investigated using thermogravimetry (TG) techniques. The dyeing of the copolymers formed has been studied using both conventional and ultrasonic techniques. The effect of dye bath pH, ultrasonic power, dyeing time and temperature were studied. Color strength values obtained were found to be higher using ultrasound than with conventional heating. The results of fastness properties of the dyed copolymers were also studied.

Doxorubicin-loaded human serum albumin nanoparticles surface-modified with TNF-related apoptosis-inducing ligand and transferrin for targeting multiple tumor types

Human serum albumin (HSA) nanoparticles (NPs) surface modified with tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and transferrin, and containing doxorubicin were designed and prepared. Surface amines of HSA were reversibly protected with dimethylmaleic anhydride (DMMA), and HSA-NPs were prepared using a desolvation technique. Furthermore, the surfaces of HSA-NPs were modified with thiolated TRAIL or transferrin using sulfosuccinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate (Sulfo-SMCC). The prepared TRAIL/transferrin plus doxorubicin HSA-NPs were characterized by TEM, FE-SEM, and particle size analysis, and their cytotoxic and apoptotic activities were evaluated in several cancer cell lines, namely, HCT 116, doxorubicin-resistant MCF-7, and CAPAN-1. In addition, the tumor-targeting abilities of NPs were assessed using an infrared imaging system in HCT 116-xenografted nu/nu mice. Results showed that the TRAIL/transferrin/doxorubicin HSA-NPs had remarkable cytotoxic and apoptotic activities in all cancer cells examined with a general or a drug-resistant character, and that these NPs had obvious synergistic cytotoxic effects particularly on CAPAN-1 cells. Moreover, these HSA-NPs were effectively localized to tumors in a HCT 116-xenografted nu/nu mouse over 32 h. The findings of this study suggest that the described TRAIL/transferrin/doxorubicin HSA-NPs are a useful targeting agent capable of killing different types of tumor cells in various tissue organs.

Functional modification of amide-crosslinked oligoethylenimine for improved siRNA delivery

The polymer OEI-HD-1, a degradable 25 kDa carrier for siRNA transfer based on β-propionamide-crosslinked oligoethylenimine, was functionalized to further improve biocompatibility and/or endosomolytic characteristics of the polymer. For this purpose OEI-HD-1 was either modified with succinic acid to reduce cationic charge density; alternatively OEI-HD-1 was grafted with 1 molar equivalent of 5 kDa polyethyleneglycol (PEG), or with 1 equivalent of PEG plus 8 molar equivalents of dimethylmaleic anhydride (DMMAn) – modified melittin peptide to enhance endosomal escape. Polymers were characterized in their capability of siRNA complex formation, cytotoxicity, and luciferase reporter gene silencing activity. Succinylation of OEI-HD-1 at 12% of nitrogens strongly reduced siRNA binding and silencing activity. All other OEI-HD-1 derivates displayed improved in vitro biocompatibility and siRNA mediated luciferase gene knockdown in Neuro2A/eGFPLuc cells. Succinylation at 7% of nitrogens strongly reduced cytotoxicity of the polymer and extended the functional window between gene silencing and cytotoxicity. Incorporation of DMMAn-Mel and PEG into OEI-HD-1 generated a pH-responsive lytic polymer conjugate with the highest potency in siRNA mediated gene knockdown and largest functional activity/biocompatibility window.

ChemInform Abstract: Dimethyl cis- and trans-1,2-Dimethylcyclohexane-1,2-dicarboxylate

1-Methoxy-3-trimethylsilyloxybuta-1,3-diene adds readily to dimethylmaleic anhydride, and the product can be converted into dimethyl cis-1,2-dimethylcyclohex-4-ene-1,2-dicarboxylate (3). The several steps required mean that this route compares unfavourably with direct addition of butadiene to the anhydride. The best route to the cis-diester (3) is cyclialkylation of the dianion from dimethyl 2,3-dimethylbutanedioate with (Z)-1,4-dichlorobut-2-ene. A bismethylation reaction is used to prepare imide (II), which can be converted into the cis-diester (1) only with considerable difficulty, and bismethylation of the dianion formed from dimethyl cis-cyclohex-4-ene-1,2- dicarboxylate gives mainly the trans-diester (8). 13C n.m.r. spectra were useful in distinguishing the isomeric pairs (1) and (2), and (3) and (8).

Synthesis and Biological Evaluation of a Bioresponsive and Endosomolytic siRNA−Polymer Conjugate

Extracellular stability of electrostatically formed siRNA polyplexes is a significant concern in the delivery process. To overcome the risk of polyplex dissociation in the extracellular environment, siRNA was covalently incorporated into a pH- and redox-responsive polymer conjugate. The novel siRNA conjugate consists of polylysine (PLL) as RNA binding and protecting polycation, polyethylene glycol (PEG) as solubilizing and shielding polymer, the lytic peptide melittin masked by dimethylmaleic anhydride (DMMAn) removable at endosomal pH, and the siRNA attached at the 5'-end of the sense strand via a bioreducible disulfide bond. The purified siRNA conjugate was stable in the presence of the polyanion heparin at conditions where the analogous electrostatic siRNA polyplexes disassemble. Only the combination of heparin plus a reducing agent such as glutathione triggered the release of siRNA from the conjugate. High in vitro biocompatibility (absence of cytotoxicity or hemolytic activity at neutral pH) and efficient and sequence-specific gene silencing was found at > or =25 nM siRNA, comparable to the corresponding electrostatic polyplexes. In vivo toxicity studies of this formulation demonstrated that conjugates remain to be optimized for therapeutic application.

Synthesis of Novel N-Substituted Dimethylmaleimidyl Esters and Their Applications as Plasticizers for Poly(Vinyl Chloride)

Three N-(hydroxylphenyl) dimethylmaleimides were directly prepared in good yields (81-86)% from the reaction of dimethylmaleic anhydride with amino phenols. The prepared imides were esterified to the corresponding benzoates, methacrylates and cinnamates via their reaction with different acid chlorides in the presence of triethylamine. The prepared esters were tested as plasticizers for PVC via preparing of thirty six samples of PVC with the prepared esters in certain weight ratio followed by recording their softening points. Comparison the results with the universal plasticizers for PVC (DOP) and (DBP) indicated that the prepared esters in general have high plasticizing efficiency.

Synthesis of Novel N-Substituted Dimethylmaleimidyl Esters and Their Applications as Plasticizers for Poly(Vinyl Chloride)

Three N-(hydroxylphenyl) dimethylmaleimides were directly prepared in good yields (81-86)% from the reaction of dimethylmaleic anhydride with amino phenols. The prepared imides were esterified to the corresponding benzoates, methacrylates and cinnamates via their reaction with different acid chlorides in the presence of triethylamine. The prepared esters were tested as plasticizers for PVC via preparing of thirty six samples of PVC with the prepared esters in certain weight ratio followed by recording their softening points. Comparison the results with the universal plasticizers for PVC (DOP) and (DBP) indicated that the prepared esters in general have high plasticizing efficiency.

A dimethylmaleic acid–melittin‐polylysine conjugate with reduced toxicity, pH‐triggered endosomolytic activity and enhanced gene transfer potential

Poor endosomal release is one major barrier of gene delivery. Endosomolytic polyethylenimine-melittin conjugates have shown to enhance gene transfer efficiency; however, cytotoxicity due to their general membrane-destabilizing properties limits their application. To overcome this drawback we grafted a polycation with a masked pH-responsive melittin derivate and investigated lytic activity, gene transfer efficiency and cytotoxicity of the resulting conjugate. Melittin (Mel) was modified with dimethylmaleic anhydride (DMMAn) and covalently coupled to poly-L-lysine (PLL). The membrane lytic activity was analyzed after incubation at neutral or endosomal pH. PLL-DMMAn-Mel polyplexes were generated in HEPES-buffered glucose and tested in transfection experiments using luciferase as reporter gene. Cellular cytotoxicity was analyzed by measurement of membrane integrity and metabolic activity. Covalent attachment of DMMAn-modified melittin to PLL resulted in a pH-responsive conjugate. No lytic activity was observed at neutral pH; after acidic cleavage of the protecting groups at pH 5 lytic activity was regained. Acute toxicity was greatly reduced (as compared to PLL-Mel or even unmodified PLL) and high gene expression levels (up to 1800-fold higher than unmodified PLL) were obtained. Modification of the polycationic carrier PLL with DMMAn-masked melittin not only enhances gene transfer efficiency, but also strongly reduces the acute toxicity of melittin and PLL. Hence this modification might be useful for optimizing polycationic gene carriers.

Reversible lipidization for the oral delivery of leu-enkephalin

The endogenous opioid peptide leu-enkephalin (ENK) was chemically modified by a method known as reversible aqueous lipidization (REAL) with a novel amine-reacting lipophilic dimethylmaleic anhydride analog, 3,4-bis(decylthiomethyl)-2,5-furandione. The binding affinity of the product, REAL-ENK, to opioid receptors was greatly reduced. This prodrug was stable in neutral and basic phosphate buffers but underwent rapid hydrolysis under acidic conditions in the presence of 50% acetonitrile. It also showed increased stability toward enzymatic degradations in various tissue preparations. The half-lives of REAL-ENK in mouse small intestinal mucosal homogenate and liver homogenate were 12 and 80 min, representing a 12- and 32-fold increase over those of ENK itself. In contrast to ENK (t1/2 6.7 min), REAL-ENK was stable in mouse plasma. More importantly, REAL-ENK produced significant and sustained antinociception mediated by peripheral opioid receptors in a rodent inflammatory pain model. Pharmacokinetic studies employing a radioimmunoassay (RIA) demonstrated that significantly higher and sustained plasma peptide levels were detected up to 24 h following the oral administration of REAL-ENK in normal mice. The peak concentration and area under the curve of oral REAL-ENK were 4.4 and 21 times higher than that of oral ENK. Our results indicate that like its disulfide-based counterpart, amine-based REAL may be an enabling technology which can be applied to enhance metabolic stability, increase oral absorption, and preserve and possibly prolong the pharmacological activity of peptide drugs.

A New Strategy for the Synthesis of Furan‐3,4‐dicarboxylic Acid

AbstractFor Abstract see ChemInform Abstract in Full Text.

A New Strategy for the Synthesis of Furan-3,4-dicarboxylic Acid

A facile route to furan-3,4-dicarboxylic acid is described. Dimethylmaleic anhydride (1) on NBS-bromination followed by aqueous KOH treatment gave bis(hydroxymethyl)maleic anhydride (3), which on intramolecular Mitsunobu ring closure followed by esterification and DDQ-oxidation furnished the desired esters of furan-3,4-dicarboxylic acid 7a/b.

An Efficient Synthesis of Dimethylmaleic Anhydride

A facile three-step synthesis of dimethylmaleic anhydride (8) with 74% overall yield has been described starting from maleimide 1, via methylmaleimide 4, using two Wittig reactions followed by an alkaline hydrolysis.

Selective enhancement of thrombopoietic activity of PEGylated interleukin 6 by a simple procedure using a reversible amino-protective reagent.

We developed a novel method for the chemical modification of cytokines with synthetic polymers to increase the therapeutic efficacy of the former in vivo. A pH-reversible amino-protective reagent, dimethylmaleic anhydride (DMMAn), was used for modification of interleukin-6 (IL-6) with polyethylene glycol (PEG). The novel PEG-conjugated IL-6 (DmPEG-IL-6), which had been pretreated with DMMAn before PEGylation, showed up to a 140% increase in in vitro specific activity compared with PEG-IL-6 that had been synthesized by the previous method. Moreover, DmPEG-IL-6 caused thrombopoiesis more potently in mice than PEG-IL-6. The DmPEG-IL-6 Fr.1, having 3-4 PEG chains attached to the cytokine, showed the strongest thrombopoietic effect among the DmPEG-IL-6s with different molecular sizes that were tested. PEG-IL-6 Fr.1 had a 500-fold higher potency in stimulating thrombopoiesis than native IL-6 and DmPEG-IL-6 Fr.1 achieved a threefold higher thrombopoietic effect than PEG-IL-6 Fr.1. In addition, side-effects, such as an increase in the plasma fibrinogen level, were not observed after injection of either PEG-IL-6s or DmPEG-IL-6s. These results suggest that PEGylation with DMMAn pretreatment may become a useful means for clinical cytokine delivery.

A novel function of yeast fatty acid synthase. Subunit alpha is capable of self-pantetheinylation.

The prosthetic group of yeast fatty acid synthase (FAS), 4'-phosphopantetheine, is covalently linked to Ser180 of subunit alpha. It originates from coenzyme A and is transferred to the enzyme by a specific phosphopantetheine:protein transferase (PPTase). The present study demonstrates that the FAS-activating PPTase of yeast represents a distinct catalytic domain of the FAS complex and resides within the C-terminal portion of subunit alpha. The autoactivation capacity of yeast FAS became evident from in vitro pantetheinylation studies using purified apo-FAS preparations. These were readily converted to pantetheinylated holo-FAS simply upon addition of free coenzyme A. Pantetheinylation-competent apo-FAS was prepared in vitro by constructing hybrid oligomers containing alpha-subunits from two different pantetheine-less FAS-mutants. The respective mutants were selected according to their ability to complement each other, in vivo. In vitro formation of hybrid apo-FAS complexes was achieved by dimethylmaleic anhydride (DMMA) -induced reversible dissociation of mixtures of the two constituent mutant enzymes. This treatment was both necessary and sufficient to produce pantetheinylation-competent apo-FAS. Specific FAS activities were comparable independent of whether the apo-enzymes were pantetheinylated in vivo or in vitro. Apart from the induction of overall FAS activity, incorporation of phosphopantetheine into apo-FAS was also demonstrated by the use of 3H-labelled coenzyme A, leading to the formation of radioactively labelled FAS. It is concluded that pantetheinylation of yeast FAS is performed by an intrinsic catalytic activity of the apo-enzyme proper. The endogenous PPTase acts in trans between different subunits alpha in the alpha6beta6 oligomer. The self-pantetheinylation of yeast FAS represents the first example of an apo-enzyme being capable of post-translational autoactivitation.

Only Multimeric Hensin Located in the Extracellular Matrix Can Induce Apical Endocytosis and Reverse the Polarity of Intercalated Cells

When an intercalated epithelial cell line was seeded at low density and allowed to reach confluence, it located the anion exchanger band 3 in the apical membrane and an H+-ATPase in the basolateral membrane. The same clonal cells seeded at high density targeted these proteins to the reverse location. Furthermore, high density cells had vigorous apical endocytosis, and low density cells had none. The extracellular matrix of high density cells was capable of inducing apical endocytosis and relocation of band 3 to the basolateral membrane in low density cells. A 230-kDa extracellular matrix (ECM) protein termed hensin, when purified to near-homogeneity, was able to reverse the phenotype of the low density cells. Antibodies to hensin prevented this effect, indicating that hensin is necessary for conversion of polarity. We show here that hensin was synthesized by both low density and high density cells. Whereas both phenotypes secreted soluble hensin into their media, only high density cells localized it in their ECM. Analysis of soluble hensin by sucrose density gradients showed that low density cells secreted monomeric hensin, and high density cells secreted higher order multimers. When 35S-labeled monomeric hensin was added to high density cells, they induced its aggregation suggesting that the multimerization was catalyzed by surface events in the high density cells. Soluble monomeric or multimeric hensin did not induce apical endocytosis in low density cells, whereas the more polymerized hensin isolated from insoluble ECM readily induced it. These multimers could be disaggregated by sulfhydryl reagents and by dimethylmaleic anhydride, and treatment of high density ECM by these reagents prevented the induction of endocytosis. These results demonstrate that hensin, like several ECM proteins, needs to be precipitated in the ECM to be functional.

A Specific Role for the Phosphorylation of Mammalian Acidic Ribosomal Protein P2

The acidic ribosomal proteins P1-P2 from rat liver were overproduced for the first time by expression of their cDNA in Escherichia coli. They were tested for their ability to reactivate inactive P1-P2-deficient core particles derived from 60 S ribosomal subunits treated with dimethylmaleic anhydride, in poly(U)-directed poly(Phe) synthesis. The recombinant P1-P2 were unable to reactivate these core particles although they could bind to them. When recombinant P1-P2 had been phosphorylated first with casein kinase II, they were as efficient in the reactivation process as P1-P2 extracted with ethanol/KCl from the 60 S subunits. Reconstitution experiments were carried out using all possible combinations of the two recombinant proteins phosphorylated or not. Reactivation of the core particles required the presence of both P1 and P2 with the latter in its phosphorylated form. These experiments reveal a distinct role for P1 and P2 in protein synthesis. Phosphorylated P2 produced a partial quenching of the intrinsic fluorescence of eukaryotic elongation factor 2, which was not observed with the unphosphorylated protein. This result demonstrates the existence of an interaction between phosphorylated P2 and eukaryotic elongation factor 2. P2 also quenched part of the intrinsic fluorescence of P1, due to the interaction between the two proteins.

High-qualityN-substituted maleimide for heat-resistant methacrylic resin

A preparation procedure for colorless, transparent N-substituted maleimide of high quality which can provide heat-resistant transparent methacryl resins was developed. N-Alkylmaleimide, the alkyl substituent of which was composed of 2 to 4 carbons, is employed, giving a polymer with enhanced heat distortion temperature (HDT) because of the higher Tg. The advantages of relatively low melting points and high vapor pressure of N-alkylmaleimide can be used for the preparation of a high-quality product with purification of the monomer by distillation. N-Isopropylmaleimide (IPMI), which fulfills these requirements, is especially useful as a monomer for transparent resins. IPMI was synthesized in a high-yield using a mixture of orthophosphoric acid and orthophosphoric acid-isopropylamine salt as catalyst. IPMI, the purity of which is 99.9 wt % or above, contains 100–200 ppm of N-isopropylmaleamic acid, maleic anhydride, dimethylmaleic anhydride, solvent, and water. IPMI, which solidifies at 25.8°C, is obtained as a colorless liquid and is freely soluble in common monomers such as methyl methacrylate (MMA), styrene (St), and acrylonitrile (AN). The obtained IPMI showed excellent thermal stability, and no quality change was observed after heating for 100 h at 50°C. The copolymer of MMA and IPMI exhibited the same YI value as a measure of coloration, and almost the same transparency as the homopolymer of MMA. An increase in IPMI content in the copolymer by 1 mol % increased the polymer Tg by 0.8°C. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1055–1062, 1997

Transcellular Delivery of an Insulin-Transferrin Conjugate in Enterocyte-like Caco-2 Cells

Insulin, acylated with dimethylmaleic anhydride, was conjugated to transferrin (Tf) via a disulfide linkage. The molar insulin: Tf ratio in the conjugate was 3:1. The insulin–Tf conjugate (insulin–Tf) was tested for the transport of insulin across enterocyte-like Caco-2 cell monolayers by the process of transferrin receptor (TfR)-mediated transcytosis. The uptake of insulin–Tf in Caco-2 cells was TfR-mediated but not insulin receptor-mediated. Transport studies showed that insulin–Tf transport was 5- to 15-fold higher than free insulin transport across Caco-2 cells in both apical-to-basal and basal-to-apical directions. Brefeldin A (BFA), an agent that we have previously shown to cause an increase in TfR transcytosis, further enhanced the transport of the conjugated insulin three-fold in both directions; thus, a combination of the conjugate and BFA can cause a net 45-fold increase in the apical-to-basolateral transport of insulin across Caco-2 cell monolayers. The transported conjugate was intact as indicated by elution on a Sephadex G-50 column. Insulin in the transcytosed conjugate, unlike the original dimethylmaleyl insulin, was capable of binding to anti-insulin antibodies, indicating that free amino groups of insulin were regenerated either during or after the transcytotic process. Because Caco-2 cell monolayers provide a good model for intestinal epithelium, the insulin–Tf conjugate in combination with BFA can be a rational approach to increase the oral absorption of insulin in vivo.

The oxygen-18 isotope shift in carbon-13 nuclear magnetic resonance spectroscopy. 15. Studies of [18O,1,4-13C2]succinic acid and [18O]dimethylmaleic anhydride

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe oxygen-18 isotope shift in carbon-13 nuclear magnetic resonance spectroscopy. 15. Studies of [18O,1,4-13C2]succinic acid and [18O]dimethylmaleic anhydrideTony L. Mega and Robert L. Van EttenCite this: J. Am. Chem. Soc. 1993, 115, 25, 12056–12059Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December 1993https://doi.org/10.1021/ja00078a050RIGHTS & PERMISSIONSArticle Views208Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (522 KB) Get e-Alerts Get e-Alerts

Synthesis of Methyl (Z)- and (E)-2-Methyl-(3-D)propenoates and Their Incorporation Into Polymethacrylates

Methyl (E)- and (Z)-2-methyl(3-D) propenoates were prepared from (E)-3-bromo-2-methylpro- penoic acid. Polymerization by free radical methods led to random incorporation, but anionic polymerization preserved labelling specificity, and the 1H n.m.r. spectra of the labelled polymers confirm earlier assignments. Dimethyl 2,3-dimethylbutanoate was prepared by two new methods from dimethylmaleic anhydride and converted by anionic polymerization into a methacrylate polymer with a head-to-head linkage approximately in the centre of the chain. Thermal degradation of this polymer could only be achieved at temperatures so high that labelled monomers were themselves isomerized. Methacrylate polymers produced by anionic polymerization in the presence of diisopropylamine do not exhibit the isotacticity found with this form of polymerization.