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At least 163 records · Page 9Linked to original sources
PubMed2006

Inhibition of photosystem II electron transport by acyl derivatives of 2,2-dimethyl-1,3-dioxane-4,6-dione (Meldrum's acid).

In the course of the synthesis of gamma-pyrones, well-known inhibitors of photosystem II electron transport, it turned out that the starting material, acyl derivatives of 2,2-dimethyl-1,3-dioxane-5,6-dione (Meldrum's acid) are potent inhibitors of photosystem II electron transport. Thus, in a simple one-step synthesis from commercial available substances, highly potent photosystem II inhibitors are generated. The biological activity of the acyl derivatives is in a parabolic fashion dependent from the length of the alkyl side chain.

Dioxanes↗
PubMed2004

Structure-activity relationship of anti-malarial spongean peroxides having a 3-methoxy-1,2-dioxane structure.

In order to study the structure-activity relationship of anti-malarial spongean peroxides, several analogues concerning with the 6-methoxyacetyl moiety and the 3-pentyl residue in methyl 2-(3-methoxy-3-pentyl-1,2-dioxan-6-yl)acetate were synthesized and evaluated for anti-malarial activity. The tert-butyl ester analogue 14 showed stability in mouse serum and a high selectivity index against the malaria parasite, Plasmodium falciparum, and the citronellyl analogue 31 exhibited the strongest in vitro anti-malarial activity among them, and the imidazole analogue 25 showed desirable in vivo anti-malarial activity against P. berghei infected mice.

Animals↗
PubMed2006

Dioxane and oxathiane nuclei: suitable substructures for muscarinic agonists.

Muscarinic agonists, bearing 1,4-dioxane and 1,4-oxathiane nuclei, were synthesized and tested to evaluate their potency at M(1)-M(4) muscarinic receptor subtypes. The stereochemical relationship between the 2-side chain and the 6-methyl group plays an important role in drug-receptor interaction, since the cis isomers are more potent than the corresponding trans isomers. However, the latter are able to discriminate between the muscarinic receptor subtypes. Among them compound 5b proves particularly interesting, since it selectively activates the ileal M(3) receptor subtype and is devoid of agonist activity at the others.

Animals↗
PubMed2004

Use of apple seed meal as a new source of beta-glucosidase for enzymatic glucosylation of 4-substituted benzyl alcohols and tyrosol in monophasic aqueous-dioxane medium.

A facile method for enzymatic glycosylation of 4-substituted benzyl alcohols and tyrosol with glucose in a monophasic aqueous-dioxane medium was reported, using a crude meal of apple seed as a new catalyst. The corresponding beta-d-glucosides were synthesized in moderate yields (13.1-23.1%), among which the salidroside was obtained in 15.8% yield.

Benzyl Alcohol↗
PubMed2006

Removal of 1,4-dioxane from water using sonication: effect of adding oxidants on the degradation kinetics.

This research investigates the effect of adding oxidants such as Fe0, Fe2+ and S2O8(2-) in the sonication of 1,4-dioxane (1,4-D). The results indicate that the degradation pattern of 1,4-D kinetically could be divided into three steps (initiation, acceleration, and stabilization), with the first two steps predominating. The initiation step agreed with zero order rate model, while the acceleration step was the pseudo-first order. In the presence of HCO3- as a radical scavenger, the degradations of 1,4-D and TOC were suppressed, indicating that OH radical is an important factor in the sonolysis, especially at the acceleration step. The overall degradation efficiency of 79.0% in the sonolysis of 1,4-D was achieved within 200 min. While Fe0, Fe2+ and S2O8(2-) were individually combined with sonication, the total degradation efficiency of 1,4-D increased 18.6%, 19.1% and 16.5% after 200 min, respectively. The addition of oxidants not only increased the rate constant in the acceleration step, but also changed the kinetic model from zero to pseudo-first order at the initiation step. The addition of oxidants such as Fe2+, Fe0 and S2O8(2-) in the sonication of 1,4-D also improved the mineralization of 1,4-D. However, the degradation efficiencies of 1,4-D and TOC were not statistically different (p = 0.709, ANOVA) with different oxidants such as Fe2+, Fe0 and S2O8(2-).

Dioxanes↗
PubMed1999

Synthesis and biological activity of 4-methyl-3,5-dioxane derivatives as thromboxane A2 receptor antagonists.

The synthesis and biological activity of novel 4-methyl-3,5-dioxane analogues are described. All compounds were produced through modification of the substituent formally corresponding to the omega-octenol side chain of thromboxane A2 (TXA2), in reference to the structure of SQ29548. Several compounds were found to be potent TXA2 receptor antagonists. Compound 8b was the most effective inhibitor of 9,11-epoxymethano PGH2 (U-46619)-induced human platelet aggregation (IC50 = 7.4 nM).

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2002

The rodent carcinogens 1,4-dioxane and thiourea induce meiotic non-disjunction in Drosophila melanogaster females.

The ability of the rodent carcinogens 1,4-dioxane (DX) and thiourea (TU) to induce meiotic non-disjunction (ND) was assessed in 3- and 6-day-old Drosophila melanogaster females. The chemicals were administered orally and three 24 h and one 48 h broods were obtained after mating, to sample oocytes treated in increasingly earlier stages of development. The broods represent mainly mature oocytes (brood I), nearly mature oocytes (brood II), early oocytes (brood III) and very early oocytes (brood IV). The toxicity of DX increased with dose (1% (not toxic), 1.5, 2, 3, 3.5%) as well as a reduction in fecundity which was moderate. Induction of ND in mature oocytes was positive with 2, 3 and 3.5% concentrations and was not related to dose. In immature oocytes it was also positive though already at the lowest concentration tested (1%), suggesting a sensitivity higher than that of mature oocytes. TU at 0.10-10%, did not affect viability, but since fecundity was seriously impaired at high doses, ND was not assessed beyond the 1.5% concentration. TU also induced ND in mature and in immature oocytes; neither a threshold nor a dose effect was detected. The response of mature oocytes was lower than that of immature oocytes. TU induced increases of ND in the earliest cells tested in a more consistent fashion than DX. The data clearly show that both chemicals induced ND in mature oocytes and in the three subsets in which immature oocytes were fractionated. Though toxicity may play a significant unspecific role in the induction of chromosome malsegregation by DX and TU, the induction of ND at low doses, moderately toxic to the oocytes, suggests that the interaction with specific targets contributed to the results obtained.

Animals↗
PubMed2000

Enzyme-catalyzed ring-opening copolymerization of 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) with trimethylene carbonate (TMC): synthesis and characterization.

Enzymatic ring-opening copolymerization of 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) with trimethylene carbonate (TMC) was investigated. A route to aliphatic polycarbonates decorated with pendent carboxylic acid groups is demonstrated. Lipase from Pseudomonas fluorescens (AK) was selected to perform the copolymerization at various monomers feed ratios. Copolymers with different composition were prepared by varying the monomer feed ratio from 10% to 80% MBC. 1H, 13C, and 1H-13C HETCOR NMR spectra were used to analyze the microstructure of the copolymers. The 1H NMR spectra indicated lower incorporation of TMC in the copolymer than was expected from the monomer feed ratio. Analysis of the 13C spectra did not indicate an ordered structure but instead suggested the formation of random polymers. This was further confirmed by the thermal data obtained for representative samples. The thermal properties at different feed ratios of poly[MBC-co-TMC] copolymers were investigated by differential scanning calorimetry (DSC). No melting temperature (Tm) for either homopolymers or copolymers was observed. A plot of 1/Tg(K) vs the weight composition of MBC in the copolymers was constructed and was consistent with copolymers that tend toward random distribution; this was confirmed from the NMR data.

Calorimetry, Differential Scanning↗
PubMed2006

Enzymatic synthesis and characterization of novel biodegradable copolymers of 5-benzyloxy-trimethylene carbonate with 1,4-dioxan-2-one.

Enzymatic ring-opening copolymerization of 5-benzyloxy-trimethylene carbonate (BTMC) and 1,4-dioxan-2-one (DON) was investigated for the first time. Immobilized porcine pancreas lipase (IPPL) on silica particles was selected to perform the copolymerization. A series of novel biodegradable copolymers with different compositions were characterized by (1)H NMR, (13)C NMR, and GPC. The influences of reaction conditions such as polymerization time and catalyst concentration on the yield and molecular weight of the copolymers were also studied. The copolymerizations of different monomer feed ratios were carried out in bulk at 150 degrees C with 4.5 wt per thousand IPPL as a catalyst for 24 h. With the increase of the BTMC molar feed ratio from 20% to 79%, the M(n) of the resulting copolymers increased from 5600 to 63400. Water uptake and static contact angle experiments showed that the hydrophilicity of copolymers could be improved with increasing DON content in the copolymers. Moreover, the in vitro drug release rate (ibuprofen as the model drug) of the resulting copolymers also increased along with the DON content in the copolymers.

Analgesics, Non-Narcotic↗
PubMed1987

(5Z)-7-(2,2-Dimethyl-4-phenyl-1,3-dioxan-cis-5-yl)heptenoi c acid: a specific thromboxane A2 receptor antagonist.

(5Z)-7-(2,2-Dimethyl-4-phenyl-1,3-dioxan-cis-5-yl)heptenoic acid (2) was found to be a specific, competitive thromboxane A2 receptor antagonist that acts at platelet, vascular, and pulmonary receptors. No antagonism was detected at receptors for prostacyclin, SRSA, norepinephrine, and serotonin. The synthesis of a series of analogues is described; activity at the thromboxane receptor was observed in cis-substituted compounds but not in their trans counterparts. Compound 2 inhibited the bronchoconstriction induced by a stable thromboxane mimetic in the anesthetized guinea pig.

Animals↗
PubMed2002

Chiral C(2)-symmetric ligands with 1,4-dioxane backbone derived from tartrates: syntheses and applications in asymmetric hydrogenation.

Chiral 1,4-diphenylphosphines 5-7 as well as thioether 8 were synthesized from tartrates employing Ley's "BDA" and "Dispoke" methodologies as the key step. Rhodium(I) complexes with 5-7 are efficient catalysts for the asymmetric hydrogenation of beta-substituted enamides and MOM-protected beta-hydroxyl enamides, which furnished chiral amines or beta-amino alcohols with 94-->99% ee. These results indicated that the 1,4-dioxane backbone in the ligands having the general structure 2 played an important role in stabilizing metal-ligand chelate conformation. Higher enantioselectivities with ligand 2 were achieved compared with the analogous ligands having the general structure 1.

Dioxanes↗
PubMed2005

Computer simulation of the linear and nonlinear optical susceptibilities of p-nitroaniline in cyclohexane, 1,4-dioxane, and tetrahydrofuran in quadrupolar approximation. I. Molecular polarizabilities and hyperpolarizabilities.

This is the first part of a study of the local field effects on (non)linear optical susceptibilities of solutions of para-nitroaniline (pNA) in three different solvents, cyclohexane (CH), 1,4-dioxane (DI), and tetrahydrofuran (THF), using a discrete molecular representation of the condensed phase. To account for dipolar and quadrupolar effects, the latter of which are especially important for DI solution, all the electric properties necessary to compute the local fields and local field gradients in quadrupolar approximation as well as the dipolar hyperpolarizabilities for the four molecules are computed, including frequency dispersion and vibrational contributions to the dipolar properties. The convergence of the perturbation treatment for the pure vibrational (PV) contributions is examined by comparison of the values obtained at the lowest order with those of partially computed second order in mechanical and electrical anharmonicity. For pNA, for which previous computations of the hyperpolarizabilities have generally found poor agreement with experimental results, a thorough investigation of the effects of solvent-induced geometry changes, dynamic and static correlation, frequency dispersion, and classical thermal averaging over the torsional modes of the substituent groups and the inversion mode of the amino group on the dipolar properties is carried out. Computations using self-consistent continuum reaction field models show that the amino group is substantially less pyramidalized in polar solvents than in the gas phase. With all the effects taken into account, reasonable agreement with the experimental electric-field induced second harmonic generation (EFISH) result on pNA vapor of Kaatz, Donley, and Shelton is obtained.

Aniline Compounds↗
PubMed2005

Plasma deposition and surface characterization of oligoglyme, dioxane, and crown ether nonfouling films.

Plasma-deposited PEG-like films are emerging as promising materials for preventing protein and bacterial attachment to surfaces. To date, there has not been a detailed surface analysis to examine the chemistry and molecular structure of these films as a function of both precursor size and structure. In this paper, we describe radio-frequency plasma deposition of a series of short-chain oligoglymes, dioxane, and crown ethers onto glass cover slips to create poly(ethylene glycol)-like coatings. The resultant films were characterized by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), dynamic contact angle goniometry, and radiolabeled fibrinogen adsorption. Detailed analysis of the high-mass (120-300 m/z) TOF-SIMS oligoglyme film spectra revealed six classes of significant fragments. Two new models are proposed to describe how these fragments could be formed by distinct film-building processes: incorporation of intact and fragmented precursor molecules. The models also provide for the incorporation of hydrocarbon--a species that is not present in the precursors but is evidenced in XPS C(1s) spectra of these films. Two additional models describe the effects of incorporating intact and fragmented cyclic precursors.

Anti-Infective Agents↗
PubMed1998

Two new C22 1,2-dioxane polyketides from the marine sponge Acarnus cf. bergquistae.

Two new cyclic peroxide-containing polyketide C22 methyl esters, peroxyacarnoic acid methyl esters A and B, 1 and 2, have been isolated from the Red Sea marine sponge Acarnus cf. bergquistae. Both 1 and 2 are proposed to contain a single 1,2-dioxane ring, an eneyne functionality, and a terminal double bond or triple bond, respectively. The structures were elucidated mainly through 1D and 2D NMR spectral analysis.

Animals↗
PubMed2002

Empirical model for the molar rotations of syn-2,2-dimethyl-1,3-dioxanes.

[structure: see text] A useful method for the prediction of molar rotation ([Phi]) of syn-2,2-dimethyl-1,3-dioxanes (acetonides) is described. A series of acetonides were prepared by standard methods. A simple additive relationship between the substituents (R, R') and molar rotation was realized.

Biological Factors↗
PubMed2001

Effect of chronic inhalation of toluene and dioxane on activity of free radical processes in rat ovaries and brain.

The effects of toluene and dioxane inhalations on the intensity of free radical oxidation in rat ovaries and brain cortex were studied. Both toxins in a dose 10-fold surpassing the maximum permissible concentration increased activity of glutathione peroxidase in brain tissue; moreover, toluene increased chemiluminescence intensity, which attested to activation of free radical processes. In ovarian tissue toluene increased activities of glutathione peroxidase and catalase and the intensity of lipid peroxidation. These changes were associated with the appearance of normally absent circadian rhythm.

Administration, Inhalation↗