Synthesis, Characterization and Thermal Decomposition Kinetics of a Novel Benzofuran Ketoxime Derived Polymer.

A novel benzofuran ketoxime derived polymer, poly(benzofuran-2-yl-methylketoxime-O-methacrylate) [poly(BMKMA], was firstly synthesized by free radical polymerization method. Its thermal degradation studies were performed by thermogravimetric analysis (TGA) in order to determine the actual reaction mechanisms of the decomposition process. The activation energy of the solid-state process was determined using Flynn-Wall-Ozawa method, which resulted to be 235.94 kJ/mol. The activation energies of different mechanism models were determined by Coats-Redfern, Madhusudanan and Van Krevelen kinetic methods. Compared with the Ozawa method, the actual reaction mechanism obeyed deceleration type, phase boundary controlled reaction (R1).

Synthesis of benzofuran based 1,3,5-substituted pyrazole derivatives: as a new class of potent antioxidants and antimicrobials--a novel accost to amend biocompatibility.

In search for a new antioxidant and antimicrobial agent with improved potency, we synthesized a series of benzofuran based 1,3,5-substituted pyrazole analogues (5a-l) in five step reaction. Initially, o-alkyl derivative of salicyaldehyde readily furnish corresponding 2-acetyl benzofuran 2 in good yield, on treatment with 1,8-diaza bicyclo[5.4.0]undec-7-ene (DBU) in the presence of molecular sieves. Further, aldol condensation with vanillin, Claisen-Schmidt condensation reaction with hydrazine hydrate followed by coupling of substituted anilines afforded target compounds. The structures of newly synthesized compounds were confirmed by IR, (1)H NMR, (13)C NMR, mass, elemental analysis and further screened for their antioxidant and antimicrobial activities. Among the tested compounds 5d and 5f exhibited good antioxidant property with 50% inhibitory concentration higher than that of reference while compounds 5h and 5l exhibited good antimicrobial activity at concentration 1.0 and 0.5 mg/mL compared with standard, streptomycin and fluconazole respectively.

In vivo antihyperlipidemic activity of a new series of N-(benzoylphenyl) and N-(acetylphenyl)-1-benzofuran-2-carboxamides in rats.

A new series of N-(benzoylphenyl) and N-(acetylphenyl)-1-benzofuran-2-carboxamides (3a-3d and 4a'-4c') were synthesized. Compounds (3a, 3b, and 4a'-4c') were tested in vivo using Triton-WR-1339-induced hyperlipidemic rats as an experimental model for their hypolipidemic activity. The tested animals were divided into eight groups: control, hyperlipidemic, 3a, 3b, 4a', 4b', 4c', and bezafibrate. At a dose of 15 mg/kg, the elevated plasma triglyceride (TG) levels were significantly reduced in compounds 3b (p <0.0001) and 4c' (p <0.05) after 12 and 24 h compared to the normal control group. Furthermore, high-density lipoprotein-cholesterol levels were remarkably increased in compounds 3b (p <0.001) and 4c' (p <0.05). Meanwhile, compound 4b' slightly reduced the TG levels after 12 and 24 h. The present study demonstrated new properties of the novel series of benzofuran-2-carboxamides 3b and 4c' as potent lipid-lowering agents. It is, therefore, reasonable to assume that compounds 3b and 4c' may have a promising potential in the treatment of hyperlipidemia and coronary heart diseases.

Clay mediated route to natural formation of Polychlorodibenzo-p-dioxins.

Recent studies have documented the ubiquitous occurrence of polychlorodibenzo-p-dioxins and dibenzofurans (PCDD/Fs) of unknown origin in soils and clay deposits. Interestingly, the PCDD/F congener profiles do not match any known natural or anthropogenic source, and global PCDD/F budgets fail to account for the observed levels in soils. To reconcile these observations, clay minerals had been hypothesized to play a central role in the natural in situ synthesis of PCDD/Fs. We recently demonstrated the clay-mediated formation of the most prevalent PCDD congener in soils, octachlorodibenzo-p-dioxin (OCDD), supporting this hypothesis. Here we report the formation of the direct precursors ("predioxins") of the most toxic PCDD congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), and of 1,2,4,7,8-pentachlorodizenzodioxin (1,2,4,7,8-PeCDD), and two additional dimers, from the reaction of 2,4,5-trichlorophenol (2,4,5-TCP) with Fe(III)-montmorillonite clay. We propose plausible reaction pathways, each initiated by single electron transfer from 2,4,5-TCP to Fe(III)-montmorillonite forming the 2,4,5-TCP radical cation. The operative reaction mechanisms, inferred from experimental results, are supported by quantum mechanical calculations. The key role of montmorillonite is apparently to stabilize the reactive radical cation intermediate. Fortuitously, PCDD formation reactions on clay surfaces are more facile for less toxic higher chlorinated congeners like OCDD, as predicted by the proposed reaction mechanism and consistent with the observed PCDD congener distributions in soils. Importantly, increasing the toxicity equivalency factor of OCDD would immediately cause many soils to exceed PCDD regulatory levels due to the predominance of this congener.

The hypolipidemic activity of novel benzofuran-2-carboxamide derivatives in Triton WR-1339-induced hyperlipidemic rats: a comparison with bezafibrate.

Using Triton WR-1339-induced hyperlipidemic rats as an experimental model, we investigated whether compound 4 [N-(9,10-dihydro-9,10-dioxoanthracen-2-yl)benzofuran-2-carboxamide] and compound 5 [N-(4-benzoylphenyl)benzofuran-2-carboxamide], two novel anti-hyperlipidemic agents, have any effect on plasma triglyceride (TG), total cholesterol (TC), and high-density lipoprotein cholesterol levels (HDL-C) levels. The tested animals were divided into control (CG), hyperlipidemic (HG), and compounds 4, 5, and bezafibrate (BF) treated groups. At a dose of 15 mg/kg body weight, compounds 4, 5, and BF significantly reduced elevated plasma TG levels after 7 and 24 h. Furthermore, HDL-C levels were remarkably increased in all treated groups after 7 and 24 h compared to the hyperlipidemic control group. However, only compounds 4 and 5 treated groups clearly showed a significant reduction in plasma total cholesterol levels after 7 and 24 h. It is therefore reasonable to assume that compounds 4 and 5 may have promising potential in the treatment of hyperlipidemia and atherosclerosis.

Synthesis and insect antifeedant activity of aurones against Spodoptera litura larvae.

A series of aurones were prepared from various phenols via phenoxy acetic acids and coumaranones and evaluated for insect antifeedant activity against the common cutworm (Spodoptera litura). The naturally occurring aurone was most active at an ED50 of 0.12 micromol/cm2. The synthetic precursor, coumaranones, showed that the introduction of methoxyl and methyl groups to the benzene ring increased insect antifeedant activity. Similarly, the tested aurones showed that the introduction of methoxyl group to the A and/or B rings increased the insect antifeedant activity, but 4,5,6- and 3',4',5'-trisubstituted compounds did not show this activity in this test. The hydroxylation of aurones in the B ring should be disadvantageous for insect antifeedant activity against S. litura. Although the melting points did not correlate well with the insect antifeedant activity, compounds that were nearly inactive had high melting points. A significant correlation was noted between biological activity (pED50) and a hydrogen-bonding parameter calculated from the Rf value obtained from SiOH thin-layer chromatography and a lipophilicity parameter (log k) calculated from the retention time in ODS high-performance liquid chromatography. The respective correlation coefficients (r) were -0.83 and -0.70. The introduction of alkoxy and alkyl groups along with adequate hydrogen bonding seems to contribute to the antifeedant activity of the compounds tested.

Novel combretastatin analogues endowed with antitumor activity.

We studied the anticancer activity of a series of new combretastatin derivatives with B-ring modifications. The structure-activity relationship (SAR) information confirmed the importance of cis-stereochemistry and of a phenolic moiety in B-ring. We selected the benzo[b]thiophene and benzofuran combretastatin analogues 11 (ST2151) and 13 (ST2179) and their phosphate prodrugs (29 and 30) for their high antitumor activity in in vitro and in vivo models. Cell exposure to IC50 of 11, 13, and CA-4 led to the arrest of various cell types in the G2/M phase of the cell cycle and induction of apoptosis. Mainly, 11 and 13 induced the formation of multinucleated cells with abnormal chromatin distribution, with only a minimal effect on the microtubule organization, with respect to CA-4. Interestingly, both the pharmacokinetic profile of 29 and its in vivo antitumor effect and those of 30, active even after oral administration, suggest additional pharmacological differences between these compounds and CA-4P.

Nanoencapsulation of psoralidin via chitosan and Eudragit S100 for enhancement of oral bioavailability.

Psoralidin (PL) has recently been attracting more attention as a new anticancer agent candidate. Nevertheless, peroral administration of PL is largely challenged by its insoluble nature and intestinal efflux. This article aimed to develop a nanoencapsulation formulation of PL using water-soluble chitosan and Eudragit S100 and to evaluate its potential for bioavailability enhancement. PL-loaded nanocapsules (PL-NCs) were prepared by a solvent diffusion and high-pressure homogenization technique with Poloxamer 188 as a stabilizer. The resultant PL-NCs were approximately 132.5nm in particle size and possessed a high entrapment efficiency (98.1%). In vitro release showed that PL was released less from the nanocapsules due to electrostatic complexation. A lipolytic experiment demonstrated that our prepared PL-NCs were not degraded by lipase, in contrast with the most commonly used lipid nanoparticles. Furthermore, PL-NCs appeared to have less affinity for intestinal mucins. Following oral administration, the bioavailability of PL was significantly enhanced via the PL-NCs, with a value of 339.02% relative to the reference (suspensions). Excellent intestinal adhesion and transepithelial permeability accounted for the enhancement of oral bioavailability. Taken together, these results indicate that nanoencapsulation of PL with chitosan and Eudragit S100 is a promising strategy for improved PL oral delivery.

Formation of PCDD/Fs in the sintering process: role of the grid-Cr2O3 catalyst in the de novo synthesis.

The sintering process is among the major sources of the very toxic polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in the environment. At the industrial scale, it has been shown that dust collected on the grid, which supports the feed, contains PCDD/Fs amounts between the values found in the bottom of the cake and the values found on dust collected during gas sampling in the wind boxes. This fact suggests that the grid, containing 25wt.% of chromium, could have a catalytic activity in PCDD/Fs formation during the sintering process. This research tries to study this potential role. The de novo synthesis of PCDD/Fs is simulated at laboratory scale by thermal treatments of samples mixed with grid filings or Cr2O3. The thermal experiments performed with E.S.P. dust (dust collected in the electrostatic precipitator of a sintering plant) or graphite mixed with grid filings do not allow to confirm a role of the grid in PCDD/Fs formation during the industrial process. On the other hand, it has been shown that Cr2O3 can be considered as a catalyst in the de novo synthesis of PCDD/Fs. This compound takes place in the two steps of the de novo synthesis: the degradation of the carbon matrix as well as the chlorination reactions.

Structure-activity relationship studies on benzofuran analogs of propafenone-type modulators of tumor cell multidrug resistance.

A series of benzofurylethanolamine analogs of propafenone (1a) have been prepared and evaluated for multidrug resistance-reversing activity in two in vitro assay systems. As for propafenones, an excellent correlation of biological data with calculated lipophilicity values was found for benzofurans, whereby the latter generally had lower activity/lipophilicity ratios. Almost identical slopes of the regression lines were obtained for both propafenones and benzofurans. Multiple linear regression analysis of the complete data set yielded an equation with excellent predictive power (r2 cross-valid = 0.968). Interaction measurements with artificial membranes indicated that the differences in activity between these two series of compounds are not due to differences in the interaction pattern with biological membranes.

One-pot synthesis of benzo[b]furan and indole inhibitors of tubulin polymerization.

Benzo[b]furan and indole analogues of some recently identified benzo[b]thiophene inhibitors of tubulin polymerization have been prepared, and their biological activity has been assessed. Several very potent analogues were identified.

Synthesis of the putative structure of eupomatilone-6.

[reaction: see text] The synthesis of eupomatilone-6 (1) has been achieved by using Suzuki coupling, Sharpless asymmetric dihydroxylation, and intramolecular Horner-Wadsworth-Emmons reactions. The spectroscopic studies carried out on synthetic eupomatilone-6 do not agree with those reported for the natural product, and therefore revision of the assigned structure is warranted.

Palladium(II)-mediated cascade carbonylative annulation of o-alkynyl-phenols on silyl linker-based macrobeads: a combinatorial synthesis of a 2,3-disubstituted benzo[b]furan library.

[reaction: see text] A palladium(II)-mediated cascade carbonylative annulation of o-alkynylphenols was achieved successfully on silyl linker-based macrobeads, which led to an efficient combinatorial synthesis of a 2,3-disubstituted benzo[b]furan library.

Cytotoxic activity of 2-aminomethylene-3(2H)-benzofuranones against human oral tumor cell lines.

A total of 23 newly-synthesized 2-aminomethylene-3(2H)-benzofuranone and structurally-related compounds were compared for their cytotoxic activity against both normal (human gingival fibroblast HGF) and tumor cells (human oral squamous cell lines HSC-2, HSC-3 and human salivary gland tumor cells HSG). There was a significant variability of drug sensitivity among the oral tumor cell lines. In general, HSC-2 cells were the most sensitive, followed by HSG cells, while HSC-3 cells were the most resistant. HGF normal cells were highly resistant to all compounds, suggesting their tumor-specific cytotoxic action. The cytotoxic activity of the compounds with morpholine, 1-methylpiperazine or piperidine structure was generally elevated by the introduction of fluorine, but not chlorine and methoxy functional groups, to the benzofuranone structure, whereas that of compounds attached by 1-phenylpiperazine or 1-(2-pyridyl)piperazine was rather reduced. The most active compounds induced internucleosomal DNA fragmentation in human promyelocytic leukemia HL-60 cells, but not in HSG, further confirming that oral tumor cell lines are resistant to DNase digestion.

Determination of singlet oxygen quantum yields with 1,3-diphenylisobenzofuran in model membrane systems.

The oxidation of 1,3-diphenylisobenzofuran by singlet oxygen was investigated in methanol and in two different types of liposomes. It was found that at high concentrations of scavenger 1,3-diphenylisobenzofuran, e.g., > 100 microM in methanol, the 1:1 oxidation stoichiometry is lost and more than one scavenger molecule per molecule of singlet oxygen is consumed. In model membrane systems, where local scavenger concentrations are high due to compartmentalization, correct singlet oxygen quantum yields with 1,3-diphenylisobenzofuran are only determined if the increased oxidation is taken into account.

Comparative antilipidemic effects of various ethyl 5-substituted benzofuran-, 2,3-dihydrobenzofuran-, and 3(2H)-benzofuranone-2-carboxylate analogs of clofibrate in a triton hyperlipidemic rat model.

The antilipidemic properties of certain benzofuran-, 2,3-dihydrobenzofuran-, and 3(2H)-benzofuranone-2-carboxylate analogs of clofibrate in a hyperlipidemic rat model are described. The hyperlipidemia was induced by intraperitoneal injection of Triton WR-1339. The results were analyzed in light of structural modifications as well as the lipid solubility of substituted compounds as assessed by a consideration of calculated log P values. Comparisons are made between the activity of these compounds and the activity of related cyclic analogs previously reported. Among the various compounds tested, only the 5-C1 and phenylsybstituted dihydrobenzofurans were selective against elevated serum cholesterol levels in this animal model. The data presented support the hypothesis that the cholesterol and triglyceride lowering activity of clofibrate related analogs in this animal model may be separated through a consideration of log P, conformational, and electronic changes. The proposal is advanced that relatively minor structural modification of clofibrate related analogs may lead to compounds which are not only selective in the Triton model but also to compounds which are likely to exert their effects by differing modes of action.

Efficient domino strategy for the synthesis of polyfunctionalized benzofuran-4(5H)-ones and cinnoline-4-carboxamides.

An efficient, three-component strategy for the improved synthesis of multifunctionalized 6,7-dihydrobenzofuran-4(5H)-ones under microwave irradiation in ethyl alcohol within short periods has been established. The synthesized benzofuran-4(5H)-ones have been readily converted into polyfunctionalized cinnoline-4-carboxamides by treating with hydrazine hydratein in the same solvent through a regioselective ring-opening of the furan. Tedious workup procedures can be avoided because of the direct precipitation of products from the reaction solution by water addition, thus rendering the two-steps process ecofriendly.

Chalcone epoxide intermediates in the syntheses of lignin-related phenylcoumarans.

Compounds (2R*,3S*)-1-(3,4-dimethoxyphenyl)-3-{3-methoxy-2-[(2R*)-tetrahydropyran-2-yloxy]phenyl}-2,3-epoxy-1-propanone, C23H26O7, (I), and trans-1-(3,4-dimethoxyphenyl)-3-[3-methoxy-2-(methoxymethoxy)phenyl]-2,3-epoxy-1-propanone, C20H22O7, (II), were obtained on epoxidation of chalcones. The stereochemistries of (I) and (II) were elucidated. In both compounds, the substituents on the oxirane ring are trans-oriented. Compound (I) was obtained together with a diastereometric form that differs from (I) with respect to the configuration of the asymmetric C atom in the tetrahydropyran group. The geometries of the substituted oxirane rings of (I) and (II) are very similar. The hydrogen-bonding patterns, mediated via weak C-H...O interactions, differ considerably. The crystal structures of (I) and (II) are compared with those of related chalcone epoxides. The conversion of (I) and (II) into lignin-related phenylcoumarans is discussed.

Antiallergic agents. IV - Substituted 2-benzylidene-3(2H)-benzofuranone-5-carboxylic acids.

A series of substituted 2-benzylidene-3(2H)-benzofuranone-5-carboxylic acids were synthetized and tested for antiallergic activity by the passive cutaneous anaphylactic reaction in the rat. Many compounds display an antiallergic activity comparable to that of disodium chromoglycate when administered parenterally: in addition some derivatives are effective when given by mouth.