Catechol Type Research Articles

Beryllium(II) as a Probe for Study of the Interactions of Metals and Fulvic Acids by Synchronous Fluorescence Spectroscopy

The interaction of Be(II) with two samples of fulvic acids (fua), extracted from materials present in a pinewood soil (fua2 from upper and fua3 from lower soil horizons), was followed by synchronous molecular fluorescence spectroscopy at pH = 6 and 11. The variations observed in the spectral data were analyzed by evolving factor analysis (EFA). It was found that Be(II) is a useful probe for detecting different ligand structures in complex mixtures of the fua type. The existence of common ligand structures in the two fua samples at both pH values studied was observed. These are probably of the salicylic acid type. Dihydroxylic structures of the catechol type were also detected. The logarithm of the mean conditional stability constants for coordination of the fua ligand structures of the salicylic acid type and Be(II) were obtained (at a pH of 6 and 11, respectively): fua2, 5.85(2) and 5.24(9); fua3, 6.5(1) and 5.08(4). This strong coordination indicates that fua can have an important function in the immobilization of Be(II) dispersed into the environment.

Distribution of plasmid- and chromosome-mediated iron uptake systems in Vibrio anguillarum strains of different origins

We investigated the incidence of plasmid-mediated and chromosome-mediated iron uptake systems in strains of Vibrio anguillarum that belong to serotypes O1 and O2 and were isolated from different fish species and in different geographic areas. All of the strains gave positive reactions in CAS agar medium and in the Arnow test, which indicated that catechol types of siderophores were produced. The majority of V. anguillarum serotype O1 strains harbored a 65-kb plasmid similar to plasmid pJM1 from strain 775, which encodes the siderophore anguibactin and its outer membrane receptor, protein OM2. All of the isolates harboring this plasmid promoted the growth of an anguibactin-deficient receptor-proficient mutant derived from strain 775, but none of these isolates promoted the growth of mutants lacking receptor OM2. Furthermore, under iron-limiting conditions all of these strains induced outer membrane proteins that were identical in size to protein OM2 of strain 775. In contrast, none of the serotype O2 strains contained a high-molecular-weight plasmid, but all of them induced the growth of mutants defective in the anguibactin-mediated system regardless of the presence or absence of receptor OM2. The serotype O2 strains, but not the plasmid-bearing serotype O1 strains, also induced the growth of Salmonella typhimurium enb-1 which utilizes only enterobactin as a siderophore.(ABSTRACT TRUNCATED AT 250 WORDS)

Potentiometric and spectroscopic studies on oxovanadium(IV) complexes of salicylic acid and catechol and some derivatives

The interaction of oxovanadium(IV) with ligands containing phenolate and carboxylate donors, such as salicylic acid, catechol, 2,x-dihydroxybenzoic acids (x= 3–6), and 3,4-dihydroxybenzoic acid has been studied in aqueous solution by means of potentiometric and spectroscopic (electronic absorption, e.s.r., and electron nuclear double resonance) techniques. Over the low pH range the salicyclic acid-type mode of co-ordination predominates, while the catechol type is preferred in basic media. A mixture of these donor sets is observed in the ternary oxovanadium(IV)–salicylic acid-catechol and binary oxovanadium(IV)-2,3-dihydroxybenzoic acid systems. Besides monomeric complexes, dinuclear species are also formed by the potentially ambidentate dihydroxybenzoic acid derivatives over the intermediate pH range. In the latter complexes both CO2– and O– groups take part in metal bridging.

The effect of Cu(II) ions on dopaquinone cyclization

The kinetics of the dopaquinone cyclization in the absence and presence of Cu(II) ions at pHs from 6 to 7.4 has been studied by cyclic, normal and reverse pulse voltammetry. Distinct inhibition of the dopaquinone ring closure reaction was observed in the presence of Cu(II) ions. At pHs below 6 this effect is attributed to the formation of amino acid type complexes. At pH 7.4 the amino acid type and the catechol type Cu(II)—DOPA chelates coexist, and simultaneous interactions of copper ions with both ends of the DOPA molecule result in the association of the Cu(II)—DOPA complexes. These effects, observed at physiological pH, suggest that the rate of melanin formation is affected by the presence of Cu(II) ions.

The effect of Cu(II) ions on dopaquinone cyclization

The kinetics of the dopaquinone cyclization in the absence and presence of Cu(II) ions at pHs from 6 to 7.4 has been studied by cyclic, normal and reverse pulse voltammetry. Distinct inhibition of the dopaquinone ring closure reaction was observed in the. presence of Cu(II) ions. At pHs below 6 this effect is attributed to the formation of amino acid type complexes. At pH 7.4 the amino acid type and the catechol type Cu(II)-DOPA chelates coexist, and simultaneous interactions of copper ions with both ends of the DOPA molecule result in the association of the Cu(II)-DOPA complexes. These effects, observed at physiological pH, suggest that the rate of melanin formation is affected by the presence of Cu(II) ions.

Charge Transfer Complexes of Indole:Catechol Type II

Charge transfer complexes between tryptamine: epinephrine, tryptamine: isoproterenol, tryptamine: catechol, and indole: catechol were demonstrated spectrophotometrically in aqueous solutions containing 0.1M HCI. It was possible to make precise measurements and to calculate thermodynamic parameters and molar absorptivities. In general, the equilibrium constant was found to be quite low and ranged from 4.00 ± 0.04 to 0.30 ± 0.02M−1 These interactions are exothermic and have relatively large standard enthalpy and entropy changes (ΔH° values ranged from −7.4 ± 0.3 to −5.2 ± 0.4kcal mol−1; ΔS° ranged from −25 ± 5.0 to −16 ± 1.3cal K−1 mol−1). The similarity in ΔH° and ΔS° values for all the combinations indicates a similar interacting system. This result has led us to propose the involvement of the charge transfer effect, induced in the indole: catechol system, in the mechanism occurring in nerve conductions.

Evidence for the involvement of iron siderophore in the transport of molybdenum in cowpeaRhizobium

The production of a catechol type of siderophore by an iron-depleted culture of cowpeaRhizobium decreased with the increase in the concentration of molybdenum in the growth medium above 1 mM. In vitro addition of molybdenum at pH 5 and 7 changed the absorbance maxima of siderophore, indicating the interaction of molybdenum with siderophore. Tungsten, which is a competitive inhibitor of molybdenum, was unable to dissociate the molybdenum-siderophore conjugate. In the presence of iron, siderophore increased the uptake of molybdenum. Under these conditions, the addition of 2,3-dihydroxybenzoic acid did not show an increase in the uptake. This suggests that an entire siderophore molecule is involved in the transport of molybdenum.

Enthalpies of formation of M(η-C 5H 5) 2L complexes (M = Mo, W, Ti; L = C 6H 4O 2, C 10H 6O 2, C 14H 8O 2)

The standard molar enthalpies of formation, at 298.15 K, of five crystalline bent metallocenes, [M(η-C 5H 5) 2L] (M = Mo, W, Ti) (LH 2 = 1,2-benzenediol, C 6H 4-(OH) 2; 2,3-napthalenediol, C 10H 6(OH) 2; 9,10-phenanthrenediol, C 14H 8(OH) 2), have been derived from enthalpies of hydrolyses in acid solution measured by precision solution-reaction calorimetry. The results were: Δ H f° [Mo(η-C 5H 5) 2(O 2 6H 4),c] = −130.6±2.9, Δ H f°[Mo(η-C 5H 5) 2(O 2C 10H 6),c] = −80.3± 2.2, Δ H f° [ Mo(η-C 5H 5) 2(O 2C 14H 8,c] = −53.25 ± 10.4, Δ H f° [ W(η-C 5H 5) 2 (O 2C 6H 4),c] = −112.8 ±2.9, Δ H f° [Ti(η-C 5H 5) 2(O 2C 14H 8),c] = −322.6 ± 12.7 kJ mol−1. The metaloxygen bond strengths were evaluated as mean bond enthalpy terms ( E). Comparison with corresponding values in similar comlexes reveals that small steric energy arises from the binding of a catechol type ligand to a metal atom.

Detection and assay of siderophores in cowpea rhizobia (Bradyrhizobium) using radioactive Fe (59Fe)

In this paper we describe a method for the detection and assay of siderophore (catechol type) using radioactive 59Fe. Using this method we have found that cowpea rhizobia (Bradyrhizobium) differ in their ability to produce this type of siderophore.

Mössbauer studies on protoporphyrin IX iron(II) frozen solutions containing ligands that cause the iron to be in a five coordinate high spin iron(II) environment

Mössbauer parameters are presented for a number of protoporphyrin IX iron(II) complexes containing ligands that allow the iron to be in a five coordinate high spin iron(II) electronic environment. Such environments are characterised by large quadrupole splittings in the range 4.0 to 4.4 mm s −1. These compounds have characteristic electronic spectra. The implications of catechol type ligands binding protoporphyrin IX iron II/III moieties are discussed.

Studies on 1,2,3,4-tetrahydroisoquinoline derivatives. I. Syntheses and beta-adrenoceptor activities of positional isomers of trimetoquinol with respect to its 6,7-dihydroxyl groups.

In a series of phenylethanolamine β-stimulants, transformation of hydroxyl groups of the catechol type into those of the resorcinol type has been reported to improve the bioavailability. Therefore, five possible positional isomers (1-5) of trimetoquinol (TMQ) with respect to its 6, 7-dihydroxyl groups were synthesized and tested for bronchodilating activity. Among these positional isomers, the 5, 7-dihydroxyl derivative (4) exhibited more potent bronchodilating activity and longer duration of activity than (±)-TMQ and isoproterenol on intraduodenal administration.

Stereochemical aspects of the metabolism of 5-(4'-fluorophenyl)-5-phenylhydantoin in the rat.

Racemic 5-(4'-fluorophenyl)-5-phenylhydantoin was synthesized to examine its metabolism in rat. This compound differs from the antiepileptic agent 5,5-diphenylhydantoin in that the normal site of hydroxylation in 5,5-diphenylhydantoin is blocked on one of the phenyl groups by a fluorine atom. The 4'-fluoro analogue gives a major metabolite, which was isolated and identified as (R)-(-)-5-(4'-fluorophenyl)-5-(4'-hydroxyphenyl)hydantoin of 37% enantiomeric purity. The absolute configuration and enantiomeric purity of the metabolite was determined by chemical conversion to (S)-(-)-5-(4'-hydroxyphenyl)-5-phenylhydantoin. A second metabolite of the catechol type, possibly as a mixture of 5-(3',4'-dihydroxyphenyl)-5-(4'-fluorophenyl)hydantoin, and the corresponding O-3'-methyl derivative was detected by gas chromatography-mass spectrometry after methylation.

Melanin produced by Cochliobolus miyabeanus. I. The physical and chemical properties (author's transl)

Cochliobolus miyabeanus, the pathogenic mold for the leaf spot disease of rice plants, was shake-cultured in a potato medium at 27° for 10 days. A dark brown pigment was extracted from the cultured cells, physical and chemical properties of the pigment were examined, and these properties were compared with those of indole-melanin, extracted from human hair, and of catechol-melanin, extracted from sunflower seeds. It was thereby found that the pigment produced by C. miyabeanus was a melanin, close to the catechol type rather than the indole type from its nitrogen content. However, distribution of molecular weight, solubility, and absorption spectra in the visible and infrared region of this melanin were different from those of other melanins, and it could not be determined definitely as the catechol type.

SIDEROCHROMES IN CYANOPHYCEAE: ISOLATION AND CHARACTERIZATION OF SCHIZOKINEN FROM ANABAENA SP.1

SUMMARYSchizokinen, a high affinity iron transport compound (siderochrome), previously described from Bacillus megaterium, has been isolated and characterized from low‐iron cultures of a bluegreen alga, Anabaena sp. No conclusive evidence for production of an iron‐repressible hydroxamate or catechol type siderochrome was observed in certain other bluegreen algae, such as Anabaena cylindrica Lemm., Coccochloris peniocystis (Kütz.) Drouet & Daily, Anacystis sp., Gloeocapsa alpicola (Lyng.) Born. or Chroococcus sp.

Studies on the hardening and darkening of insect cuticles

The protein components of hardened and unhardened insect cuticles have been analysed for their amino acid composition. These analyses show that the puparia of muscoid flies and the oötheca of the cockroach, which have been extensively studied as examples of sclerotization, differ markedly from insects in which hardening of the cuticle occurs after an ecdysis. β-Alanine and cyst(e)ine take part in the hardening of cuticles. Melanins occur in darkly coloured cuticles and the melanins may be either of the indole type or a mixture of indole and catechol types. During the formation of the puparium in Lucilia cuprina changes take place in the composition of the larval cuticle which are similar to those which occur during insect ecdysis. Approximately 20 per cent of both the protein and chitin of the larval cuticle were either absorbed during puparium formation and pupation or were converted to moulting membranes, or both. About the same amount of tanning material was added to the cuticle.

Action of a Ring-Cleaving Enzyme in Preventing Oxidative Darkening of Juices

Catechol type compounds such as chlorogenic acid are the natural substrates for polyphenol oxidase in fruit juices, and these compounds are converted by the enzyme to polymers that result in a dark juice. When apple juice, in the presence of ascorbate, was treated with the enzyme protocatechuate 3,4-dioxygenas, darkening was permanently prevented since the enzyme oxidatively cleaves the benzene ring of the substrates to yield branched chain derivatives of muconic acid. The muconic acid derivatives cannot participate in the polyphenol oxidase browning reaction.

Detection and Identification of the Polyphenoloxidase Substrate of the Banana

BLACKENING of the fruit of the banana may occur during cultivation, when the cause is usually of pathological origin, or during storage if ripening is not adequately controlled. The biochemical changes involved in the blackening of the fruit have received little study, although evidence for the existence of an enzyme system in the fruit of the banana capable of oxidizing substances of the catechol type was presented by Onslow1 in 1920. The existence of flavonoid compounds in the edible banana has been reported2,3. Robinson2 detected delphinidin in the hydrolysis products of the pulp of an edible banana while Simmonds3, who has described the anthocyanin pigments of the bracts of a number of banana species in detail, reported that the skin and pulp of fruit of the edible varieties contained large amounts of leucoanthocyanins. Indirect evidence was, however, obtained3 that the polyphenol oxidase system of the banana was unable to act on the leucoanthocyanins present to produce brown colorations. Recently, the presence of serotonin and related compounds in the fruit of the banana was reported by Waalkes et al. 5. The ability of these compounds to serve as substrates for polyphenoloxidase was not, however, explored.

Organic adsorbents from indian tannins. I. Preparation, activation and relative adsorptive power

AbstractMany workers have described costly phenol‐formaldehyde or amine‐formaldehyde resins for ion‐exchange. Tannins of the catechol type can also be used for the same purpose. In a previously published communication (Bhatnagar & Singh, 1950), it has been shown that katha (the edible material used in betel leaves) yields on sulphonation products which exhibit calcium and magnesium exchange. More resins from katha and cutch have now been prepared and their adsorptive properties have been studied.The products obtained by sulphonation of katha and cutch and subsequent condensation with formalin are found to adsorb about 95% and 65% fatty acids respectively from centimolar solutions. The resins obtained by mere sulphonation show little adsorption of acids. The products obtained by direct condensation of katha and cutch with formalin exhibit 15% and 0% adsorption respectively of benzoic acid. On the other hand, resinous products obtained by incorporation of katha and cutch in phenolic resins prepared using ammonia as a catalyst show high adsorption values, namely, 55% and 70% respectively of formic acid. The adsorptive properties of standard resins, e.g. Amberlites, Zeo‐karbs, etc., have also been studied. The study reveals that the prepared resins are comparable with standard resins.

Inactivation of Pressor Amines by Quinones and Related Diketones

Summary1. The pressor activity of certain aromatic amines is destroyed by aeration in vitro in the presence of quinones. 2. Simultaneous injection of dihydroxyphenyl-alanine and small amounts of copper salts in hypertensive rats causes a considerable lowering of blood pressure. 3. It is suggested that tyrosinase reduces the blood pressure by its oxidative effect on acceptor substances of the catechol type such as dopa and epinephrine, which in turn, upon oxidation to ortho-quinones, destroy the pressor amines in vivo.