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In the presence of the flavonols myricetin and quercetin, oxidation of hydroethidine (HE) by superoxide yielded ethidium (E + ) instead of 2-hydroxyethidium (2-OH-E + ). As a known pro-oxidant, myricetin alone was also found to be able to catalyze air oxidation of HE yielding exclusively E + . The reaction is inhibited by added superoxide dismutase, suggesting that superoxide is involved in the rate limiting step of the oxidation.

To test the hypothesis that targeting the microenvironment (soil) may effectively kill cancer cells (seeds) through a small-molecular weight sequential dual-targeting theragnostic strategy, or dual-targeting approach.With approval from the institutional animal care and use committee, 24 rats were implanted with 48 liver rhabdomyosarcomas (R1). First, the vascular-disrupting agent combretastatin A4 phosphate (CA4P) was injected at a dose of 10 mg/kg to cause tumor necrosis, which became a secondary target. Then, the necrosis-avid agent hypericin was radiolabeled with iodine 131 to form (131)I-hypericin, which was injected at 300 MBq/kg 24 hours after injection of CA4P. Both molecules have small molecular weight, are naturally or synthetically derivable, are intravenously injectable, and are of unique targetablities. The tumor response in the dual-targeting group was compared with that in vehicle-control and single-targeting (CA4P or (131)I-hypericin) groups with in vivo magnetic resonance imaging and scintigrams and ex vivo gamma counting, autoradiography, and histologic analysis. Tumor volumes, tumor doubling time (TDT), and radiobiodistribution were analyzed with statistical software. P values below .05 were considered to indicate a significant difference.Eight days after treatment, the tumor volume of rhabdomyosarcoma in the vehicle-control group was double that in both single-targeting groups (P.001) and was five times that in the dual-targeting group (P.0001), without treatment-related animal death. The TDT was significantly longer in the dual-targeting group (P.0001). Necrosis appeared as hot spots on scintigrams, corresponding to 3.13% of the injected dose of (131)I-hypericin per gram of tissue (interquartile range, 2.92%-3.97%) and a target-to-liver ratio of 20. The dose was estimated to be 100 times the cumulative dose of 50 Gy needed for radiotherapeutic response. Thus, accumulated (131)I-hypericin from CA4P-induced necrosis killed residual cancer cells with ionizing radiation and inhibited tumor regrowth.This dual-targeting approach may be a simple and workable solution for cancer treatment and deserves further exploitation.

A high-throughput method for rapid determination of starch hydrolase inhibition was developed using a 96-well microplate UV-vis reader to monitor the turbidity decrease over time. The area under the curve of turbidity measured over time was used to quantify the inhibitory effect of polyphenolic compounds on porcine pancreatic amylase, rat intestine α-glucosidase, and fungal amyloglucosidase. Acarbose equivalence (AE) was introduced for the first time and defined as IC50 of acarbose divided by the IC50 of the sample measured under the same 96-well plate. This way, the run-to-run variations are canceled out. Among the plant extracts tested, grape seed extracts (1,440 μmolAE/g) and cinnamon bark extracts (1600 μmolAE/g) are the most active in inhibiting rat intestine α-glucosidase. For porcine α-amylase inhibition, grape seed extracts (5710 μmol AE/g) are close to four times more active (equal weight basis) than acarbose (1550 μmolAE/g).

The primary purpose of this study was to characterize and investigate the antioxidant and anti-diabetic activities of the flavonoid baicalin in type 2 diabetic Goto-Kakizaki rats.Four groups of Goto-Kakizaki rats (n=6) were subjected to the following oral treatments for 30 days: (1) metformin - 500 mg/kg (2) baicalin - 120 mg/kg (3) metformin 500 mg/kg and baicalin - 120 mg/kg (4) vehicle treated diabetic controls receiving distilled water. The plasma glucose, triglyceride, total cholesterol, lipid peroxide and protein carbonyl contents were measured on a weekly basis. Following the completion of the treatment, the rats were sacrificed and their blood, heart, pancreatic and hepatic tissues were collected for analysis. The antioxidant enzyme activities as well as their expression were quantified using Western Blot, microarray and RT-PCR.The respective analyses showed that the baicalin- and the metformin and baicalin-treated groups had statistically significant increases (p0.05) in the activity and expression of the antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) compared with vehicle- and metformin-treated groups. Further complementing the antioxidant enzyme activity increases, the oxidative stress markers of plasma lipid peroxide and protein carbonyl contents were reduced in these groups as well. These treatment groups also had reduced plasma total cholesterol and triglyceride levels compared with vehicle-treated and metformin-treated groups (p0.05).Baicalin was an efficient antioxidant in reducing hyperglycemia-induced oxidative stress through the increased expression of antioxidant enzyme activities. It was also an efficient anti-hypertriglyceridemic as well as anti-hypercholesterolemic agent compared with metformin.

The effects of food grade fungus Rhizopus oligosporus stress on phytochemicals and phytoalexins of germinating peanut seeds were investigated by comparing the metabolic profiles of ungerminated (UG), germinated (G), and germinated seeds under fungal stress (GS). Three types of peanut seeds with different skin color (red, reddish brown, and black) were compared in the process. The polyphenolic contents were analyzed and correlated with antioxidant capacity for specific free radicals including peroxyl radical ROO(•) (ORAC), hydroxyl radical HO(•) (HORAC), superoxide radical O(2)(•-) (SORAC), and DPPH radical. The polyphenolic fingerprints analyzed by HPLC and LC-MS(n) showed that phenolic acids (coumaric, sinapinic, and ferulic acids derivatives) were the major group of phenolic compounds in ungerminated seeds. G or GS increased the level of phenolic acids, phytoalexins, and antioxidant capacity values in reddish and red peanuts but not in black peanuts. From the LC-MS(n) spectral data, 45 compounds were identified tentatively in the germinated peanuts, including 14 coumaric acids, 3 ferulic acids, 4 sinapinic acids, 2 hydroxybenzoic acids, 1 caffeic acid, 2 flavonoids, and 19 stilbenoids derivatives. Reddish brown germinated peanuts produced the highest amount of phytoalexins after GS with 55 compounds detected. Forty-five of these compounds were suggested as stilbenoid phytoalexins derivatives. The high content of phytoalexins may enhance the bioactivity of peanut seeds as functional food ingredients.

Aim of the study This study aims to investigate the hypoglycemic properties of Vernonia amygdalina Del. (VA) and its possible mechanisms of action in a single-dose STZ induced diabetic rat model. Materials and methods A dose–response study was conducted to determine optimum dose for the hypoglycemic effect of VA in STZ-induced diabetic rats. The optimum dose (400 mg/kg) was used throughout the 28-day chronic study. Body weight, food and water intakes of the rats were monitored daily. Fasting blood serum, pancreas, liver and soleus muscle were collected for biochemical analyses. Chemical composition of VA was analysed using HPLC and LC–ESI-MS. Results The study reveals that ethanolic extract of VA contains high level of polyphenols mainly 1,5-dicaffeoyl-quinic acid, dicaffeoyl-quinic acid, chlorogenic acid and luteolin-7-O-glucoside. In an oral glucose tolerance test, 400 mg/kg VA exhibited a significant improvement in glucose tolerance of the STZ-induced diabetic rats. 28-day treatment with 400 mg/kg VA resulted in 32.1% decrease in fasting blood glucose compared to diabetic control. VA also caused significant decrease (18.2% and 41%) in triglyceride and total cholesterol level. Besides, VA showed protective effect over pancreatic β-cells against STZ-induced damage, causing a slight increase in insulin level compared to diabetic control. VA administration also showed positive regulation of the antioxidant system, both enzymatic and non-enzymatic. Furthermore, VA was found to increase expression of GLUT 4 (24%) in rat skeletal muscle. Further tissue fractionation revealed that it can increase the GLUT 4 translocation (35.7%) to plasma membrane as well, suggesting that VA may stimulate skeletal muscle's glucose uptake. This observation is in line with the restoration in skeletal muscle glycogenesis of VA-treated group. However, no alteration was observed in GLUT 1 expression. In addition, VA also suppressed (40% inhibition) one of the key hepatic gluconeogenic enzymes, glucose-6-phosphatase (G6Pase). Conclusions VA possesses antihyperglycemic effect, most probably through increasing GLUT 4 translocation and inhibiting hepatic G6Pase. The polyphenols in the extract may be the candidates that are responsible for the above-mentioned biological activities.

In this review, we systematically analyzed the complicated interrelationship between photoluminescent quantum dots (QDs) and reactive oxygen species of biological importance. QDs, when photoexcited, generate reactive oxygen species (ROS), which are partially blamed for the cytotoxicity of QDs. On the positive side, the ability of generating ROS by QDs are exploited in photodynamic therapy using QDs alone or in combination with QD-surface bound organic sensitizers via resonance energy transfer from QDs to the organic dyes. Lastly, depending on the chemical composition and the functionalization of the QDs, ROS are known to quench or switch-on the QD photoluminescence. The selectivity and sensitivity toward specific ROS can be achieved through judicious chemical modification of QD surface coating layers by taking into account the reactivity difference among different ROS. The flexible QD surface functionalization opens up the unprecedented possibility of designer-made nanoprobes for sensing and quantifying ROS of biological importance.

Thirty-eight types of fruits commonly consumed in Singapore were systematically analysed for their hydrophilic oxygen radical absorbance capacity (H-ORAC), total phenolic content (TPC), ascorbic acid (AA) and various lipophilic antioxidants. Antioxidant composition and concentration varied widely across different fruits. Many of the tropical fruits tested were high in antioxidants. Amongst all fruits tested, sapodilla (Manilkara zapota) had the highest H-ORAC and TPC whilst guava had the highest AA per gram fresh weight. Papaya, red watermelon and cantaloupe had the highest β-cryptoxanthin, lycopene and β-carotene per gram fresh weight, respectively. On the other hand, durian and mangosteen were high in tocopherols and tocotrienols, respectively. Based on consumption data, Chinese Singaporeans appear to have a higher intake of carotenoids and tocopherols rich fruits compared to the US population. As fruits are a rich source of diverse antioxidants, efforts to promote consumption of a variety of fruits should be continued for public health benefits.

This paper investigates the boundary value in the heat conduction problem by a variational iteration method. Applying the iteration method, a sequence of convergent functions is constructed, the limit approximates the exact solution of the heat conduction equation in a few iterations using only the initial condition. This method does not require discretization of the variables. Numerical results show that this method is quite simple and straightforward for models that are currently under research.

Aims The present study aims to investigate the interaction between nitric oxide (NO) and hydrogen sulfide (H2S), the two important gaseous mediators in rat hearts. Methods and results Intracellular calcium in isolated cardiomyocytes was measured with a spectrofluorometric method using Fura-2. Myocyte contractility was measured with a video edge system. NaHS (50 µM, an H2S donor) had no significant effect on the resting calcium level, electrically induced (EI) calcium transients, and cell contractility in ventricular myocytes. Stimulating endogenous NO production with l-arginine or exogenous application of NO donors [sodium nitroprusside (SNP) and 2-( N , N -diethylamino)-diazenolate-2-oxide] decreased myocyte twitch amplitudes accompanied by slower velocities of both cell contraction and relaxation. Surprisingly, NaHS reversed the negative inotropic and lusitropic effects of the above three NO-increasing agents. In addition, the mixture of SNP + NaHS increased, whereas SNP alone decreased, the resting calcium level and the amplitudes of EI calcium transients. Angeli's salt, a nitroxyl anion (HNO) donor, mimicked the effect of SNP + NaHS on calcium handling and myocyte contractility. Three thiols, N -acetyl-cysteine, l-cysteine, and glutathione, abolished the effects of HNO and SNP + NaHS on myocyte contraction. Neither Rp-cAMP [a protein kinase A (PKA) inhibitor] nor Rp-cGMP [a protein kinase G (PKG) inhibitor] affected the effects of SNP + NaHS, suggesting a cAMP/PKA- or cGMP/PKG-independent mechanism. Conclusion H2S may interact with NO to form a thiol sensitive molecule (probably HNO) which produces positive inotropic and lusitropic effects. Our findings may shed light on the interaction of NO and H2S and provide new clues to treat cardiovascular diseases.

Durian fruit is rich in volatile sulfur compounds (VSCs), especially thiols and disulfides, which contribute to its onion-like odor. After fermentation, these VSCs were reduced to trace or undetectable levels in durian wine. The possible reduction mechanism of these VSCs (especially diethyl disulfide and ethanethiol) was investigated in a modified buffer in the presence of sulfite at different pH. An interconversion between diethyl disulfide and ethanethiol was found to be dependent on the pH: the higher the pH, the higher production of ethanethiol. It is suggested that, during durian wine fermentation, disulfides endogenous to durian pulp might be firstly converted into their corresponding thiols in the presence of reductant sulfite formed by yeast. The produced thiols as well as the thiols endogenous to the durian pulp were then removed by the mannoproteins of yeast lees.

Sixty-six types of vegetables commonly consumed in Singapore were analysed for their hydrophilic oxygen radical absorbance capacity (H-ORAC), total phenolic content (TPC), ascorbic acid (AA) and various lipophilic antioxidants. A single batch analysis of each vegetable showed that antioxidant composition and concentration varied widely across different vegetables. The vegetables with intense colours typically have high H-ORAC, TPC, AA, and carotenoid contents. Vegetables unique to the Asian market such as matrimony vine (Lycium chinense Miller), coriander, Chinese kale, water spinach and red chilli were consistently ranked high in H-ORAC, TPC, carotenoids and vitamin E levels. Based on consumption data, Chinese Singaporeans appear to have a higher intake of lutein, zeaxanthin, β-carotene, and tocopherols compared to the US population. Overall findings suggest that dark green leafy and brightly-coloured vegetables tend to contain high antioxidants. Our data are useful reference and substantiate many public health agencies’ recommendation to consume more vegetables, particularly the dark green leafy and brightly-coloured varieties.

Reaction of dried mangosteen pericarps powders with mercaptoacetic acid in the presence of hydrochloric acid in methanol afforded 4β-(carboxymethyl)sulphanyl-(−)-epicatechin methyl ester, 1, in 4.5% yield. The structure of 1 was characterised by 1H, 13C NMR, and mass spectra. Two protons on the prochiral methylene carbon next to sulphur atom give rise to characteristic AB pattern peaks indicating its association to chiral environment as is the case in 1. Compound 1 is a potential synthon towards other epicatechin derivatives due to its labile C–S bond under weakly basic conditions. Reaction 1 with epicatechin gave B2. If 3,5-dimethoxyaniline was used, 4β-(2′-amino-4′,6′-dimethoxyphenyl)epicatechin, 2, was isolated in moderate yield. Reaction of 1 with mercaptoethanol leads to synthesis of 4β-(2-hydroxyethylthio)epicatechin, 3, in good yield. Finally mercaptoacetic acid was used as an alternative for successful determination of mean degree of polymerisation of PAs isolated from pine bark, grape seeds, cocoa bean, and mangosteen.

This study investigated the antioxidant and antidiabetic effects of baicalin, as well as its effects in combination with the antidiabetic drug metformin. Three groups of streptozotocin-induced diabetic rats were given the following treatments for 30 days: (1) 500 mg/kg metformin; (2) 120 mg/kg baicalin; (3) 500 mg/kg metformin + 120 mg/kg baicalin. In addition, vehicle-treated diabetic and nondiabetic controls were used in the experiment. The rats treated with baicalin and metformin + baicalin had significantly elevated (p < 0.05) hepatic activities of superoxide dismutase, catalase, and glutathione peroxidase compared with the vehicle- and metformin-treated groups. Plasma and hepatic lipid peroxide concentrations of the baicalin- and baicalin + metformin-treated groups were significantly reduced (p < 0.05). In addition, baicalin significantly reduced plasma and hepatic triglycerides and cholesterol levels. The study thus showed that baicalin mitigated oxidative stress as well as enhanced the antidiabetic effect of metformin by improving the antioxidant status.

A novel high-throughput assay for measuring antioxidant capacity against superoxide anion has been developed and validated. In this assay, hydroethidine (HE), a fluorescent probe, is oxidized by superoxide anion generated by xanthine and xanthine oxidase and increases its fluorescence intensity. Therefore, the inhibition of loss of HE's fluorescence intensity in the presence of antioxidant is an index of antioxidant capacity. The result is expressed as superoxide dismutase (SOD) equivalent. Unlike other probes, such as tetrazolium and lucigenin, one major advantage of this assay is that the use of HE is not prone to artifact. The method was rigorously validated through linearity, precision, accuracy, and ruggedness. The linear range, limit of quantitation (LOQ), and limit of detection (LOD) are 0.22-3.75 units/mL, 0.30 unit/mL, and 0.10 unit/mL, respectively. A wide variety of phenolic compounds and fruit extracts were analyzed.

Twenty-seven cultivars of mulberry fruits ( Morus atropurpurea Roxb) were analyzed for their total phenolic content, total anthocyanin content, and peroxyl radical scavenging capacities. The proanthocyanidin contents of the fruit were also quantified using 4-dimethylamino-cinnamaldehyde assay, and characterization was attempted using electrospray ionization mass spectra. The phenolic compounds of mulberry fruits were characterized using HPLC with ESI-MS and diode array detection. Results showed that the content of mulberry fruits varied with different cultivars with total phenolic content, total anthocyanin content, total proanthocyanidin content, and peroxyl radical scavenging capacities ranging from 0.060-0.244, 0.001-0.056, 0.001-0.015, and 0.301-1.728, respectively. Good correlations were observed among the phenolic, anthocyanin, and proanthocyanidin contents and the radical scavenging capacities of mulberry fruits. Mulberry fruits were found to contain low amount of proanthocyanidins. The high total phenolic content of mulberry fruits were mainly contributed by anthocyanins, rutin, and chlorogenic acids. The lipid soluble antioxidants are profiled by an HPLC method developed in-house, and the results of selected mulberry fruits revealed significant amounts of lutein and delta- and gamma-tocopherols but low alpha-tocopherol. Our results provide useful antioxidant nutritional information of a mulberry cultivar that has potential for large scale plantations.

Oxidative stress is the root cause of diabetic macro- and microvascular complications. Biochemical and epidemiological studies indicate that current treatments for diabetes do not reduce risks of developing complications, suggesting their inability to alleviate the levels of oxidative stress. This study in streptozotocin (STZ)-induced diabetic rats was carried out to investigate the effect of combining the antidiabetic drug, metformin, with an ethanolic extract of Scutellaria baicalensis, a plant whose root is known for its radical scavenging activity. Three groups of STZ-induced diabetic rats were given the following treatments for 30 days: (1) metformin 500 mg/kg, (2) S. baicalensis 400 mg/kg, (3) metformin 500 mg/kg + S. baicalensis extract 400 mg/kg. In addition, vehicle-treated diabetic and nondiabetic controls were used in the experiment. The rats treated with S. baicalensis and metformin + S. baicalensis had elevated hepatic activities of the antioxidant enzymes — superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) compared to the vehicle- and metformin-treated diabetic groups ( p < 0.05). Plasma and hepatic lipid peroxide concentrations in the herb-treated and herb + metformin-treated groups were also significantly reduced ( p < 0.05). In addition, the combined treatment caused significant elevations of plasma and pancreatic insulin levels and reductions of plasma and hepatic triglycerides (TG) and cholesterol levels. The study thus showed that S. baicalensis enhanced the antidiabetic effect of metformin in STZ-induced diabetic rats by improving the antioxidant status. It also increased pancreatic insulin content as well as improved the lipid profile in these rats.

Alpha-amylase inhibitor (alpha-AI) activity of Garcinia mangostana, commonly known as mangosteen, pericarp extracts was studied by assay guided fractionations from lipophilic to hydrophilic using combined solvent extraction and Amberlite XAD2 adsorption chromatography. Neither the lipophilic, xanthone containing fraction, nor the highly polar fraction, which has no affinity on Amberlite XAD2, showed any alpha-AI. The fraction that shows very high inhibitory activity contains primarily polyphenols and can be adsorbed on Amberlite XAD2. The IC50 of 5.4 microg/mL of this fraction is comparable to that of acarbose, a prescribed alpha-AI used in the control of type II diabetes, at 5.2 microg/mL. Total phenolic content (TPC) of each fraction was measured and the TPC has no correlation with the alpha-AI activity. The lipophilic fraction contains mainly xanthones as revealed by HPLC-MS analysis. Colorimetric analysis coupled with UV-vis and IR spectroscopic analysis demonstrated that the fractions with high alpha-AI activity are primarily oligomeric proanthocyanidins (OPCs) with little gallate moiety. There is also evidence to show that the alpha-AI by these OPCs is not purely by nonspecific protein complexation. Both tannic acid and G. mangostana OPCs precipitate BSA equally well but G. mangostana OPCs are 56 times more effective in inhibiting alpha-amylase.

A complete economic assessment of fusion and fusion-driven subcritical system (FDS) systems should include the internalities and externalities, which reflect the costs/benefits of economy, environment and safety. A method of internalization of external costs and benefits, which are quantified by a tax levied on the environmental pollution of energy production, is presented. Based on the methodology, cost–benefit models of FDS are constructed. The economic performances of FDS-I (a typical design of FDS) has been calculated and compared with those of pure fusion energy systems. The impacts of the characteristic parameters of FDS-I on economy have been studied. The results have been specified to give recommendations for the improvement of the design.

Oligomeric proanthocyanidins were extracted from mangosteen pericarps and fractionated by a Sephadex LH-20 column to give 0.66% yield (dry matter). (13)C and (1)H NMR signals showed the presence of predominantly procyanidins together with a few prodelphinidin units along with small amounts of stereoisomers of afzelechin/epiafzelechin, catechin/epicatechin, and gallocatechin/epigallocatechin. Depolymerization with benzylmercaptan resulted in epicatechin thioether as the major product, and the mean degree of polymerization was determined to be 6.6. The electron spray ionization-mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectra revealed the dominant B type oligomers with mainly epicatechin units and with a small amount of A type oligomers. The isolated proanthocyanidins are potent peroxyl radical scavengers as evidenced by the high oxygen radical scavenging capacity at 1.7 x 10 (4) micromol TE/g, much higher than that of pine bark and grape seed extracts.

Diallyl trisulfide (DATS) reacts rapidly with glutathione (GSH) to release H2S through thiol-disulfide exchange followed by allyl perthiol reduction by GSH. Yet diallyl disulfide (DADS) only releases a minute amount of H2S via a sluggish reaction with GSH through an α-carbon nucleophilic substitution pathway. The results clarify the misunderstanding of DADS as a rapid H2S donor, which is attributed to its DATS impurity.

Herein, we report a novel approach to the rapid visual detection of gaseous sulfur dioxide (SO2) by manipulating the surface chemistry of 3-aminopropyltriethoxysilane (APTS)-modified quantum dots (QDs) using fluorescent coumarin-3-carboxylic acid (CCA) for specific reaction with SO2. The CCA molecules are attached to the surface amino groups of the QDs through electrostatic attraction, thus the fluorescence of CCA is greatly suppressed because of the formation of an ion-pair complex between the ATPS-modified QDs and CCA. Such an interaction is vulnerable to SO2 because SO2 can readily react with surface amino groups to form strong charge-transfer complexes and subsequently release the strongly fluorescent CCA molecules. The mechanism has been carefully verified through a series of control experiments. Upon exposure to different amounts of SO2, the fluorescent color of the nanoparticle-based sensor displays continuously changes from red to blue. Most importantly, the approach owns high selectivity for SO2 and a tolerance of interference, which enables the sensor to detect SO2 in a practical application. Using this fluorescence-based sensing method, we have achieved a visual detection limit of 6 ppb for gaseous SO2.

Hydrogen sulfide (H2S) is now recognized as a physiologically important gasotransmitter. Compounds which release H2S slowly are sought after for their potential in therapy. Herein the synthesis of a series of phosphordithioates based on 1 (GYY4137) are described. Their H2S release profiles are characterized using 2,6-dansyl azide (2), an H2S specific fluorescent probe. Most compounds have anticancer activity in several solid tumor cell lines and are less toxic in a normal human lung fibroblast, WI38. A preferred compound, 14, with 10-fold greater anticancer activity than 1, was shown to release H2S in MCF7 cells using a cell active probe, 21. Both permeability and intracellular pH (pHi) were found to be significantly improved for 14 compared to 1. Furthermore, 14 was also negative in the AMES test for genotoxicity. Cyclization of these initial structures gave a series of 2,3-dihydro-2-phenyl-2-sulfanylenebenzo[d][1,3,2]oxazaphospholes, of which the simplest member, compound 22 (FW1256), was significantly more potent in cells. The improved therapeutic window of 22 in WI38 cells was compared with three other cell types. Potency of 22 was superior to 1 in MCF7 tumor spheroids and the mechanism of cell death was shown to be via apoptosis with an increase in cleaved PARP and activated caspase-7. Evidence of H2S release in cells is also presented. This work provides a "toolbox" of slow-release H2S donors useful for studies of H2S in biology and as potential therapeutics in cancer, inflammation, and cardiovascular disease.

// Xuejiao Liu 1, 2 , Cuihua Jiang 1, 5 , Dongjian Zhang 1, 5 , Meng Gao 1 , Fei Peng 1 , Dejian Huang 1 , Ziping Sun 3 , Yicheng Ni 1, 4 , Jian Zhang 1 , Zhiqi Yin 5 1 Laboratory of Translational Medicine, Jiangsu Province Academy of Traditional Chinese Medicine, Nanjing 210028, Jiangsu Province, P.R.China 2 College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, Jiangsu Province, P.R.China 3 Shandong Academy of Medical Sciences, Jinan 250062, Shandong, P.R.China 4 Theragnostic Laboratory, Campus Gasthuisberg, KU Leuven, 3000 Leuven, Belgium 5 Department of Natural Medicinal Chemistry & State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, Jiangsu Province, P.R.China Correspondence to: Zhiqi Yin, e-mail: chyzq2005@126.com Jian Zhang, e-mail: zjwonderful@hotmail.com Keywords: tumor necrosis targeted radiotherapy, necrosis-avid agent, radiopharmaceutical, protohypericin, drug combination Received: April 14, 2015 Accepted: July 10, 2015 Published: July 21, 2015 ABSTRACT Lung cancer is the leading cause of cancer-related death. About 80% of lung cancers are non–small cell lung cancers (NSCLC). Radiotherapy is widely used in treatment of NSCLC. However, the outcome of NSCLC remains unsatisfactory. In this study, a vascular disrupting agent (VDA) combretastatin-A4-phosphate (CA4P) was used to provide massive necrosis targets. 131 I labeled necrosis-avid agent protohypericin ( 131 I-prohy) was explored for therapy of NSCLC using tumor necrosis targeted radiotherapy (TNTR). Gamma counting, autoradiography, fluorescence microscopy and histopathology were used for biodistribution analysis. Magnetic resonance imaging (MRI) was used to monitor tumor volume, ratios of necrosis and tumor doubling time (DT). The biodistribution data revealed 131 I-prohy was delivered efficiently to tumors. Tracer uptake peaked at 24 h in necrotic tumor of 131 I-prohy with and without combined CA4P (3.87 ± 0.38 and 2.96 ± 0.34%ID/g). 131 I-prohy + CA4P enhanced the uptake of 131 I-prohy in necrotic tumor compared to 131 I-prohy alone. The TNTR combined with CA4P prolonged survival of tumor bearing mice relative to vehicle control group, CA4P control group and 131 I-prohy control group with median survival of 35, 20, 22 and 27 days respectively. In conclusion, TNTR appeared to be effective for the treatment of NSCLC.

A weakly fluorescent complex derived from a binaphthol-benzimidazole ligand was designed and synthesized for hydrogen sulfide at different pH conditions. It was demonstrated that the probe showed the same reactivity to various hydrogen sulfide species in a broad range of pH values to generate highly fluorescent product through a displacement reaction mechanism, whereas the product's fluorescence spectrum exhibited a hypsochromic shift of ∼73 nm (2393 cm(-1)) as pH increased from neutral to basic, which can be used for distinguishing the various species of hydrogen sulfide. This turn-on fluorescence probe was highly selective and sensitive to hydrogen sulfide with a detection limit of 0.11 μM. It was then applied for evaluating the total content of sulfide (including hydrogen sulfide, hydrosulfide, and sulfide) as well as for the visual detection of gaseous H2S in air using a simple test paper strip.

Chemical compositions of durian wines fermented with Metschnikowia pulcherrima Flavia, Torulaspora delbrueckii Biodiva, Pichia kluyveri FrootZen and Kluyveromyces thermotolerans Concerto were investigated.Sucrose was not utilized by M. pulcherrima and P. kluyveri, resulting in little formation of ethanol (0.3-0.5%, v/v), while about 7% ethanol was produced by the other two yeasts. Volatiles such as esters and sulfur-containing compounds were synthesized or catabolized and distinctive differences existed among yeasts. Larger amounts of higher alcohols and ethyl esters were detected in wines fermented by T. delbrueckii and K. thermotolerans, whereas M. pulcherrima and P. kluyveri produced more acetate esters such as ethyl acetate (1034.43 and 131.05 mg L(-1) respectively) and isoamyl acetate (0.56 and 27.68 mg L(-1) respectively). Most endogenous sulfur volatiles such as disulfides declined to trace levels, but new ones such as thioesters were formed. Sulfur volatiles in wines fermented by T. delbrueckii accounted for 0.20% relative peak area (RPA), followed by K. thermotolerans (0.23% RPA), P. kluyveri (1.43% RPA) and M. pulcherrima (4.16% RPA).The findings showed that a more complex flavor could result from fermentation with different non-Saccharomyces yeasts and the typical durian odor would still remain.

Non-invasive "hot spot imaging" and localization of necrotic tissue may be helpful for definitive diagnosis of myocardial viability, which is essential for clinical management of ischemic heart disease. We labeled Sennidin A (SA), a naturally occurring median dianthrone compound, with (131)I and evaluated (131)I SA as a potential necrosis-avid diagnostic tracer agent in rat model of reperfused myocardial infarction. Magnetic resonance imaging (MRI) was performed to determine the location and dimension of infarction. (131)I-SA was evaluated in rat model of 24-hour old reperfused myocardial infarction using single-photon emission computed tomography/computed tomography (SPECT/CT), biodistribution, triphenyltetrazolium chloride (TTC) histochemical staining, serial sectional autoradiography and microscopy. Gamma counting revealed high uptake and prolonged retention of (131)I SA in necrotic myocardium and fast clearance from non-targeted tissues. On SPECT/CT images, myocardial infarction was persistently visualized as well-defined hotspots over 24h, which was confirmed by perfect matches of images from post-mortem TTC staining and autoradiography. Radioactivity concentration in infarcted myocardium was over 9 times higher than that of the normal myocardium at 24h. With favorable hydrophilicity and stability, radioiodinated SA may serve as a necrosis-avid diagnostic agent for assessment of myocardial viability.

Stinky beans (Parkia speciosa) were hydrodistilled and solvent-extracted and the oil obtained was analyzed by GC–MS/FID. Nine cyclic and one acyclic organosulfides were identified comprising 36% of total volatiles. Solvent extracts contained significantly (p < 0.05) higher total organosulfides (680 ppm) as compared to distilled oil (444 ppm). The concentrations of organosulfides are highly dependent on the pH values of the matrix, with control sample (pH 5.40) giving the highest total organosulfides (424 ppm) followed by that of pH 7.0 (234 ppm), pH 9.0 (195 ppm), and pH 3.0 (152 ppm). The H2S-releasing capacity, expressed as diallyl trisulfide equivalents (DATS-E in mmol DATS/g), corresponded well with the differences in organosulfide concentrations as affected by pH with control having the highest value (24.35) followed pH 7.0 (7.27), pH 9.0 (3.27), and pH 3.0 (1.80). We conclude that stinky bean oil is a potent H2S-releasing agent that could have health-beneficial properties.

The aim of the present study is to verify the trapping effect of combretastatin A-4-phosphate (CA4P) on small molecular drugs in rodent tumors. Mice with H22 hepatocarcinoma were randomized into groups A and B. Magnetic resonance imaging (MRI) of T1WI, T2WI, and DWI was performed as baseline. Mice in group A were injected with Gd-DTPA and PBS. Mice in group B were injected with Gd-DTPA and CA4P. All mice undergo CE-T1WI at 0 h, 3 h, 6 h, 12 h, and 24 h. Enhancing efficacy of the two groups on CE-T1WI was compared with the signal-to-noise ratio (SNR) calculated. Concentrations of gadolinium measured by ICP-AES in the tumor were compared between groups. On the early CE-T1WI, tumors were equally enhanced in both groups. On the delayed CE-T1WI, the enhancing effect of group A was weaker than that of group B. The SNR and the concentration of gadolinium within the tumor of group A were lower than that of group B at 6 h, 12 h, and 24 h after administration. This study indicates that CA4P could improve the retention of Gd-DTPA in the tumor and MRI allowed dynamically monitoring trapping effects of CA4P on local retention of Gd-DTPA as a small molecular drug.

Hypericin has an excellent necrosis-specific targeting capacity; thus, we explored small-molecular tumor necrosis therapy (SMTNT) for inhibiting tumor growth in rodent tumor models. H22 and S180 tumor-bearing Kunming (KM) mice were intratumorally injected with (131)I-monoiodohypericin ((131)I-MIH) to investigate the biodistribution of (131)I-MIH as a function of time. Single-photon emission computed tomography (SPECT), autoradiography, fluorescence microscopy and hematoxylin and eosin (HE) staining were performed to determine the intra-tumoral distribution of (131)I-MIH. A therapeutic evaluation study was also performed in the tumor-bearing KM mice using saline and a positive drug as controls. Gamma counting, SPECT images, autoradiography and fluorescence microscopy and HE staining results revealed intense retention of (131)I-MIH in the necrotic tumor over 168 h and good in vivo stability of the agent. Therapy with a single dose of intra-tumoral administration of (131)I-MIH caused significant tumor growth delay. A histopathological analysis of the tumors and normal organs further validated the therapeutic efficacy and limited systemic toxicity of (131)I-MIH. The prolonged tumor retention and effective therapy indicated that (131)I-MIH may be a promising intratumorally injected SMTNT agent.

We have developed an alternative methodology for determining the stabilities of DNA hairpin structures based on a specially designed oligonucleotide template and the T4 DNA ligase. This method was systematically tested by evaluation of DNA hairpin stabilities when varying the loop size and the nature of the loop sequence. MOE (Min. of Education, S’pore)

Euterpe oleraceae is a large palm tree indigenous to the Amazon River and its tributaries and estuaries in South America. Its fruit, known as acai, is of great economic value to native people. In this study, a standardized freeze-dried acai fruit pulp/skin powder was used for all analyses and tests. Among many findings, anthocyanins (ACNs), proanthocyanidins (PACs), and other flavonoids were found to be the major phytochemicals. Two ACNs, cyandin 3-glucoside and cyanidin 3-rutinoside were found to be predominant ACNs; three others were also found as minor ACNs. The total content of ACNs was measured as 3.1919 mg/g dry weight (DW). Polymers were found to be the major PACs. The concentration of total PACs was calculated as 12.89 mg/g DW. Other flavonoids, namely, homoorientin, orientin, isovitexin, scoparin, and taxifolin deoxyhexose, along with several unknown flavonoids, were also detected. Resveratrol was found but at a very low concentration. In addition, components including fatty acids, amino acids, sterols, minerals, and other nutrients were analyzed and quantified. Total polyunsaturated fatty acid, total monounsaturated fatty acid, and total saturated fatty acids contributed to 11.1%, 60.2%, and 28.7% of total fatty acid. Oleic acid (53.9%) and palmitic acid (26.7%) were found to be the two dominant fatty acids. Nineteen amino acids were found; the total amino acid content was determined to be 7.59% of total weight. The total sterols accounted for 0.048% by weight of powder. The three sterols B-sitosterol, campesterol, and sigmasterol were identified. A complete nutrient analysis is also presented. Microbiological analysis was also performed.

Autoxidation of methyl linoleate (8:2 mixture with decane, 37 degrees C) was induced by 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN, 17.7 mM) and the kinetics of oxygen consumption monitored using a 96-well microplate coated with an oxygen-sensitive fluorescence probe, a ruthenium dye, embedded in a silicone matrix at the bottom of the microplate. The probe does not participate in the reaction; instead, its fluorescence intensity is inversely proportional to the solution oxygen concentration as it changes during oxidation. In the absence of antioxidants, the oxidation rate has a linear relationship with the square root of the initiator concentrations. This is in agreement with theoretical autoxidation kinetics equations. In the presence of tocopherol-type antioxidants, a sharp lag phase appears. The quantitation of the antioxidant capacity is achieved using the area under the curve (AUC) approach. The assay has a 2 h running time, a linearity range from 1.56 to 18.7 microM (Trolox), and a limit of quantitation at 2.7 microM Trolox equivalency. The peroxyl radical scavenging capacities of several cold-pressed and organically grown plant seed oils were quantified along with the tocopherol concentrations of the oils. Tocopherols contribute only a fraction of the peroxyl radical scavenging capacity of the oils, and there is poor correlation between total tocopherol concentrations and radical scavenging capacity, suggesting that the antioxidant capacity of oils is due not only to tocopherols but also to other lipid-soluble antioxidants.

A novel approach to monitoring of mainstream smoke reactive oxygen species (ROS) has been developed and applied to the quantitation of smoke oxidants. Redox-active fluorescent probe dihydrorhodamine 6G (DHR-6G) was selected as the molecular probe because it is sensitive to typical smoke ROS. The experimental system couples an automatic cigarette smoke machine fiber-optic fluorometer for real-time monitoring of the reaction progress between cigarette smoke and DHR-6G. Quantitation was achieved based on the amount of rhodamine 6G, which is the sole product from DHR-6G oxidation. With the optimization of the trapping efficiency, we detected 391 nmol of ROS/cigarette in the mainstream CS for a standard cigarette 2R4F under standard Federal Trade Commission smoking protocol. Applying this method, we quantified the ROS of selected cigarettes and found that the cigarettes made of burley tobacco have much ( approximately 10 times) higher ROS content in the smoke than that in the tobacco made of bright tobacco. The smokeless cigarette, Eclipse, has comparable ROS with cigarettes made of bright tobacco.

Both MH(Ph)(CO)L2 (L = PtBu2Me; M = Ru and Os) react with vinyl fluoride to form M–F bonds; however, Ru eliminates benzene, while Os eliminates ethylene. In contrast, Ru(H)2(CO)L2 and Os(H)2(CO)(1-butene)L2 both react with vinyl fluoride to give ethylene and MHF(CO)L2. Ethylene production from both dihydrides is attributed to β-F migration to M from an MCH2CH2F transient, while the unique behavior of RuH(Ph)(CO)L2 (giving the C–F oxidative addition product Ru(η1-vinyl)F(CO)L2) is attributed to the difficulty of achieving RuIV, and the ability of the strongly π-acidic vinyl fluoride to rapidly trigger reductive elimination of benzene. The products of reaction of RuH(Ar)(CO)L2 with vinyl fluoride are redirected more towards ethylene formation when Ar carries fluorine substituents. The reaction products of OsH(R)(CO)L2 with vinyl fluoride revert to R-H elimination when R is methyl. Finally, the more π-acidic H2C CF2 triggers very rapid CH4 elimination from OsH(CH3)(CO)L2; cleavage of the second C–F bond yields the vinylidene OsF2(CCH2)(CO)L2. All selectivity is rationalized via the fate of the adduct MH(R)(C2H4 − nFn)(CO)L2.

This review summarizes the multifaceted aspects of antioxidants and the basic kinetic models of inhibited autoxidation and analyzes the chemical principles of antioxidant capacity assays. Depending upon the reactions involved, these assays can roughly be classified into two types: assays based on hydrogen atom transfer (HAT) reactions and assays based on electron transfer (ET). The majority of HAT-based assays apply a competitive reaction scheme, in which antioxidant and substrate compete for thermally generated peroxyl radicals through the decomposition of azo compounds. These assays include inhibition of induced low-density lipoprotein autoxidation, oxygen radical absorbance capacity (ORAC), total radical trapping antioxidant parameter (TRAP), and crocin bleaching assays. ET-based assays measure the capacity of an antioxidant in the reduction of an oxidant, which changes color when reduced. The degree of color change is correlated with the sample's antioxidant concentrations. ET-based assays include the total phenols assay by Folin-Ciocalteu reagent (FCR), Trolox equivalence antioxidant capacity (TEAC), ferric ion reducing antioxidant power (FRAP), "total antioxidant potential" assay using a Cu(II) complex as an oxidant, and DPPH. In addition, other assays intended to measure a sample's scavenging capacity of biologically relevant oxidants such as singlet oxygen, superoxide anion, peroxynitrite, and hydroxyl radical are also summarized. On the basis of this analysis, it is suggested that the total phenols assay by FCR be used to quantify an antioxidant's reducing capacity and the ORAC assay to quantify peroxyl radical scavenging capacity. To comprehensively study different aspects of antioxidants, validated and specific assays are needed in addition to these two commonly accepted assays.

[RuHClL2]2, L = PiPr3, reacts with H2CCH(O2CR) (R = CH3, CF3, C6H5) during mixing at 20 °C, via two observable intermediates, to give RuCl(O2CR)(CHMe)L2; this carbene complex then redistributes the Cl and O2CR groups. Vinyl tosylate gives RuCl(OTs)(CHMe)L2 already at −60 °C. Vinyl chloroformate, H2CCH(O2CCl) reacts rapidly with [RuHClL2]2 to give the olefin metathesis catalyst RuCl2(CHMe)L2 and CO2. Os(H)3ClL2 (L = PiPr3 or PtBu2Me) reacts with vinyl esters H2CCHE (E = O2CR) to form first an η2-olefin adduct. This is followed by C/O bond cleavage, giving the carbyne OsHCl(O2CCF3)(CMe)L2. Vinyl chloroformate and Os(H)3ClL2 gives OsHCl2(CMe)L2 and CO2. RuHCl(PPh3)3 reacts with vinyl chloroformate, via RuCl(O2CCl)(CHMe)(PPh3)2, to give RuCl2(CHMe)(PPh3)2 while OsHCl(PPh3)3 reacts analogously, through observable OsCl2(CHMe)(PPh3)2, to form OsHCl2(CMe)(PPh3)2. Vinyl trifluoroacetate converts OsHCl(PPh3)3, to OsHCl(O2CCF3)(CMe)(PPh3)2. The less π-basic metal in OsH(CO)(PtBu2Me)2+ reacts with vinyl esters to give only an olefin adduct; detectable binding of the ester oxygen to Os in this adduct suggests a mechanism for carboxylate migration from carbene carbon to metal. The mechanisms of these reactions are explored, and the thermodynamic disparity between Ru and Os is discussed. DFT (B3PW91) calculations have been carried out to establish the energy pattern of possible products. The thermodynamic preference for cleaving the C–O2CR bond is shown to have a thermodynamic origin associated with the energy of the formed Ru–O2CR bond. The calculations also indicate the very large thermodynamic driving force for loss of CO2 in the case of H2CCH(O2CCl). The corresponding loss of CO2 is shown to be thermodynamically unfavorable in the case of H2CCH(O2CR). The energy of the Ru-R bond is a key factor.

The oxygen radical absorbance capacity (ORAC) assay has been widely accepted as a standard tool to measure the antioxidant activity in the nutraceutical, pharmaceutical, and food industries. However, the ORAC assay has been criticized for a lack of accessibility due to the unavailability of the COBAS FARA II analyzer, an instrument discontinued by the manufacturer. In addition, the manual sample preparation is time-consuming and labor-intensive. The objective of this study was to develop a high-throughput instrument platform that can fully automate the ORAC assay procedure. The new instrument platform consists of a robotic eight-channel liquid handling system and a microplate fluorescence reader. By using the high-throughput platform, the efficiency of the assay is improved with at least a 10-fold increase in sample throughput over the current procedure. The mean of intra- and interday CVs was ≤15%, and the limit of detection and limit of quantitation were 5 and 6.25 μM, respectively. Keywords: ORAC; anti...

The strongly near-IR-active mixed-valence diruthenium complex [Ru(2)TIEDCl(4)]Cl, where TIED = tetraiminoethylenedimacrocycle, was found to be a highly active catalyst for air oxidation of HS(-) forming polysulfide species and H(2)O(2). The reaction provides a convenient method for the detection of the HS(-) generation rate of a H(2)S donor of medical importance.

The development of convenient methods for sulfur dioxide and its derivatives analysis is critically important because SO2 causes worldwide serious environmental problems and human diseases. In this work, we show an unprecedented example of an energy-transfer-based fluorescence nanoprobe for selective and quantitative detection of SO2, through molecular engineering of the fluorescent carbon nanodots by a cyanine dye which have a unique reactivity to bisulfite, achieving a detection limit of 1.8 μM with a linear relationship (R(2) = 0.9987). The specific detection was not interfered with other potential coexisted species. In addition, the probe is demonstrated for the determination of SO2 gas in aqueous solution as well as for visually monitoring of SO2 gas in air. This nanomaterial based probe is easily prepared, fast responding, and thus potentially attractive for extensive application for the determination of SO2 and other similar air pollutants.

The aim of this study was to investigate the antitumor and antivascular effects of PD806, a new oral prodrug of AVE8063 in vitro and in vivo. The cytotoxicity of PD806 was determined against H22, Walker 256, A549, MCF-7, and BEL-7402 cells using MTT assays. Plasma pharmacokinetic analysis of AVE8063 generated in rats after a single oral administration of PD806 was carried out using the high-performance liquid chromatography method. H22 tumor-bearing mice models were used to show the antitumor activity. Antivascular responses were monitored by in vivo MRI and immunohistochemistry (CD31) in W256 tumor-bearing rats. A blood test and histopathology were performed to evaluate the toxicity of PD806. PD806 showed cytotoxicity against five types of tumor cell lines with the IC50 values in the micromolar concentration. A pharmacokinetic study indicated that PD806 converted into the active form, AVE8063, which showed a half-life of 5.24±0.70 h in rats. Daily oral administration of PD806 inhibited the growth of subcutaneously implanted H22 tumors in a dose-dependent manner. The tumor volume in the 300 mg/kg PD806 group was obviously smaller than that of the vehicle control group from day 6 onward (P

Hypericin (Hy) has shown great promise as a necrosis-avid agent in cancer imaging and therapy. Given the highly hydrophobic and π-conjugated planarity characteristics, Hy tends to form aggregates. To investigate the effect of aggregation on targeting biodistribution, nonaggregated formulation (Non-Ag), aggregated formulation with overconcentrated Hy in dimethyl sulfoxide (Ag-DMSO) solution, and aggregated formulation in water solution (Ag-water) were selected by fluorescence measurement. They were labeled with ¹³¹I and evaluated for the necrosis affinity in rat model of reperfused hepatic infarction by gamma counting and autoradiography. The radioactivity ratio of necrotic liver/normal liver was 17.1, 7.9, and 6.4 for Non-Ag, Ag-DMSO, and Ag-water, respectively. The accumulation of two aggregated formulations (Ag-DMSO and Ag-water) in organs of mononuclear phagocyte system (MPS) was 2.62 ± 0.22 and 3.96 ± 0.30 %ID/g in the lung, and 1.44 ± 0.29 and 1.51 ± 0.23 %ID/g in the spleen, respectively. The biodistribution detected by autoradiography showed the same trend as by gamma counting. In conclusion, the Non-Ag showed better targeting biodistribution and less accumulation in MPS organs than aggregated formulations of Hy. The two aggregated formulations showed significantly lower and higher accumulation in targeting organ and MPS organs, respectively.

There is a growing account of the health benefits of H2S as an endogenous cell-signaling molecule. H2S from organic polysulfides, in particular, is increasingly gaining attention for their beneficial effects to cardiovascular health. Here, we studied shallot as a potential dietary source of organic polysulfides and examined the effects of processing conditions on its polysulfide profiles. Boiling, autoclaving, and freeze-drying were tested on whole and crushed shallot bulbs, analyzing their effect on the yield of organosulfides. Seventeen organosulfides, including disulfides, trisulfides, and cyclic polysulfides, were identified. Significant differences in the quantitative and qualitative profiles of organosulfides in the hydrodistilled and solvent extracted oils were observed. Freeze-drying retained the majority of the organosulfides, but the whole-autoclaved and whole-boiled shallots lost more than 95% of their organic polysulfides. Crushed-boiled and crushed-autoclaved shallot lost 76-80% of their organosulfides, likely due to the thermal sensitivity of these compounds. The organosulfide profiles are sensitive to the pH values of the processing media. In general, disulfides increased at basic pH (pH 9.0) while trisulfides and cyclic organosulfides are much higher at the acidic to neutral pH values (pH 3.0-5.0). Our results provide important information on the effects of processing conditions that are relevant for optimizing extraction of organosulfides from shallot for further studies evaluating their H2S-releasing activity.

Taking advantage of a nitrogen dioxide (NO2)-selective probe reported by our group previously, we have developed a fluorescent assay for quantifying NO2 absorbance capacity of flavanols and related polyphenolic compounds. A non-fluorescent Ni(II) dithiocarbamate complex containing sulforhodamine fluorophore reacted rapidly and selectively with NO2 and turned on the fluorescence of the rhodamine. In the presence of radical scavengers, such as tea catechins, the rates of the fluorescence turning on by NO2 were suppressed in a dose-dependent manner. When a simple kinetic equation of the initial reaction rates is applied, the rate constants of the antioxidant reaction with NO2 can be derived using epicatechin as a reference standard, and the value is comparable to that obtained by the pulse radiolysis method. The scavenging capacity against NO2 of nine common phenolic compounds was evaluated, and their structure-activity relationship was also established. Additionally, the mechanism behind NO2 scavenging by phenolic compounds was determined by liquid chromatography-mass spectrometry and secondary mass, using epicatechin and gallic acid as examples. Our assay serves as the first example for convenient and sensitive quantification of NO2 scavenging activity of antioxidants.

Oligomeric proanthocyanidins (OPCs, Ar′ = 3,4-(HO) 2 (C 6 H 3 ) are abundant natural products found in agricultural and forestry waste such as pine bark, grape seeds, and the peels of mangosteen. We have demonstrated that the OPCs can be converted into small molecule chiral ligands by using proper nucleophiles for acid depolymerization of the OPCs. The chiral ligands may have potential for sustainable asymmetric catalysis.