Diphenol Compounds Research Articles

Update on the source of phenoloxidase activity in the hemolymph of kuruma prawn Marsupenaeus japonicus

Crustacean phenoloxidase (PO) and hemocyanin (Hc) are classified as type 3 copper proteins. PO catalyzes the oxidation of mono- and di-phenol compounds, which is the rate-limiting step of melanization, while Hc generally functions as a dioxygen-transporting protein in the hemolymph of arthropods. To date, many studies have shown PO activity in Hc, which is inspired by their structural similarity. Here, the source of PO activity in crustaceans was re-examined by purifying Hc and PO exclusively from the hemolymph of kuruma prawn. The conventional procedure for the preparation of arthropod Hc, which includes precipitation of Hc by ultracentrifugation and subsequent purification by size exclusion chromatography, was not able to completely remove hemolymph-type PO from Hc. In contrast, fractionation with 50% saturation of ammonium sulfate and subsequent hydrophobic chromatography yielded sufficiently pure Hc, which contained no detectable PO protein and virtually no PO enzymatic activity. These results indicate that the main source of PO activity in the hemolymph of kuruma prawn is hemolymph-type PO and that the improved purification method of Hc is preferable for evaluating the PO activity of Hc.

Cellobiose-dehydrogenase production by some fungal species isolated in rain forests of Northern Vietnam

Fungal enzymes are well-known as effective in hydrolyze lignocellulose-rich materials. This decomposition process requires many enzymes to participate in a coordinated factor to hydrolyze the polymer structure. Among them, there are some of popular oxidized enzymes such as lignin peroxidase, mangan peroxidase and laccase. Cellobiose dehydrogenase (CDH) is an extracellular enzyme found in various fungi, it was first discovered in 1974 by Westermark in white rot fungus Trametes verscolor and Phanerochaete chrysosporium. The biological role of CDH has been proven to participate in the decomposition of natural polymers such as cellulose, hemicellulose and lignin by generating hydroxyl radical through Fenton reaction. CDH has unique biochemical and catalytic properties that have been used in biosensors to detect cellodextrin, maltose, lactose and diphenol compounds or in biomedical applications such as lactobionic acid production. Therefore, CDH is an important component of the extracellular enzyme system for lignocellulose decomposition. In this study, 47 fungal strains isolated from rainforests of Cuc Phuong and Muong Phang National Parks and screened for CDH activity. Of which, 33 active fungi exhibited CDH activity from 8.89 to 74.4 U/L during growth on solid medium with rice straw as raw substrate. The highest enzyme production was identified for Coprinellus aureogranulatus (MPG14) reach 77.4 U/L on basic medium and its CDH activity of up to 237.4 U/L under optimal condition: supplemented with carbon source of α- cellulose (20 g/L), nitrogen source (5 g/L peptone) incubated for 12 days at 30℃, pH 5.5 and 200 rpm after inoculation. Thus, the fungus has the potential to exploit the CDH enzyme applied in the pretreatment of lignocellulose-rich materials.

Review article: health benefits of some physiologically active ingredients and their suitability as yoghurt fortifiers.

The article is concerned with health benefits of two main physiologically active ingredients namely, Isoflavones and γ-Aminobutyric acid, with emphasis on their fitness for fortification of yoghurt to be consumed as a functional food. Isoflavones (ISO) are part of the diphenol compounds, called "phytoestrogens," which are structurally and functionally similar to estradiol, the human estrogen, but much less potent. Because of this similarity, ISO were suggested to have preventive effects for many kinds of hormone-dependent diseases. In nature, ISO usually occur as glycosides and, once deconjugated by the intestinal microflora, the ISO can be absorbed into the blood. At present, it seems convincing their possible protective actions against various cancers, osteoporosis and menopausal symptoms and high levels of blood cholesterol as well as the epidemiological evidence. Γ-Aminobutyric acid (GABA), it is an amino acid that has long been reported to lower blood pressure by intravenous administration in experimental animals and in human subjects. GABA is present in many vegetables and fruits but not in dairy products. GABA was reported to lower blood pressure in people with mild hypertension. It was suggested that low-dose oral GABA has a hypotensive effect in spontaneously hypertensive. Yoghurt beyond its ability to be probiotic food via its culturing with the gut strains, it could further carry more healthy benefits when it was fortified with physiological active ingredients, especially GABA versus ISO preferring, whether, bacteriologically or biochemically, a fortification level of 50mg ISO/kg or 200mg GABA/kg.

Novel blue-emitting carboxyl-functionalized poly(arylene ether nitrile)s with excellent thermal and mechanical properties

A series of novel carboxyl-functionalized poly(arylene ether nitrile)s (CPAENs) were synthesized via nucleophilic substitution polycondensation reactions of 2,6-dichlorobenzonitrile with carboxyl-functionalized phenolphthalin and diphenol compounds, using N-methyl-2-pyrrolidone (NMP) as solvent in the presence of anhydrous potassium carbonate. The resulting CPAENs exhibited high glass transition temperatures ranging from 181 °C to 251 °C, and were thermally stable up to 400 °C under either nitrogen or air atmospheres. The incorporation of phenolphthalin-units into the polymer chain imparted an improved solubility of CPAENs in organic solvents, such as NMP, N,N-dimethylformamide, and tetrahydrofuran. The CPAENs were amorphous and can be readily cast into transparent films with a tensile strength of 75.1–104.7 MPa and a tensile modulus of 2.6–3.2 GPa. All CPAENs displayed a highly intense UV absorption in the wavelength range of 280–330 nm and a characteristic blue-emitting fluorescence under the UV irradiation.

Expression pattern and substrate specificity of Clonorchis sinensis tyrosinases

Tyrosinase (TYR) is a copper-containing glycoenzyme that mediates hydroxylation of tyrosine into dihydroxyphenylalanine and oxidation of dihydroxyphenylalanine into dihydroxyphenylalanine quinone. TYRs play pivotal roles in eggshell sclerotisation of trematode parasites, while their comprehensive biochemical properties remain elusive. We characterised genes encoding four TYRs (CsTYR1–4) of Clonorchis sinensis, a causative agent of human hepatobiliary disease. These genes shared tightly conserved amino acid residues, two copper binding catalytic motifs and a cysteine-rich epidermal growth factor-like domain. The native and recombinant CsTYRs showed high reactivity against diphenol compounds, especially those with hydroxyl groups in ortho-positions (catechol and l-dihydroxyphenylalanine), but showed minimal activity toward monophenol compounds. Diphenolase activity was enhanced by increased pH of the reaction buffer from 5.0 to 7.0. The temporal induction of CsTYR expression coordinated with the sexual maturation of the worm; enzyme activity was mainly in the vitelline glands and intrauterine immature eggs proximal to the ovary. The primary structures and functional domains of CsTYRs showed significant similarities to those of the vertebrate orthologs, whereas the amino acids shared with the nematode and insect proteins were largely restricted in the bicopper active center. Unlike highly diverged TYR homologs in vertebrates, multiple paralogs have not yet evolved into the separate lineages in trematode genomes, suggesting that duplication of TYR genes might relate to increased genic dosage/redundancy in trematodes. In vitro treatment of copper chelator, diethyldithiocarbamic acid, inhibited generation of phenotypically normal egg. TYR proteins are essential for C. sinensis reproduction, thus might be targeted for therapeutic and vaccine strategies against clonorchiasis, which is prevalent in several Asian countries and is one of the most important predisposing factors for human cholangiocarcinoma. The close phylogenetic relationships between trematode and vertebrate homologs also provide a molecular clue to understand the multifaceted evolutionary pathway of TYR homologs across animal taxa.

Synthesis and evaluation of diphenol aldimines as inhibitors of <i>Escherichia coli</i> ATPase and cell growth

A series of structurally related diphenol aldimines (DPAs) were synthesized. These aldimines involve different substitution patterns of their phenolic groups, for the purpose of optimizing their ability to inhibit ATP synthase. The inhibitory effects of these DPA compounds were evaluated using purified F1 and membrane-bound F1F0 E. coli ATP synthase. Structure-activity relationship studies of these di-phenol compounds showed that maximum inhibition was achieved when both phenolic groups are either in the meta-positions (DPA-7, IC50 = 2.0 μM), or in the ortho-positions (DPA-9, IC50 = 5.0 μM). The lowest ATP synthase inhibition was found to be when the phenolic groups are both in the para-positions (DPA-2, IC50 = 100.0 μM). Results also show that the inhibitory effects of these compounds on ATPase are completely reversible. Identical inhibition patterns of both the purified F1 and the membrane bound F1F0 enzyme were observed. Study of E. coli cell growth showed that these diphenol aldimines effectively inhibit both ATP synthesis and cell growth.

Study of the Influence of Different Diphenol Compounds on Soil Microbial Activity by Microcalorimetry

AbstractMicrocalorimetry was applied to follow the toxic effects caused by different diphenol compounds on microbial activity of Chinese fir soil. The activity of the microorganisms in soil was stimulated by adding 0.3 mL of a nutrient solution containing 2.5 mg of glucose and 2.5 mg of ammonium sulfate and the measurements were performed under a 35% controlled humidity at 28°C. Power‐time curves recorded on a microcalorimeter were followed by increasing the amount of diphenol compounds, which affected directly the total thermal effects evolved by the microorganisms. The curves showed a synergism on total thermal effect obtained by the addition of 2000 mg·kg−1 of resorcinol, causing a consumption of resorcinol by the microorganisms as a new source of nutrients. Above this dose, the total thermal effect decreased exponentially. However, the addition of catechol and hydroquinone caused the total thermal effects to decrease directly. It was concluded that the increase in the diphenol concentration strongly affected the microbial life in this ecosystem. Microcalorimetry appears as a suitable technique to carry out both qualitative and quantitative comparative studies of microbial activity in soil.

Study on the toxic effects of diphenol compounds on soil microbial activity by a combination of methods

Microcalorimetric technique based on heat-output measurement, direct microorganism counting and enzymatic activity determination, have been explored to evaluate the toxic effects of diphenol species (catechol, resorcinol, and hydroquinone) on soil microbial activity. The thermokinetic parameters including growth rate constant ( k), inhibitory ratio, half inhibitory concentration and total thermal effect ( Q total), were calculated and compared using the data obtained from the power–time curves of the microcalorimeter. It was found that addition of high concentrations of diphenol compounds to the soil samples resulted in low microorganism counts. The trend of the number of cultivable microorganisms with increasing concentration of diphenols was similar to specific growth rate k. It appeared that the higher the water soluble carbon (WSC) content, the higher the Q total value. The low dehydrogenase and β-glucosidase found in the soils treated by catechol and hydroquinone was possibly due to their low WSC concentration and high inhibitory effects, respectively. The results reveal the toxicity of the three diphenols in a descending sequence: hydroquinone, resorcinol and catechol. The combination of the three methods is a more comprehensive toxicological investigation of a complex microbiological system. Microcalorimetry is for studying the metabolic growth of microorganisms, the plate counting method is for quantifying the real microbial growth, and the soil enzyme activity is for assessing the intracellular and extracellular activity of microbial biomass. Our proposed methods can provide toxicological information of diphenols to soil microbes from the metabolic, microbial and biochemical point of views which are consistent with and correlated to each other.

Possible Influences of Water Loss and Polyphenol Oxidase Activity on Anthocyanin Content and Discoloration in Fresh Ripe Strawberry (cv. Oso Grande) During Storage at 1 °C

F : F : F : F : Fresh ' '' ''Oso Grande' strawberr awberr awberr awberr awberries wr ies wr ies wr ies wr ies wrapped in polyvinyl chlor apped in polyvinyl chlor apped in polyvinyl chlor apped in polyvinyl chlor apped in polyvinyl chloride str ide str ide str ide str ide stretch film lost 0.7% of their initial etch film lost 0.7% of their initial etch film lost 0.7% of their initial etch film lost 0.7% of their initial etch film lost 0.7% of their initial weight during storage for 8 d at 1 °C, whereas unwrapped fruit lost 11%. Greater water loss was associated with weight during storage for 8 d at 1 °C, whereas unwrapped fruit lost 11%. Greater water loss was associated with weight during storage for 8 d at 1 °C, whereas unwrapped fruit lost 11%. Greater water loss was associated with weight during storage for 8 d at 1 °C, whereas unwrapped fruit lost 11%. Greater water loss was associated with weight during storage for 8 d at 1 °C, whereas unwrapped fruit lost 11%. Greater water loss was associated with darker and less red fruit, lower concentrations of anthocyanins and other soluble phenolics, and higher polyphenol darker and less red fruit, lower concentrations of anthocyanins and other soluble phenolics, and higher polyphenol darker and less red fruit, lower concentrations of anthocyanins and other soluble phenolics, and higher polyphenol darker and less red fruit, lower concentrations of anthocyanins and other soluble phenolics, and higher polyphenol darker and less red fruit, lower concentrations of anthocyanins and other soluble phenolics, and higher polyphenol o o o oxidase (PPO) activity xidase (PPO) activity xidase (PPO) activity xidase (PPO) activity xidase (PPO) activity. Anthocyanin degr . Anthocyanin degr . Anthocyanin degr . Anthocyanin degr . Anthocyanin degradation and o adation and o adation and o adation and o adation and oxidation of soluble phenolic compounds xidation of soluble phenolic compounds during storage. Proper handling to reduce water loss during postharvest operations should be used to maintain during storage. Proper handling to reduce water loss during postharvest operations should be used to maintain during storage. Proper handling to reduce water loss during postharvest operations should be used to maintain acceptable color of strawberries during shipping and retailing. acceptable color of strawberries during shipping and retailing. acceptable color of strawberries during shipping and retailing. acceptable color of strawberries during shipping and retailing. acceptable color of strawberries during shipping and retailing. K K K red color of strawberry fruit is due to the presence of anthocyanin pigments in the fruit epidermis and cortex. Pelargonidin-3-gluco- side (PGN) and cyanidin-3-glucoside were identified as the main monomeric anthocyanins of strawberry fruit. PGN comprises 80% of the total anthocyanin content in strawberry while cyanidin-3- glucoside is present in smaller amounts (Bakker and others 1994). Strawberry pigments, like other anthocyanins, are relatively un- stable and may easily lose their bright color due to degradation by oxidative enzymes such as polyphenol oxidase (PPO), which is primarily localized in the cortex of strawberry fruit with the antho- cyanins and other phenolics (Lopez-Serrano and Ros Barcelo 2001). In fact, browning in fruits is primarily attributed to PPO activity, which is able to act on phenolic compounds in the pres- ence of oxygen (Nicolas and others 1994). PPO catalyzes the hy- droxylation of monophenolics, leading to the formation of o- diphenol compounds and to the oxidation of o-dihydroxy compounds to quinones. The quinones subsequently undergo polymerization, producing characteristic yellow to brown colors in the fruit tissue (Mayer and Harel 1979; Spanos and Wrolstad 1992). Changes in anthocyanins seem to be one of the causes of fruit browning, and their degradation is the result of coupled ox- idation by PPO in the presence of other phenolic compounds (Wesche-Ebeling and Montgomery 1990; Kader and others 1999; Jiang 2000; Zhang and others 2000). These authors suggested that oxidation and polymerization reactions of anthocyanins with PPO- produced quinones and intermediate oxidation products, rather than direct PPO action on anthocyanins, may play a role in antho- cyanin losses and color changes in processed fruits. However, little is known about the development of superficial browning in fresh

Development of an amperometric sensor for phenol compounds using a Nafion® membrane doped with copper dipyridyl complex as a biomimetic catalyst

The use of [CuDipyCl 2] as a biomimetic catalyst in the construction of an amperometric enzymeless biosensor for phenol determinations is reported. The sensor was prepared modifying a glassy carbon electrode with a Nafion® membrane doped with [CuDipyCl 2]. The sensor presented a higher response for dopamine in 0.1 mol l −1 phosphate buffer at pH 7, with an applied potential of −50 mV versus SCE. With the optimized operational conditions a linear response range between 4.0×10 −5 and 6.0×10 −4 mol l −1, with a sensitivity of 350±10 nA l mmol −1 cm −2 and a detection limit of 9.0×10 −6 mol l −1 were observed for the sensor. The response time presented for this sensor was approximately 1 s, presenting the same response for at least 50 measurements, with good repeatability (R.S.D. 3.8%, for n=9). The difference of the response between four preparations was 7%. Detailed investigations of the sensor response for monophenol and diphenol compounds and interfering species were carried out.

Synthesis of ether‐linked bisoxazolines and their use in step‐growth polymerization reactions with phenolics

AbstractSix new ether‐linked bisoxazolines have been synthesized via reaction of p‐hydroxyphenyl‐2‐oxazoline with dihalides. These bisoxazolines may be used as chain extenders or crosslinkers for resins, monomers or polymers containing various acidic groups, including phenolics, via step‐growth (1 : 1) reactions. As an illustration, a phenol‐formaldehyde polycondensate (Alnovol) and an enzyme oligomerized bisphenol A resin, as well as poly (p‐hydroxystyrene), was chain extended and crosslinked to produce thermosets with high glass transition temperatures. The new bisoxazolines were also polymerized with diphenol compounds, such as diphone D and bisphenol P to generate linear or branched oligomers and polymers. Differential scanning calorimetry was used to evaluate the potential for polymerization and crosslinking reactions. Preliminary results showed that the new, ether‐linked bisoxazolines have potential for formulating high performance thermosets. Copyright © 2002 John Wiley & Sons, Ltd.

Polyaddition of divinyloxyl compounds with diphenol or diol to novel degradable polymers

The polyaddition of equimolar amounts of ethylene glycol divinyl ether (EGDE) and a diphenol or a diol proceeded smoothly in tetrahydrofuran, in the presence of a trace amount of pyridinium p-toluenesulfonate as a catalyst, at room temperature. Several diphenol and diol compounds, such as catechol, resorcinol, hydroquinone, substituted hydroquinones, ethylene glycol, and 1,6-hexanediol, were subjected to polyaddition with EGDE, and the corresponding polymers were obtained in every case. All the polymers were stable in basic or neutral environments but exhibited degradation in acidic media.

CYTOTOXIC AND CYTOSTATIC EFFECTS OF POLYPHENOLS AGAINST RAT 3Y1 FIBROBLASTS TRANSFORMED BY E1A GENE OF HUMAN ADENOVIRUS-TYPE-12

Toxicity of polyphenols against rat 3Y1 fibroblasts and the cells transformed by human adenovirus (Ad12-3Y1), its EIA gene (EIA-3Y1), or simian virus 40 (SV-3Y1) was examined. Among the diphenol compounds examined, pyrocatechol (o-diphenol) and hydroquinone (p-diphenol) showed selective toxicity against Ad12-3Y1 and EIA-3Y1 cells, while resorcinol (m-diphenol) showed a much weaker non-specific toxicity against these cells. Another o-diphenol (dopamine) and triphenols (gallic acid and pyrogallol) were less toxic but showed selective toxicity. At lower concentrations where they were not toxic, all polyphenols attenuated toxicity of phosphatidylcholine against EIA-3Y1 cells. Among antioxidants examined, ascorbic acid reduced the toxicity of pyrocatechol, but alpha-tocopherol and butyrated hydroxytoluene did not. Oxidation of pyrocatechol was not enhanced in the presence of 3Y1 or EIA-3Y1 cells and their homogenates. These results suggest that the selective toxicity of polyphenols against Ad12-3Y1 and E1A-3Y1 cells is not related to their oxidation velocity but other factors such as the activity of active oxygen-scavenging enzymes.

Regulation of melanin production by Cryptococcus neoformans.

Species of Filobasidiella, the agents of cryptococcosis, produced melanin-like pigments within 4 to 48 h with diphenol, aminophenol, and diaminobenzene compounds as substrates. The rate of phenyloxidase activity was found to be regulated by glucose and nitrogen catabolite repression. Increased glucose concentration reduced pigmentation of all serotypes of Filobasidiella, whereas repression by nitrogen sources varied with the strain. Glutamine repressed the phenyloxidases of all isolates except those of serotype B, and (NH4)2SO4 repressed the phenyloxidase of all isolates except that of serotype A. Tyrosine and glycine appeared to be near optimal for phenyloxidase activity but not necessarily for growth of all strain examined. Representatives of serotype C were unique in that their phenyloxidase system was adpative in contrast to the constitutive system found in the other serotypes. No single medium was found to support pigmentation of all strains of Cryptococcus neoformans within a 72-h incubation period; false-negative reactions can occur.

The ‘ o-diphenol-row’, a new method for the differentiation of nocardia: A preliminary report

Certain species of Nocardia can be identified by their ability brak down some o-diphenol compounds. All strains, of N. asteroides, N. pellegrini, N. rubra and N. corallina examined were able to break down pyrocatechol completely. Three of five strains of N. asteroides were the only Nocardia strains able to break down 3-hydroxytyramine; and N. pellegrini was the only one able to break down caffeic acid and 3-methoxycaffeic acid. Certaines espèces de Nocardia peuvent être identifiées par leur capacité de scinder certainscomposés o-diphenol. Toutes les souches de N. asteroides, N. pellegrini, N. rubra et N. corollina examinées étaient capables de scinder complètement le pyrocatechol. Trois souches sur cinq de N. asteroides étaient les seules souches de Nocardia capables de scinder le 3-hydroxytyramine, et N. pellegrini a été le seul capable de scinder l'acide caffeique et l'acide 3-methoxycaffeique. Algunas especies de Nocardia pueden ser identificadas por su capacidad para desintegraralgunos compuestos de o-diphenol. Todas las cepas examinadas de N. asteroides, N. pellegrini, N. rubra y N. coralina eran capaces de desintegrar completamente el pirocatecol. Sobre cinco cepas de N. asteroides, solamente tres desintegraron la 3-hidroxytiramina. La N. pellegrini fué la única capaz de desintegrar el ácido cafeico y el ácido 3-metoxicafeico. Gewisse Nocardia-Stämme können auf Grund ihrer Fähigkeit, einige o-Diphenyl-Verbindungen zu spalten, identifiziert werden. Alle untersuchten Stämme von N. asteriodes, N. pellegrini, N. rubra und N. corallina konnten Pyrokatechol vollständig aufspalten. Drei von fünf N. asteroides-Stämmen, waren als einzigste Nocardia-Stämme in der Lage. 3-Hydroxytyramin zu spalten; und N. pelligrini war der einzigste Stamm, der Coffeinsäure und 3-Hydroxytyramin zu spalten; und N. pelligrini war der einzigste Stamm, der Coffeinsäure und 3-Methoxycoffeinsäure spalten konnte.