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PubMed2004

Assay of plasma semicarbazide-sensitive amine oxidase and determination of its endogenous substrate methylamine by liquid chromatography.

Semicarbazide-sensitive amine oxidase (SSAO) is present in plasma, as well as in other tissues. Previous studies indicated that SSAO is of important physiological and pathophysiological functions. HPLC methods were developed for the assay of SSAO in plasma, and for the determination of plasma methylamine, an SSAO's endogenous substrate. Benzylamine was used as artificial substrate for the enzyme activity assay of SSAO. A 0.2-ml aliquot of plasma was incubated with benzylamine at 37 degrees C for 30min. Benzaldehyde, the enzymatic reaction product, was derivatized with 2,4-dinitrophenylhydrazine (DNPH), and analyzed with HPLC and UV detection. SSAO enzyme activity is defined as benzaldehyde (nmol) formed per ml plasma per hour. Recoveries of benzaldehyde spiked to plasma were between 63.5 and 68.2% with relative standard deviation less than 3%. To determine methylamine in plasma, a 0.1-ml aliquot of plasma was deproteinized by trichloroacetic acid and centrifugation. The supernatant was derivatized with dansyl chloride and analyzed by HPLC with fluorescence detection. Recoveries of spiked methylamine at ppb (ng/ml) level were between 93.7 and 97.6% with relative standard deviation less than 2.5%.

Amine Oxidase (Copper-Containing)↗
PubMed2002

Preparation of soluble and insoluble polymer supported IBX reagents.

A series of soluble and insoluble polymer supported versions of the versatile oxidizing reagent IBX has been prepared. Each of the reagents were evaluated for their efficiency in the conversion of benzyl alcohol to benzaldehyde. Results from this study were that the soluble, non-crosslinked polystyrene supported IBX reagent gave the best rate of conversion to benzaldehyde, while the macroporous polymer supported IBX resin provided a superior rate of conversion to benzaldehyde when compared with a gel type resin. The macroporous IBX reagent was also shown to convert a series of alcohols to the corresponding aldehydes and ketones.

Benzaldehydes↗
PubMedDate not supplied

The use of dielectric permittivity for the control of the biomass level during biotransformations of toxic substrates in continuous culture.

Since the permittivity signal of a cell suspension measured using dielectric spectroscopy at radio frequencies is essentially determined only by viable (intact) cells, it can be used to monitor the concentration of viable cells in a fermentor in which a large proportion of the cells is nonviable. This could be used to select for organisms that are highly resistant to stress, for example from toxic chemicals used in biotransformations. We sought to control the concentration of viable yeast cells in a fermentor by adding small amounts of benzaldehyde, thus imposing a selection regime for cells highly resistant to benzaldehyde. However, after the addition of benzaldehyde, an increase in the permittivity is seen first followed by a decrease, thus making the control of biomass using a standard on-off controller difficult. It is shown that it is possible effectively to control the level of viable biomass in the fermentor in the presence of a large concentration of necromass using a combination of an inverse response compensator and a PID controller.

Algorithms↗
PubMed2005

Uncertainty analysis of a dynamic vapor sorption-fast gas chromatography-flame ionization detection method for the rapid analysis of volatile release from glassy matrices.

Uncertainty analysis was conducted with a dynamic vapor sorption-fast gas chromatography-flame ionization detection (DVS-fast GC-FID) method, developed to rapidly analyze the extent of volatile release that occurs from carbohydrate glasses due to humidification and temperature increases. Triplicate samples progressed through a two-step special automatic operation method in the DVS. Samples were exposed to relative humidities ranging from 40 to 90% (in 10% increments) at 15, 25, and 35 degrees C. Uncertainty analysis shows that the DVS-fast GC-FID method uncertainty is smaller than the natural sample uncertainty, indicating that the variability in a sample's physical properties has a dominant impact on the overall uncertainty of the volatile retention results obtained using the DVS-fast GC-FID method. Uncertainty analysis also indicates that the variance associated with the mass of benzaldehyde measured by the DVS-fast GC-FID is the largest contributor to the overall benzaldehyde retention variance when the cumulative mass of benzaldehyde measured is small.

Adsorption↗
PubMed2003

Screening of yeasts for cell-free production of (R)-phenylacetylcarbinol.

105 yeast strains from 10 genera and 40 species were evaluated for cell-free production of (R)-phenylacetylcarbinol (PAC), the chiral precursor in the manufacture of the pharmaceuticals ephedrine and pseudoephedrine. Carboligase activity of pyruvate decarboxylase (PDC), forming PAC from benzaldehyde and pyruvate, was found in extracts of 98 strains. PAC was not formed from benzaldehyde and acetaldehyde, an activity of bacterial PDCs from Zymomonas mobilis and Zymobacter palmae. Two interesting groups of candidates were identified in the yeast screening: carboligase activities of Schizosaccharomyces pombe PDCs were very low but showed best resistance to pre-incubation with acetaldehyde and benzaldehyde; and highest carboligase activities combined with medium resistance were found in strains of Candida utilis, C. tropicalis and C. albicans.

Acetaldehyde↗
PubMed1975

The regulation of the biosynthesis of ubiquinone in the rat.

The urinary excretion of p-hydroxybenzoate was not altered by ubiquinone feeding, but, although decreased considerably, was not eliminated in protein deficiency. The incorporation of p-hydroxy[U-14C]benzaldehyde into ubiquinone in vivo increased in cold-exposed and p-chlorophenoxyisobutyrate (clofibrate)-fed rats, and these changes were parallel with the changes in the incorporation of [2-14C]mevalonate under these conditions. Starvation, cholesterol feeding and cholic acid feeding resulted in the decreased incorporation of p-hydroxy[U-14C]benzaldehyde into ubiquinone, confirming the decreased ubiquinone synthesis. Feeding exogenous ubiquinone increased the hepatic ubiquinone concentration, but did not cause any decrease in the incorporation of p-hydroxy[U-14C]benzaldehyde into ubiquinone, indicating the absence of a feedback control.

Animals↗
PubMed2003

Degradation of benzyldimethylalkylammonium chloride by Aeromonas hydrophila sp. K.

AIMS: The aim of this work was to study the biodegradation of benzyldimethylalkylammonium chloride (BAC) by Aeromonas hydrophila sp. K, an organism isolated from polluted soil and capable of utilizing BAC as sole source of carbon and energy. METHODS AND RESULTS: High performance liquid chromatography and gas chromatography-mass spectrometry (GC-MS) analysis was used to study BAC degradation pathway. It was shown that during BAC biodegradation, formation of benzyldimethylamine, benzylmethylamine, benzylamine, benzaldehyde and benzoic acid occurred. Formation of benzyldimethylamine as the initial metabolite suggested that the cleavage of Calkyl-N bond occurred as the first step of BAC catabolism. Liberation of benzylmethylamine and benzylamine likely resulted from subsequent demethylation reactions, followed by deamination with formation of benzaldehyde. Benzaldehyde was rapidly converted into benzoic acid, which was further degraded. CONCLUSIONS: Aer. hydrophila sp. K is able to degrade BAC. A degradation pathway for BAC and related compounds is proposed. SIGNIFICANCE AND IMPACT OF STUDY: These findings are significant for understanding biodegradation pathways of benzyl-containing quaternary ammonium compounds.

Aeromonas hydrophila↗
PubMed1998

Inhibition of rat lung mixed-function oxidase activity following repeated low-level toluene inhalation: possible role of toluene metabolites.

Toluene is a commonly used solvent that has been shown to alter mixed-function oxidase (MFO) activity, in an organ- and isozyme-specific pattern, following intraperitoneal administration. The purpose of this study was to determine whether similar changes occurred following repeated, low-level inhalation exposure, and to investigate the role of toluene metabolites in these alterations. Exposure to 375 ppm toluene, 6 h/d for up to 5 d, resulted in significant inhibition of the activity of pulmonary arylhydrocarbon hydroxylase (AHH), cytochrome P-4502B1 (CYP2B1), and CYP4B1, but not CYP1A1. After exposure to lower toluene levels (125 ppm, 6 h/d, 3 d), the activities of lung AHH, CYP2B1, and CYP4B1 were also significantly decreased, but in a dose-related manner. MFO activity was not consistently altered in liver. Control pulmonary or liver microsomes were incubated with various concentrations (0.01-10 mM) of toluene or its metabolites and CYP2B1, CYP1A1, and/or CYP4B1 activities were subsequently determined. Benzaldehyde produced a significant dose-related inhibition in the activity of all three lung P-450s examined (IC50 10(-3) M). Toluene was found to be a more potent inhibitor of lung CYP2B1 and CYP1A1 (IC50, 10(-4) M) than benzaldehyde, but neither toluene nor benzyl alcohol was an effective inhibitor of lung CYP4B1. Toluene and its metabolites were weaker inhibitors of CYP1A1 than of CYP2B1. For CYP2B1 and CYP1A1, the order of inhibitory potency was toluene > benzaldehyde > benzyl alcohol and suggests that both the parent molecule and its metabolites may act in concert to inhibit catalytic activity of these cytochromes. The MFO inhibition seen after repeated low-level toluene inhalation exposure could result in altered metabolic profiles of other xenobiotics in an organ-specific fashion.

Administration, Inhalation↗
PubMed2002

Oxidative deamination by hydrogen peroxide in the presence of metals.

Various amines, including lysine residue of bovine serum albumin, were oxidatively deaminated to form the corresponding aldehydes by a H2O2/Cu2+ oxidation system at physiological pH and temperature. The resulting aldehydes were measured by high-performance liquid chromatography. We investigated the effects of metal ions, pH, inhibitors, and O2 on the oxidative deamination of benzylamine by H202. The formation of benzaldehyde was the greatest with Cu2+, and catalysis occurred with Co2+, VO2+, and Fe3+. The reaction was greatly accelerated as the pH value rose and was markedly inhibited by EDTA and catalase. Dimethyl sulfoxide and thiourea, which are hydroxyl radical scavengers, were also effective in inhibiting the generation of benzaldehyde, indicating that the reaction is a hydroxyl radical-mediated reaction. Superoxide dismutase greatly stimulated the reaction, probably due to the formation of hydroxyl radicals. O2 was not required in the oxidation, and instead slightly inhibited the reaction. We also examined several oxidation systems. Ascorbic acid/O2/Cu2+ and hemoglobin/H2O2 systems also converted benzylamine to benzaldehyde. The proposed mechanism of the oxidative deamination by H2O2/Cu2+ system is discussed.

Benzaldehydes↗
PubMed1997

Differences in aldehyde oxidase activity in cytosolic preparations of human and monkey liver.

This study presents data showing individual differences in aldehyde oxidase activity in human and monkey liver cytosols. When assayed with benzaldehyde as a substrate, a significant inter-subject variation in the activity was found in the human liver preparations. When assayed with N1-methylnicotinamide as a substrate, the inter-subject variation of the activity was also observed, but to a lesser extent compared with that of the activity with benzaldehyde. Similarly, variations in aldehyde oxidase activity were found in the monkey liver preparations when assayed with benzaldehyde or N1-methylnicotinamide. The present study suggested that at least two isozymes of aldehyde oxidase exist in the human liver preparations.

Aged↗
PubMed1975

Regulation of growth of Acinetobacter calcoaceticus NCIB8250 on L-mandelate in batch culture.

Batch culture of Acinetobacter calcoaceticus in L-mandelate- or phenylglyoxylate-salts medium showed an unusual non-exponential pattern unless the inoculum had been grown on benzyl alcohol. There were transient accumulations of benzaldehyde and benzyl alcohol caused by the limitation of L-mandelate oxidation by low activities of benzaldehyde dehydrogenase and the diversion of reducing power to the formation of benzyl alcohol. In vivo enzymic activities were estimated from patterns of substrate utilization in batch cultures containing pairs of substrates. When bacteria previously grown in L-mandelate-salts medium were inoculated into media containing L-mandelate and a second carbon source, metabolism of L-mandelate was arithmetical in the presence of benzoate, catechol or succinate, but accelerated on exhaustion of the second substrate. This indicated repression of the enzymes involved in L-mandelate oxidation. Inoculation of bacteria grown in benzoate-salts medium into medium containing L-mandelate and benzoate gave diauxie with initial utilization of benzoate. Similar experiments showed that benzoate oxidation was not repressed by catechol and only partially repressed by succinate. Measurement of L-mandelate dehydrogenase, phenylglyoxylate carboxy-lyase and benzaldehyde dehydrogenase I in bacterial extracts showed no evidence for feedback inhibition by intermediates of the pathway. The rates of L-mandelate and benzoate utilization by bacterial suspensions were inhibited by succinate and catechol but not by other intermediates of the pathway.

Acinetobacter↗
PubMed1976

Regulation of growth of Acinetobacter calcoaceticus NCIB8250 on benzyl alcohol in batch culture.

Formation of benzoate and catechol during oxidation of benzyl alcohol by washed suspensions of Acinetobacter calcoaceticus NCIB8250 confirmed earlier results indicating that this organism metabolizes benzyl alcohol via benzaldehyde, benzoate, and the 3-oxoadipate pathway. There was no evidence for feedback inhibition of benzyl alcohol dehydrogenase or benzaldehyde dehydrogenase II. Examination of growth curves and patterns of substrate utilization, as well as measurement of enzyme activities, showed that benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase II are repressed when A. calcoaceticus utilizes L-mandelate or phenylglyoxylate. Growth of bacteria on L-mandelate prior to their inoculation into benzyl alcohol/salts medium leads to an exceptionally long lag period before benzyl alcohol is used at the maximum rate. Benzyl alcohol metabolism is also suppressed during growth on benzoate.

Acinetobacter↗
PubMed2000

Novel scheme for biosynthesis of aryl metabolites from L-phenylalanine in the fungus Bjerkandera adusta.

Aryl metabolite biosynthesis was studied in the white rot fungus Bjerkandera adusta cultivated in a liquid medium supplemented with L-phenylalanine. Aromatic compounds were analyzed by gas chromatography-mass spectrometry following addition of labelled precursors ((14)C- and (13)C-labelled L-phenylalanine), which did not interfere with fungal metabolism. The major aromatic compounds identified were benzyl alcohol, benzaldehyde (bitter almond aroma), and benzoic acid. Hydroxy- and methoxybenzylic compounds (alcohols, aldehydes, and acids) were also found in fungal cultures. Intracellular enzymatic activities (phenylalanine ammonia lyase, aryl-alcohol oxidase, aryl-alcohol dehydrogenase, aryl-aldehyde dehydrogenase, lignin peroxidase) and extracellular enzymatic activities (aryl-alcohol oxidase, lignin peroxidase), as well as aromatic compounds, were detected in B. adusta cultures. Metabolite formation required de novo protein biosynthesis. Our results show that L-phenylalanine was deaminated to trans-cinnamic acid by a phenylalanine ammonia lyase and trans-cinnamic acid was in turn converted to aromatic acids (phenylpyruvic, phenylacetic, mandelic, and benzoylformic acids); benzaldehyde was a metabolic intermediate. These acids were transformed into benzaldehyde, benzyl alcohol, and benzoic acid. Our findings support the hypothesis that all of these compounds are intermediates in the biosynthetic pathway from L-phenylalanine to aryl metabolites. Additionally, trans-cinnamic acid can also be transformed via beta-oxidation to benzoic acid. This was confirmed by the presence of acetophenone as a beta-oxidation degradation intermediate. To our knowledge, this is the first time that a beta-oxidation sequence leading to benzoic acid synthesis has been found in a white rot fungus. A novel metabolic scheme for biosynthesis of aryl metabolites from L-phenylalanine is proposed.

Basidiomycota↗
PubMed2005

Characterization of an inducible phenylserine aldolase from Pseudomonas putida 24-1.

An inducible phenylserine aldolase (L-threo-3-phenylserine benzaldehyde-lyase, EC 4.1.2.26), which catalyzes the cleavage of L-3-phenylserine to yield benzaldehyde and glycine, was purified to homogeneity from a crude extract of Pseudomonas putida 24-1 isolated from soil. The enzyme was a hexamer with the apparent subunit molecular mass of 38 kDa and contained 0.7 mol of pyridoxal 5' phosphate per mol of the subunit. The enzyme exhibited absorption maxima at 280 and 420 nm. The maximal activity was obtained at about pH 8.5. The enzyme acted on L-threo-3-phenylserine (Km, 1.3 mM), l-erythro-3-phenylserine (Km, 4.6 mM), l-threonine (Km, 29 mM), and L-allo-threonine (Km, 22 mM). In the reverse reaction, threo- and erythro- forms of L-3-phenylserine were produced from benzaldehyde and glycine. The optimum pH for the reverse reaction was 7.5. The structural gene coding for the phenylserine aldolase from Pseudomonas putida 24-1 was cloned and overexpressed in Escherichia coli cells. The nucleotide sequence of the phenylserine aldolase gene encoded a peptide containing 357 amino acids with a calculated molecular mass of 37.4 kDa. The recombinant enzyme was purified and characterized. Site-directed mutagenesis experiments showed that replacement of K213 with Q resulted in a loss of the enzyme activity, with a disappearance of the absorption maximum at 420 nm. Thus, K213 of the enzyme probably functions as an essential catalytic residue, forming a Schiff base with pyridoxal 5'-phosphate.

Aldehyde-Lyases↗
PubMedDate not supplied

Identification of benzene metabolites in dermal fibroblasts as nonphenolic: regulation of cell viability, apoptosis, lipid peroxidation and expression of matrix metalloproteinase 1 and elastin by benzene metabolites.

The skin is exposed to benzene and its derivatives, prevalent environmental chemicals. They may impair the structural integrity of the skin by increased expression of matrix metalloproteinase 1 (MMP-1; degrades structural collagen) and elastin, synthesized primarily by the dermal fibroblasts. We examined the metabolism of benzene in dermal fibroblasts and identified the benzene metabolites as toluene, benzaldehyde, aniline and benzoic acid. These metabolites were not toxic to the cells with regard to cell viability, apoptosis and lipid peroxidation, unlike the phenolic benzene metabolites (hydroquinone, t-butyl hydroquinone and phenol) or hydrogen peroxide. Toluene and phenol, which compose cigarette smoke, and benzaldehyde stimulated MMP-1 and/or elastin expression. In summary, the dermal fibroblasts metabolize benzene to nonphenolic metabolites that are less toxic to the cellular components than the phenolic benzene derivatives. Toluene, benzaldehyde and phenol can directly cause facial wrinkling and impaired structural integrity by upregulating MMP-1 and/or elastin.

Aniline Compounds↗
PubMed2006

Investigational agents for sickle cell disease.

Developments in the treatment of sickle cell disease (SCD) have not kept pace with advances in understanding the pathophysiology of this haemoglobinopathy. Drugs undergoing preclinical and clinical assessment for the therapy of these globin gene disorders are discussed in this article. Beginning with investigational agents for treatment of SCD as a whole, the discussion proceeds to drugs being developed for specific manifestations or iatrogenic complications. Despite being licensed in the USA, the prototype antisickling agent, hydroxycarbamide, has not attained worldwide clinical use because of concerns about long-term toxicity. The less toxic decitabine, which (as with hydroxycarbamide) increases fetal haemoglobin level, cannot be administered orally; therefore, the search continues for effective and safe antisickling drugs that can be taken orally. The naturally occurring benzaldehyde 5-hydroxymethyl-2-furfural has shown promising antisickling properties in vitro, and when administered to transgenic sickle mice. These effects are surpassed by the new synthetic pyridyl derivatives of benzaldehyde. Studies in humans with SCD are required to assess the clinical efficacy of these benzaldehydes. Niprisan, another antisickling agent with significant clinical efficacy and an attractive safety profile, is undergoing further development. The prospects of antiadhesion therapy in SCD are demonstrated by a recombinant protein containing the Fc fragment of IgG fused to the natural ligand for selectins: the conjugate significantly inhibited blood vessel occlusion in transgenic sickle mice. Whereas the orally administrable iron-chelating agent deferasirox is likely to increasingly take the place of desferioxamine (which can only be given parenterally), effective treatment of priapism in SCD remains a distressing challenge.

Acetamides↗
PubMed2001

Odor exposure causes central adaptation and morphological changes in selected olfactory glomeruli in Drosophila.

In an attempt to correlate behavioral and neuronal changes, we examined the structural and functional effects of odor exposure in Drosophila. Young adult flies were exposed to a high concentration of the selected odor, usually benzaldehyde or isoamyl acetate, for 4 d and subsequently tested for their olfactory response to a variety of odorants and concentrations. The behavioral response showed specific adaptation to the exposed odor. By contrast, olfactory transduction, as measured in electroantennograms, remained normal. In vivo volume measurements were performed on olfactory glomeruli, the anatomical and functional units involved in odor processing. Pre-exposed flies exhibited volume reduction of certain glomeruli, in an odor-selective manner. Of a sample of eight glomeruli measured, dorsal medial (DM) 2 and ventral (V) were affected by benzaldehyde exposure, whereas DM6 was affected by isoamyl acetate. Estimation of the number of synapses indicates that volume reduction involves synapse loss that can reach 30% in the V glomerulus of flies adapted to benzaldehyde. Additional features of odorant-induced adaptation, including concentration dependence and perdurance, also show correlation, because both effects are elicited by high odor concentrations and are long-lasting (>1 week). Finally, the dunce mutant fails to develop behavioral adaptation as well as morphological changes in the olfactory glomeruli after exposure. These neural changes thus appear to require the cAMP signaling pathway.

Acetates↗
PubMed2003

[Analysis on the volatile flavor compounds in Agaricus blazei by GC-MS].

The volatile flavor compounds in Agaricus blazei fruit bodies and mycelia were analyzed by head space analysis GC-MS. 7 kinds of volatile flavor compounds were identified in fruit bodies, and 16 in mycelia. Benzaldehyde and benzyl alcohol are main compounds in fruit bodies, their contents are 43.20% and 28.98% respectively. Benzaldehyde is the main compound in the mycelia and its content is 38.50%. Benzaldehyde and benzyl alcohol are main volatile flavor compounds in Agaricus blazei.

Agaricus↗