Aromatic furazan has numerous pharmacologic and industrial applications. As part of our work on aromatic furazan chemistry and biochemistry, benzofurazan N-oxides, on irradiation using a ...high-pressure mercury lamp with a Pyrex filter in acetonitrile containing a little water, afforded 1H-azepine-2,7-dione. Mechanistic studies on the photoreaction using a low-pressure mercury lamp and photosensitizer suggest that photosensitized formation of 1H-azepine-2,7-dione with the aromatic hydrocarbon may be carried out by reabsorption of fluorescence. Quinoxaline 1,4-dioxide, phenazine 5,10-dioxide, and pyrido2,3-bpyrazine derivatives were synthesized from the corresponding aromatic or heteroaromatic furazan N-oxides by silica gel or molecular sieves under solvent-free conditions using microwave irradiation. The toxicities of some benzofurazans were examined on Escherichia coli; these may due to their reduction within the E. coli cell and their reoxidization by molecular dioxygen to form superoxide and hydrogen peroxide. The formation of 4,7-dicyanobenzofurazan anion radical in the E. coli cell suspension-4,7-dicyanobenzofurazan-glucose system in the absence of O2 was followed by ESR spectroscopy. 4,7-Dimethylbenzofurazan was transformed by 1O2 produced by irradiation of C60 into 4,7-dimethylbenzofurazan 4,7-endoperoxide. The endoperoxide decomposed back to 4,7-dimethylbenzofurazan at room temperature. 4,7-Dimethylbenzofurazan was transformed by irradiation with the third harmonic of a Quanta-Ray Nd:YAG laser (355 nm) into (2Z,4Z)-2,5-dimethylhexa-2,4-dienedinitrile monoxide. Irradiation of 4,7-dimethylbenzofurazan yielded a photoproduct with a quantum yield 0.48 and chemical yield 99%.
Synthesis of analogs of
Pseudomonas quorum-sensing autoinducer,
N-3-oxododecanoyl-
l-homoserine lactone (
1) and their structure–activity relationship for the apoptosis induction in macrophages are ...described.
The synthesis of the analogs of
N-3-oxododecanoyl-
l-homoserine lactone (
1) and their structure–activity relationship for the apoptotic induction in macrophages, P388D1 cells, are described. It was revealed that the position of the oxo group in the acyl side chain in addition to the presence of the
l-homoserine lactone unit is crucial for the apoptosis-inducing activity. Furthermore, the long acyl side chains with hydrophobic distal ends are preferable for the activity.
Quorum-sensing systems have been reported to play a critical role in the pathogenesis of several bacterial infections. Recent data have demonstrated that Pseudomonas N-3-oxododecanoyl-L-homoserine ...lactone (3-oxo-C12-homoserine lactone, 3-oxo-C12-HSL), but not N-butanoyl-L-homoserine lactone (C4-HSL), induces apoptosis in macrophages and neutrophils. In the present study, the effects of active immunization with 3-oxo-C12-HSL-carrier protein conjugate on acute P. aeruginosa lung infection in mice were investigated. Immunization with 3-oxo-C12-HSL-BSA conjugate (subcutaneous, four times, at 2-week intervals) elaborated significant amounts of specific antibody in serum. Control and immunized mice were intranasally challenged with approximately 3 x 10(6) c.f.u. P. aeruginosa PAO1, and survival was then compared. All control mice died by day 2 post bacterial challenge, while 36 % of immunized mice survived to day 4 (P<0.05). Interestingly, bacterial numbers in the lungs did not differ between control and immunized groups, whereas the levels of pulmonary tumour necrosis factor (TNF)-alpha in the immunized mice were significantly lower than those of control mice (P<0.05). Furthermore, the extractable 3-oxo-C12-HSL levels in serum and lung homogenate were also significantly diminished in the immunized mice. Immune serum completely rescued reduction of cell viability by 3-oxo-C12-HSL-mediated apoptosis in macrophages in vitro. These results demonstrated that specific antibody to 3-oxo-C12-HSL plays a protective role in acute P. aeruginosa infection, probably through blocking of host inflammatory responses, without altering lung bacterial burden. The present data identify a promising potential vaccine strategy targeting bacterial quorum-sensing molecules, including autoinducers.
As part of our research on benzofurazans (BZs), we have reported the bacterioses of BZs in Escherichia coli, which may be due to O2-. produced within E. coli in the presence of dioxygen (O2). ...Incubation of E. coli with 4,7-dicyanobenzofurazan (1) lowered the 2,3-dihydroxyisovalerate dehydratase activity detectable in extracts from these cells. Addition of branched chain amino acids such as valine and leucine protected E. coli from growth inhibition by compound 1, though it could not protect E. coli from the damage by paraquat (PQ). Addition of Fe(III)-trisN-(2-pyridylmethyl)-2-aminoethylamine (Fe-TPAA), a novel superoxide dismutase mimic, protected the dehydratase in a dose-dependent manner, which confirms that inactivation of the dehydratase is largely due to production of O2-.. The possibility was discussed that the bacteriostatic effect of compound 1 is due to the inactivation of 2,3-dihydroxyisovalerate dehydratase.
Abstract
Photolysis of 1
H
‐azepine‐2,7‐dione
2
proceeded with alkali as in the photoreaction of
N
‐alkylimide to give 7‐hydroxy‐1
H
‐azepine‐2‐one
13
.
A reaction from various kinds of nitroquinoline with hydroxylamine in potassium hydroxide alkalinity produced a novel product, furazanoquinoline, besides the known amino derivatives. The products ...obtained were furazano 3,4-f quinoline (5) from 5-nitroquinoline (1) and 6-nitroquinoline (6), and furazano 3,4-h quinoline (10) from 7-nitroquinoline (8) and 8-nitroquinoline (11). The reaction mechanism was believed to be as shown in Figs. 2 and 3. The photoreaction of benzofuroxan (19) in acetonitrile containing a little water, under a high pressure mercury lamp, produced 1H-azepine-2,7-dione (20), while under irradiation using a low pressure lamp, 6H-furazano 4,5-c carbazole-3-oxide (21) and compound 20 were obtained. Then the photoproduct 20 produced photodimer 22 by irradiation in acetonitrile: water (9:1, v/v) using a high or low pressure mercury lamp, while photolysis with alkali proceeded as in the photoreaction of N-alkylimide to give 7-hydroxy-1H-azepine-2-one (23). When pyrido 2,3-c furoxan (24) was irradiated in acetonitrile containing a little water with a low pressure mercury lamp, 3-nitro-2-pyridone (25) was obtained. When compound 24 was irradiated in the presence of morpholine with a low pressure mercury lamp in an argon atmosphere, 6-morpholinopyridine 2,3-dioxime (26) was produced. Quinoxaline 1,4-dioxyde derivatives (31, 33), phenazine 5, 10-dioxide derivatives (36, 37) and pyrido 2,3-b pyrazine derivatives (38, 39) were synthesized from the corresponding furoxan catalyzed by silica gel or molecular sieves, and their antibacterial properties were evaluated. The results of antibacterial screening tests in vitro, revealed strong activity against Bacteroides fragilis.
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