Fluorescent derivatization of aromatic carboxylic acids with horseradish peroxidase in the presence of excess hydrogen peroxide.

The fluorescent derivatization of aromatic carboxylic acids by the catalytic activity of horseradish peroxidase (HRP) in the presence of excess H2O2 was investigated. Four monocarboxylic acids, nine dicarboxylic acids, and two tricarboxylic acids, all of which are non- or weakly fluorescent, were effectively converted into fluorescent compounds using this new method. This technique was further developed for the fluorometric determination of trace amounts of terephthalic acid (3c) and lutidinic acid (2b), and linear calibration curves for concentrations between 2.

Spectrophotometric determination of hydrogen peroxide, glucose, uric acid, and cholesterol using peroxidase-like activity of an Fe(III) complex of thiacalix[4]arenetetrasulfonate attached to an anion-exchanger.

An iron(III) complex of thiacalix[4]arenetetrasulfonate attached to an anion-exchanger (Fe(3+)-TCASA-500) showed high peroxidase-like catalytic activity at pH 5 - 8 for the formation of quinoid dye, following the color reaction between 3-methyl-2-benzothiazolinone hydrazone (MBTH) and N-ethyl-N-(3-sulfopropyl)aniline (ALPS) in the presence of H2O2. This catalytic activity of Fe(3+)-TCASA-500 for the MBTH-ALPS system was applied for the spectrophotometric determination of H2O2, glucose, uric acid, and cholesterol. The calibration curves were linear in the concentration range from 1.

Catalytic activity of thiacalix[4]arenetetrasulfonate metal complexes on modified anion-exchangers for ascorbic acid oxidation.

The catalysis of ascorbic acid (AsA) oxidation by anion-exchangers modified with metal complexes of thiacalix[4]arenetetrasulfonate (Me-TCAS[4]A-500, Me=Mn(3+), Fe(3+), Co(3+), Ce(4+), Cu(2+), Zn(2+), Ni(2+), and H2) were investigated. Me-TCAS[4]A-500 (Me=Mn(3+), Fe(3+), Ce(4+), and Cu(2+)) all exhibited the ability to catalyze the oxidative reaction of AsA to dehydroascorbic acid. However, in the presence of high concentrations of AsA, only Cu(2+)-TCAS[4]A-500 was capable of complete oxidation of the acid.

Photodegradation of environmental mutagens by visible irradiation in the presence of xanthene dyes as photosensitizers.

The photodegradation of environmental mutagens, such as 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAαC), and 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ), was investigated by visible irradiation in the presence of xanthene dyes as photosensitizers. Although the environmental mutagens themselves were very stable during visible irradiation under the conditions in this study, they were effectively photodegraded in the presence of the xanthene dyes (erythrosine, rose bengal, and phloxine). Moreover, photodegradation of the mutagens was further enhanced for xanthene dyes loaded onto a water-soluble diethylaminoethyl (DEAE)-dextran anion-exchanger via ionic interactions (xanthene-dyeDEX).

Fluorescent derivatization of xanthurenic acid and nicotinic acid with horseradish peroxidase in the presence of excess hydrogen peroxide.

The fluorescent derivatization of tryptophan metabolites (xanthurenic acid, nicotinic acid, picolinic acid, and 3-hydroxyanthranilic acid) by the catalytic activity of horseradish peroxidase (HRP) was investigated in the presence of excess H(2)O(2). Non-fluorescent xanthurenic acid (XA) and nicotinic acid (NA) were converted into a fluorescent compound with maximum excitation and emission wavelengths at 325 and 425 nm, and 318 and 380 nm, respectively. This fluorescent derivatization was developed for the fluorometric determination of trace amounts of XA and NA.

Scavenging effects of metal complexes of water-soluble thiacalix[4]arenetetrasulfonate on superoxide anion radicals.

The scavenging effects of metal complexes of thiacalix[4]arenetetrasulfonate (Me-TCAS[4], Me=H₂, Fe³(+), Mn³(+), Mn²(+), Cu²(+), and Zn²(+)) on superoxide anion radicals (O₂⁻) generated from the xanthine-xanthine oxidase system were investigated by the nitroblue tetrazolium (NBT) method and electron spin resonance (ESR) spin-trapping method using 5,5-dimethyl-1-pyrroline-N-oxide as a trapping reagent. As a reference, calix[4]arenetetrasulfonate (H₂)-CAS[4]), calix[6]arenehexasulfonate (H₂-CAS[6]) and calix[8]areneoctasulfonate (H₂-CAS[8]) were also examined. The results by the NBT method indicated that Fe³(+)- and Mn³(+)-TCAS[4] exhibited the highest O₂⁻ scavenging activity among Me-TCAS[4] and H₂-CAS[n] (n = 4, 6, 8) in this study.

Peroxidase-like catalytic activity of water-insoluble complex linked Fe(III)-thiacalix[4]arenetetrasulfonate with tetrakis(1-methylpyridinium-4-yl)porphine via ionic interaction.

A new water-insoluble Fe(3+)-TCAS[4]/TMPyP complex linked tetraanionic Fe(III)-thiacalix[4]arenetetrasulfonate (Fe(3+)-TCAS[4]) with tetracationic tetrakis(1-methylpyridinium-4-yl)porphine (TMPyP) via ionic interaction was prepared. The peroxidase-like catalytic activity of the Fe(3+)-TCAS[4]/TMPyP complex was investigated based on the dye formation reaction by oxidation of 4-aminoantipyrine and phenol with H(2)O(2) catalyzed by peroxidase. This Fe(3+)-TCAS[4]/TMPyP complex showed the highest activity in pH 5.

Spectrofluorometric determination of kynurenic acid with horseradish peroxidase in the presence of hydrogen peroxide.

The catalytic activity of horseradish peroxidase (HRP) in the presence of hydrogen peroxide has been investigated for the fluorescent derivatization of kynurenic acid under conditions with no exposure to light. Non-fluorescent kynurenic acid was converted into a fluorescent compound (Ex: 367 nm, Em: 470 nm) with HRP in the presence of hydrogen peroxide, and the optimum conditions of this fluorescent derivatization were investigated. Moreover, this fluorescent derivatization was developed for a spectrofluorometric determination of trace amounts of kynurenic acid by measuring the fluorescence intensity of the fluorescent compound.

Spectrofluorometric determination of hydrogen peroxide based on oxidative catalytic reactions of p-hydroxyphenyl derivatives with metal complexes of thiacalix[4]arenetetrasulfonate on a modified anion-exchanger.

The peroxidase-like catalytic activity of metal complexes of thiacalix[4]arenetetrasulfonate (TCAS[4]) on a modified anion-exchanger (Me(n+)-TCAS[4]A-500; Me(n+) = H2, Fe3+, Fe2+, Mn3+, Co3+, Co2+, Cu2+, Zn2+, Ni2+) for the oxidation of p-hydroxyphenyl derivatives to produce fluorescent substances in the presence of hydrogen peroxide has been investigated. Among the Me(n+)-TCAS[4]A-500 tested, Fe(3+)-TCAS[4]A-500 exhibited the highest level of catalytic activity for the oxidation of p-acetoamidophenol in a carbonate buffer solution of pH 10. The catalytic activity of Fe(3+)-TCAS[4]A-500 was then used for the spectrofluorometric determination of hydrogen peroxide.

Catalytic activity for decomposition of hydrogen peroxide by metal complexes of water-soluble thiacalix[4]arenetetrasulfonate on the modified anion-exchangers.

The catalytic activity for the decomposition of hydrogen peroxide by anion-exchangers modified with metal complexes of thiacalix[4]arenetetrasulfonate (Me(n+)-TCAS[4], Me(n+)=Mn(3+), Mn(2+), Fe(3+), Co(3+), Co(2+), Cu(2+), Zn(2+) and Ni(2+)) was investigated. As a reference, calix[4]arenetetrasulfonate, calix[6]arenehexasulfonate and calix[8]areneoctasulfonate were also examined. Mn(3+)- and Fe(3+)-TCAS[4] on the modified anion-exchangers showed high catalytic activity in alkaline buffer solutions among metal complexes tested.