Azino-bis(3-ethylbenzothiazoline-6-sulfonic Acid) Diammonium Salt Research Articles

Lead(II)-Induced Allosteric G-Quadruplex DNAzyme as a Colorimetric and Chemiluminescence Sensor for Highly Sensitive and Selective Pb2+ Detection

The lead ion (Pb(2+)) has been proven to induce a conformational change of K(+)-stabilized G-quadruplex DNAzyme and inhibit the peroxidase-like activity [Li, T.; Wang, E.; Dong, S. J. Am. Chem. Soc. 2009, 131, 15082-15083]. This provides a rationale for utilizing Pb(2+)-induced allosteric G-quadruplex DNAzyme to probe aqueous Pb(2+). Here, we choose a common G-quadruplex DNAzyme named PS2.M to develop a novel Pb(2+) sensor with two detection means: colorimetry and chemiluminescence (CL). In the presence of K(+), PS2.M (with hemin as a cofactor) exhibits a superior DNAzyme activity and effectively catalyzes the H(2)O(2)-mediated oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) or luminol, which results in a color change or generates CL emission. Upon the addition of Pb(2+), K(+)-stabilized PS2.M is induced to convert to the Pb(2+)-stabilized structure with higher stability but lower DNAzyme activity, which is reflected by an obvious increase in DNA melting temperature but a sharp decrease in readout signal. This allows us to utilize PS2.M for quantitative analysis of aqueous Pb(2+) using the ABTS-H(2)O(2) colorimetric system and luminol-H(2)O(2) CL system. In each case, the readout signal is linearly dependent on the logarithm of Pb(2+) concentration within a certain range. Nevertheless, two sensing systems provide different sensitivity for Pb(2+) analysis. With colorimetry, Pb(2+) can be detected at a level of 32 nM (approximately 7 ppb), whereas the detection limit of Pb(2+) is 1 nM (0.2 ppb) when utilizing the CL method. In addition to high sensitivity, the above sensing systems exhibit good selectivity for Pb(2+) over other metal ions. These results demonstrate the facility and effectivity of our introduced DNAzyme-based sensor for quantitative Pb(2+) analysis.

Composition, content and antioxidative activity of the carotenoids in yellow-fleshed sweetpotato (Ipomoea batatas L.)

The total carotenoid contents in eight sweetpotato (Ipomoea batatas L.) cultivars or breeding lines with yellow flesh were evaluated by absorption spectrophotometry and compared to those of four cultivars with orange flesh. The content ranged from 1.3 mg/100 g dry weight to 3.9 mg/100 g dry weight in yellow-fleshed cultivars and from 13.5 mg/100 g dry weight to 39.9 mg/100 g dry weight in orange-fleshed cultivars. Seventeen carotenoids were detected in yellow- and orange-fleshed sweetpotato by HPLC analysis. The amount of carotenoids analyzed by HPLC correlated highly with the carotenoid content analyzed spectrophotometrically. The main carotenoids were β-carotene 5,8;5′,8′-diepoxide (ca. 32%–51%) and β-cryptoxanthin 5,8-epoxide (ca. 11%–30%) in yellow-fleshed cultivars/lines, while β-carotene (ca. 80%–92%) was dominant in orange-fleshed cultivars. These results suggest that the content of each carotenoid differs according to flesh color, yellow or orange, although the carotenoid component in the yellow and orange flesh was almost identical. The antioxidative activities of carotenoids isolated from yellow-fleshed sweetpotato were analyzed by the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical-scavenging activity. The activity of ipomoeaxanthin A was comparable to β-carotene, and that of β-cryptoxanthin 5,8-epoxide was the lowest. The carotenoids in yellow-fleshed sweetpotato might contribute to the prevention of some diseases due to their antioxidative effect. β-carotene epoxides and β-crypthoxanthin epoxides, which are abundant in the yellow-fleshed cultivars, are noteworthy components for the breeding selection of sweetpotato with deep yellow flesh.

Use of 3-(4-hydroxyphenyl)propionic acid as electron donating compound in a potentiometric aflatoxin M 1-immunosensor

We developed a potentiometric aflatoxin M 1-immunosensor which utilizes 3-(4-hydroxyphenyl)propionic acid (p-HPPA) as electron donating compound for horseradish peroxidase (HRP; EC 1.11.1.7). The assay system consists of a polypyrrole-surface-working electrode coated with a polyclonal anti-M 1 antibody (pAb–AFM 1), a Ag/AgCl reference electrode and a HRP–aflatoxin B 1 conjugate (HRP–AFB 1 conjugate). To optimize the potentiometric measuring system p-HPPA as well as related compounds serving as electron donating compounds were compared. Also the influence of different buffer systems, varying pH and substrate concentrations on signal intensity was investigated. Our results suggest that reaction conditions that favor the formation of Pummerer's type ketones lead to an increase in signal intensity rather than formation of fluorescent dye. Comparison with commercial ready-to-use HRP electron donating compounds such as 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), o-phenylenediamine (OPD) or 3,3′,5,5′-tetramethylbenzidine (TMB) showed that only 34%, 77% and 49% of the signal intensity of p-HPPA were reached, respectively. The optimized assay had a detection limit of 40 pg mL −1 and allowed detection of 500 pg mL −1 (FDA action limit) aflatoxin M 1 (AFM 1) in pasteurized milk and UHT-milk containing 0.3–3.8% fat within 10 min without any sample treatment. The working range was between 250 and 2000 pg mL −1 AFM 1.

Antioxidant and anti-inflammatory properties of cancer preventive peptide lunasin in RAW 264.7 macrophages

Oxidative stress and inflammation are two of the most critical factors implicated in carcinogenesis and other degenerative disorders. We have investigated how lunasin, a known anti-cancer seed peptide, affect these factors. This peptide inhibits linoleic acid oxidation and acts as 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenger. Furthermore, using LPS-stimulated RAW 264.7 macrophages, we have demonstrated that lunasin reduces, in a significant dose-dependent manner, the production of reactive oxygen species (ROS) by LPS-induced macrophages. Lunasin also inhibits the release of pro-inflammatory cytokines (tumor necrosis factor-α [TNF-α] and interleukine-6 [IL-6]). On the basis of these potent antioxidant and anti-inflammatory properties, we propose lunasin not only as a cancer preventive and therapeutic agent but also as an agent against other inflammatory-related disorders.

Label-Free Colorimetric Detection of Aqueous Mercury Ion (Hg2+) Using Hg2+-Modulated G-Quadruplex-Based DNAzymes

Mercury ion (Hg(2+)) is able to specifically bind to the thymine-thymine (T-T) base pair in a DNA duplex, thus providing a rationale for DNA-based selective detection of Hg(2+) with various means. In this work, we for the first time utilize the Hg(2+)-mediated T-T base pair to modulate the proper folding of G-quadruplex DNAs and inhibit the DNAzyme activity, thereby pioneering a facile approach to sense Hg(2+) with colorimetry. Two bimolecular DNA G-quadruplexes containing many T residues are adopted here, which function well in low- and high-salt conditions, respectively. These G-quadruplex DNAs are able to bind hemin to form the peroxidase-like DNAzymes in the folded state. Upon addition of Hg(2+), the proper folding of G-quadruplex DNAs is inhibited due to the formation of T-Hg(2+)-T complex. This is reflected by the notable change of the Soret band of hemin when investigated by using UV-vis absorption spectroscopy. As a result of Hg(2+) inhibition, a sharp decrease in the catalytic activity toward the H(2)O(2)-mediated oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) is observed, accompanied by a change in solution color. Through this approach, aqueous Hg(2+) can be detected at 50 nM (10 ppb) with colorimetry in a facile way, with high selectivity against other metal ions. These results indicate our introduced label-free method for colorimetric Hg(2+) detection is simple, quantitative, sensitive, and highly selective.

Effects of Baking Conditions, Dough Fermentation, and Bran Particle Size on Antioxidant Properties of Whole-Wheat Pizza Crusts

This study investigated the effects of processing conditions including bran particle size, dough fermentation time, and baking time and temperature on the extractable antioxidant properties of whole-wheat pizza crust. Experiments were carried out using two different varieties of hard white winter wheat, Trego and Lakin. Antioxidant properties examined included oxygen radical absorbing capacity (ORAC), hydroxyl radical scavenging capacity (HOSC), relative 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity (RDSC), cation 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging capacity, total phenolic contents (TPC), and ferulic acid contents. Results indicated that bran particle size had no effect on the antioxidant properties evaluated. Increasing dough fermentation time from 0 to 48 h had no significant influence on antioxidant properties except HOSC, which increased as much as 28%, possibly as a result of increase in soluble free ferulic acid, which increased as much as 130%. Increasing baking temperature from 204 to 288 degrees C with a 7 min bake time increased all evaluated antioxidant properties by as much as 82%. Increasing baking time from 7 to 14 min with 204 degrees C baking temperature might increase some antioxidant properties as much as 60%. The results from this study suggest that longer dough fermentation times and increased baking time or temperature may be potential approaches to increase the antioxidant availability in whole-wheat pizza crust.

(−)-Epigallocatechin gallate/gelatin layer-by-layer assembled films and microcapsules

A new type of protein/polyphenol microcapsules on the basis of naturally occurring polyphenol (−)-epigallocatechin gallate (EGCG) and gelatin, type A, was obtained using the layer-by-layer (LbL) assembly method. The microcapsules show a more pronounced dependence of permeability on molecular weight of permeating substances than commonly used polyallylamine/polystyrene sulfonate capsules. The regularities of EGCG adsorption in alternation with type A and B gelatins have been investigated using quartz crystal microbalance and electrophoretic mobility measurements on microparticles and found to be dependent on gelatin properties. EGCG in the LbL assemblies retains its antioxidant activity. The kinetics of the reaction of 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) cation-radicals with films consisting of 1–10 gelatin/EGCG bilayers is affected by film structure. The EGCG content in the protein/polyphenol film material is as high as 30% w/w. Encapsulation of EGCG via its alternated adsorption with gelatins can be a perspective way to new formulations containing the polyphenol for drug delivery applications.

Coffee as a source of antioxidants: An EPR study

Antioxidant properties of commercially-available ground and instant coffees were investigated by means of electron paramagnetic resonance (EPR) using as oxidants 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH), 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxyl (TEMPOL) and thermally decomposed K 2S 2O 8. Only moderate differences were found in the antioxidant capacities of individual samples (expressed as trolox equivalent antioxidant capacity TEAC) with TEAC ABTS = 0.22 ± 0.02 mmol g −1 for ground and TEAC ABTS = 0.71 ± 0.07 mmol g −1 for instant coffees. Two coffee components (caffeic acid and caffeine) were investigated using moderate hydrogen/electron scavengers ABTS + and DPPH, and a powerful oxidant OH radical (photochemically generated from H 2O 2). Caffeine is inert to ABTS + and DPPH oxidants, but effective in the scavenging of OH radicals, with a bimolecular rate constant k = 2.6 × 10 9 M −1 s −1. Caffeic acid is a very effective antioxidant in all oxidant systems, with k = 9.4 × 10 9 M −1 s −1 in the bimolecular reaction with OH radicals. From the evaluated correlation matrix, a good linear relationship was found for the ground coffees between TEAC ABTS and TEAC DPPH values ( r TEAC ABTS / TEAC DPPH = 0.859 ) and also between the phenolics content expressed in gallic acid equivalents (GAE) and TEAC antioxidant capacities ( r GAE / TEAC ABTS = 0.729 and r GAE / TEAC DPPH = 0.922 ).

Selective, peroxidase substrate based “signal-on” colorimetric assay for the detection of chromium (VI)

Due to the potentially adverse effects of the chromium (VI) on the human health and also on the environment, the quantitative determination of Cr(VI) is of particular interest. This work herein reports a facile, selective and rapid colorimetric determination of Cr(VI) based on the peroxidase substrate-2,2′-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) as the color developing agent. ABTS, which was usually acted as peroxidase substrate for the enzyme linked immunosorbent assay, is used here for the first time to fabricate the “signal-on” colorimetric Assay for Cr(VI). The ABTS was chosen instead of the commonly used 1,5-diphenylcarbazide (DPC) due to its good solubility, stability, sensitivity and low background. This method provided a convenient colorimetric detection of Cr(VI) with a wider linear range from 8.33 μg L −1 to 1.25 mg L −1 by recording the absorption spectra at the wavelength of 419 nm and a low detection limit of 7.87 μg L −1. In addition, the entire detection takes less than 10 min.

Effects of Extraction Methods on Phenolic Contents and Antioxidant Activity in Aerial Parts of Potentilla atrosanguinea Lodd. and Quantification of Its Phenolic Constituents by RP-HPLC

The effects of different solvent systems (methanol, ethanol, acetone, and their 50% aqueous concentrations) and extraction procedures (microwave, ultrasound, Soxhlet and maceration) on the antioxidant activity of aerial parts of Potentilla atrosanguinea were investigated by three different bioassays: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays and ferric reducing antioxidant potential (FRAP). The 50% aqueous ethanol extracts exhibited strong antioxidant activity measured in terms of Trolox equivalent antioxidant capacity (TEAC) [(54.34 to 122.96, 29.82 to 101.22 and 13.64 to 41.43) mg of Trolox/g] with ABTS (*+), DPPH (*) and FRAP assays, respectively. In general, TEAC of Soxhlet extracts was found to be 1.8 and 3 times higher than ultrasound and maceration but slightly (1.2 times) higher than microwave. A positive correlation (r(2) = 0.931 to 0.982) was observed between total polyphenol (TPC) and total flavonoid (TFC) contents which ranged between 26.7 to 30.7 mg/g gallic acid equivalent and 16.8 to 20.8 mg/g quercetin equivalent respectively, with antioxidant activity. In addition, some of its bioactive phenolic constituents which contribute largely toward antioxidant potential such as chlorogenic acid, catechin, caffeic acid, p-coumaric acid and quercetin were also quantified in different extracts by RP-HPLC.

Effect of degree of hydrolysis on the antioxidant activity of loach (Misgurnus anguillicaudatus) protein hydrolysates

Abstract Loach ( Misgurnus anguillicaudatus ) proteins were hydrolysed by papain and Protamex, the antioxidant activity of loach protein hydrolysates (LPH) was investigated. The results demonstrated that extensive hydrolysis by papain and Protamex led to the browning of the hydrolysates. When the degree of hydrolysis (DH) was 23%, hydrolysates prepared by papain (HA) exhibited the strongest antioxidant activity. The maximum values of the hydroxyl, 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activities and the reducing power were 56.1%, 95.5%, 2.80 mM and 1.46, respectively. The hydrolysates prepared by Protamex (HB) showed the strongest hydroxyl radical scavenging activity (55.0%) at DH 28%, DPPH radical scavenging activity (92.2%) and ABTS radical scavenging activity (2.81 mM) at DH 23%, and the reducing power (1.17) at DH 33%. At the same DH value, there were significant ( p Industrial relevance Loach has long been employed as a traditional Chinese medicine for the treatment of many kinds of diseases. From our previous work, loach was determined to be a good source of protein (accounts for approximately 17% (w/w) of the body weight). In this work, loach proteins were hydrolyzed by papain and Protamex to specific extent. The effect of DH on the antioxidant activities of hydrolysates was investigated. The results indicated that loach protein hydrolysates were potent antioxidants which were significantly affected by DH. This research is helpful for extensive development of loach product.

Antioxidant Activities of Eleven Australian Essential Oils

Essential oils are gaining increasing interest due to their multiple biological activities and great potential for therapeutic use. The antioxidant effect of essential oils is of special interest in diseases with inflammatory aspects. In this paper, the antioxidant activities of eleven essential oils extracted from Australian native plants were examined by the 2,2-diphenyl-1-picryhydrazyl (DPPH) and 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assays. In the DPPH assay, all of the essential oils showed substantial antioxidant potential, with a radical-scavenging activity ranging from 12.9% ± 0.3% to 86.9% ± 0.2% at the concentration of 1.6 × 10−2 mL/mL. In the ABTS assay, lemon-scented tea-tree oil ( Leptospermum petersonii Bailey) (80.6% ± 0.7%), Australian blue cypress oil ( Callitris intratropica R. T. Baker & H. G. Smith) (78.6% ± 1.3%), lemon-scented eucalyptus oil ( Eucalyptus citriodora Hook.) (56.7% ± 0.9%) and lemon-scented ironbark oil ( Eucalyptus staigeriana F. Muell. ex Bailey) (58.9% ± 0.8%) exhibited relatively high radical-scavenging activities at the concentration of 1.6 × 10−2 mL/mL. Taken together, in both DPPH and ABTS assays, lemon-scented tea-tree oil (with IC50 of 1.5 × 10−3 mL/mL and 1.5 × 10−3 mL/mL, respectively), Australian blue cypress oil (with IC50 of 9.5 × 10−3 mL/mL and 3.0 × 10−3 mL/mL, respectively), lemon-scented eucalyptus oil (with IC50 of 4.8 × 10−3 mL/mL and 8.9 × 10−3 mL/mL, respectively) and lemon-scented ironbark oil (with IC50 of 6.4 × 10−3 mL/mL and 7.0 × 10−3 mL/mL, respectively) showed the highest antioxidant potential of the essential oils tested. By comparison, the antioxidant capacity of vitamin E had IC50 values of 5.3 × 10−5 mL/mL and 4.3 × 10−6 mL/mL in the DPPH and ABTS tests respectively.

Fe3O4 Magnetic Nanoparticles as Peroxidase Mimetics and Their Applications in H2O2 and Glucose Detection

Artificial enzyme mimetics are a current research interest because natural enzymes bear some serious disadvantages, such as their catalytic activity can be easily inhibited and they can be digested by proteases. A very recently study reported by Yan et al. has proven that Fe(3)O(4) magnetic nanoparticles (MNPs) exhibit an intrinsic enzyme mimetic activity similar to that found in natural peroxidases, though MNPs are usually thought to be biological and chemical inert (Gao, L. Z.; Zhuang, J.; Nie, L.; Zhang, J. B.; Zhang, Y.; Gu, N.; Wang, T. H.; Feng, J.; Yang, D. L.; Perrett, S.; Yan, X. Y. Nat. Nanotechnol. 2007, 2, 577-583). In the present work, we just make use of the novel properties of Fe(3)O(4) MNPs as peroxidase mimetics reported by Yan et al. to detect H(2)O(2). The Fe(3)O(4) MNPs were prepared via a coprecipitation method. The as-prepared Fe(3)O(4) MNPs were then used to catalyze the oxidation of a peroxidase substrate 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) by H(2)O(2) to the oxidized colored product (see eq 1) which provides a colorimetric detection of H(2)O(2). As low as 3 x 10(-6) mol/L H(2)O(2) could be detected with a linear range from 5 x 10(-6) to 1 x 10(-4) mol/L via our method. More importantly, a sensitive and selective method for glucose detection was developed using glucose oxidase (GOx) and the as-prepared Fe(3)O(4) MNPs. The detection platforms for H(2)O(2) and glucose developed in the present work not only further confirmed that the Fe(3)O(4) MNPs possess intrinsic peroxidase-like activity but also showed great potential applications in varieties of simple, robust, and easy-to-make analytical approaches in the future.

In Vitro Antioxidant Activity of Enicostemma axillare

Four successive extracts of the whole plant of Enicostemma axillare (E. axillare), were examined for in vitro antioxidant activity using nine different methods. In the 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) method, all the four extracts of E. axillare showed potent antioxidant activity with IC50 values ranging from 13.26 to 24.36 μg/ml. The chloroform extract has shown potent antioxidant activity in H2O2, nitric oxide, and hydroxyl radical using the deoxyribose and lipid peroxidation methods, with IC50 values of 16.99±0.38, 60.66±0.30, 25.06±0.12, and 94.66±2.40 μg/ml, respectively. Potent activity was also observed for the petroleum ether extract with the deoxyribose, p-nitroso dimethyl aniline (p-NDA), and H2O2 methods and for the ethyl acetate extract with the H2O2 and nitric oxide methods. All extracts showed moderate total antioxidant capacity using the phosphomolybdenum method. The activity was not correlated with the total phenol content of the extracts.

Microwave-Assisted Efficient Extraction of Different Parts of Hippophae rhamnoides for the Comparative Evaluation of Antioxidant Activity and Quantification of Its Phenolic Constituents by Reverse-Phase High-Performance Liquid Chromatography (RP-HPLC)

The outcome of different extraction procedures (microwave, ultrasound, Soxhlet, and maceration) on the antioxidant activity of seeds, leaves, pulp, and fruits of Hippophae rhamnoides (sea buckthorn or SBT) was investigated by two different bioassays: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. The SBT extracts were found to possess strong antioxidant activity measured in terms of TEAC (2.03-182.13 and 6.97-282.75 mg/g) with ABTS and DPPH assays, respectively. In general, the antioxidant capacity of microwave-assisted extracts was found to be significantly higher than those obtained by ultrasound-assisted extraction (UAE) and maceration while being slightly higher than Soxhlet extracts. Further, microwave extracts of seeds were found to possess maximum antioxidant capacity followed by leaves, fruits, and pulp. Also, the chemical composition of extracts, studied in terms of the total phenolic content, was found to be in the range of 1.9-23.5 mg/g Gallic acid equivalent (GAE), which indicates a strong correlation between antioxidant activity and phenolic content present in the SBT. In addition, some of its bioactive phenolic constituents, such as rutin ( 1), quercetin-3- O-galactoside ( 2), quercetin ( 3), myricetin ( 4), kaempferol ( 5), and isorhamnetin ( 6), were also quantified in different extracts by reverse-phase high-performance liquid chromatography (RP-HPLC).

The atherosclerotic heart disease and protecting properties of garlic: contemporary data

This article reviews the contemporary data concerning atherosclerosis and protecting properties of garlic. Recent advances in basic science have established a fundamental role for inflammation in mediating all stages of this disease from initiation through progression and, ultimately, the thrombotic complications of atherosclerosis. These new findings provide important links between risk factors and the mechanisms of atherogenesis and garlic properties. Numerous in vitro studies have confirmed the ability of garlic to reduce the parameters of the risk of atherosclerosis: total cholesterol, LDL, triglycerides, oxidized LDL. Bioactive compounds and antioxidant potentials in fresh, cooked, boiled and commercial garlic from different regions are presented, using beta-carotene, 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide (NO), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) with K2S2O8 or MnO2, ferric-reducing/antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC) and others assays for antioxidant status. In vivo studies were reviewed on with garlic and cholesterol supplemented diets. The positive influences of garlic on plasma lipids, proteins, antioxidant activity, and some indices of blood coagulation are dose dependent. Garlic could be a valuable component of atherosclerosis-preventing diets only in optimal doses. Many recently published reports show that garlic possesses plasma lipid-lowering and plasma anticoagulant and antioxidant properties and improves impaired endothelial function.

Changes in the antioxidant properties of protein solutions in the presence of epigallocatechin gallate

β-Casein and α-casein showed radical-scavenging activities in aqueous solution, whereas bovine serum albumin (BSA), α-lactalbumin and β-lactoglobulin showed much weaker antioxidant activity, when assessed by the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical-scavenging assay. However, β-casein and α-casein showed reduced antioxidant activity after storage at 30 °C. An increase in radical-scavenging activity and a fall in fluorescence of the protein component were evident after 6 h, when BSA, β-lactoglobulin or casein were mixed with EGCG, and excess EGCG was removed, indicating the formation of a complex with this protein on mixing. Storage of all the proteins with EGCG at 30 °C caused an increase in the antioxidant activity of the isolated protein component after separation from excess EGCG. This showed that EGCG was reacting with the proteins and that the protein-bound catechin had antioxidant properties. The reaction of EGCG with BSA, casein and β-lactoglobulin was confirmed by the loss of fluorescence of the protein on storage, and the increase in UV absorbance between 250 and 400 nm. The increase in antioxidant activity of BSA after storage with EGCG was confirmed by the ferric reducing antioxidant potential (FRAP) and the oxygen radical antioxidant capacity (ORAC) assays.

Hofmeister Effects in Biology: Effect of Choline Addition on the Salt-Induced Super Activity of Horseradish Peroxidase and Its Implication for Salt Resistance of Plants

The effect of choline addition on the salt-induced super activity of horseradish peroxidase (HRP) is investigated. HRP is presented in the literature as an efficient H(2)O(2) scavenger, and choline is the precursor of glycine betaine, a strong osmoprotectant molecule. Both the regulations of H(2)O(2) and of osmoprotectant concentrations are implicated in plants in order to counteract salt-induced cell damage. For the oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), sulfate anions were found to play a crucial role in the increase of HRP activity. This induced super activity can be strongly reduced by adding choline chloride. The phenomena provide an example of physicochemical Hofmeister effects playing a central regulatory role in an important biological system.

A Rapid Microassay for Determination of Peroxidase in Wheat and Flour

ABSTRACTA rapid sensitive microplate assay for the determination of peroxidase activity in wheat, flour, or individual wheat kernels has been developed using a commercially prepared 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS) solution. The assay derives a six‐point calibration curve based on commercially available horseradish peroxidase (r2 > 0.990), while simultaneously analyzing eight extracts in triplicate. The coefficients of variation (CV) of triplicate assays of a single extract from any of the three sources investigated were generally <2.0%. Multiple extracts (n = 5) of either whole meal or flour yielded assays with an average CV < 5.0%. Preparation of the calibration standards with commercially available peroxidase stabilizing buffer allowed the standards to be used for five days without any deterioration in the assay's reproducibility. This assay is ideally suited for high‐throughput operations such as millstream analysis or plant breeder screening evaluations.

Important role of fungal intracellular laccase for melanin synthesis: purification and characterization of an intracellular laccase from Lentinula edodes fruit bodies

A laccase (EC 1.10.3.2) was isolated from the fully browned gills of Lentinula edodes fruit bodies. The enzyme was purified to a homogeneous preparation using hydrophobic, cation-exchange and size-exclusion chromatography. SDS-PAGE analysis showed the purified laccase, Lcc 2, to be a monomeric protein of 58.0 kDa. The enzyme had an isoelectric point of around pH 6.9. The optimum pH for enzyme activity was around 3.0 against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS), and it was most active at 40 degrees C and stable up to 50 degrees C. The enzyme contained 8.6 % carbohydrate and some copper atoms. The enzyme oxidized ABTS, p-phenylenediamine, pyrogallol, guaiacol, 2,6-dimethoxyphenol, catechol and ferulic acid, but not veratryl alcohol and tyrosine. Beta-(3,4-dihydroxyphenyl)alanine (L-DOPA), which was not oxidized by a laccase previously reported from the culture filtrate of L. edodes, was also oxidized by Lcc 2, and the oxidative product of L-dopa was identified as L-DOPA quinone by HPLC analysis. Lcc 2 was able to oxidize phenolic compounds extracted from fresh gills to brown-coloured products, suggesting a role for laccase in melanin synthesis in this strain.