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We investigated the mechanism of selenium (Se) tolerance using an Arabidopsis thalianaknockout mutant of a sulfate transporter, sultr1;2. Se stress inhibited plant growth, decreased chlorophyll contents, and increased protein oxidation and lipid peroxidation in the wild type, whereas the sultr1;2mutation mitigated damage of these forms, indicating that sultr1;2is more tolerant of Se than the wild type is. The accumulation of symplastic Se was suppressed in sultr1;2as compared to the wild type, and the chemical speciation of Se in the mutant was different from that in the wild type. Regardless of Se stress, the activities of ascorbate peroxidase, catalase, and peroxidase in the mutant were higher than in the wild type, while the activity of superoxide dismutase in the mutant was the same as in the wild type. These results suggest that the sultr1;2mutation confers Se tolerance on Arabidopsis by decreasing symplastic Se and maintaining antioxidant enzyme activities.

We tested synthetic food colorants for their antioxidative potential by the in vitrosuperoxide generation assay in differentiated HL-60 cells in response to phorbol ester. Among the 12 colorants tested, such fluorescein-type red colorants as rose bengal showed potent inhibitory activity without any cytotoxicity under dark conditions. The intracellular accumulation and superoxide anion scavenging effect of rose bengal were at least partly involved in the inhibitory activity.

The application of exogenous proline and glycinebetaine (betaine) confers salt tolerance on plants under salt stress. The effects of exogenous proline and betaine on apoplastic flow in rice plants under saline conditions were investigated using trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS), an apoplastic tracer. Rice plants took up more PTS under light conditions than under dark conditions. Salt stress increased PTS uptake and Na+content of rice leaves, but did not affect K+content, resulting in a lower K+/Na+ratio. Addition of proline or betaine to the saline medium suppressed Na+-induced PTS uptake and Na+accumulation, while the K+content was slightly increased, which led to a high K+/Na+ratio under saline conditions. These results suggest that exogenous proline and betaine suppressed Na+-enhanced apoplastic flow to reduce Na+uptake in rice plants.

Cellular phototoxicity induced by UVA irradiation and its potential application to therapy has been reported. In the present study, the induction of apoptosis induced by β-carotene and dimethyl tetrasulfide (Me2S4) assisted by UVA irradiation in HL-60 cells was assessed. β-carotene assisted by UVA significantly decreased the cell viability and induced DNA fragmentation in HL-60 cells. Me2S4combined with β-carotene and assisted by UVA significantly inhibited the cell viability, and enhanced the caspase-3 activity which was completely inhibited by N-acety-L-cysteine. β-carotene was significantly degraded by UVA, but this was not accelerated by Me2S4in a cell culture system. The photodegradation products of β-carotene prepared by UVA irradiation regardless of the addition of Me2S4showed lower cytotoxicity than β-carotene itself in HL-60 cells. These results suggest that the ROS- and caspase-3-dependent apoptosis induced by β-carotene and Me2S4assisted by UVA was due to a synergistic action rather than to the sole effect of the photodegradation products of β-carotene in HL-60 cells.

(−)-Epigallocatechin-3-gallate (EGCG)-induced apoptosis was along both the extracellular signal-regulated protein kinase (ERK) and c-jun N-terminal kinase (JNK) pathways in Jurkat cells. Co-treatment with EGCG potentiated the cytotoxicity induced by benzyl isothiocyanate (BITC) and H2O2, both being inhibited by ERK and JNK inhibitors. These results suggest the significant role of mitogen-activated protein kinase (MAPK) signaling in the apoptosis induction regulated by EGCG alone and in combination.

Organosulfur compounds have been established to possess anticancer effects. To provide a better understanding of the biological function of dimethyl sulfides, dimethyl monosulfide (Me2S), dimethyl disulfide (Me2S2), dimethyl trisulfide (Me2S3) and dimethyl tetrasulfide (Me2S4) were used as experimental materials to investigate their effects on apoptosis induction in human leukemia Jurkat cells and HL-60 cells. Treatment with 20 μMdimethyl sulfides for 24 h decreased the viability of both cells. The cell viability-reducing effect of these sulfides was in the following order: Me2S4≈ Me2S3> Me2S2≈ Me2S for Jurkat cells and Me2S4> Me2S3> Me2S2≈ Me2S for HL-60 cells. Me2S3and Me2S4significantly induced DNA fragmentation and caspase-3 activation. The addition of GSH or NAC completely suppressed the sulfide-induced apoptosis. Our results indicate that dimethyl sulfides with a larger number of sulfur atoms more strongly induced apoptosis in both human leukemia cells viaROS production and caspase-3 activation.

We investigated the role of glutathione (GSH) in stomatal movements using a GSH deficient mutant, chlorinal-1 (ch1-1). Guard cells of ch1-1mutants accumulated less GSH than wild types did. Light induced stomatal opening in ch1-1and wild-type plants. Abscisic acid (ABA) induced stomatal closure in ch1-1mutants more than wild types without enhanced reactive oxygen species (ROS) production. Therefore, GSH functioned downstream of ROS production in the ABA signaling cascade.

Carotenoids are used in wide-ranging food applications, but they are susceptible to degradation by many factors including light. We examined the photodegradation of five kinds of carotenoids and three kinds of anthocyanins to clarify which structures of pigments were favorable to accelerated degradation by sulfides under UVA irradiation. Under UVA irradiation, crocetin and crocin were decomposed more rapidly in the presence of dimethyl tetrasulfide than in the absence of the sulfide, but not as rapidly as β-carotene, zeaxanthin and β-cryptoxanthin were. However, cyanidin was decomposed more slowly in the presence of sulfide than in the absence of sulfide. Moreover, the photodegradation of kuromanin and keracyanin was not affected by the addition of a sulfide. We also examined the mechanism for this accelerated degradation. Normal hexane was more favorable to the photodegradation of β-carotene than methanol and ethanol. The accelerated degradation was inhibited by free radical scavengers, but enhanced by the addition of deuterium oxide. These results suggest that conjugated double bonds were favorable to the accelerated photodegradation by sulfide and that this reaction was mediated by free radicals.

The photodegradation of carotenoids by UVA irradiation in the presence of sulfides was investigated. The sulfides accelerated the photodegradation of carotenoids. A larger number of sulfur atoms of coexistent sulfides was more favorable to the acceleration effect of sulfides on the photodegradation of β-carotene, but the alk(en)yl group of sulfides was less favorable to the acceleration effect of sulfur compounds. The acceleration effect depended on light intensity, temperature, and the initial concentrations of β-carotene and sulfide.

A simple and sensitive specrophotometric method combined with solid-phase extraction (SPE) for the simultaneous determination of sodium linear-dodecylbenzenesulfonate (DBS) and sodium dodecyl sulfate (SDS) is described. The C2 (ethyl group bonded silicagel) cartridge could be repeatedly used more than 500 times for SPE, and it enabled the anionic surfactants to be concentrated by 50-fold. The calibration graph for DBS was linear in the range from 1.6×10−8Mto 5.0×10−7Mand for SDS from 2.0×10−9Mto 3.0×10−7M. The relative standard deviation (n=5) for 5.0×10−7MDBS was 3.1% and for 2.5×10−7MSDS was 1.7%. The proposed method was applied to the simultaneous determination of DBS and SDS in river-water samples.

A tyrosinase inhibitor was isolated from the seeds of Euphorbia lathyrisL. by bioassay-guided fractionation and purification, using silica gel column chromatography. It was identified as esculetin by comparing its physical properties and spectral data with those of an authentic sample. The IC50value of esculetin in the mushroom tyrosinase activity test was 43 μM. The kinetic study indicates that esculetin exhibited competitive inhibition against the oxidation of 3-(3,4-dihydroxyphenyl)-alanine by mushroom tyrosinase. The structure-activity relationships among five esculetin analogs suggest that hydroxyl groups at the C6 and C7 positions of the coumarin skeleton played an important role in the expression of tyrosinase inhibitory activity.

A rapid and sensitive spectrophotometric method for the simultaneous determination of sodium dodecyl sulphate (SDS) and sodium linear-dodecylbenzenesulphonate (DBS) with 1-stearyl-4-(4-aminonaphthylazo)-pyridinium bromide (SAPB) is described using the difference at the maximum absorption wavelength of the SDS- and the DBS-ion associate. SDS and DBS have been determined independently by measuring their respective absorbances at the maximum absorption wavelength. The apparent molar absorptivities of the SDS- and the DBS-ion associate are 8.0×104 l mol-1 cm-1 at 445 nm and 4.5×104 l mol-1 cm-1 at 424 nm, respectively. The calibration graph for SDS is linear in the range from 0.1 to 1.0×10-6 mol/l in the presence of 1.2×10-6 mol/l DBS and for DBS from 0.8 to 2.0×10-6 mol/l in the presence of 8.0×10-7 mol/l SDS. The relative standard deviation (n=15) for 8.0×10-7 mol/l SDS is 3.4% and for 1.6×10-6 mol/l DBS 2.1%. The proposed method has been applied to the simulatenous determination of SDS and DBS in river water samples.

A new cationic dye, 1-(10-bromodecyl)-4-(4-aminonaphthylazo)-pyridinium bromide, was synthesized and evaluated as a new reagent for the determination of anionic surfactants. The reagent reacts with anionic surfactants, such as sodium dodecylsulphate and sodium dodecylbenzenesulphonate, to produce an ion associate in an aqueous medium. The colour change occurs simultaneously, and the colour development is very stable. This makes it possible to determine anionic surfactants directly by spectrophotometry without solvent extraction. The stoichiometric ratio of the ion associate was found to be 1:1 by the mole ratio method. The calibration graph was linear up to 2.5×10-6 mol/l. The apparent molar absorptivity of the ion associate was 5.3×104 l mol-1 cm-1 (at 595 nm). The relative standard deviation (n=10) for 1.2×10-6 mol/l sodium dodecylsulphate was 4.9%. The proposed method was applied to the determination of anionic surfactants in tap and river waters.

A facile and efficient synthetic procedure of o-phenylenedizinc(II) compound from o-diiodobenzene and zinc powder under the irradiation of ultrasound is reported. The compound was proved to be a unique reagent supplying o-phenylenedianion of high chemoselectivity. Symmetrically 1,2-diaryl or diaroyl substituted benezenes were obtained in good yields by Pd(0)-catalyzed cross-coupling of the compound with aryl halides or acyl halides.

Eleven pyridinium azo dyes with straight-chain alkyl groups CnH2n+1-(n=6-18) and bromoalkyl groups BrCmH2m-(m=6-12) were synthesized with the intention of developing reagents for the determination of low levels of anionic surfactants in an aqueous medium. The effect of the alkyl chain length of these reagents on the reactivity with anionic surfactants such as sodium dodecylsulphate (SDS), sodium linear-dodecylbenzenesulphonate (DBS), sodium dodecylsulphonate (DS) and sodium laurate (SL) was studied. It was found that the alkyl chain length played an important role in the formation of ion associates and the composition of the ion associates formed. These reagents were classified into four groups with respect to the reactivity with anionic surfactants. The first group (n,m=6) reacts only with DBS. The second group (n,m=8) reacts with SDS, DBS and DS. The third group (n,m=10, 12) reacts with SDS, DBS and DS; however, the colour intensity of the DBS-ion associate was unstable. The fourth group (n=14, 16, 18) reacts with all anionic surfactants examined, and the composition of the ion associates with SDS and DS was 2:1 ([reagent]/[surfactant]) though that of the ion associates of the three reagent groups mentioned above was 1:1. The optimal conditions for the determination of anionic surfactants in river water with 1-octyl-4-(4-aminonaphthylazo)-pyridinium bromide was examined. The calibration graph was linear up to 3×10-6 mol/l, and the apparent molar absorptivity of the ion associate was 3.8×104 l mol-1 cm-1 (at 427 nm). The relative standard deviation for 2.4×10-6 mol/l SDS was 4.9%. Recoveries of 88–107% were found for 8.0×10-7 mol/l SDS in river water samples.

A rapid and sensitive spectrophotometric method for the determination of sodium iinear-dodecylbenzenesulfonate (DBS) with 1-pentyl-4-(4-aniinonaphthylazo)-pyridinium bromide (PANP) in the presence of sodium dodecyl sulfate (SDS) is proposed. The method is based on the formation of the ion associate of DBS with PANP, and does not require any solvent-extraction procedure. PANP was found to react selectively with DBS to form an ion associate, which caused a new light-absorption near to 416 nm, The apparent molar absorptivity of the DBS-ion associate with PANP was found to be 4.6×104dm3mol−1cm−1at 416 nm. A calibration graph was linear over the ranges from 0.1 to 2.0× 10−6mol dm−3DBS. The relative standard deviation (n=10) for 1. 2×10−6mol dm−3DBS was 2.0%. The proposed method can be applied preferably to the determination of DBS in river-water samples.

The gas-chromatographic method using an electron-capture detector has a high sensitivity for the determination of selenium. Moreover, as the reaction of selenium(IV) with 4-nitro-o-phenylenediamine is scarcely disturbed by other elements, the chemical separation from the matrix element is not necessary. The direct determination of very small amounts of selenium in copper and copper salts has been investigated. A mixture of equal volumes of nitric acid, hydrochloric acid, and perchloric acid dissolves the copper sample and also oxidizes the selenium to the quadrivalent state quantitatively. No loss of selenium was observed upon this treatment. The proposed method can determine the selenium in copper samples in amounts as low as 0.005 µg/g.

Selenium(IV) reacts with 4-nitro-o-phenylenediamine to form 5-nitropiaselenol, which is detected by means of a gas chromatograph equipped with an electron-capture detector. By this highly sensitive method, the determination of very small amounts of selenium in plant materials has been investigated. Fuming nitric acid digests the plant sample completely, and the selenium is converted to the quadrivalent state. No loss of selenium can be found by this treatment. A method is proposed for the determination of selenium in plant materials at levels as low as 0.005 µg/g in dried material.

2-(1,8-Dihydroxy-3,6-disulfo-2-naphthylazo)-phenoxyacetic acid reacts with the uranyl ion in an acidic medium to form a violet chelate. The composition of the chelate is 1 : 1 in the molar ratio. The apparent stability constants over the pH range from 3.4 to 5.2 and the formation constant of the chelate, are estimated spectrophotometrically at 25°C and an ionic strength of 0.1 by the use of KNO3. The value of the formation constant was calculated as 1.25×1010from the apparent stability constants.

Liposomes, in which β-carotene, β-cryptoxanthin, zeaxanthin, β-cryptoxanthin palmitate or β-cryptoxanthin acetate had been embedded, were irradiated by UVA, and the rate of degradation of each carotenoid was measured. There was no significant difference in the degradation rate between β-carotene, β-cryptoxanthin and zeaxanthin. The degradation rates of β-cryptoxanthin palmitate and β-cryptoxanthin acetate were faster than that of β-cryptoxanthin, and the degradation rate of β-cryptoxanthin palmitate was faster than that of β-cryptoxanthin acetate.

Ethyl 4,7,10,13,16,19-docosahexaenoate (DHA-Et) dissolved in an ethanol solution or embedded in liposomes was degraded by irradiating with γ rays in a dose-dependent manner. The degradation rate of DHA-Et embedded in liposomes was higher than that of DHA-Et dissolved in ethanol. Antioxidants suppressed the degradation of DHA-Et embedded in liposomes, the order of activity of the antioxidants being luteolin>fisetin>kaempferol>quercetin>rutin. These results suggest that the hydrophobicity (logP) of an antioxidant is one of determinants for antioxidative activity, but that a vicinal diol structure in the B ring is not favorable for the antioxidative activity.

Selenium (IV) reacts with 4-nitro-o-phenylenediamine to form 5-nitropiaselenol, which is detected by means of a gas chromatograph equipped with an electron-capture detector. By this highly sensitive method, the selenium in pure tellurium metal (99.9–99.999%) can easily be determined. Aqua regia oxidizes both selenium and tellurium to the quadrivalent state, and no loss of selenium is found upon this treatment. This method requires only 10–30 mg of a tellurium sample, and the presence of foreign ions does not interfere. It was found that pure tellurium, commercially available, always contains 10-3–10-4% selenium.

The method of determining micro amounts of fluorine is based on the bleaching of the thorium complex of 2-(1, 8-dihydroxy-3, 6-disulfo-2-naphthylazo)-phenoxyacetic acid (PAC) by fluoride ions, which are strongly coordinated to the thorium in the complex and with thus liberate the free PAC. The complex is composed of thorium and PAC in a 1 : 1 molar ratio. PAC has an absorption maximum at 525 mµ, while the thorium complex shows a maximum at 555 mµ. The determination is based on the decrease in the absorbance at 610 mµ. Beer’s law holds up to 30 µg fluoride ions per 25 ml. The optimum pH range is from 2.5 to 3.5. The apparent molar extinction coefficient is calculated to be 20000.

A new reagent, 1-(N-methylpyridinium-4-yl-azo)-4-(4-diethylaminophenylazo)naphthalene iodide, can react with sodium 4-dodecylbenzenesulfonate to show a color change in an aqueous phase in the presence of iodide ion. The calibration graph is straight line up to 1.2×10-5M (1 M=1 mol dm-3); e=3.25×1041 mol-1cm-1at 580 nm.

A new reagent, 1-(4-N-methylpyridiniumazo)-4-(4-aminophenylazo) naphthalene iodide, can react with sodium alkylbenzenesulfonate to show a color change in an aqueous medium. The calibration graph is straight line over the range from 8×10−6to 3.0×10−5M of sodium dodecylbenzenesulfonate. The practical molar absorptivity is 1.8×1041 mol−1cm−1at 594 nm.