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PubMed1993

Toluene metabolism in isolated rat hepatocytes: effects of in vivo pretreatment with acetone and phenobarbital.

Hepatocytes isolated from control, acetone- and phenobarbital-pretreated rats were used to study the metabolic conversion of toluene to benzyl alcohol, benzaldehyde, benzoic acid and hippuric acid at low (< 100 microM) and high (100-500 microM) toluene concentrations. The baseline formation rates of toluene metabolites (benzyl alcohol, benzoic acid and hippuric acid) were 2.9 +/- 1.7 and 10.0 +/- 2.3 nmol/mg cell protein/60 min at low and high toluene concentrations, respectively. In vivo pretreatment of rats with acetone and phenobarbital increased the formation of metabolites: at low toluene concentrations 3- and 5-fold, respectively; at high toluene concentrations no significant increase (acetone) and 8-fold increase (phenobarbital). Apparent inhibition by ethanol, 7 and 60 mM, was most prominent at low toluene concentrations: 63% and 69%, respectively, in control cells; 84% and 91% in acetone-pretreated cells, and 32% (not significant) and 51% in phenobarbital-pretreated cells. Ethanol also caused accumulation of benzyl alcohol. The apparent inhibition by isoniazid was similar to that of ethanol at low toluene concentrations. Control and acetone-pretreated cells were apparently resistant towards metyrapone; the decrease was 49% and 64% in phenobarbital-pretreated cells at low and high toluene concentrations, respectively. In these cells, the decrease in presence of combined ethanol and metyrapone was 95% (low toluene concentrations). 4-Methyl-pyrazole decreased metabolite formation extensively in all groups. Benzaldehyde was only found in the presence of an aldehyde dehydrogenase inhibitor. Increased ratio benzoic/hippuric acid was observed at high toluene concentrations. These results demonstrate that toluene oxidation may be studied by product formation in isolated hepatocytes. However, the influence of various enzymes in the overall metabolism could not be ascertained due to lack of inhibitor specificity.

Acetone↗
PubMed2006

Fragrance of Canada thistle (Cirsium arvense) attracts both floral herbivores and pollinators.

The evolution of floral scent as a plant reproductive signal is assumed to be driven by pollinator behavior, with little attention paid to other potential selective forces such as herbivores. I tested 10 out of the 13 compounds emitted by dioecious Cirsium arvense, Canada thistle, including 2-phenylethanol, methyl salicylate, p-anisaldehyde, benzaldehyde, benzyl alcohol, phenylacetaldehyde, linalool, furanoid linalool oxides (E and Z), and dimethyl salicylate. Single compounds (and one isomer) set out in scent-baited water-bowl traps trapped over 10 species of pollinators and 16 species of floral herbivores. The two dominant components of the fragrance blend of C. arvense, benzaldehyde and phenylacetaldehyde, trapped both pollinators and florivores. Other compounds attracted either pollinators or florivores. Florivores of C. arvense appear to use floral scent compounds as kairomones; by advertising to pollinators, C. arvense also attracts its own enemies.

Acetaldehyde↗
PubMed1983

Acyl phosphate and cyclic AMP inhibition of reactions of D-glyceraldehyde-3-phosphate dehydrogenase with aldehyde and acyl phosphate substrates: multiple inhibition analysis.

The effects of the inhibitors trimethylacetyl phosphate and cAMP have been determined in reactions catalyzed by D-glyceraldehyde-3-phosphate dehydrogenase. These inhibitors must influence the oxidation of aldehydes through substrate dependent cooperative conformational changes. Both trimethylacetyl phosphate and cAMP give sigmoidal 1/V vs (I) plots in oxidation of glyceraldehyde 3-phosphate, but exert linear competitive effects on the acyl phosphatase site in acylation reactions of beta-(2-furyl) acryloyl phosphate. The linear inhibition in the latter reactions indicates that one inhibitor molecule is bound per active site. Hydride transfer to NAD+ is the rate-determining step in oxidation of benzaldehyde to an acylenzyme, as shown by the threefold decrease in Vmax without change in Km when 1-deuterobenzaldehyde is the substrate; it is very likely this step that is affected by acyl phosphate inhibitors. Plots of 1/V vs cAMP concentration for oxidation of benzaldehyde at a series of trimethylacetyl phosphate concentrations are parallel at concentrations of acyl phosphate less than 0.00625 M, which demonstrates that binding of the inhibitors is mutually exclusive. However, at higher concentrations of trimethylacetyl phosphate, the slopes are affected, which shows that both inhibitors are then binding. Thus, the binding of high concentrations of acyl phosphate must result in a conformational change of the enzyme that permits binding of both inhibitors. A number of conformations with different kinetic properties are formed with the various substrate and inhibitor combinations. In reactions of muscle D-glyceraldehyde-3-phosphate dehydrogenase, binding of these inhibitors is best explained in terms of induced fit and a sequential model of conformational changes.

Acrylates↗
PubMed1984

Detection of beta-carbanion formation during kynurenine hydrolysis catalyzed by Pseudomonas marginalis kynureninase.

2-Amino-4-hydroxy-4-phenylbutyric acid has been shown to be formed during the Pseudomonas marginalis kynureninase-catalyzed hydrolysis of kynurenine in the presence of benzaldehyde and pyridoxal phosphate. The formation of 2-amino-4-hydroxy-4-phenylbutyric acid is the first demonstration, to our knowledge, of the controlled trapping of an amino acid beta-carbanion generated either chemically or enzymatically, and is perhaps the best empirical evidence to date that enzyme mechanisms can proceed through a beta-carbanionic intermediate. The lifetime of the beta-carbanionic alanyl intermediate generated by kynureninase is of sufficient duration to allow reaction with benzaldehyde. Other aromatic, but no aliphatic, aldehydes will undergo electrophilic addition with kynureninase-generated beta-carbanionic alanyl intermediates to form the corresponding amino acid.

Benzaldehydes↗
PubMed1987

Effect of phenobarbital and 3-methylcholanthrene on aldehyde dehydrogenase activity in cultures of HepG2 cells and normal human hepatocytes.

Aldehyde dehydrogenase (ALDH) activity was measured in primary cultures of normal human hepatocytes and of the human hepatoma cell line HepG2 after application of phenobarbital (PB) or 3-methylcholanthrene (MC) for 5 days. Treatment with PB alone resulted in a significant increase in both protein and DNA content at concentrations of 2 and 3 mM. Treatment with MC at a concentration as low as 5 microM led to a significant loss of cells when it lasted more than 5 days. Concentrations of 3-5 mM of PB in the media of HepG2 cell cultures caused a 2-fold enhancement of the activity of ALDH, as measured with NAD and propionaldehyde (P/NAD) or benzaldehyde (B/NAD). On the other hand, MC-treated cultures (5 microM) showed a 20-fold increase in enzyme activity measured with NADP and benzaldehyde (B/NADP), and a 2-fold increase in B/NAD activity. Combined treatment with both PB and MC led to an effect of dynamic synergism as far as B/NAD and B/NADP activities are concerned, suggesting a metabolite of MC as the mediator for the increase of ALDH activity. Normal human hepatocytes in primary cultures responded to PB (3 mM) in a similar way as HepG2 cells as far as DNA and protein content and ALDH activity are concerned. It is concluded, that HepG2 hepatoma cells behave similar to the normal hepatocytes in terms of ALDH regulation and can be used for studies on the activity of ALDH as modified by added xenobiotics.

Aldehyde Dehydrogenase↗
PubMed1987

Oxidation of phenylpyruvic acid.

Mn2+ catalyzes the aerobic oxidation of phenylpyruvic acid. Benzaldehyde and oxalate are the major products, the former being generated to some extent in an excited state, as indicated by chlorophyll-sensitized emission. Both oxygen consumption and emission are enhanced by addition of horseradish peroxidase. In the presence of the enzyme, halogen-containing xanthene dyes also sensitize the emission. From the values of the benzaldehyde/oxalate product ratio, it is inferred that two oxidation pathways are operative. One of these proceeds via a dioxetane intermediate and is responsible for the excited benzaldehyde; the other, which involves an alpha-keto-beta-peroxylactone, does not produce oxalate. The enzyme appears to favour the dioxetane route. The relative importance of these routes in biological systems is discussed.

Benzaldehydes↗
PubMed1988

Effects of antibodies against odorant binding proteins on electrophysiological responses to odorants.

Monoclonal antibodies against two olfactory mucosal proteins, one with affinity for anisole-like and the other for benzaldehyde-like compounds, were applied to mouse olfactory epithelium. Responses to three odorants (anisole, benzaldehyde and amyl acetate) were measured. Of 26 antibodies, three (12%) inhibited responses only to the odorant with affinity for the antigen, nine (35%) inhibited responses to all three odorants, and 14 (54%) were without effect. None reduced responses by as much as 50%. The data support the hypothesis that there is a class of related proteins in olfactory neuronal cell membranes that function as receptor molecules and that other mechanisms also mediate odorant stimulation.

Animals↗
PubMed1992

Degradation of chlorotoluenes by in vivo constructed hybrid strains: problems of enzyme specificity, induction and prevention of meta-pathway.

The activities of the TOL plasmid-coded xylene oxygenase, benzylalcohol dehydrogenase, benzaldehyde dehydrogenase of Pseudomonas putida strain PaW1 were tested with substituted toluenes, benzylalcohols and benzaldehydes, respectively, as substrates. Several chlorinated toluenes were shown to induce enzymes of the xylene degradation sequence. Conjugative transfer of the TOL plasmid from Pseudomonas putida strain PaW1 to Pseudomonas sp. strain B13 and Pseudomonas cepacia strain JH230 allowed the isolation of hybrid strains capable of growing in the presence of 3-chloro-, 4-chloro- and 3,5-dichlorotoluene. Hybrid strains revealed new ways to prevent the dead-end meta-pathway for cholorocatechols.

Alcohol Oxidoreductases↗
PubMed2004

Diverse odor-conditioned memories require uniquely timed dorsal paired medial neuron output.

Amnesiac mutant flies have an olfactory memory defect. The amn gene encodes a homolog of vertebrate pituitary adenylate cyclase-activating peptide (PACAP), and it is strongly expressed in dorsal paired medial (DPM) neurons. DPM neurons ramify throughout the mushroom bodies in the adult fly brain, and they are required for stable memory. Here, we show that DPM neuron output is only required during the consolidation phase for middle-term odor memory and is dispensable during acquisition and recall. However, we found that DPM neuron output is required during acquisition of a benzaldehyde odor memory. We show that flies sense benzaldehyde by the classical olfactory and a noncanonical route. These results suggest that DPM neurons are required to consolidate memory and are differently involved in memory of a volatile that requires multisensory integration.

Analysis of Variance↗
PubMed1983

Assay for monoamine oxidases A and B by high-performance liquid chromatography with fluorescence detection.

A sensitive method for the assay of monoamine oxidases A and B is described which employs high-performance liquid chromatography with fluorescence detection. Rat brain mitochondria were used as a preparation of the enzymes. p-Sulfamoylbenzaldehyde and benzaldehyde formed enzymatically from p-sulfamoylbenzylamine (the substrate of monoamine oxidase A) and benzylamine (the substrate of monoamine oxidase B), respectively, are converted simultaneously into fluorescent compounds with 2,2'-dithiobis(1-aminonaphthalene). These compounds are separated by reversed-phase chromatography on mu Bondapak CN. The limits of detection for p-sulfamoylbenzaldehyde and benzaldehyde formed enzymatically are 30 and 10 pmol per assay tube, respectively.

Animals↗
PubMed2003

Stereoselective biosynthesis of chloroarylpropane diols by the basidiomycete Bjerkandera adusta.

Previously we have shown that 1-arylpropane-1,2-diols are catabolic products of L-phenylalanine during idiophasic metabolism of B. adusta that are stereoselectively biosynthesized from a C(7)-unit (ring+benzylic carbon) and a C(2)-unit as predominantly erythro 1R, 2S enantiomers.In order to probe the mechanism of 1-arylpropane-1,2-diol formation, the products of the incubation of isotopically labelled aromatic aldehydes as substrates with Bjerkandera adusta (DAOM 215869) have been characterized. The aromatic aldehydes were benzaldehyde (ring D(5)) and 4-methoxy- and 4-hydroxybenzaldehydes (ring 13C(6)). These aldehydes were all stereoselectively incorporated into the corresponding 1-arylpropane-1,2-diols, including the chloro analogues, as well as into the corresponding alpha-ketols (phenyl acetyl carbinols (PAC's) and 2-hydroxy propiophenones (2-HPP's)) the presumed precursors of the diols. Benzoic acid (ring D(5)) was likewise incorporated into the diols, chlorodiols and alpha-ketols. These results lead us to conclude that the aromatic aldehydes benzaldehyde, 4-hydroxybenzaldehyde and 4-methoxybenzaldehyde are likely C(7)-unit precursors in the carboligation reaction(s) that leads to 1-arylpropane-1,2-diol biosynthesis. The metabolic role of the diols remains to be elucidated but they may be important intermediates in CAM (chlorinated anisyl metabolite) aldehyde-alcohol cycling and also act as substrates for the chlorination/hydroxylation enzymes yet to be identified in white rot fungi.

Acetylation↗
PubMed2003

Oxidative deamination of benzylamine by glycoxidation.

In the present study, model reactions for the oxidative deamination by glycoxidation using benzylamine were undertaken to elucidate the detail of the reaction. Glucose, 3-deoxyglucosone (3-DG), and methylglyoxal (MG) oxidatively deaminated benzylamine to benzaldehyde in the presence of Cu(2+) at a physiological pH and temperature but not glyoxal. 3-DG and MG were more effective oxidants than glucose. We have determined the effects of metal ions, pH, oxygen, and radical scavengers on the oxidative deamination. The formation of benzaldehyde was greatest with Cu(2+), and was accelerated at a higher pH and in the presence of oxygen. EDTA, catalase, and dimethyl sulfoxide significantly inhibited the oxidation, suggesting the participation of reactive oxygen species. From these results, we propose a mechanism for the oxidative deamination by the Strecker-type reaction and the reactive oxygen species-mediated oxidation during glycoxidation.

Benzaldehydes↗
PubMed2002

Inter-strain variability in aldehyde oxidase activity in the mouse.

Aldehyde oxidase (AO) is a cytosolic enzyme expressed predominantly in the liver. AO is involved in the metabolism of many xenobiotics of pharmacological and toxicological importance including antivirals (famciclovir), antimalarials (quinine) and anticancer drugs (5-fluoro-2-pyrimidine and methotrexate). The aim of this study was to characterize AO activity in different strains of mice using two different substrates. AO activity in the cytosolic fraction was characterized using the metabolism of N-[2-(dimethylamino)ethyl]acridine-4-carboxamide (DACA), a novel antitumor drug, to form DACA-9(10H)-acridone (quantified by HPLC with fluorescence detection) and benzaldehyde to form benzoic acid (quantified spectrophotometrically). Characterization of mouse AO activity with DACA showed 15-fold variation in K(m), 10-fold variation in apparent V(max) and twofold differences in intrinsic clearance. Nude mice and C129/C57 had the highest intrinsic clearance (0.66 and 0.l53 ml/min per mg protein, respectively). Nude mice cleared DACA faster than nude tumor bearing mice by a factor of 2. Male Swiss CD had higher intrinsic clearance than female Swiss CD (0.36 and 0.28 ml/min per mg protein). A similar pattern of enzyme activity was observed with benzaldehyde; however, the extent of variation was less than that found with DACA. In conclusion, our results show that there are both strain and gender differences in AO activity. These differences are better detected by DACA. Furthermore, these results suggest caution when extrapolating the data obtained from mouse AO studies to humans.

Acridines↗
PubMed1980

Determination of the equilibrium distibution between alcohol and aldehyde substrates when bound to horse liver alcohol dehydrogenase using magnetic resonance.

The interactions of horse liver alcohol dehydrogenase (LADH) with the rho-trifluoromethyl derivatives of benzyl alcohol, benzaldehyde, and benzoic acid have been investigated by use of 19F nuclear magnetic resonance. The aldehyde and alcohol are good substrates for the enzyme and display kinetic characteristics similar to other alcohol/aldehyde pairs. In single-turnover experiments with NADH, rho-(trifluoromethyl)benzaldehyde shows biphasic kinetics similar to those shown by other aromatic aldehydes, which led Bernhard and co-workers [Bernard, S. A., Dunn, M. F., Luisi, P. L., & Shack, P. (1970) Biochemistry 9, 185] to propose half-of-the-sites reactivity for this enzyme. Fluorine magnetic resonance demonstrates that under equilibrium conditions at 4 degrees C and pH 8.75 rho-(trifluoromethyl)benzyl alcohol binds to LADH with a dissociation constant of 1 x 10(-3) M. Addition of 1 equiv of NAD to a stoichiometric complex of LADH and the alcohol generates a discrete resonance. This resonance corresponds to the ternary complex of LADH, NAD, and alcohol with little contribution from the NADH and aldehyde ternary complex. Quantitation shows that the bound NAD-alcohol pair is favored by at least a factor of 20 over the bound NADH-aldehyde pair at equililbrium. These results are consistent with explanations for the biphasic kinetics which involve half-of-the-sites reactivity of multiple steps in the reaction of each catalytic site. These results eliminate explanations for the biphasic kinetics of this system which require this equilibrium constant to have a value near unity or those which give greatest thermodynamic stability to the heterodimer LADH [(NAD-alcohol)(NADH-aldehyde)].

Alcohol Oxidoreductases↗
PubMed2006

Total synthesis of (+)-rishirilide B: development and application of general processes for enantioselective oxidative dearomatization of resorcinol derivatives.

A concise synthesis of (+)-rishirilide B (2) is described. This is the first synthesis to be reported for the (+)-enantiomer of rishirilide B (2) as found in nature. The strategy accentuates the valuable combination of a method for o-quinone methide coupling with a method for enantioselective resorcinol dearomatization, which provides a densely functionalized chiral building block. The convergent synthesis illustrates several improvements and refinements to these methods and their supporting chemistries. Among these is the in situ generation of PhI[OTMS]OTf. Combination of this oxidant with phenol 31 constitutes the first example of a diastereoselective oxidative dearomatization of a resorcinol displaying a 2-alkyl substituent. In addition, the preparation of the cyclic sulfone 34 is reported. As a new dimethide precursor expressing a readily cleavable O-benzyl residue, sulfone 34 should prove useful in future endeavors. A protocol using the aluminum amide of dimethylhydrazine for opening and cleavage of a [1,4]-dioxan-2-one is also described. This procedure unmasks the hydroxy dione 36 by jettisoning the chiral directing group. Regioselective O-carbamylation of the 1,3-dione 36 enables the transformation of the remaining carbonyl into the alpha-hydroxy carboxylic acid found in 2. The total synthesis of (+)-rishirilide B (2) requires 15 pots from benzaldehyde 17 and 13 pots from benzaldehyde 32. The final product emerges in yields of 12.5% and 20.3% from compounds 17 and 32, respectively. The longest linear sequence requires eight chromatographies. Important observations leading to the development of the principle asymmetric method are described within the context of the total synthesis.

1,2-Dimethylhydrazine↗
PubMed2002

Application of pulsed field gradient NMR techniques for investigating binding of flavor compounds to macromolecules.

Two diffusion-based NMR techniques are presented and used to investigate the binding of selected flavor compounds to macromolecules. A pulsed field gradient NMR (PFG-NMR) method was applied to measure the apparent diffusion coefficients of four alkanone compounds as they associated with bovine serum albumin (BSA). The change in the apparent diffusion coefficient as a function of the BSA/alkanone ratio was fitted to yield binding constants (K(a)()) and binding stoichiometry (n) for each alkanone. The results showed that the apparent diffusion coefficients of alkanones increased with a decrease in the BSA/alkanone ratios, and the measured values of K(a)() and n were comparable with those obtained with other methods and depended on the alkanone structure. A diffusion-based nuclear Overhauser effect (called diffusion NOE pumping) method was also applied to screen mixtures of flavor compounds and identify those that have a binding affinity to complex macromolecules. Using this technique benzaldehyde and vanillin were observed to bind with bovine serum albumin, whereas 2-phenylethanol was identified as a nonbinding or weakly binding ligand with BSA. The diffusion NOE pumping method was also applied to a hydro alcoholic solution of cacao bean tannin extracts to which a mixture of ethylbenzoate, benzaldehyde, and 2-phenylethanol was added. The diffusion NOE pumping technique clearly indicated that ethylbenzoate had a stronger binding affinity to the polymeric (-)-epicatechin units of the cacao bean tannin extracts than the other two flavor compounds. The results successfully demonstrate the potential applications of diffusion-based NMR techniques for studying flavors and nonvolatile food matrix interactions.

Benzaldehydes↗
PubMed2003

L-tryptophan reacts with naturally occurring and food-occurring phenolic aldehydes to give phenolic tetrahydro-beta-carboline alkaloids: activity as antioxidants and free radical scavengers.

The reaction between the essential amino acid l-tryptophan and flavoring or naturally occurring phenyl and phenolic aldehydes was studied, and the alkaloidal reaction products were characterized by NMR and HPLC-MS. Benzaldehyde, vanillin, syringaldehyde, salicylaldehyde, and anisaldehyde condensed with l-tryptophan in aqueous-acidic media affording the corresponding phenolic tetrahydro-beta-carboline-3-carboxylic acid as two diastereoisomers, 1S,3S-cis and 1R,3S-trans. With the exception of benzaldehyde, the rest of the aldehydes needed heating conditions (70 degrees C) to significantly form tetrahydro-beta-carbolines over time with the cyclization highly favored at low pH. This suggests a likely formation of these compounds under conditions that may occur in foods, food processing, or cooking. The new phenolic tetrahydro-beta-carboline alkaloids were assayed, for the first time, for their activity as free radical scavengers and antioxidants and showed good antioxidant properties with Trolox equivalent antioxidant capacity (TEAC) values much higher than those of ascorbic acid and the water soluble vitamin E analogue, Trolox, in the 2,2'-azinobis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) assay.

Aldehydes↗
PubMed2005

Structure-function analysis of the vanillin molecule and its antifungal properties.

The aim of the present study was to evaluate which structural elements of the vanillin molecule are responsible for its observed antifungal activity. MICs of vanillin, its six direct structural analogues, and several other related compounds were determined in yeast extract peptone dextrose broth against a total of 18 different food spoilage molds and yeasts. Using total mean MICs after 4 days of incubation at 25 degrees C, the antifungal activity order was 3-anisaldehyde (1.97 mM) > benzaldehyde (3.30 mM) > vanillin (5.71 mM) > anisole (6.59 mM) > 4-hydroxybenzaldehyde (9.09 mM) > phenol (10.59 mM) > guaiacol (11.66 mM). No correlation was observed between the relative antifungal activity of the test compounds and log P(o/w). Furthermore, phenol (10.6 mM) was found to exhibit a greater activity than cyclohexanol (25.3 mM), whereas cyclohexanecarboxaldehyde (2.13 mM) was more active than benzaldehyde (3.30 mM). Finally, the antifungal order of isomers of hydroxybenzaldehyde and anisaldehyde was found to be 2- > 3- > 4- and 3- > 2- > 4-, respectively. In conclusion, the aldehyde moeity of vanillin plays a key role in its antifungal activity, but side-group position on the benzene ring also influences this activity. Understanding how the structure of natural compounds relates to their antimicrobial function is fundamentally important and may help facilitate their application as novel food preservatives.

Benzaldehydes↗