Dimethoxy Groups Research Articles

Synthesis and characterization of new polyphenols derived from o-dianisidine: The effect of substituent on solubility, thermal stability, and electrical conductivity, optical and electrochemical properties

In this study, we proposed to synthesize soluble polyphenol derivatives containing azomethine bond. For this reason, o-dianisidine was chosen to synthesize Schiff base monomers due to containing dimethoxy groups. Four phenolic Schiff bases were synthesized by condensation reaction of o-dianisidine with salicylaldehyde (2-HBADIAN), 4-hydroxybenzaldehyde (4-HBADIAN), vanillin (MHBADIAN) and 3-ethoxy-4-hydroxybenzaldehyde (EHBADIAN). These monomers were converted to their polyphenol derivatives via oxidative polycondensation reaction (OP). The structures of the obtained compounds were confirmed by FT-IR, UV–vis, 1H NMR and 13C NMR techniques. Progressing of OP was also followed by a time-controlled spectrum mode of a UV–vis spectrophotometer. The molecular weight distribution parameters of the synthesized polyphenols were determined by the size exclusion chromatography (SEC). The synthesized compounds were also characterized by solubility tests, TG-DTA and DSC. Cyclic voltammetry (CV) measurements were carried out and HOMO–LUMO energy levels and electrochemical band gaps ( E g ′ ) were calculated. Additionally, optical band gaps ( E g) were determined by using UV–vis spectra of the materials. Electrical conductivities of both doped and undoped states of the synthesized materials were measured by four-point probe technique using a Keithley 2400 electrometer showing that P-2-HBADIAN has approximately 130 times higher electrical conductivity than the others. Also, it was stressed that the synthesized polyphenols are semiconductors which have a potential for electronic and optoelectronic applications, with fairly low band gaps.

Nonlinear optical studies on 1,3-disubstituent chalcones doped polymer films

We report the measurements of the third-order nonlinear optical properties of recently synthesized and characterized two different 1,3-disubstituent chalcones doped PMMA films, with the prospective of reaching a good compromise between processability and high nonlinear optical properties. The measurements were done using nanosecond Z-scan at 532 nm. The Z-scan spectra reveal a large negative nonlinear refraction coefficient n 2 of the order 10 −11 esu and the molecular two photon absorption cross section is 10 −46 cm 4 s/photon. The doped films exhibit good optical power limiting property under nanosecond regime and the two photon absorption (TPA) is the dominating process leading to the nonlinear behavior. The improvement in the nonlinear properties has been observed when methylenedioxy group is replaced by dimethoxy group due to increase in conjugation length. The observed nonlinear parameters of chalcone derivatives doped PMMA film is comparable with stilbazolieum derivatives, a well-known class of optical materials for photonics and biophotonics applications, which suggests that, these moieties have potential for the application of all-optical limiting and switching devices.

Berberine Targets Assembly of Escherichia coli Cell Division Protein FtsZ

The ever increasing problem of antibiotic resistance necessitates a search for new drug molecules that would target novel proteins in the prokaryotic system. FtsZ is one such target protein involved in the bacterial cell division machinery. In this study, we have shown that berberine, a natural plant alkaloid, targets Escherichia coli FtsZ, inhibits the assembly kinetics of the Z-ring, and perturbs cytokinesis. It also destabilizes FtsZ protofilaments and inhibits the FtsZ GTPase activity. Saturation transfer difference NMR spectroscopy of the FtsZ-berberine complex revealed that the dimethoxy groups, isoquinoline nucleus, and benzodioxolo ring of berberine are intimately involved in the interaction with FtsZ. Berberine perturbs the Z-ring morphology by disturbing its typical midcell localization and reduces the frequency of Z-rings per unit cell length to half. Berberine binds FtsZ with high affinity ( K D approximately 0.023 microM) and displaces bis-ANS, suggesting that it may bind FtsZ in a hydrophobic pocket. Isothermal titration calorimetry suggests that the FtsZ-berberine interaction occurs spontaneously and is enthalpy/entropy-driven. In silico molecular modeling suggests that the rearrangement of the side chains of the hydrophobic residues in the GTP binding pocket may facilitate the binding of the berberine to FtsZ and lead to inhibition of the association between FtsZ monomers. Together, these results clearly indicate the inhibitory role of berberine on the assembly function of FtsZ, establishing it as a novel FtsZ inhibitor that halts the first stage in bacterial cell division.

Adsorption mechanism of physiologically active l-phenylalanine phosphonodipeptide analogues: Comparison of colloidal silver and macroscopic silver substrates

Here we present SERS spectra of several l-phenylalanine (Phe) phosphonodipeptides, i.e., l-Phe- l-Ala-PO 3H 2 ( MD1), l-Phe- l-Va l-PO 3H 2 ( MD2), l-Phe-β-Ala-CH(OH)-PO 3H 2 ( MD3), l-Phe- l-Ala-CH(OH)-PO 3H 2 ( MD4), l-Ala-(3,4-dimethoxy)- l-Phe-PO 3H 2 ( MD5), and l-Ala-(3,4-dimethoxy)-(des-CH 2)- l-Phe-PO 3H 2 ( MD6), immobilized on electrochemically roughened silver electrodes. These spectra are analyzed by theoretical calculations using density functional theory (DFT) at the B3LYP level with 6-31++G∗∗ basis set. In addition, these spectra are compared with SERS spectra of these species adsorbed on a colloidal silver surface. We showed that on the macroscopic silver substrate, the Phe aromatic ring of MD3 and MD4 is oriented vertically, while for MD1 it almost “stands up” on this surface. In the other three cases, the Phe ring adopts a tilted orientation in regard to the substrate. We also find that the phosphonate ( – PO 3 2 - ) , methyl/methane, or dimethoxy groups of MD1, MD2, MD3, MD5, and MD6 are involved in the interaction of these phosphonodipeptides with the electrochemically roughened surface. This phenomenon is clearly seen for –CH 2–/–CH 3/–OCH 3 moieties as well as for the PO 3 2 - group that adsorbs on the macroscopic silver substrates mainly via the P O fragment. We also showed that MD4 binds to the macroscopic silver substrate through the hydroxyl, amine, and phosphonate groups, while the methylene/methane moieties are remote from this surface. We found that studied phosphonodipeptides often adsorb differently on the macroscopic silver substrate and on the colloidal silver nanoparticles. For example, MD1 adopts an almost vertical orientation on the electrochemically roughened silver substrate and is tilted or close to flat on the silver nanoparticles.

Synthesis and evaluation of antiplatelet activity of trihydroxychalcone derivatives

In an effort to develop potent antiplatelet agents, a series of trihydroxychalcones was synthesized and screened in vitro for their inhibitory effects on washed rabbit platelet aggregation induced by arachidonic acid (100 μM) and collagen (10 μg/ml). Of five compounds with potent inhibitory effects on arachidonic acid- and collagen-induced platelet aggregation, compound 4e was found to be the most potent. The structure–activity relationships suggested that antiplatelet activity was governed to a greater extent by the substituent on B ring of the chalcone template, and most of the active compounds had methoxy or dimethoxy groups on B ring.

Theoretical Investigation of Optical and Electronic Property Modulations of π-Conjugated Polymers Based on the Electron-Rich 3,6-Dimethoxy-fluorene Unit

Poly(fluorene)-type materials are widely used in polymer-based emitting devices. One of the drawbacks of light-emitting diodes based on polyfluorene derivatives is the injection of holes from the anode due to the high ionization potential (IP) of most derivatives. Substitution by electron-donating alkoxy substituents or by adding charge carriers on the conjugated polymer's backbone produces a remarkable influence on its electrical and optical properties. In this contribution, we apply quantum-chemical techniques to investigate a family of pi-conjugated polymers with substituted dimethoxy groups at the 3,6 positions of the fluorene ring, namely, poly(2,7-(3,6-dimethoxy-fluorene)(PDMOF), poly(2,7-(3,6-dimethoxy-fluorene)-co-alt-fluorene (PDMOFF), and poly(2,7-(3,6-dimeth-oxy-fluorene)-co-alt-2,5-thiophene (PDMOFT). The electronic properties of the neutral molecules, HOMO-LUMO gaps (Delta(H)(-)(L)), in addition to the positive and negative ions, are studied using the B3LYP functional. The lowest excitation energies (E(g)) and the maximal absorption wavelength lambda(abs) of PDMOF, PDMOFF, and PDMOFT are studied by employing time-dependent density functional theory (TD-DFT) and the ZINDO semiempirical method. The IP, EA, and E(g) values of each polymer were obtained by extrapolating those of the oligomers to the inverse chain length equal to zero ((1)/(n)() = 0). The influence of the presence of methoxy groups on the fluorene moiety on the ionization potential is especially emphasized. The outcomes show that the HOMO energies of these systems under study increase by about 0.4 eV and the IP values decrease by about 0.3 eV compared to those of the corresponding polyfluorene. Both effects result in a reduction of the energy barrier for the injection of holes in related polymeric light-emitting devices and should contribute to the enhancement of their performances. Because of the cooperation with thiophene in PDMOFT, which results in a good planar conformation, both the hole-creating and electron-accepting abilities are improved.

Antiplasmodial chalcones inhibit sorbitol-induced hemolysis of Plasmodium falciparum-infected erythrocytes.

A series of alkoxylated and hydroxylated chalcones previously reported to have antiplasmodial activities in vitro were investigated for their effects on the new permeation pathways induced by the malaria parasite in the host erythrocyte membrane. Of 21 compounds with good antiplasmodial activities (50% inhibitory concentrations [IC(50)s], < or = 20 microM), 8 members were found to inhibit sorbitol-induced lysis of parasitized erythrocytes to a significant extent (< or = 40% of control values) at a concentration (10 microM) that was close to their antiplasmodial IC(50)s. Qualitative structure-activity analysis suggested that activity was governed to a greater extent by a substitution on ring B than on ring A of the chalcone template. Most of the active compounds had methoxy or dimethoxy groups on ring B. Considerable variety was permitted on ring A in terms of the electron-donating or -withdrawing property. Lipophilicity did not appear to be an important determinant for activity. Although they are not exceptionally potent as inhibitors (lowest IC(50), 1.9 microM), the chalcones compare favorably with other more potent inhibitors in terms of their selective toxicities against plasmodia and their neutral character.

11 H-Isoquino[4,3- c]cinnolin-12-ones : novel anticancer agents with potent topoisomerase I-targeting activity and cytotoxicity

Recent studies have identified 2,3-dimethoxy-8,9-methylenedioxy-11-[(2-dimethylamino)ethyl]-11 H-isoquino[4,3- c]cinnolin-12-one ( 1a) as a novel topoisomerase I-targeting agent with potent cytotoxic activity. The effect of varied substituents at the 11-position of 2,3-dimethoxy-8,9-methylenedioxy-11 H-isoquino[4,3- c]cinnolin-12-ones on topoisomerase I-targeting activity and cytotoxicity was evaluated. Potent TOP1-targeting activity was observed when the 11-position was substituted with either a 2-( N, N-dimethylamino)ethyl, a 2-( N, N-diethylamino)ethyl, a n-butyl, or a 2-(pyrrolidin-1-yl)ethyl group. The addition of a β-methyl group to 1a provided an analogue with dramatically reduced TOP1-targeting activity and cytotoxicity. Analogues of 1a wherein the 2-( N, N-dimethylamino)ethyl group was replaced with a (2-tetrahydrofuranyl)methyl, a 2-(piperidin-1-yl)ethyl, or a 2-(4-methylpiperazin-1-yl)ethyl substituent exhibited decreased activity as TOP1-targeting agents. Replacement of the dimethoxy groups of 1a with hydrogen atoms resulted in an analogue with significantly decreased TOP1-targeting activity and cytotoxicity. Removal of both the vicinal dimethoxyl groups and the methylenedioxy moiety resulted in a complete loss of TOP1-targeting activity. The presence of a 9-nitro substituent in place of the 8,9-methylenedioxy group of 1a resulted in a decrease in relative TOP1-targeting activity and cytotoxicity. Compounds 1a and the 11- n-butyl analogue 1d were evaluated for antitumor activity in the human tumor xenograft model using athymic nude mice. The non-estrogen responsive breast tumor cell line MDA-MB-435 was used in these assays. At dose levels that approached its maximum tolerated dose, 1a proved to be effective in inhibiting tumor growth in vivo when administered orally or by ip injection.

Poly(ethylene terephthalate) copolyesters derived from (2S,3S)‐2,3‐dimethoxy‐1,4‐butanediol

AbstractNovel poly(ethylene terephthalate) (PET) copolyesters, abbreviated PEDMBT, containing optically active (2S,3S)‐2,3‐dimethoxy‐1,4‐butanediol (DMBD) as the second comonomer were investigated. Copolymers with ethylene glycol to DMBD ratios between 95/5 and 50/50 as well as the two parent homopolymers, PET and PDMBT, were prepared by a two‐step melt polycondensation. The resulting copolymers were found to approximately have the composition of the polymerization reaction feed and a random microstructure. Polymer intrinsic viscosities varied from 0.4 to 0.6 dL g−1 with weight‐average molecular weights ranging from 16,000 to 44,000. PEDMBT copolyesters were distinguished in being much more soluble than PET and showing an increasing affinity for water with the content in dimethoxy groups. According to the asymmetric constitution of DMBD, they displayed optical activity in solution. Both melting and glass‐transition temperatures of the copolyesters were observed to steadily decrease with the content in DMBD. PEDMBTs were found to be crystalline for contents in DMBD up to 30 mol %. Both powder and fiber X‐ray diffraction revealed that the same crystalline structure is shared by PET and the crystalline copolyesters. The homopolyester PDMBT resulted in becoming a polymer with a crystallinity comparable to PET but with a significantly different crystalline structure. © 2001 John Wiley &amp; Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3250–3262, 2001

Crystal structure of an angiogenesis inhibitor bound to the FGF receptor tyrosine kinase domain.

Angiogenesis, the sprouting of new blood vessels from pre-existing ones, is an essential physiological process in development, yet also plays a major role in the progression of human diseases such as diabetic retinopathy, atherosclerosis and cancer. The effects of the most potent angiogenic factors, vascular endothelial growth factor (VEGF), angiopoietin and fibroblast growth factor (FGF) are mediated through cell surface receptors that possess intrinsic protein tyrosine kinase activity. In this report, we describe a synthetic compound of the pyrido[2,3-d]pyrimidine class, designated PD 173074, that selectively inhibits the tyrosine kinase activities of the FGF and VEGF receptors. We show that systemic administration of PD 173074 in mice can effectively block angiogenesis induced by either FGF or VEGF with no apparent toxicity. To elucidate the determinants of selectivity, we have determined the crystal structure of PD 173074 in complex with the tyrosine kinase domain of FGF receptor 1 at 2.5 A resolution. A high degree of surface complementarity between PD 173074 and the hydrophobic, ATP-binding pocket of FGF receptor 1 underlies the potency and selectivity of this inhibitor. PD 173074 is thus a promising candidate for a therapeutic angiogenesis inhibitor to be used in the treatment of cancer and other diseases whose progression is dependent upon new blood vessel formation.

X-ray structures of two methoxybenzo[b]thiophenes

The crystal and molecular structures of two methoxybenzo[b]thiophenes have been determined by three-dimensional, single-crystal X-ray diffractometry. Both 3-(4′-hydroxy-3′, 5′-dimethoxybenzoyl)-2-(4′-methoxyphenyl)-6-methoxybenzo[b]thiophene and 3-(2′,6′-dimethoxybenzoyl)-2-(4′-methoxyphenyl)-6-methoxybenzo[b]thiophene (hereafter referred to asI andII, respectively) crystallize in the monoclinic centrosymmetric space groupP21/n (No. 14, C 2h 5 ) with four formula units-per cell witha=6.866(1),b=28.638(2),c=11.830(2) A, and β=105.52(1)° anda=9.328(1),b=7.977(1),c=29.650(4) A, and β=97.87(1)°, respectively. The phase problems were solved by direct methods and the respective final full-matrix least-squares refinements converged toR=0.046 and 0.031. The structures differ in the positioning of the dimethoxy groups of the benzoyl ligands and the addition of a hydroxyl group inI. The molecules in the crystal lattice are held together by van der Waals forces plus the addition of hydrogen bonding in compoundI. Selected bond distances and angles and torsion angles are tabularized.

Oxidative rearrangement of chalcones without a hydroxy group by thallium(III) nitrate in methanol

Oxidative rearrangement of chalcones with no free hydroxy group with thallium(III) nitrate (TTN) in methanol was studied in detail and the following results were found. The reactions were greatly accelerated when there were methoxy groups at the 2-, 4-, and/or 6-position on the B ring and formed the corresponding 1,2-diaryl-3,3-dimethoxypropan-1-one (acetal) only. The methoxy groups on the A ring also had a tendency to accelerate the reaction, but the 2′,6′-dimethoxy groups greatly retarded the reaction. The 2′-methoxy group in the chalcones with no substituent at the 6′-position apparently accelerated the reaction, although other 2′-substituents retarded it. In the reaction of the 2′,4′-dimethoxychalcones (3a and 3g) with no electron-donating group on the B ring, a mixture of the acetal, methyl 2,3-diaryl-3-methoxypropanoate, and thallium compounds were obtained. The three thallium compounds obtained from compound 3h were assigned as cyclic complexes of thallium() chloride with two molecules of the acetal and/or propanoate. Based on these results, the mechanism of the oxidative rearrangement was proposed as shown in Schemes 3 and 4.

Matairesinol as precursor of Podophyllum lignans

The dibenzylbutyrolactone lignan (−)-[ 14C]matairesinol was efficiently incorporated into the aryltetralin lactone lignans podophyllotoxin, 4′-demethylpodophyllotoxin, β-peltatin, α-peltatin and 4′-demethyldesoxypodophyllotoxin in one or more of the plant systems Podophyllum hexandrum root, P. peltatum leaf or Diphylleia cymosa leaf. This demonstrates matairesinol to be a common precursor of the 3′,4′,5′-trimethoxy and 4′-hydroxy-3′,5′-dimethoxy groups of Podophyllum lignans, and it may represent the branch-point compound to the two series of compounds. No incorporation of matairesinol into the arylnaphthalene lactone lignan diphyllin in D. cymosa was detected.

ChemInform Abstract: Formation of Methoxynitrones and Stable Nitroxyl Radicals with Geminal Dimethoxy Groups at the α‐Carbon Atom by Oxidation of Aldonitrones.

AbstractOxidation of the nitrones (I) gives the methoxy derivative (IIb) or the nitroxyls (III) and the N‐hydroxy compounds (IV), depending on the structure of (I).

Ubiquinone analyses in fish tissues and in some marine invertebrates

1. 1. Ubiquinone contents were determined in species of marine invertebrates, and in heart, red and white muscle and liver of three species of fish. 2. 2. Three different methods of determination were compared, based on spectrophotometry, reduction and a reaction with the dimethoxy groups of ubiquinone. 3. 3. Using ubiquinone homologues 6–10 prepared from beef heart and commercially available microorganisms (SCP) as standards, ubiquinone 10 was found in all samples. In addition were found minor amounts of Q-9 in samples of saithe heart and red muscle. 4. 4. Less than 10 mg/kg wet wt of ubiquinone was found in the samples of marine invertebrates and in white muscle and liver of the fish samples, with one exception: 40 mg/kg in a sample of mackerel liver. 5. 5. Higher contents of ubiquinone were found in fish heart and red muscle tissues, ranging from 24 to 116 mg/kg wet wt. The ubiquinone contents were comparable in the two tissues. 6. 6. A test on cellular fragments of red muscle tissue of saithe showed that the ubiquinone was concentrated in the mitochondria fraction.

The preparation and properties of cage polycyclic systems—III: The cleavage in alkaline conditions of acetals derived from pentacyclo[5.3.0.0 2,5.0 3,9.0 4,8]decane and pentacyclo[4.3.0.0 2,5.0 3,8.0 4,7]nonane systems

The synthesis of some acetals derived from pentacyclo[5.3.0.0 2,5.0 3,9.0 4,8]decane is described. The reductive cleavage of an ethylenedioxy group [Display omitted] and a dimethoxy group [Display omitted] in pentacyclo[5.3.0.0 2,5.0 3,9.0 4,8]decane and pentacyclo[4.3.0.0 2,5.0 3,8.0 4,7]nonane systems to give the methylene group is shown to occur in alkaline conditions in the presence of hydrazine. Evidence is presented for a mechanism which involves initial cleavage of the acetal by alkali to form the ketone. The substitution of a Br atom in the position neighbouring the CO group of 5-bromo-6,6-ethylenedioxypentacyclo[5.3.0.0 2,5.0 3,9.0 4,8]decan-10-one facilitates the Wolff-Kishner reaction to such an extent that hydrazine hydrate is a sufficiently strong base to induce the decomposition of the hydrazone directly.

Supplementary Observations on the Chemistry of the Alkaloids of Berberine Series. II. The Ultraviolet Absorption Spectra of Berberines and Related Compounds

AbstractThe ultraviolet absorption spectra of berbines and ϕ‐berbines consist of a single, weak and narrow band in which λmax position dependeds on the kind of auxochrome group i. e., methylenedioxy‐or dimethoxy group attached to 2–3 position. The effect of the auxochrome group at 11–12 position or 12–13 position is very small.The shape of the band of oxyberberine, oxy‐ϕ‐berberine and oxyprotoberberine are similar, especially those of the latter two substances resemble closely.Comparing with isoquinoline, the bands (b), (c) and (d) of G‐berberines and protoberberine are considered as characteristic of isoquinoline structure, while the band (a) in visible region is of berberinium structure, however, the absorption curve of ϕ‐berberines does not show any characteristic of isoquinoline or berberinium structure.

Biological and Chemical Properties of Dimethoate and Related Derivatives1

Seventeen dimethoate derivatives were prepared in the laboratory, purified, and characterized. Derivatives containing dimethoxy groups were more effective against the house fly, Musca domestica L., than the diethoxy compounds. As the N-carbamoyl chain length increased in number of carbon atoms, the toxicity to house flies decreased; the monoalkyl-substituted amides were more effective than the dialkyl-substituted amides. Increase in chain length of the dialkoxy or N-carbamoyl groups resulted in increased stability to alkaline hydrolysis. The most toxic materials to t he house fly were those having the C = 0 band between 5.90 and 5.95 µ. The absorption, distribution, metabolism, and excretion or P32-labeled dimethoate were studied in rats and three species of insects; the house fly, the German cockroach. Blattella germanica (L.), and the American cockroach, Periplaneta americana (L.). Phosphorothioate oxidation was prevalent in rats, but the degrading rather than activating systems were predominant. Amidase activity was more pronounced in rats than in insects immediately following treatment with dimethoate; this major metabolic difference may partially explain selectivity. Phosphatase activity was also more evident in rats than in insects.

THE ALKALOIDS OF FUMARACEOUS PLANTS: V. THE CONSTITUTION OF ADLUMINE

A chemical examination of the alkaloid adlumine, which the author recently isolated from Adlumia fungosa, has disclosed an intimate relation to hydrastine and bicuculline. It differs from hydrastine only by the fact that the positions of the methylene-dioxy and the dimethoxy groups are reversed. Hydrolytic oxidation yields the expected products.