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PubMed1999

Relationship between tyrosinase inhibitory action and oxidation-reduction potential of cosmetic whitening ingredients and phenol derivatives.

The oxidation-reduction potentials of cosmetic raw materials, showing tyrosinase inhibitory action, and phenolic compounds structurally similar to L-tyrosine were determined by cyclic voltammetry. The voltammograms obtained could be classified into 4 patterns (patterns 1-4). Pattern 1, characterized by oxidation and reduction peaks as a pair, was observed with catechol, hydroquinone or phenol, and pattern 2 exhibiting another oxidation peak in addition to oxidation and reduction peaks as a pair was found with arbutin, kojic acid, resorcinol, methyl p-hydroxybenzoate and L-tyrosine as the substrate of tyrosinase. Pattern 3 with an independent oxidation peak only was expressed by L-ascorbic acid, and pattern 4 with a reduction peak only at high potentials, by hinokitiol. The tyrosinase inhibitory activity of these compounds was also evaluated using the 50% inhibitory concentration (IC50) and the inhibition constant (Ki) as parameters. Hinokitiol, classified as pattern 4, showed the highest inhibitory activity (lowest IC50 and Ki). Hydroquinone showing the second highest activity belonged to pattern 1, which also included compounds showing no inhibition of tyrosinase activity. The inhibitory activity of compounds exhibiting pattern 2 was relatively low with Ki values being in the order of 10(-4) M. Although there was no consistent relationship between oxidation-reduction potentials and tyrosinase inhibitory action, the voltammetry data can be used as an additional index to establish the relationship between the structure and the tyrosine inhibitory activity.

Cosmetics↗

PubMed2000

Anaerobic degradation of phenolic compounds.

Mononuclear aromatic compounds are degraded anaerobically through three main pathways, the benzoyl-CoA pathway, the resorcinol pathway, and the phloroglucinol pathway. Various modification reactions channel a broad variety of mononuclear aromatics including aromatic hydrocarbons into either one of these three pathways. Recently, a further pathway was discovered with hydroxyhydroquinone as central intermediate through which especially nitrate-reducing bacteria degrade phenolic compounds and some hydroxylated benzoates. Comparison of the various strategies taken for the degradation of aromatics in the absence of oxygen demonstrates that the biochemistry of breakdown of these compounds is determined largely by the overall reaction energetics and, more precisely, by the redox potentials of the electron acceptor systems used. Nitrate reducers differ in their strategies significantly from those used by sulfate-reducing or fermenting bacteria.

Anaerobiosis↗

PubMed1997

Desulfovibrio inopinatus, sp. nov., a new sulfate-reducing bacterium that degrades hydroxyhydroquinone.

A new sulfate-reducing bacterium was isolated from marine sediment with hydroxyhydroquinone (1,2,4-trihydroxybenzene) as the sole electron and carbon source. Strain HHQ 20 grew slowly with doubling times of > 20 h and oxidized hydroxyhydroquinone, lactate, pyruvate, ethanol, fructose, and ribose incompletely to acetate and carbon dioxide, with concomitant reduction of sulfate to sulfide. Cells were large, vibrio-shaped, and gram-negative with a G+C content of 49.7 mol%, and contained desulfoviridin. Based on analysis of the 16S rRNA sequence, strain HHQ 20 was found to be related to the genus Desulfovibrio but formed a separate line, thus justifying the establishment of a new species within this genus. Hydroxyhydroquinone was the only aromatic compound utilized among numerous hydroxybenzoates, hydroxybenzenes, methoxybenzoates, and methoxybenzenes tested, suggesting that phloroglucinol and resorcinol are not degradation intermediates. Cell-free extracts of strain HHQ 20 did not contain pyrogallol-phloroglucinol transhydroxylase activity. First experiments indicated that this strain uses a new reductive pathway for anaerobic hydroxyhydroquinone degradation.

Acetates↗

PubMed1998

Anaerobic degradation of alpha-resorcylate by Thauera aromatica strain AR-1 proceeds via oxidation and decarboxylation to hydroxyhydroquinone.

Anaerobic degradation of alpha-resorcylate (3,5-dihydroxybenzoate) was studied with the denitrifying strain AR-1, which was assigned to the described species Thauera aromatica. alpha-Resorcylate degradation does not proceed via the benzoyl-CoA, the resorcinol, or the phloroglucinol pathway. Instead, alpha-resorcylate is converted to hydroxyhydroquinone (1,2,4-trihydroxybenzene) by dehydrogenative oxidation and decarboxylation. Nitrate, K3[Fe(CN)6], dichlorophenol indophenol, and the NAD+ analogue 3-acetylpyridine adeninedinucleotide were suitable electron acceptors for the oxidation reaction; NAD+ did not function as an electron acceptor. The oxidation reaction was strongly accelerated by the additional presence of the redox carrier phenazine methosulfate, which could also be used as sole electron acceptor. Oxidation of alpha-resorcylate with molecular oxygen in cell suspensions or in cell-free extracts of alpha-resorcylate- and nitrate-grown cells was also detected although this bacterium did not grow with alpha-resorcylate under an air atmosphere. alpha-Resorcylate degradation to hydroxyhydroquinone proceeded in two steps. The alpha-resorcylate-oxidizing enzyme activity was membrane-associated and exhibited maximal activity at pH 8.0. The primary oxidation product was not hydroxyhydroquinone. Rather, formation of hydroxyhydroquinone by decarboxylation of the unknown intermediate in addition required the cytoplasmic fraction and needed lower pH values since hydroxyhydroquinone was not stable at alkaline pH.

Anaerobiosis↗

PubMed2000

Two distinct pathways for anaerobic degradation of aromatic compounds in the denitrifying bacterium Thauera aromatica strain AR-1.

Denitrifying bacteria degrade many different aromatic compounds anaerobically via the well-described benzoyl-CoA pathway. We have shown recently that the denitrifiers Azoarcus anaerobius and Thauera aromatica strain AR-1 use a different pathway for anaerobic degradation of resorcinol (1,3-dihydroxybenzene) and 3,5-dihydroxybenzoate, respectively. Both substrates are converted to hydroxyhydroquinone (1,2,4-trihydroxybenzene). In the membrane fraction of T. aromatica strain AR-1 cells grown with 3,5-dihydroxybenzoate, a hydroxyhydroquinone-dehydrogenating activity of 74 nmol min(-1)(mg protein)-1 was found. This activity was significantly lower in benzoate-grown cells. Benzoate-grown cells were not induced for degradation of 3,5-dihydroxybenzoate, and cells grown with 3,5-dihydroxybenzoate degraded benzoate only at a very low rate. With a substrate mixture of benzoate plus 3,5-dihydroxybenzoate, the cells showed diauxic growth. Benzoate was degraded first, while complete degradation of 3,5-dihydroxybenzoate occurred only after a long lag phase. The 3,5-dihydroxybenzoate-oxidizing and the hydroxyhydroquinone-dehydrogenating activities were fully induced only during 3,5-dihydroxybenzoate degradation. Synthesis of benzoyl-CoA reductase appeared to be significantly lower in 3,5-dihydroxybenzoate-grown cells as shown by immunoblotting. These results confirm that T. aromatica strain AR-1 harbors, in addition to the benzoyl-CoA pathway, a second, mechanistically distinct pathway for anaerobic degradation of aromatic compounds. This pathway is inducible and subject to catabolite repression by benzoate.

Acyl Coenzyme A↗

PubMed2001

Determination of REEs distribution in monazite and xenotime minerals by ion chromatography and ICP-AES.

Ion chromatographic techniques were investigated for the separation and the quantitative determination of some rare earth elements (REEs) in monazite and xenotime minerals. The influences of selected eluents containing complexing acids including oxalic and alpha-hydroxy isobutyric acid (alpha-HIBA) on the retention and hence the separation efficiency of REEs was studied. Different variables affecting the separation of different REEs such as pH, type, and concentration of the mobile phase were investigated. Gradient elution, using an advanced gradient pump, was controlled automatically by the Dionex AI-450 computer software. Separation of REEs was carried out using an Ion Pac CS5A column followed by a post column derivatization reaction with 4-(2-pyridylazo)resorcinol (PAR) and UV-VIS spectrophotometric detection. Mineral dissolution was carried out using sulfuric acid. A comparative evaluation of REE distribution in monazite and xenotime minerals using both ion chromatography (IC) and inductively coupled plasma atomic emission spectrometric (ICP-AES) techniques was carried out.

Journal Article↗

PubMed2002

Separation and determination of vanadium in fertiliser by capillary electrophoresis with a light-emitting diode detector.

A method has been developed for determination of vanadium, as an anionic ternary complex of vanadium(V) with 4-(2-pyridylazo) resorcinol (PAR) and hydrogen peroxide, after separation by capillary electrophoresis (CE). The optimum conditions for the formation of the ternary complex were acetate buffer (3 mmol L(-1)) at pH 6 containing 0.15 mmol L(-1) PAR and 7.1 mmol L(-1) H(2)O(2). The CE separation was conducted using 15 mmol L(-1) acetate buffer at pH 6 as the background electrolyte; the separation potential was -30 kV and the injection time 100 s. The vanadium complex was detected photometrically at 568 nm, by use of a light-emitting diode (LED); the detection limit was 19 ppb. The method was applied to the analysis of vanadium in fertilisers. Clean-up of the digested fertiliser sample, with Sep-Pak C(18) coated with tetrabutylammonium hydroxide, before analysis was used to remove matrix ions which otherwise caused electrophoretic de-stacking. Vanadium levels found in the fertiliser samples by use of the CE method were found to be comparable with results obtained by HPLC and ICP-MS.

Journal Article↗

PubMed2003

Investigation of antioxidant and catalytic properties of some biologically active substances by voltammetry.

Antioxidants play a major role in protecting biological systems against many incurable diseases. The biological activity of 12 plant aqueous-alcohol extracts, some standard antioxidants (vitamin C, glucose, resorcinol, and catechol), Na(2)SO(3), humic acids, phthalocyanines, and chlorophyll have been investigated in this work together with evaluation of their influence on the kinetics of the oxygen electroreduction. Finally the use of these substances for prophylactic purposes has been recommended.

Antioxidants↗

PubMed2004

Investigation of the separation of scandium and rare earth elements from red mud by use of reversed-phase HPLC.

A chromatographic method has been developed for separation and determination of scandium (Sc) and rare earth elements (REEs) in samples from a red mud (RM)-utilization process. Reversed-phase high-performance liquid chromatography (RP-HPLC) with post-column derivatization using 4-(2-pyridylazo)-resorcinol (PAR) and UV-visible detection at 520 nm was tested using different gradient elution profiles and pH values to optimize separation and recovery, primarily for Sc but also for yttrium and the individual lanthanides, from iron present in the samples. The separation was performed in less than 20 min by use of a mobile phase gradient. The concentration of alpha-hydroxyisobutyric acid ( alpha-HIBA), as eluent, was altered from 0.06 to 0.4 mol L(-1) (pH 3.7) and 0.01 mol L(-1) sodium salt n-octane sulfonic acid (OS) was used as modifier. Very low detection limits in the nanogram range and a good resolution for Sc and REEs except for Y/Dy were achieved. Before application of the method to the red mud samples and to the corresponding bauxites, Sc and REEs were leached from red mud with 0.6 mol L(-1) HNO(3) and mostly separated, as a group, from the main elements by ion exchange/selective elution (6 mol L(-1) HNO(3)) in accordance with a pilot-plant process developed in this laboratory. After evaporation of the eluent to dryness the extracted elements were re-dissolved in the mobile phase. By use of this chromatographic method Sc, which is the most expensive of the elements investigated and occurs in economically interesting concentrations in red mud, could be separated not only from co-existing Fe but also from Y/Dy, Yb, Er, Ho, Gd, Eu, Sm, Nd, Pr, Ce and La. All the elements investigated were individually recovered. Their recoveries were found to be nearly quantitative.

Journal Article↗

PubMed2004

Solvent extraction and extraction-voltammetric determination of phenols using room temperature ionic liquid.

The phenolic compounds phenol, 4-nitrophenol, 2,4-dinitrophenol, 2,6-dinitrophenol, 1-naphthol, 2-naphthol, and 4-chlorophenol are extracted nearly quantitatively from aqueous solution into the room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMImPF6) in molecular form at pH < p Ka. Picric acid is extracted efficiently in anionic form. Recovery of pyrocatechol and resorcinol is much lower. The effect of pH, phenol concentration, and volume ratio of aqueous and organic phases were studied. Ionic liquid BMImPF6 is shown to be suitable for extraction-voltammetric determination of phenols without back-extraction or addition of support electrolyte. The electrochemical window of BMImPF6 at various electrodes was determined, and voltammetric oxidation of phenols and reduction of nitrophenols in BMImPF6 was studied.

Journal Article↗

PubMed2005

Naked eye detection of cadmium using inorganic-organic hybrid mesoporous material.

A novel and low-cost optical sensor for the naked eye detection of Cd2+ in aqueous media based on mesoporous silica containing 4-(2-pyridylazo)resorcinol (PAR) as a probe molecule anchored by N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TMAC) was prepared. The effects of various factors such as pH, solvent volume, temperature, reaction time, amount of the material, and the presence of various ions were studied in order to optimize operating conditions. The detection was based on the color change of PAR from orange-yellow to purple as a result of complexation with Cd2+. The intensity of the Cd-PAR complex varies linearly with the Cd2+ concentration, from zero to 1.78x10(-7) mol dm(-3). The detection and quantification limits for the method when determining Cd2+ were 1.75x10(-8) and 5.77x10(-8) mol dm(-3), respectively, with a correlation coefficient of 0.99. Good chemical stability of the material was observed for a period of five months. The developed sensor was applied to the analysis of various industrial effluents and tap water samples.

Cadmium↗

PubMed1996

Ion chromatographic determination of transition metals in irradiated nuclear reactor surveillance samples.

The determination of transition metal ions in radioactive (+/-25 microCi/g) low-alloy steels (nuclear reactor surveillance samples) by ion chromatography (IC) is described. The analysis has been done directly without prior separation of the iron matrix. The eluted metal ions have been detected with a UV-visible spectrophotometric detector after post-column complexation with 4-(2-pyridylazo)resorcinol. The results are in a good agreement with the certified values for the standard reference material used. The method was applied to nuclear reactor surveillance samples for the determination of Cu, Mn, Co and Ni.

Journal Article↗

PubMed2005

Physiological regulation, xenobiotic induction, and heterologous expression of P450 monooxygenase gene pc-3 (CYP63A3), a new member of the CYP63 gene cluster in the white-rot fungus Phanerochaete chrysosporium.

In order to characterize the functional diversity in CYP63 cluster of tandemly linked P450 genes (pc-1, pc-2, and pc-3) in Phanerochaete chrysosporium, here we report the functional characterization of pc-3 (CYP63A3), a newly cloned member of this group. pc-3 expression was favored in nutrient-limited versus nutrient-rich media in 3-6-day-old cultures and was upregulated by starch as a carbon source or by oxygenation of cultures. pc-3 was induced by various xenobiotics in defined nutrient-limited (3-9-fold) and nutrient-rich (2-5-fold) cultures. Particularly, a range of unsubstituted and substituted aliphatic hydrocarbons (alkanes and fatty acids) induced the expression under the two nutrient conditions albeit in a differential manner. Interestingly, pc-3 was also inducible by certain oxygenated mono aromatics (nitrophenol, benzoate, and resorcinol), lower molecular weight (2 to 4 ring size) polycyclic aromatic hydrocarbons (PAHs) and alkali-treated lignin derivatives in nutrient-rich malt extract cultures. The study further establishes that the three CYP63 genes (CYP63A1, A2, and A3) are independently regulated despite being members of the tandem gene cluster with high gene structural similarity (13-14 introns) and protein sequence homology (59-85%). The pc-3 cDNA (1,812 bp) was expressed in E. coli as a His-tagged protein (approximately 74 kDa). This constitutes the first report on heterologous expression of a P450 monooxygenase enzyme from this model white-rot fungus.

Adaptation, Physiological↗

PubMed2005

Chronic contained rupture of the descending thoracic aorta due to infection by Escherichia coli.

A 71-year-old man presented with hemoptysis due to chronic contained rupture of the descending thoracic aorta after sepsis by Escherichia coli complicated with transrectal biopsy of the prostate, and underwent urgent graft replacement. The aorta had an almost normal caliber and ruptured into the left lung without abscess. The perforated site of the lung was filled with gelatin-resorcinol-formaldehyde glue, and the defect of the aortic wall was closed. Without graft infection, lung abscess, or sepsis, the patient was discharged followed by 1 month's intravenous administration of cefazolin and piperacillin sensitive to Escherichia coli after the surgery.

Aged↗

PubMed2003

ABC transporters of the wheat pathogen Mycosphaerella graminicola function as protectants against biotic and xenobiotic toxic compounds.

We have studied the role of five ABC transporter genes (MgAtr to MgAtr5) from the wheat pathogen Mycosphaerella graminicola in multidrug resistance (MDR). Complementation of Saccharomyces cerevisiae mutants with the ABC transporter genes from M. graminicola showed that all the genes tested encode proteins that provide protection against chemically unrelated compounds, indicating that their products function as multidrug transporters with distinct but overlapping substrate specificities. Their substrate range in yeast includes fungicides, plant metabolites, antibiotics, and a mycotoxin derived from Fusarium graminearum (diacetoxyscirpenol). Transformants of M. graminicola in which individual ABC transporter genes were deleted or disrupted did not exhibit clear-cut phenotypes, probably due to the functional redundancy of transporters with overlapping substrate specificity. Independently generated MgAtr5 deletion mutants of M. graminicola showed an increase in sensitivity to the putative wheat defence compound resorcinol and to the grape phytoalexin resveratrol, suggesting a role for this transporter in protecting the fungus against plant defence compounds. Bioassays with antagonistic bacteria indicated that MgAtr2 provides protection against metabolites produced by Pseudomonas fluorescens and Burkholderia cepacia. In summary, our results show that ABC transporters from M. graminicola play a role in protection against toxic compounds of natural and artificial origin.

ATP-Binding Cassette Transporters↗

PubMed2004

Repair of delayed left ventricular rupture after mitral valve replacement: report of a case.

Rupture of the left ventricle (LV) after mitral valve replacement (MVR) is a devastating complication, associated with high mortality. A 64-year-old woman with a type I delayed LV rupture, which occurred after MVR with a 27-mm St. Jude Medical mitral prosthesis for mitral stenosis, was successfully treated by a combination of intracardiac and extracardiac surgical repair techniques. The extracardiac repair involved approximating the edges of myocardium around the tear with large sutures bolstered by strips of Teflon felt, then covering the epicardial hematoma with another porcine pericardial patch, using gelatin resorcinol formaldehyde glue and collagen sheets. The intracardiac repair involved suturing the edges of an oval piece of porcine pericardium to the endocardium around the laceration. No LV pseudoaneurysm was detected postoperatively on echocardiography or computed tomography scans. The patient is well 2 years after the operation.

Bioprosthesis↗

PubMed2002

Ganglioside a/b ratio in different rat brain regions following chronic diazepam treatment.

Gangliosides are sialic acid-containing glycosphingolipids that play a variety of important functions in neurons. The main purpose of this study was to determine the a/b ratio of gangliosides in different rat brain regions (cerebral cortex, hypothalamus, caudate nucleus, hippocampus, thalamus and cerebellum) after prolonged diazepam treatment. Male Wistar rats were maintained on a nutritionally adequate diet and diazepam was administered in a dose of 10 mg/kg day for 180 days. Total gangliosides were extracted according to Harth and the total ganglioside-NeuAc content was determined by Svennerholm's resorcinol method, modified by Miettinen and Takki-Luukkainen. The a/b ratio remained unchanged in rat hypothalamus, thalamus and cerebellum. It was slightly decreased in the caudate nucleus and hippocampus, but this was not statistically significant. A drastic decrease ( p<0.01) in ganglioside content, compared to control animals, was found in rat cerebral cortex. Ganglioside a/b profile did not change significantly in most of the brain regions (except in cerebral cortex), which suggests that adaptive changes occurred upon prolonged exposure to diazepam, in order to maintain the physiological ratio of ganglioside a- and b-series in distinct brain areas.

Animals↗

PubMed2005

New fluorescent labels: 4- and 7-chlorofluorescein.

A new mixture of 4- and 7-chlorofluorescein were synthesized by condensation of resorcinol with 3-chlorophthalic anhydride in the presence of methanesulfonic acid or zinc chloride. These regioisomers were successfully separated by chromatography. The photophysical properties were examined and their absorption and emission maxima at long wavelength, high fluorescence quantum yield, and narrow emission bandwidth were found, highly favorable for detecting multiple target substances in the same sample. Furthermore, 4(7)-chlorofluorescein was found to be strongly pH-dependent between 4.0 and 8.0, and could be used as pH-sensitive fluorescent probe to measure intracellular pH.

Fluoresceins↗