[Studies on heterocyclic compounds. XXVI. Preparation of 5-(3-pyridyl)-2-furaldehyde, 5-(3-quinolyl)-2-furaldehyde and these Schiff's bases (author's transl)].
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Furaldehyde↗
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Further studies on the mechanism of phenol-sulfuric acid reaction with furaldehyde derivatives.
Even though the chromogens formed from mannose and galactose showed comparable absorbances at 480 nm in the conventional (developer present during heat of dilution) and modified (developer reacted at room temperature after cooling; epsilon mannose = 13,700, galactose = 14,000) phenol-sulfuric acid reactions, shoulders in the region 420-430 nm were prominent in the former method. Fucose was 10 times less reactive in the modified method (epsilon = 800) than in the conventional method. 2-Formyl-5-furan sulfonic acid reacted equally efficiently in the two methods (epsilon = 40,800). 5-Methyl-2-furaldehyde, unlike the sulfonate derivative or 5-hydroxymethyl-2-furaldehyde, required heat for condensation with phenol. 2-Furaldehyde dimethylhydrazone reacted 25 times better to form a chromogen (epsilon = 40,500) in the modified phenol-sulfuric acid method. The possible roles of intermediates between hexoses and furaldehydes in forming chromogens and the effect of substitution at the 2- and 5-positions of furaldehyde on the rates of condensation with phenol for the observed differences between the conventional and the modified methods are discussed.
Fucose↗
Inhibition of platelet aggregation by 5-nitro-2-furaldehyde diacetate with observations on structure-activity relationships.
Nitrofurantoin [1-(5'-nitro-2'-furfurylideneamino)-2, 4-diketoimidazole] is a potent inhibitor of primary ADP-induced platelet aggregation. The nitro group on the furan ring and the specific arrangement of the two keto groups on the imidazole ring are the molecular characteristics of nitrofurantoin critical to its inhibitory effect. The present studies report that 5-nitro-2-furaldehyde diacetate is also a potent inhibitor of primary ADP-induced platelet aggregation. 5-Nitro-2-furaldehyde diproprionate, 5-nitro-2-furaldehyde dibutyrate, and 5-nitro-2-furfuryl acetate are essentially inactive. These results indicate that a diacetate moiety can replace the diketoimidazole moiety of nitrofurantoin and form a compound that fully retains the inhibitory effect upon primary ADP-induced platelet aggregation.
Adenosine Diphosphate↗
High-performance liquid chromatographic determination of 2-furaldehyde in spirits.
Official methods for the determination of 2-furaldehyde in spirits involve for a spectrophotometric evaluation, which is characterized by poor specificity. Gas chromatographic evaluations have also been proposed, which offer a much higher sensitivity, particularly when capillary columns are used. In this paper a high-performance liquid chromatographic (HPLC) method based on the formation of the 2,4-dinitrophenylhydrazones of carbonyl compounds and subsequent reversed-phase separation of these derivatives is described. Derivatization is carried out by utilizing an acidic solution of 2,4-dinitrophenylhydrazine in acetonitrile. Precipitation of the derivatives is avoided and direct injection of the sample into the HPLC system is allowed. The determination offers a high specificity and a detection limit of the order of 10(-8) mol/l. Accuracy and reproducibility data are presented.
Alcoholic Beverages↗
Degradation of furfural (2-furaldehyde) to methane and carbon dioxide by an anaerobic consortium.
Furfural, a byproduct formed during the thermal/chemical pretreatment of hemicellulosic biomass, was degraded to methane and carbon dioxide under anaerobic conditions. The consortium of anaerobic microbes responsible for the degradation was enriched using small continuously stirred tank reactor (CSTR) systems with daily batch feeding of biomass pretreatment liquor and continuous addition of furfural. Although the continuous infusion of furfural was initially inhibitory to the anaerobic CSTR system, adaptation of the consortium occurred rapidly with high rates of furfural addition. Addition rates of 7.35 mg furfural/700-mL reactor/d resulted in biogas productions of 375%, of that produced in control CSTR systems, fed the biomass pretreatment liquor only. The anaerobic CSTR system fed high levels of furfural was stable, with a sludge pH of 7.1 and methane gas composition of 69%, compared to the control CSTR, which had a pH of 7.2 and 77% methane. CSTR systems in which furfural was continuously added resulted in 80% of the theoretically expected biogas. Intermediates in the anaerobic biodegradation of furfural were determined by spike additions in serum-bottle assays using the enriched consortium from the CSTR systems. Furfural was converted to several intermediates, including furfuryl alcohol, furoic acid, and acetic acid, before final conversion to methane and carbon dioxide.
Acetates↗
[Studies on heterocyclic compounds. XXVII. Syntheses and antimicrobial activity of 5-nitro-3,4-diphenyl-2-furaldehyde and it's derivatives (4) (author's transl)].
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Escherichia coli↗
Inhibition of T cell mitogenesis by nitrofurans.
A group of nitrofurans (5-nitro-2-furaldehyde, nifuroxime, nitrofurazone, nitrofurantoin, 5-nitro-2-furoic acid and 2-nitrofuran) were evaluated for inhibition of mitogenesis (DNA synthesis) in human peripheral blood T cells. T cells, either triggered by phorbol myristate acetate (PMA) or in the presence of accessory cells, were activated with a specified mitogen [phytohemagglutin (PHA), concanavalin A (ConA), or anti-CD3] and the amount of tritiated thymidine incorporated into DNA was determined. The results obtained indicate that nitrofurans inhibit mitogenesis irrespective of activator. 5-Nitro-2-furaldehyde was much more inhibitory than the other compounds, while 2-nitrofuran was less inhibitory. When the aldehyde group (5-nitro-2-furaldehyde) was replaced by a carboxyl group (5-nitro-2-furoic acid), the inhibitory activity was also reduced greatly. These results show that while the nitro group alone confers inhibitory activity to the furan ring, the group at the 2 position is crucial. In general, the mitogenic response of purified T cells (lacking accessory cells) triggered by PMA (phorbol ester) was inhibited less than that of the T cell-accessory cell system. With the latter, 50% inhibition of T cell mitogenesis was achieved by nifuroxime, nitrofurazone, and nitrofurantoin at 45-51 and 34-39 microM with PHA and ConA respectively. When purified T cells were used, the values were 71-85 and 55-60 microM respectively. For a given drug concentration, mitogenesis was more inhibited when induced by ConA or anti-CD3 than by PHA. The importance of using a single cell system (purified T cells) was emphasized by the interesting finding that only this system showed enhancement of mitogenesis, up to 35-40% at low drug levels. With the exception of the nitrofuraldehyde, the nitrofurans at strongly inhibitory levels were only moderately cytotoxic, exhibiting 62-85% cell survival after exposure to drug for 68 hr. Our results suggest that nitrofurans inhibit T cell mitogenesis by a relatively non-toxic mechanism; these results are comparable to those obtained for mammalian cells under aerobic conditions.
Adult↗
Discoloration of dental pellicle by tannic acid.
The ability of tannic acid to discolor pellicle was studied in vitro and in vivo. Freshly extracted teeth were submerget in solutions of tannic acid, and in the clinical study individuals rinsed three times daily with 0.1% or 0.2% tannic acid. It was fount that 0.2% tannic acid caused brownish discolorations within 10-12 days both in vitro and in vivo. Discolored pellicle material collected from the in vivo test group was shown to contain furaldehyde after hydrolysis. The origin of the furaldehyde is not ascertained, but could be due to the presence of dietary deposits, transformation of pellicle pentoses, or from reactions between reducing sugars and amino compounds.
Dental Enamel↗
The inhibitory effect of cysteine on the mutagenic activities of several carcinogens.
The Salmonella/microsome mutagenesis assay was used to determine the effect of cysteine (alpha-amino-beta-mercaptopropionic acid) on the mutagenic actions of several carcinogens: N-methyl-N'-nitro-N-nitrosoguanidine. N-acetoxy-2-acetylaminofluorene, N-hydroxy-2-acetylaminofluorene, 4-nitroquinoline-1-oxide, methyl methanesulfonate, 5-nitro-2-furaldehyde semicarbazone, 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide, aflatoxin B1 and the nitrosation products of methylurea and methylguanidine. Cysteine, at non-toxic concentrations, significantly decreased the frequency of reversion to histidine prototrophy when it was added to treatment mixtures. The extent of the inhibition of mutagenic action by cysteine depended on the carcinogen studied as well as the doses of cysteine and carcinogen employed. Cysteine (2.5--10 mM) completely inhibited the mutagenic actions of N-methyl-N'-nitro-N-nitrosoguanidine and methylguanidine nitrosation products while only partially preventing the mutagenic effects of the other carcinogens assayed. Inhibition of 5-nitro-2-furaldehyde semicarbazone-induced mutagenesis occurred only with higher cysteine concentrations (20--200 mM).
2-Acetylaminofluorene↗
Mutagenic action of nitrofurans on Euglena gracilis and Mycobacterium phlei.
There is a pronounced difference between the action of antibiotics and nitrofurans on Euglena gracilis. Those antibiotics that induce hereditary loss of chloroplasts do so only when they affect dividing cells. On the other hand, nitrofurans induce a mass mutation in both dividing and nondividing cells (under conditions of continuous illumination of cultures). It was found that a breakdown product, 5-nitro-2-furaldehyde, is liberated from furadantin and furoxone. This intermediate is responsible for the observed specific mutagenicity of 5-nitrofuran drugs. The mutagenic action of 5-nitro-2-furaldehyde is very similar to that of nitrosoguanidine. Both compounds induce bleached mutants of E. gracilis when acting on growing or resting cells, regardless of the dark or light conditions. Similarly, both compounds induce reverse mutations in auxotrophic strains of Mycobacterium phlei.
Animals↗
Volatile degradation products of l-dehydroascorbic acid.
Volatile degradation products were isolated from a solution of L-dehydroascorbic acid in phosphate buffer solution of pH 2,4,6 and 8 heated under reflux for 3 h or left at 25 degrees C for 200 h. The products were identified by comparison of their gas chromatographic retention data, infra-red and mass spectra with those of authentic compounds. Fifteen products were identified, among which 12 had not yet been reported as degradation products of L-dehydroascorbic acid. Concentrations of 5 main degradation products, i.e. 3-hydroxy-2-pyrone, 2-furancarboxylic acid, 2-furaldehyde, acetic acid and 2-acetylfuran depended on the pH values and temperature; the presence of oxygen had no pronounced effect.
Acetates↗
Specificity of the in vitro interaction of methylfurfural with DNA.
Methylfurfural (MF) or 5-methyl 2-furaldehyde is a dietary mutagen and is present in various food products and beverages. Alkaline unwinding of calf thymus DNA and the protection of cleavage sites in lambda phage DNA from the action of various restriction enzymes was used to study the interaction of MF with DNA. Alkaline unwinding experiments showed the formation of an increasing number of strand breaks in duplex DNA, both with increasing MF concentration and time of reaction. Treatment of lambda phage DNA with MF protected cleavage with restriction endonucleases EcoRI and EcoRI* but not with SmaI and HaeIII. These results indicate that under the conditions used MF reacts exclusively with AT base pairs. A minimum of three to four consecutive AT base pairs is required for this reaction. This was determined by the use of restriction enzymes whose hexanucleotide recognition sequences contain subsets of AT base pairs. Indirect evidence further indicates that modification (possibly alkylation) of DNA bases and phosphates may also occur.
Alkylating Agents↗
Furfurals in chlorhexidine-discolored pellicle.
The purpose of the present study was to investigate the possible presence of furfurals in chlorhexidine-discolored pellicle. Pellicle material was scraped off teeth and hydrolyzed in sulfuric acid and the hydrolysate then extracted with ether and examined by thin layer chromatography and gas chromatography-mass spectrometry. The presence of furaldehyde in discolored pellicle was demonstrated by these methods. There were also indications of hydroxymethyl furfuraldehyde in the thin layer chromatograms.
Chlorhexidine↗
The use of different time/temperature combinations in the optimization of sterilization of Ringers/glucose infusion solution.
The effect of sterilization temperature and sterilization efficacy (F0) on the amount of 5-hydroxymethyl-2-furaldehyde (5-HMF) and glucose, number of particles generated and color of Ringers/glucose infusion solution is described. The infusion solution was a 5% glucose solution containing Ringer-type electrolytes. The solutions were autoclaved in a pilot scale autoclave using different temperature/time combinations to produce the target F0 values of 10, 15, 20 and 25 minutes. The amounts of 5-HMF and glucose were determined by HPLC. The use of the shortest possible sterilization cycle to yield the target F0 resulted in the lowest 5-HMF concentrations in the Ringers/glucose infusion solutions studied. The spectrochromatograms of the sterilized solutions showed that glucose is degraded into various degradation products in the presence of Ringer-type electrolytes. It was also demonstrated by SEM/EDX that a significant part of the particles result from the leaching of the silicon oil used in the manufacture of rubber stoppers for LVP solutions. The number of particles generated in different solutions and the particle size distributions were determined with a Coulter-Counter. The particle size distributions show no clear correlation between sterilization process conditions and the number of particles. The results show that it is possible to minimize the amount of 5-HMF generated even when the same F0 is used, by choosing the highest sterilization temperature possible. This also leads in practice to the shorter sterilization processes, saving both process time and energy.
Furaldehyde↗
On the induction of umu gene expression in Salmonella typhimurium strain TA1535/pSK1002 by some nitrofurans.
Several nitrofurans were found to induce umu gene expression in Salmonella typhimurium TA1535/pSK1002 as defined on the basis of at least a 2-fold increase of beta-galactosidase activity over the background level. beta-Galactosidase activity increased with increasing concentrations of the chemical, attained a maximum at a concentration which was different for different nitrofurans used, and then gradually decreased with a further increase of the nitrofuran concentration. The umu gene expression test revealed that the genotoxic activity was highest for furazolidone and lowest for 5-nitro-2-furaldehyde.
Azides↗
Substituted 1-[(5-nitrofurfurylidene)amino]-4-imidazolin-2-ones.
A series of 1-[(5-nitrofurfurylidene)amino]-4-imidazolin-2-ones has been prepared. A new synthesis of 4-alkyl-1-[(5-nitrofurfurylidene)amino]-4-imidazolin-2-ones involving the oxidative ring closure of 5-nitro-2-furaldehyde 2-(2-hydroxyethylalkyl)semicarbazones is described. The in vitro testing of the compounds against a variety of bacteria is reported.
Anti-Bacterial Agents↗
Synthesis and antibacterial properties of methylsulfinyl and methylsulfonyl analongs of some nitrofurans.
The sulfoxides 5-methylsulfinyl-2-furaldehyde semicarbazone (2) and 1-[(5-methylsulfinyl-2-fufurylidene)amino]hydantoin (3) as well as the sulfones 1-[(5-methylsulfonyl-2-furfurylidene)animo]hydantoin (1) and 1-(5-methylsulfonly-2-furyl)-2-(6-amino-3-p-ridazyl)ethylene hydrochloride (4) have been prepared and tested for antibacterial activity against a number of gram-negative and gram-positive organisms. The compounds are much less active than the corresponding 5-nitrofuran derivatives, possibly because their reduction potentials are too negative for them to interfere with reductive enzyme systems within the bacteria.
Anti-Bacterial Agents↗
Radiosensitization of hypoxic cells by a nitrofuran; dose-modifying and shoulder effects.
The radiosensitizer nifurpipone dihydrochloride (5-nitro-2-furaldehyde N-methyl piperazino acetyl hydrazone dihydrochloride) sensitizes hypoxic V79 mammalian cells by at least two mechanisms. Sensitization is by a reduction of ñ in addition to an increase in slope. Both these affects are absent under oxygenated conditions. When hypoxic V79 cells are irradiated in the presence of nifurpipone dihydrochloride combined with Ro-07-0582, sensitization greater than that due to air alone is observed; this effect is due to a reduction in ñ and an increased slope. Again this effect is absent under oxygenated conditions. Rapid-mix studies using Serratia marcescens show that full senitization occurs with a pre-irradiation contact time of 4 msec; this contrasts with data for V79 cells where a pre-irradiation contact time of 40 msec is insufficient for any sensitization to occur. This sensitizer also exerts a differential toxic effect, being more toxic to hypoxic cells than to oxygenated ones. It is concluded from these results that nifurpipone dihydrochloride sensitizes by at least two mechanisms, one of which resembles that of the electron-affinic type.
Cell Line↗