Study on fluorometric determination of hydrogen peroxide catalyzed by iron(III)-tetrasulfonato-phthalocyanine with thiamine hydrochloride as a substrate

Iron(III)-tetrasulfonatophthalocyanine(FeTSPc) has been used as a mimetic enzyme in the determination of hydrogen peroxide with thiamine hydrochloride as a fluorogenic substrate. The determinations were carried out in both acidic and basic environments, with different limits of detection and linear ranges. In acidic condition, the linear calibration graph was obtained from 5.0x10(-8) mol/L to 8.0x10(-6) mol/L, with a detection limit of 2.1x10(-8) mol/L H2O2 when Na2HPO4-citric buffer solution (pH 2.8) was used as the reaction medium. It was also found that using one of the three polybasic carboxylic acids such as citric acid, tartaric acid and malonic acid as the catalytic reaction medium can lead to particularly sensitive systems, permitting a detection limit as low as 3.5x10(-9) mol/L H2O2; whereas in basic reaction medium (Na2CO3-NaHCO3 buffer solution, pH = 10.0), the linear range of the calibration graph was from 5.0x10(-8) mol/L to 2.0x10(6) mol/L H2O2 with a detection limit of 1.4x10(-8) mol/L. The applicability of the method to the determination of glucose in human serum was demonstrated by investigating the recovery of the known glucose added to human serum

A new red-region substrate, tetra-substituted amino aluminium phthalocyanine, for the fluorimetric determination of H2O2 catalyzed by mimetic peroxidases

A new red-region fluorogenic substrate, tetra-substituted amino aluminium phthalocyanine, was developed for the selective determination of H2O2 based on the catalytic effect of mimetic peroxidases, viz., hemin or iron tetrasulfonatophthalocyanine (FeTSPc). Under the optimum conditions, the linearity of the calibration graph for the determination of H2O2 with hemin (or FeTSPc) as the catalyst was in the range from 0.0 to 3.0 X 10(-7) mol L-1 (or from 0.0 to 2.0 x 10(-6) mol L-1). The detection limits were 3.7 X 10(-9) and 4.9 x 10(-9) mol L-1 H2O2, respectively. The relative standard deviation (n = 7) was within 1.5% in the middle of the linear range. The peroxidase activity of the mimetic enzymes hemin and FeTSPc, the effects of some experimental conditions and the influence of foreign substances were investigated. With this substrate, 0.0-7.5 x 10(-8) mol L-1 hemin and 0.0-2.0 x 10(-6) mol L-1 FeTSPc can be determined with an accuracy and precision of about 1.3%. The potential application of the reagent was tested by the determination of H2O2 in rainwater

Sensitive fluorimetric determination of formaldehyde by the co-quenching effect of formaldehyde and sulfite on the fluorescence of tetra-substituted amino aluminium phthalocyanine

A novel and sensitive fluorimetric method was developed for the determination of formaldehyde based on the co-quenching effect of formaldehyde and sulfite on the fluorescence of tetra-substituted amino aluminium phthalocyanine. Formaldehyde in the concentration range 0.040-1.19 mug ml(-1) can be determined with a limit of detection of 7.5 ng ml(-1). The relative standard deviation for nine replicate measurements of 80.0 ng ml(-1) formaldehyde is 1.8%. The method was applied to the analysis of real samples with satisfactory results

Novel spectrofluorimetric method for the determination of thiamine with iron(III) tetrasulfonatophthalocyanine as a catalyst

A sensitive, selective and rapid spectrofluorimetric method is proposed for the determination of thiamine by using mimetic enzyme iron(iii) tetrasulfonatophthalocynanine (FeTSPc) as a catalyst for the oxidation reaction between thiamine and hydrogen peroxide. It is based on the oxidation of thiamine in alkaline medium to give an intensively fluorescent compound, which has an excitation wavelength of 375 nm and an emission wavelength of 440 nm. The determination was found to be activated by fluorogenic substrates with a p-hydroxyphenyl structure such as L-tyrosine, tyramine and p-hydroxyphenylpropionic acid. Under optimum conditions, the responses for thiamine were linear from 1.0 x 10(-8) to 1.0 x 10(-4)mol L-1, with a detection limit of 4.3 x 10(-9) mol L-1. The relative standard deviation was 2.2% for 2.0 X 10(-7) mol L-1 thiamine (n = 6). The activation of the p-hydroxyphenyl substrates, the effects of some experimental conditions and the influence of foreign substances were investigated. The potential application of the method was tested by selectively determining thiamine in commercial vitamin B-1, vitamin B complex and rice

Studies on tetra-substituted amino aluminum phthalocyanine as a new red-region substrate for mimetic peroxidase

Tetra-substituted amino aluminum phthalocyanine (TAAlPc) has been synthesized and used for the first time as a new red region fluorescent substrate for the determination of hydrogen peroxide catalyzed by peroxidase or mimetic peroxidase. Under optimum conditions, the calibration graph has a linear range of 0.0-3.0 x 10(-7) mol/L H2O2 with a detection limit of 3.7 x 10(-9) mol/L. The feasibility of TAAlPc as a new promising red-region substrate in practical application has been proven in the determination of H2O2 in rainwater. The proposed method can largely minimize the interference that results from background fluorescence or scattering light and has a high analytical sensitivity

Overexpression and Small Molecule-Triggered Downregulation of CIP2A in Lung Cancer

Lung cancer is the leading cause of cancer deaths worldwide, with a five-year overall survival rate of only 15%. Cancerous inhibitor of PP2A (CIP2A) is a human oncoprotein inhibiting PP2A in many human malignancies. However, whether CIP2A can be a new drug target for lung cancer is largely unclear.Normal and malignant lung tissues were derived from 60 lung cancer patients from southern China. RT-PCR, Western blotting and immunohistochemistry were used to evaluate the expression of CIP2A. We found that among the 60 patients, CIP2A was undetectable or very low in paratumor normal tissues, but was dramatically elevated in tumor samples in 38 (63.3%) patients. CIP2A overexpression was associated with cigarette smoking. Silencing CIP2A by siRNA inhibited the proliferation and clonogenic activity of lung cancer cells. Intriguingly, we found a natural compound, rabdocoetsin B which is extracted from a Traditional Chinese Medicinal herb Rabdosia coetsa, could induce down-regulation of CIP2A and inactivation of Akt pathway, and inhibit proliferation and induce apoptosis in a variety of lung cancer cells.Our findings strongly indicate that CIP2A could be an effective target for lung cancer drug development, and the therapeutic potentials of CIP2A-targeting agents warrant further investigation

Search for New Physics in e mu X Data at D0 Using Sleuth: A Quasi-Model-Independent Search Strategy for New Physics

We present a quasi-model-independent search for the physics responsible for electroweak symmetry breaking. We define final states to be studied, and construct a rule that identifies a set of relevant variables for any particular final state. A new algorithm ("Sleuth") searches for regions of excess in those variables and quantifies the significance of any detected excess. After demonstrating the sensitivity of the method, we apply it to the semi-inclusive channel e mu X collected in 108 pb^-1 of ppbar collisions at sqrt(s) = 1.8 TeV at the D0 experiment during 1992-1996 at the Fermilab Tevatron. We find no evidence of new high p_T physics in this sample.Comment: 23 pages, 12 figures. Submitted to Physical Review

Ratio of the Isolated Photon Cross Sections at \sqrt{s} = 630 and 1800 GeV

The inclusive cross section for production of isolated photons has been measured in \pbarp collisions at $\sqrt{s} = 630$ GeV with the \D0 detector at the Fermilab Tevatron Collider. The photons span a transverse energy ($E_T$) range from 7-49 GeV and have pseudorapidity $|\eta| < 2.5$. This measurement is combined with to previous \D0 result at $\sqrt{s} = 1800$ GeV to form a ratio of the cross sections. Comparison of next-to-leading order QCD with the measured cross section at 630 GeV and ratio of cross sections show satisfactory agreement in most of the $E_T$ range.Comment: 7 pages. Published in Phys. Rev. Lett. 87, 251805, (2001

Relationship between the Composition of Flavonoids and Flower Colors Variation in Tropical Water Lily (Nymphaea) Cultivars

Water lily, the member of the Nymphaeaceae family, is the symbol of Buddhism and Brahmanism in India. Despite its limited researches on flower color variations and formation mechanism, water lily has background of blue flowers and displays an exceptionally wide diversity of flower colors from purple, red, blue to yellow, in nature. In this study, 34 flavonoids were identified among 35 tropical cultivars by high-performance liquid chromatography (HPLC) with photodiode array detection (DAD) and electrospray ionization mass spectrometry (ESI-MS). Among them, four anthocyanins: delphinidin 3-O-rhamnosyl-5-O-galactoside (Dp3Rh5Ga), delphinidin 3-O-(2″-O-galloyl-6″-O-oxalyl-rhamnoside) (Dp3galloyl-oxalylRh), delphinidin 3-O-(6″-O-acetyl-β-glucopyranoside) (Dp3acetylG) and cyanidin 3- O-(2″-O-galloyl-galactopyranoside)-5-O-rhamnoside (Cy3galloylGa5Rh), one chalcone: chalcononaringenin 2′-O-galactoside (Chal2′Ga) and twelve flavonols: myricetin 7-O-rhamnosyl-(1→2)-rhamnoside (My7RhRh), quercetin 7-O-galactosyl-(1→2)-rhamnoside (Qu7GaRh), quercetin 7-O-galactoside (Qu7Ga), kaempferol 7-O-galactosyl-(1→2)-rhamnoside (Km7GaRh), myricetin 3-O-galactoside (My3Ga), kaempferol 7-O-galloylgalactosyl-(1→2)-rhamnoside (Km7galloylGaRh), myricetin 3-O-galloylrhamnoside (My3galloylRh), kaempferol 3-O-galactoside (Km3Ga), isorhamnetin 7-O-galactoside (Is7Ga), isorhamnetin 7-O-xyloside (Is7Xy), kaempferol 3-O-(3″-acetylrhamnoside) (Km3-3″acetylRh) and quercetin 3-O-acetylgalactoside (Qu3acetylGa) were identified in the petals of tropic water lily for the first time. Meanwhile a multivariate analysis was used to explore the relationship between pigments and flower color. By comparing, the cultivars which were detected delphinidin 3-galactoside (Dp3Ga) presented amaranth, and detected delphinidin 3′-galactoside (Dp3′Ga) presented blue. However, the derivatives of delphinidin and cyanidin were more complicated in red group. No anthocyanins were detected within white and yellow group. At the same time a possible flavonoid biosynthesis pathway of tropical water lily was presumed putatively. These studies will help to elucidate the evolution mechanism on the formation of flower colors and provide theoretical basis for outcross breeding and developing health care products from this plant