Presence Of Guaiacol Research Articles

Degradation of vanillic acid and production of guaiacol by microorganisms isolated from cork samples

The presence of guaiacol in cork stoppers is responsible for some cases of cork taint causing unpleasant alterations to wine. We have performed a characterization of the cork-associated microbiota by isolating 55 different microorganisms: eight yeast, 14 filamentous fungi or molds, 13 actinomycetes and 20 non-filamentous bacteria. A screening for degradation of vanillic acid and guaiacol production showed that none of the filamentous fungi could achieve any of these processes. By contrast, five of the eight yeast strains isolated were able to degrade vanillic acid, although it was not converted to guaiacol. Guaiacol production was only detected in four bacterial strains: one isolate of Bacillus subtilis and three actinomycetes, Streptomyces sp. A3, Streptomyces sp. A5 and Streptomyces sp. A13, were able to accumulate this compound in both liquid media and cultures over cork. These results suggest that guaiacol-mediated cork taint should be attributed to the degradative action of vanillic acid by bacterial strains growing on cork.

Kinetics of Hydrogen Peroxide Decomposition in Guaiacol Solution, Catalyzed by Hexacyanoferrate(II)

The kinetics of hydrogen peroxide decomposition in a guaiacol solution, catalyzed by potassium hexacyanoferrate(II), were studied. The reaction mainly follows the pathway of guaiacol hydroxylation. The reaction order is 1 with respect to H2O2, 0.5 with respect to hexacyanoferrate, and from 0.4 to 0 with respect to guaiacol (the latter parameter decreases with increasing guaiacol concentration). The apparent activation energy is 105 kJ mol- 1. A kinetic scheme of the process was proposed. An expression consistent with the experiment was obtained for the rate of hydrogen peroxide decomposition in the presence of guaiacol, catalyzed by hexacyanoferrate(II).

Presence of cork-taint responsible compounds in wines and their cork stoppers

Chloroanisoles [2,4-dichloroanisole, 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole and pentachloroanisole], chlorophenols [2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol (PCP)] and guaiacol were detected in red and white cork-tainted bottled wines. These compounds were also found in the cork stoppers from those bottles. A significant correlation was found between TCA in wines and TCA in cork stoppers, and between TCA in wine and intensity of cork taint. At low levels of TCA, the presence of guaiacol or PCP were also found to influence in cork taint.

Reactions of heme peroxidases with peroxynitrite.

The interaction of peroxynitrite, produced by ozonation of azide, with two heme peroxidases (horseradish peroxidase and lactoperoxidase) was studied. Enzymes retained full activity after incubation with peroxynitrite at neutral pH. Lactoperoxidase alone was found to catalyze peroxynitrite decomposition, whereas horseradish peroxidase accelerated peroxynitrite decomposition only in the presence of certain substrates. For example, in the presence of guaiacol the catalyzing effect was clear, but in the presence of trolox was only noticeable.

Relationships Between Demethylase Activity, Formaldehyde and Oxygen During Incubation of Rhodococcus Erythropolis with Veratrate

Relationships between demethylase activity, formaldehyde and oxygen were investigated. Demethylase activity was measured against the following substrates: veratric, vanillic, and isovanillic acids, as well as in the presence of guaiacol. The influence of ATP and GTP on demethylase activity was also checked. Demethylase activity was found to be dependent on the capability of the cells for endogenous oxygen uptake. In some cases ATP produced the opposite effect: instead of being taken up, oxygen was released, which suggested a reversibility of the demethylation reaction. Curiously enough, GTP demonstrated the same effect. Changes in enzyme activity were correlated with those occurring in the level of formaldehyde. The latter increased after addition of ATP, but decreased after addition of GTP.

Kinetic resolution of chiral α-hydroperoxy esters by horseradish peroxidase-catalyzed enantioselective reduction to α-hydroxy esters

The kinetic resolution of the methyl α-hydroperoxy esters 4 has been investigated by horseradish peroxidase (HRP)-catalyzed reduction to the corresponding optically active α-hydroxy ester 5 in the presence of guaiacol. The method allows for the first time the preparation of enantiomerically pure ( ee > 97%) methyl ( R)-2-hydroperoxybutyrate ( 4a). The HRP enzyme is sensitive to the steric demand of the ester alkyl side chain, as manifested by ethyl ( ee > 97%) and isopropyl ( ee 79%), while the tert-butyl derivative is not accepted by the enzyme (no reduction).

Enzyme-catalyzed kinetic resolution of racemic secondary hydroperoxides

The kinetic resolution of 1,2,3,4-tetrahydro[1]naphthyl and other secondary and tertiary hydroperoxides has been investigated by acylation with isopropenyl acetate in the presence of various lipases, by chloroperoxidase-catalyzed asymmetric oxidation of sulfides, and by horseradish peroxidase (HRP)-catalyzed reduction in the presence of guaiacol. For preparative purposes, the latter method is the best one and allows for the first time the isolation and characterization of the enantiomerically pure ( S)-1,2,3,4-tetrahydro[1]naphthyl hydroperoxide. Tertiary hydroperoxides are not accepted as substrates by HRP.

Enzyme‐Catalyzed Asymmetric Synthesis: Kinetic Resolution of Chiral Hydroperoxides by Enantioselective Reduction to Alcohols with Horseradish Peroxidase

Highly selective for (R)-hydroperoxides (R)-1, horseradish peroxidase (HRP) is used for the kinetic resolution of racemic 1 furnishing (R)-2 alcohols and enantiomerically pure hydroperoxides, which are difficult to prepare by nonenzymatic means. This transformation carried out in the presence of guaiacol [Eq. (a)] can be conducted on a preparative scale. R1  Ph, C(CH2)CO2Me; R2  Me, Et.

Rapid detection and quantification of peroxidase activity in liquid chromatography

A rapid and simple method for the detection and quantification of peroxidase activity is described. The method is based on the visible development of a brownish colour due the reaction of peroxidase in the presence of guaiacol and hydrogen peroxide. The main feature is the detection and quantification of a considerable number of samples at once, instead the spectrophotometric standard methods usually used for this purpose, especially in fractions obtained after liquid chromatography. The effect of substrate concentration and buffer composition on peroxidase determination by the proposed method was investigated.

Purification and properties of cytochrome P-450 from Moraxella sp.

A cytochrome P-450 has been purified to homogeneity from a Moraxella species that is able to grow on guaiacol as the sole source of carbon and energy. The pure cytochrome was a monomeric protein of about 52 kDa, with no catalytic activity towards guaiacol. The difference in mM extinction coefficients between 450 and 490 nm in the CO-difference spectrum was 89.5 mM-1.cm-1. The typical shift of the Soret band from 415 to 390 nm that is attributed to the high-spin state of the cytochrome was observed in the presence of guaiacol and other 2-alkoxyphenols with up to 5 carbons in the side chain. It was also obtained with anisole. The maximum difference in mM extinction coefficients between 390 and 420 nm in the P-450 + ligand minus P-450 spectrum was 65 mM-1.cm-1 in all instances. The dissociation constants of the complexes formed between the pure protein and various O-alkoxyphenols were measured, and ranged from 0.1 microM (guaiacol) to 24 microM (2-butoxyphenol). The dissociation constants were 1 microM for anisole, and over 90 microM for phenol. Catechol induced no spectral change in cytochrome P-450 and appeared to be a weak inhibitor of guaiacol binding. The same spectral shift as induced by guaiacol was observed at high P-450 concentration over 1 microM in the absence of any added ligand and disappeared after dilution. The reduction of pure P-450 by dithionite was immediate, but became very slow, and was complete after 10 min or more at 25 degrees C in the presence of guaiacol. This effect was also obtained with the 2 isomers, 3- and 4-methoxyphenols, and with metyrapone, an inhibitor of guaiacol binding that induced the low-spin state. Preliminary experiments using the crude cell lysate or a reconstructed system with purified P-450 and a protein fraction indicated NADH-dependent guaiacol degradation. This was in agreement with the former hypothesis of Moraxella P-450 acting as a monooxygenase in the demethylation of guaiacol. However, cis, cis-muconate rather than catechol was obtained from the substrate, most likely a consequence of the potent catechol 1,2-dioxygenase activity present in the non-purified protein fractions used.

Effect of soil organic matter on peroxidase activity of wheat roots

Some soil organic matter fractions inhibited the peroxidase activity of wheat-root filtrates, but the effect was related to the enzyme hydrogen donor used. In the presence of o-dianisidine as the hydrogen donor, humic acid and the fractions obtained from it by water or acid refluxing inhibited the enzyme activity. The greatest effects were produced by those fractions which were insoluble after such treatments. The inhibitory effects were reversible and non-competitive, the Michaelis constant of the enzyme being only slightly affected, and independent of pH of the assay media. When guaiacol was used as the enzyme substrate the inhibitory effects of the humic acid and its fractions were variable and less marked. p-Coumaric and p-hydroxybenzoic acids inhibited peroxidase activity when o-dianisidine was used as substrate, but stimulated the enzyme in the presence of guaiacol. Polymaleic acid which is thought to have a similar structure to fulvic acid, inhibited peroxidase in the presence of both hydrogen donors. whereas fulvic acid was considerably less effective.

Conversion of linoleic acid hydroperoxide by soybean lipoxygenase in the presence of guaiacol: identification of the reaction products.

Linoleic acid hydroperoxide formed by soybean lipoxygenase was metabolized by the same enzyme in the presence of guaiacol. The products of this reaction included, trihydroxyoctadecenoic acids, hydroperoxydihydroxyoctadecenoic acids, hydroxyepoxyoctadecenoic acids, dihydroxyoctadecenoic acids, hydroxyoctadecadienoic acids, and oxooctadecadienoic acids.

Beitrag zur gaschromatographischen bestimmung einwertiger phenole aus dem schwelteer

The separating power of various stationary phases was investigated, using a mixture of 13 low-boiling tar phenols. In the phenols from low-temperature carbonization tar from indigenous xylite, the presence of guaiacol was also established. A complete analysis of a mixture of 13 components is possibel by separation on at least two different phases, of which 2,4-xylyneyl phosphate and o-phthalic acid di-(3,3,5- trimethylcyclohexyl) ester are recommended.

CHANGES OF APPARENT IONIC MOBILITIES IN PROTOPLASM

In Nitella, as in Halicystis, guaiacol increases the mobility of Na(+) in the outer protoplasmic surface but leaves the mobility of K(+) unaffected. This differs from the situation in Valonia where the mobility of Na(+) is increased and that of K(+) is decreased. The partition coefficient of Na(+) in the outer protoplasmic surface is increased and that of K(+) left unchanged. Recovery after the action current is delayed in the presence of guaiacol and the action curves are "square topped."