benzofurans and catechol

Comamonas sp. JB was used to investigate the cometabolic degradation of dibenzofuran (DBF) and dibenzothiophene (DBT) with naphthalene as the primary substrate. Dehydrogenase and ATPase activity of the growing system with the presence of DBF and DBT were decreased when compared to only naphthalene in the growing system, indicating that the presence of DBF and DBT inhibited the metabolic activity of strain JB. The pathways and enzymes involved in the cometabolic degradation were tested. Examination of metabolites elucidated that strain JB cometabolically degraded DBF to 1,2-dihydroxydibenzofuran, subsequently to 2-hydroxy-4-(3'-oxo-3'H-benzofuran-2'-yliden)but-2-enoic acid, and finally to catechol. Meanwhile, strain JB cometabolically degraded DBT to 1,2-dihydroxydibenzothiophene and subsequently to the ring cleavage product. A series of naphthalene-degrading enzymes including naphthalene dioxygenase, 1,2-dihydroxynaphthalene dioxygenase, salicylaldehyde dehydrogenase, salicylate hydroxylase, and catechol 2,3-oxygenase have been detected, confirming that naphthalene was the real inducer of expression the degradation enzymes and metabolic pathways were controlled by naphthalene-degrading enzymes.

Topics: Benzofurans; Biotransformation; Catechols; Comamonas; Enzymes; Metabolic Networks and Pathways; Naphthalenes; Thiophenes

Kidney-specific delivery is critically important for the treatment of renal fibrosis with drugs such as salvianolic acid B (Sal B). Here we report a kidney-specific nanocomplex formed by the coordination-driven assembly of catechol-modified low molecular weight chitosan (HCA-Chi), calcium ions and Sal B. The prepared HCA-Chi-Ca-Sal B (HChi-Ca-Sal B) nanocomplex reversed the TGF-β1-induced epithelial-mesenchymal transition (EMT) in HK-2 cells. In vivo imaging demonstrated a kidney-specific biodistribution of the nanocomplex. The anti-fibrosis effect of HChi-Ca-Sal B was tested in a mouse model of unilateral ureteral obstruction (UUO). Significant attenuation of the morphological lesions and the levels of extracellular matrix (ECM) proteins in the tubulointerstitium was observed in mice treated with HChi-Ca-Sal B, suggesting that the nanocomplex was able to prevent fibrosis better than the treatment with free Sal B. It was concluded that the HChi-Ca-Sal B nanocomplex showed a specific renal targeting capacity and could be utilized to enhance Sal B delivery for treating renal fibrosis.

Topics: Animals; Benzofurans; Catechols; Cell Line; Chitosan; Epithelial-Mesenchymal Transition; Kidney; Mice

We present, in this study, mechanistic and kinetic accounts of the formation of dibenzofuran (DF), dibenzo-p-dioxin (DD) and their hydroxylated derivatives (OHs-DF/OHs-DD) from the catechol (CT) molecule, as a model compound for phenolic constituents in biomass. Self-condensation of two CT molecules produces predominantly a DD molecule via open- and closed-shell corridors. Coupling modes involving the o-semiquinone radical and the CT molecule (o-SQ/CT) generate two direct structural blocks for the formation of OHs-DF/OHs-DD structures, ether-type intermediates and di-keto moieties. The calculated reaction rate constants indicate that the fate of ether-type intermediates is to make hydroxylated diphenyl ethers rather than to undergo cyclisation reactions leading to the formation of preDF structures. Unimolecular loss of a H or OH moiety from a pivotal carbon in these hydroxylated diphenyl ethers then produces hydroxylated and non-hydroxylated DD molecules. Formation of OHs-DF initiated by o(C)-o(C) cross-linkages involving o-SQ/o-SQ and o-SQ/CT reactions incurs very similar reaction and activation enthalpies encountered in the formation of chlorinated DFs from chlorophenols.

Topics: Benzofurans; Catechols; Dioxins; Hydroxylation; Molecular Structure

Catechol has been identified as one of the most abundant organic products in tobacco smoke and a major molecular precursor for semiquinone type radicals in the combustion of biomass material. The high-temperature gas-phase pyrolysis of catechol under hydrogen-rich and hydrogen-lean conditions was studied using a fused-silica tubular flow reactor coupled to an in-line GC/MS analytical system. Thermal degradation of catechol over temperature range of 250-1000 degrees C with a reaction time of 2.0s yielded a variety products including phenol, benzene, dibenzofuran, dibenzo-p-dioxin, phenylethyne, styrene, indene, anthracene, naphthalene, and biphenylene. Ortho-benzoquinone which is typically associated with the presence of semiquinone radicals was not observed and is proposed to be the result of fast decomposition reactions that lead to a variety of other reaction products. This is in contrast to the decomposition of hydroquinone that produced para-benzoquinone as the major product. A detailed mechanism of the degradation pathway of catechol is proposed.

Topics: Benzofurans; Benzoquinones; Catechols; Dioxins; Gas Chromatography-Mass Spectrometry; Hot Temperature

The radical scavenging activity of maritimetin and a series of synthetic aurones has been studied by using density functional theory with the B3LYP exchange correlation functional. The computation of various molecular descriptors that could assist the elucidation of hydrogen atom and electron donating ability of the selected compounds was carried out in the gas phase and in the liquid phase (benzene, methanol, water) with the aid of IEF-PCM. For reasons of comparison a series of simple phenols of known activity were also included in the study. The results are discussed with regards to the structure-activity relationship principles of flavonoids and in particular to the capacity of the selected aurones to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH(*)) and superoxide anion (O(2)(-*)) radicals. The O-H bond dissociation enthalpy (BDE) seems to be the most proper parameter to characterize the antiradical properties of the studied compounds. The hydroxylation pattern in ring B defines the order of activity, while the extended conjugation and especially the presence of a catechol moiety in ring A are responsible for the high activity observed experimentally for the selected aurones.

Topics: Benzofurans; Biphenyl Compounds; Catechols; Drug Industry; Electron Transport; Flavonoids; Food Industry; Free Radical Scavengers; Hydrazines; Hydrogen; Picrates; Quantum Theory; Solvents; Superoxides