Photoreduction Of Nitroblue Tetrazolium Research Articles

Self-association synthesis with ortho-vanillin to promote mono- and heptanuclear complexes and their evaluation as antioxidant agents

This study describes the synthesis, crystal structure, antioxidant activity, and molecular modeling calculations for two CuII complexes obtained from the condensation of ortho-vanillin with furfurylamine. Both complexes catalyzed superoxide dismutation and were evaluated and quantified by nitro blue tetrazolium photoreduction, efficiently demonstrating McCord-Fridovich constant values from 5.50 to 2.87 × 106 (M−1s−1) in the 1.3–1.4 µM range and an aqueous solution of pH 7.8. Despite an unusual arrangement containing seven CuII cations obtained by self-association processes, the heptamer, proportionally speaking, did not show multiplicative activity as initially expected. This situation was also evaluated using molecular docking.

Evaluation of the Antioxidant Activity of Copper(II) Complexes containing Tris‐(hydroxymethyl)aminomethane (TRIS) Units

The structural analysis and the SOD‐like activity of CuII complexes [(Cu)(C16H18N3O5)]ClO4 (1) and [(Cu)4(C36H52N8O12)] (2) are described with ligands obtained from the condensation of picolinaldehyde and 2‐formylpyrrole with tris(hydroxymethyl)aminomethane (TRIS). Finally, complex 1 catalyzes the dismutation of superoxide efficiently with IC50 values in the range of 0.43 micromolar solution, evaluated through the inhibition of the photoreduction of nitro blue tetrazolium (NBT) (superoxide dismutase assay).

Antioxidant activities of different fractions of polysaccharide conjugates from green tea ( Camellia Sinensis)

Three fractions of water-soluble polysaccharide conjugates, coded as TPC-1, TPC-2, and TPC-3, were isolated and purified from low-grade green tea ( Camellia sinensis) by absorbent chromatography and ion exchange chromatography. Their chemical and physical characteristics were determined by chemical methods, gas chromatography and size exclusion chromatography with laser light scattering. Deoxyribose assay, photoreduction of Nitro Blue Tetrazolium (NBT) assay and lipid peroxidation inhibition assay were applied to test the antioxidant activities of tea polysaccharide conjugates in vitro. The results indicated that the three polysaccharide conjugates were heteropolysaccharides bounded with protein. TPC-1 was composed of l-arabinose (Ara), d-ribose (Rib), d-xylose (Xyl), d-glucose (Glc), d-galactose (Gal) and d-mannose (Man). TPC-2 was only composed of four monosaccharides: Ara, Rib, Glc and Man. There was no Man detected in TPC-3. The protein contents of TPC-1, TPC-2, and TPC-3 were 2.8%, 3.8% and 4.0% and the molecular weights were 26.8 × 10 4, 11.8 × 10 4, 4.2 × 10 4, respectively. TPC-3 showed the highest antioxidant activities among the three fractions of polysaccharide conjugates, with an IC 50 of 182 μg/ml for the deoxyribose assay, and 93 μg/ml for the photoreduction of NBT assay, values which were lower than those of TPC-1 and TPC-2 ( P < 0.01). The effects of the molecular weight and protein content of the polysaccharide conjugates on the improvement of the bioactivities appeared to be significant.

Components and antioxidant activity of polysaccharide conjugate from green tea

Tea polysaccharide conjugate (TPC) has been used to cure diabetes in China. In order to characterize the chemical properties and activities of TPC, the TPC was isolated and purified from lower grade green tea. The monosaccharide components and the average molecular weight of TPC were analyzed by gas chromatography (GC) and high performance liquid chromatography (HPLC) methods, respectively. The antioxidant activity of TPC was tested using a deoxyribose assay, a photoreduction of nitro blue tetrazolium (NBT) assay and lipid peroxidation inhibition assay. The antioxidant activity on alloxan-induced oxidative damage was also tested. TPC was a conjugate with the molecular weight (MW) of 120 kDa. TPC exerted significant inhibitory effects on hydroxyl and superoxide radicals and lipid peroxidation with IC50 values of 101, 145 and 238 μg ml−1, respectively. TPC could also improve the activity of superoxide dismutase (SOD) (p<0.05). These results suggested that TPC was a potent antioxidant and there appeared to be a direct connection between antioxidant activity and hypoglycemic activity.

Superoxide and Hydroxyl Radicai Generation, and Superoxide Dismutase in PII Membrane Fragments from Wheat

Illumination of photosystem II (PSII) membrane fragments of wheat (Triticum durum Desf. cv. Adamello) gave rise to both O2*- and *OH radicals adducts of the novel spin trap 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO). With time, *OH became predominant displaying the conversion of O2*- into *OH. An intrinsic activity of superoxide dismutase (SOD) was found in PSII. Photoreduction of nitroblue tetrazolium (NBT) by PSII membrane fragments was induced by the addition of sodium azide and hydrogen peroxide. Western blotting of PSII proteins showed that a 29 kDa protein was recognised by an antibody against chloroplastic Fe-SOD from water lily. An increased formation rate of O2*- was observed in damaged PSII where the SOD activity decreased following a treatment with a free radical-generating system. Damage in PSII consisted also in a decrease in chlorophyll and in carotenoids as well as in a change in the lipid : chlorophyll : protein ratio. Upon treatment a decrease in the unsaturation of PSII membrane fragments was also monitored together with a degradation towards more saturated molecular species of monogalactosyldiacylglycerol.

Photochemical and photoelectrochemical behaviour of chlorophyll a-smectite conjugate

Chlorophyll a was adsorbed onto smectite to form chlorophyll-smectite conjugate, which became photostable against light illumination. The chlorophyll-smectite conjugate caused the photoreduction of nitro blue tetrazolium, NBT, through the formation of superoxide anion, and the conjugate retained the photosensitive activity even after 20 hour illumination. Furthermore, the conjugate deposited on SnO2 electrode caused electron transfer under light illumination. The anodic photocurrent rose at −200 mV versus Ag/AgCl electrode (KCl saturated) and reached a maximum level at approximately +100 mV. The photocurrent spectrum was in good agreement with the absorption spectrum of chlorophyll-smectite conjugate in an aqueous solution and the quantum efficiency was approximately 1% at 670 nm.

Sensitive Nitro Blue Tetrazolium staining of proteins in high resolution two‐dimensional gel electrophoresis

AbstractA new method is described for staining proteins after high resolution two‐dimensional gel electrophoresis. The polyacrylamide gel matrix is stained blue, by photoreduction of Nitro Blue Tetrazolium, while the spots of polypeptides remain unstained. The method is much more sensitive than Coomassie Blue staining and its sensitivity is close to that obtained by silver staining.