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Young coconuts (Cocos nucifera L.) used for export are trimmed to reduce their size and weight to lower transport costs. However, trimmed coconuts have a shorter shelf life due to microbial spoilage and surface discoloration caused by enzymatic browning. To minimize these effects, trimmed coconuts were dipped in an anti-browning agent, sodium metabisulfite (SMB), and stored under ambient conditions. However, there have been no reports on the effects of SMB treatment on metabolome changes in the flesh and water of young coconuts. Hence, this study investigated the metabolite changes in trimmed young coconuts after SMB treatment under different storage conditions using a gas chromatography (GC)/mass spectrometry (MS) metabolomic profiling approach. Tall young coconut samples were trimmed and treated with a 2% SMB solution for 5 min before storage at 25 °C or 4 °C for 2–4 weeks. Coconut flesh and water samples were collected after storage for 0, 2, and 4 weeks, and were subjected to GC–MS analysis. The results showed that the major metabolites affected by coconut deterioration were amino acids, sugars, and sugar alcohols. SMB treatment and/or refrigeration can help prevent metabolite changes in the flesh and water of young coconuts. In the future, improvements in storage conditions based on metabolite profiles should be explored. [Display omitted] [ABSTRACT FROM AUTHOR]

There has been a growing demand for the development of high protein beverages in the food industry. However, during thermal processing, high-protein beverages undergo protein aggregation and gelation. In this study, thermostable soy protein was prepared by disulfide bond cleavage combined with preheating treatment. Thermostable soy protein had a higher denature extent than the control sample, which prevented the formation of larger aggregates upon reheating. Thermostable soy protein possessed lower viscosity (nearly 0 Pa·s) and an excellent fluidity index (around 0.8) after reheating at a concentration of 10 % (w / v), whereas the control sample had gelled. Moreover, rheology and dynamic light scattering collectively demonstrated that a minimum of 2.5 mM sodium metabisulfite (Na 2 S 2 O 5) was required to prepare thermostable protein solutions. The present study shows an innovative method to produce thermostable soy protein. Flowchart for Modified Protein Preparation. Diagram of Chemical Mechanism of Reductant Modification. [Display omitted] • Reducing and heat combined treatment was effective in preparing stabilized soy protein. • Combined treatment endowed proteins with larger particle size and denaturation degree than natural proteins. • Modified proteins (10 wt%) exhibited good fluidity and resisted gelling during heating. [ABSTRACT FROM AUTHOR]

To improve the toughness of the rice dough, protein transglutaminase (TGase) combined with sodium metabisulfite (SMB) modification was used. The influences of modification on rice dough and protein were investigated, and their physicochemical and structural characteristics were analyzed. Mechanical analysis results indicated that the tanδ and texture characteristics of the modified rice dough were close to those of the wheat dough. The content of weakly bound water increased after rice dough modification. The average particle size of the modified rice protein (MRP) increased. The α-helix and β-turn increased, the β-sheet of MRP was reduced. The hydrogen, ionic, and hydrophobic bond contents of the MRP were significantly higher than those of the unmodified rice protein (URP). The results showed that TGase combined with SMB changed the URP network structure, thereby effectively regulating the viscoelastic balance of the unmodified rice dough. • Rice ball modification by adding SMB combined with TGase. • Similar tanδ and texture characteristics for modified rice dough and wheat dough. • Modification-induced change in the rice protein network structure. • Effective regulation of the viscoelastic balance of the rice dough. [ABSTRACT FROM AUTHOR]

Myofibrillar protein (MP) gels are susceptible to oxidation, which can be prevented by complexing with hydrophilic polyphenols, but may cause gel deterioration. Sodium metabisulfite (Na 2 S 2 O 5) has been used to induce self-assembly of MP and analyze the impact of self-assembly on the quality of composite gels containing high amounts of (−)-epigallocatechin gallate (EGCG). Hydrophobic forces were confirmed as the main driver of self-assembly. Self-assembly reduced the size of the MP–EGCG complex to approximately 670 nm and increased the gel's hydrophobic force by approximately 3.6-fold. The maximum hardness of the Na 2 S 2 O 5 -treated MP–EGCG composite gel was 52.43 g/kg, which was approximately 49% greater than pure MP gel. After oxidative treatment, the Na 2 S 2 O 5 -treated MP–EGCG composite gel had considerably lower carbonyl and dityrosine levels (2.47-μmol/g protein and 450 a.u.) than the control (8.37-μmol/g protein and 964 a.u.). Therefore, Na 2 S 2 O 5 shows potential as a cost-effective additive for alleviating MP limitations in the food industry. • Sodium metabisulfite-induced self-assembly of myofibrillar protein (MP). • Self-assembled MP formed stronger gel via increased hydrophobic interactions. • Self-assembly reduced size of MP-epigallocatechin gallate (EGCG) complexes. • Composite gels of self-assembled MP-EGCG exhibited enhanced oxidative stability. [ABSTRACT FROM AUTHOR]

This study reports a facile synthesis and the cytotoxic evaluation of N –H benzimidazoles. This synthetic method made use of the condensation reaction between o -phenylenediamine and benzylamine and was highlighted by its solvent-free reaction conditions and short reaction time with the use of Na 2 S 2 O 5 as an inexpensive and environmentally friendly oxidizing agent. The cytotoxicity assays revealed that the benzimidazole derivatives 3l , 3h , and 3r displayed strong activity against the HeLa cancer cell line with the IC 50 of 1.54 μM, 0.86 μM, and 1.03 μM, respectively, which were 5.6-fold, 10-fold, and 8-fold stronger than the positive control 5-fluorouracil (5-FU, IC 50 = 8.61 μM). Furthermore, both compounds 3h and 3r exhibited similar cytotoxicities against MCF-7, which were equivalent to that of 5-FU and about 2.5-fold stronger than 5-FU towards the A549 cell line. [Display omitted] [ABSTRACT FROM AUTHOR]

• Metabisulfite-treated fruit and vegetable discards were subjected to 7-day aerobic exposure. • Weight loss on a dry matter basis was negligible in metabisulfite-treated silages. • Free sulfite content diminished to a negligible amount after 30-day ensiling. • The metabisulfite load of 3.2 g/kg biomass provided the best conservation indices. The high moisture and soluble carbohydrates contents of fruit and vegetable discards accelerate putrefaction; thus, the immediate use of preservatives is necessary to prevent their decay and allow further use. Two series of experiments were performed to evaluate the conservation stability of fruit and vegetable discards through ensiling. Fruit and vegetable discards were not treated or treated with 6 g sodium metabisulfite/kg fruit and vegetable discards and aerobically challenged for 7 days. In Experiment 1, sodium metabisulfite-treated fruit and vegetable discards were ensiled alone as high-moisture biomass. Silage fermentation was not effective in preventing the deterioration and mold control, which resulted in the rapid depletion of sugars and dry matter loss in control silage (without sodium metabisulfite). Conversely, the low number of undesirable microorganisms resulted in the negligible loss of nutrients in the sodium metabisulfite-treated silage. In Experiment 2, sodium metabisulfite-treated fruit and vegetable discards were co-ensiled with dry by-product feeds at varying proportions to provide sodium metabisulfite loads of 1.6, 2.4, 3.2, and 4 g/kg biomass. Based on microbiological, nutrient composition, and organoleptic evaluations, the sodium metabisulfite load of 3.2 g/kg biomass provided the most desirable conservation parameters. This study provides a clean route to the safe utilization of the discards for a prolonged period, with negligible dry matter and nutrient loss. [ABSTRACT FROM AUTHOR]

Microbial growth and browning cause quality loss in intermediate moisture foods. This research developed and characterized novel active films to prevent microbial growth and brown discoloration in dried meat and fruits. Biodegradable films based on thermoplastic starch (TPS) and poly(butylene adipate-co-terephthalate) (PBAT) blends incorporating sodium metabisulfite (SM) (up to 7% w/w) were developed using blown film extrusion. SM interacted with the TPS phase, involving O-H stretching vibration and hydrogen bonding which modified the thermal degradation behavior of the TPS phase and improved the smoothness of the film microstructures. Excessive SM formed crystal particles at ≥ 3% that were detected by X-ray diffraction. Addition of SM decreased the mechanical properties but film clarity and hydrophobicity improved, with enhanced water vapor barrier properties. The SM blend film showed significant antibacterial activity against E. coli , B. cereus , and S. aureus. TPS/PBAT/SM active films effectively prevented mold growth and darkening in packaged salami for at least 16 days, while the non-SM blend film was only effective for 6 days at room conditions. Active films with SM loading, particularly at > 3% prevented browning reaction and darkening in dried bananas and longans at both ambient (60% RH) and 85% RH stored at room temperature. SM addition improved packaging characteristics and functional efficiency, resulting in higher dried fruit and meat product quality. TPS/PBAT/SM composite films showed promise as sustainable active packaging and an alternative technique to sulfite treatment for dried fruit and meat. • Blown TPS/PBAT blended sulfites ≥ 1% prevented mold growth in dried meat. • Release of sodium metabisulfite as sulfur dioxide prevented browning in dried fruits. • Higher TPS ratio in TPS/PBAT films better prevented mold and discoloration. • Sulfite interacted with TPS phase via H-bonding, increasing amorphous starch. [ABSTRACT FROM AUTHOR]

[Display omitted] • Selective Cu-Mo flotation is studied using a complex Cu-Mo concentrate in seawater. • Sodium metabisulfite (Na 2 S 2 O 5) selectively depressed copper flotation in seawater. • The selective depressing effect of Na 2 S 2 O 5 is effective at weakly acidic condition. • Mo recovery was 94% by adding emulsified diesel oil after Na 2 S 2 O 5 treatment. • Na 2 S 2 O 5 treatment produced Cu-Mo separation efficiency of 83%. The main challenge for the selective flotation of copper and molybdenum (Cu-Mo) sulfide minerals in seawater is the formation of colloidal precipitates in strongly alkaline conditions. These precipitates hinder the selective separation of copper from molybdenum minerals in seawater by lowering the floatability of Cu-Mo sulfide minerals. The present study aimed to examine the direct utilization of seawater in the selective flotation of Cu-Mo sulfides. Additionally, the effectiveness of sodium metabisulfite (Na 2 S 2 O 5) as a copper depressant for selective flotation of Cu-Mo sulfides in seawater was studied under weakly acidic, neutral, and moderately alkaline conditions. A complex Cu-Mo concentrate that largely consisted of chalcopyrite and molybdenite, as well as a tiny amount of pyrite and quartz, was used in the flotation tests. The flotation results revealed that treatment with 3.6 kg/t Na 2 S 2 O 5 in seawater at pH 5.5 significantly lowered the copper recovery from 97% to 11% and caused a modest reduction in the molybdenum recovery from 98% to 94% with a Cu-Mo separation efficiency of 83%. These flotation results demonstrate that Na 2 S 2 O 5 treatment in seawater selectively depresses the floatability of copper minerals. Consequently, molybdenum can be separated from copper minerals under a weakly acidic condition in seawater. In addition, this study discusses the effects of various pH conditions and dosages of Na 2 S 2 O 5. The surface properties of Cu-Mo minerals were studied using X-ray photoelectron and infrared spectroscopies, and a mechanism to explain the selective flotation of Cu-Mo using Na 2 S 2 O 5 treatment in seawater is proposed. [ABSTRACT FROM AUTHOR]

Sodium benzoate and sodium metabisulfite are two of the most common artificial preservatives found in processed food. Little is known about their long-term effects on the health of consumers. Studies that investigated the potential toxic effects of these compounds have also reported a side effect of lifespan extension in the animals tested. Although lifespan extension was not the main focus of these studies, it is a noteworthy observation that warrants further investigation and discussion. Several studies also reported that animals fed with sodium benzoate and sodium metabisulfite had a reduction in their appetite, which was accompanied by an improvement in their health. This suggests that caloric restriction was likely activated when the appetite was reduced, which led to the extended lifespan observed in the animals fed with sodium benzoate and sodium metabisulfite. In addition to being implicated in longevity and appetite suppression, sodium benzoate and sodium metabisulfite are also thought to augment serotonin production. Serotonin stimulates the anorexigenic pathway leading to satiety, which could trigger caloric restriction. The elevated serotonin level may also induce a nootropic action, enhancing neurocognition. We hypothesize that sodium benzoate and sodium metabisulfite could upregulate serotonin synthesis, activating caloric restriction and leading to prolonged lifespan and enhanced cognitive function. [ABSTRACT FROM AUTHOR]

This study aimed to achieve effective in vivo detoxification of deoxynivalenol (DON) contained in piglet feedstuff by developing sodium metabisulfite (SMBS)-containing Eudragit L100-55 (ES) microparticles as a novel feed additive. DON detoxification was assessed in vitro (IPEC-J2 cell) and in vivo (piglet). Within 2 h of exposure to simulated gastric fluid (SGF), 14.31% of encapsulated SMBS was released from ES microparticles, while 82.93% was released in another 80 min in simulated intestinal fluid (SIF). In IPEC-J2 cells, 0.1% ES microparticles remediated the toxicity of DON after 2 h incubation in SGF and 40 min in SIF. Forty weaned piglets with similar body weights (10 pigs/treatment) were fed for 28 days. Four diets were used: negative control (NC, 0.00 ppm DON), positive control (PC, 3.33 ppm DON), pure SMBS (PST, 3.33 ppm DON and 0.2% SMBS), and ES microparticles (EST, 3.33 ppm DON and 0.40% ES microparticles). The PC diet reduced ADG by 21.4% and ADFI by 20.1% compared to the NC diet (P < 0.05). The EST diet increased ADG and ADFI by 21.7% and 17.7% compared to the PC diet (P < 0.05), with no significant difference from the NC diet (P > 0.05). Compared to the PC and PST diets, the EST diet increased villus height, villus height/crypt depth ratio, mRNA levels of claudin 3 and peptide transporter 1, and decreased mRNA level of toll-like receptor 4 (P < 0.05). ES microparticles could protect SMBS, and the released SMBS could mitigate the toxic effects of DON in piglets. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] Direct arylsulfonylation of arylethenes with aryl iodides and sodium metabisulfite to access β-keto sulfones is described. In this reaction, rongalite (sodium hydroxymethanesulfinate) and sodium metabisulfite serve as the radical promoter and the sulfur dioxide surrogate, respectively. [ABSTRACT FROM AUTHOR]

Four experiments were conducted to ascertain the effects of hydrothermal treatment and sodium metabisulfite (SMB) on deoxynivalenol (DON)-contaminated corn dried distillers grains with solubles (DDGS). Experiment 1 evaluated SMB and heat (autoclaving) on high-DON DDGS (20.6 mg/kg). Six levels of SMB were tested: 0.0% (control), 0.5%, 1%, 2.5%, 5%, and 5% with 100 mL/kg distilled water. Autoclaving after 1 h at 121 °C alone elicited a 9.8% reduction in DON, whereas an 82% reduction was achieved when 5% SMB was added before autoclaving. Experiment 2 tested pelleting high-DON DDGS with SMB. Four batches of DDGS (20.5 mg/kg DON) were tested: 0 (control), 1.0, 2.5, and 5.0% SMB. Pelleted samples were collected at conditioning temperatures of 66 and 82 °C and retention times of 30 and 60 s within temperature. Pelleting conditions had no effect on DON levels, but as SMB inclusion increased in pelleted DDGS, DON levels were reduced (quadratic; P < 0.001). Experiments 3 and 4 evaluated pelleting and SMB on nursery pig growth. Both trials were arranged in a 2 × 3 + 1 factorial with 5 replicate pens per treatment. In Exp. 3, 987 pigs (13.0 ± 0.2 kg) were used with main effects of (1) diet form: meal or pellet and (2) SMB level: Negative Control (NC), NC + 0.25% SMB, or NC + 0.50% SMB. Negative Control diets were formulated to contain 3 mg/kg DON. Treatment 7 was a Positive Control (PC; <0.5 mg/kg DON) fed in meal form. Pigs fed high-DON diets had reduced ( P < 0.001) ADG and ADFI, but pelleting improved ( P < 0.001) ADG and G:F. Adding SMB increased (linear; P < 0.03) ADG and tended to increase ( P < 0.10) ADFI. In Exp. 4, 1180 pigs (11.1 ± 0.32 kg) were used with main effects of (1) diet form: meal or pellet and (2) DDGS source: PC (<0.5 mg/kg DON), NC (5 mg/kg DON), or NC + DDGS pelleted and crumbled before mixing into the final diet. In meal form, treatment 7 included 2.5% SMB prior to pelleting DDGS (final diet contained 0.77% SMB). Overall, a 2-way interaction ( P < 0.04) was observed within NC diets where pelleting the final diet improved G:F by a greater margin in high-DON diets than when the DDGS was pelleted, crumbled, and re-pelleted. DON reduced ( P < 0.002) ADG and ADFI, and pelleting the diet improved ( P < 0.01) ADG and G:F. Including SMB prior to pelleting DON-contaminated DDGS increased ( P < 0.01) ADG and ADFI. Using SMB combined with thermal processing can mitigate DON effects in diets for nursery pigs. [ABSTRACT FROM AUTHOR]

Inhibition properties of sodium metabisulfite (Na 2 S 2 O 5 ) on pitting corrosion of 6061 aluminum alloy, in 5 × 10 −2 M NaCl solution of pH near 7.2 at 298 K, are characterized using open circuit potential, polarization resistance, cyclic and chrono-amperometric polarization measurements. In addition, scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray photoelectrons are employed. Sodium metabisulfite, which is well compatible with environmental requirements, seems to act as a cathodic-type corrosion inhibitor. The passivation range and the polarization resistance increase with Na 2 S 2 O 5 concentration. The inhibition effects are also reflected through the substantial reduction of both the rate of pit nucleation and the current rise characterizing the pit propagation progress. The SEM–EDS and XPS analyses reveal the formation of a passive film, which contains sulfur atoms. [ABSTRACT FROM AUTHOR]

Sodium metabisulfite (SMB) is most commonly used as the preservative in many food preparations and drugs. So far, few studies about its negative effects were reported. The purpose of this study was to investigate the effect of SMB on the expression of big-conductance Ca 2+ -activated K + (BK Ca ), ATP-sensitive K + (K ATP ), and L-type calcium (L-Ca 2+ ) channels in rat aorta in vivo and in vitro. The results showed that the mRNA and protein levels of the BK Ca channel subunits α and β1 of aorta in rats were increased by SMB in vivo and in vitro. Similarly, the expression of the K ATP channel subunits Kir6.1, Kir6.2, and SUR2B were increased by SMB. However, SMB at the highest concentration significantly decreased the expression of the L-Ca 2+ channel subunits Ca v 1.2 and Ca v 1.3. These results suggest that SMB can activate BK Ca and K ATP channels by increasing the expression of α, β1, and Kir6.1, Kir6.2, SUR2B respectively, while also inhibit L-Ca 2+ channels by decreasing the expression of Ca v 1.2 and Ca v 1.3 of aorta in rats. The molecular mechanism of SMB-induced vasorelaxant effect might be related to the expression changes of BK Ca , K ATP , and L-Ca 2+ channels subunits. Further work is needed to determine the relative contribution of each channel in SMB-mediated vasorelaxant effect. [ABSTRACT FROM AUTHOR]

Sodium metabisulfite is used as a preservative in many food preparations but can oxidize to sulfite radicals initiating molecular oxidation. Ghrelin is a peptide hormone primarily produced in the stomach and has anti-inflammatory and anti-oxidant effects on gastrointestinal and cardiovascular systems. This study was performed to elucidate the effect of ghrelin on sulfite-induced endoplasmic reticulum (ER) stress and caspase activation in rat peripheral organs. Xanthine oxidase (XO), xanthine dehydrogenase (XDH) enzyme activities, ER stress markers [phosphorylated PKR-like ER kinase (pPERK); C/EBP-homologous protein (CHOP)], caspase-3, -8, -9 activities, nuclear factor kappa-B (NF-κB) levels were determined in liver, heart and kidney of rats treated with sodium metabisulfite and/or ghrelin for 5 weeks. Sodium metabisulfite treatment significantly elevated XO activity, induced expression of GRP78, CHOP and increased caspase-3, -8 and -9 activities in liver but had no significant effect in heart and kidney. Ghrelin treatment decreased XO activity to baseline levels and attenuated ER stress and caspase activation in liver tissue of sodium metabisulfite treated rats. In conclusion, metabolism of sodium metabisulfite in liver tissue increased XO activity, induced ER stress and caused caspase activation which was attenuated by ghrelin treatment. Ghrelin's hepatoprotective effect could be through modulation of XO activity. [ABSTRACT FROM AUTHOR]

• The black fungus treated with SO 2 has bright color and is not easy to rot. • The effect of SO 2 on the color and content of black fungus were revealed. • The correlation between SO 2 and the composition of fungus were analyzed. • The effect on the quality of black fungus was minimized. In the present study, the color, total sugar, contents of soluble protein, total polyphenols, total flavonoids, and soluble vitamins, and other indicators of black fungus treated with sodium metabisulfite under different conditions were measured to evaluate the sensory and nutritional changes in black fungus after sulfite treatment. The results showed that use of sodium metabisulfite increased the lightness of black fungus, significantly increased the contents of total polyphenols and reducing sugars in the fungus (p < 0.05), increased the content of soluble protein, and decreased the content of total flavonoids. In addition, sodium metabisulfite destroyed vitamin C and B 1 in black fungus. When the concentration of sodium metabisulfite was 0.5% and the soaking time 20 or 30 min, the color of black fungus improved markedly, and nutrients were not negatively affected. Therefore, the use of sodium metabisulfite improved the quality of fungus to a certain extent. [ABSTRACT FROM AUTHOR]

In the flotation of complex copper ores containing chalcopyrite in seawater, sodium metabisulfite (SMBS) has been widely used as a pyrite depressant. Here, calcium ions in seawater or in process water because of pH control using lime (CaO) or slaked lime (Ca(OH) 2) can affect the floatability of chalcopyrite. However, the effect of SMBS on the floatability of chalcopyrite in the presence of calcium ions is unknown. Therefore, the current study investigated the flotation behavior and surface properties of chalcopyrite after treatment with SMBS in the absence and presence of Ca(OH) 2. The flotation experiments demonstrated that both SMBS treatment and the addition of Ca(OH) 2 exhibited a depressing effect on the natural floatability of chalcopyrite. This depressing effect of SMBS and Ca(OH) 2 on the floatability of chalcopyrite was significantly decreased in the presence of potassium amyl xanthate (PAX). However, the combination of SMBS treatment and Ca(OH) 2 formed calcium sulfite (CaSO 3) on the surface of chalcopyrite, which significantly reduced the recovery of chalcopyrite from 97% to 66% when in the presence of PAX and at a pH of 9. [Display omitted] • The effect of Na 2 S 2 O 5 (SMBS) and Ca(OH) 2 on the floatability of chalcopyrite was studied. • Both SMBS and Ca(OH) 2 exhibited a depressing effect on the recovery of chalcopyrite. • SMBS produced sulfate and hydrophilic species on the surface of chalcopyrite. • SMBS and Ca(OH) 2 form CaSO 3 precipitate that reduced the recovery of chalcopyrite. • SMBS reduced the adsorbed PAX on the surface of chalcopyrite. [ABSTRACT FROM AUTHOR]

Abstract: This study aimed to investigate the effect of ghrelin administration on sulfite induced oxidative and apoptotic changes in rat gastric mucosa. Forty male albino Wistar rats were randomized into control (C), sodium metabisulfite (Na2S2O5) treated (S), ghrelin treated (G) and, Na2S2O5 +ghrelin treated (SG) groups. Sodium metabisulfite (100mg/kg/day) was given by gastric gavage and, ghrelin (20μg/kg/day) was given intraperitoneally for 5weeks. Plasma-S-sulfonate level was increased in S and SG groups. Na2S2O5 administration significantly elevated total oxidant status (TOS) levels while depleting total antioxidant status (TAS) levels in gastric mucosa. Ghrelin significantly decreased gastric TOS levels in the SG group compared with the S group. Additionally, TAS levels were found to be higher in SG group in reference to S group. Na2S2O5 administration also markedly increased the number of apoptotic cells, cleaved caspase-3 and PAR expression (PARP activity indicator) and, decreased Ki67 expression (cell proliferation index) in gastric mucosal cells. Ghrelin treatment decreased the number apoptotic cells, cytochrome C release, PAR and, caspase-3 expressions while increasing Ki67 expression in gastric mucosa exposed to Na2S2O5. In conclusion, we suggest that ghrelin treatment might ameliorate ingested-Na2S2O5 induced gastric mucosal injury stemming from apoptosis and oxidative stress in rats. [Copyright &y& Elsevier]

Highlights: [•] Derivatization of levodopa and carbidopa with fluorescamine. [•] Derivatization improved chromatographic retention and sensitivity. [•] The method was validated over the concentration range of 5/3–5000/3000ng/mL for levodopa/carbidopa. [•] This method was successfully employed in the analysis of rat and monkey plasma study samples. [Copyright &y& Elsevier]

Abstract: A number of studies on sulfur dioxide (SO2) in toxicology and pharmacology have been reported, however spectral properties of SO2 and its derivatives were seldom investigated. We investigated the absorption spectra of SO2, sodium sulfite (Na2SO3), sodium bisulfite (NaHSO3) and sodium metabisulfite (Na2S2O5) in aqueous solution. In the meanwhile, the effects of HCl on spectral properties of SO2 and its derivatives were also investigated. We found that gaseous SO2 in ethanol, n-butyl-alcohol and glycerol had a characteristic absorption peak at 276 nm. Na2S2O5 and NaHSO3 exhibited an absorption peak at 257 nm. Absorption of SO2 at 276 nm was strongly enhanced in the presence of HCl. NaHSO3, Na2SO3 and Na2S2O5 also exhibited absorption at 276 nm with the addition of HCl, which was enhanced with the increase of HCl concentration. Importantly, two conclusions have been reached on the basis of our results. First, we attributed the absorbing power of SO2 to SO2 molecule, rather than hydrated sulfur dioxide. Second, absorption of SO2 strongly enhanced by HCl at 276 nm was due to H+, instead of the formation of a complex SO2Cl-. Primary studies also indicated that NaHSO3 and Na2S2O5 with HCl had a similar effect as SO2 did in rat thoracic aortic rings, which prompted us believe that NaHSO3 and Na2S2O5 with HCl may be acted as a donor of SO2 in biology and other area. [Copyright &y& Elsevier]

Abstract: Sodium metabisulfite (SMB) is most commonly used as a food additives, however few study was performed on the vasodilator effect of SMB. In the present paper, the vasodilator effects of SMB and roles of Ca2+ and K+ channels as well as the cGMP pathway on isolated rat aortic rings were studied. The results show that: (1) SMB could relax isolated aortic rings precontracted by norepinephrine in a concentration-dependent manner. The maximal endothelium-dependent vasorelaxation was approximately 20% whereas that not depending on the presence of the endothelium was more than 90%. (2) The vasorelaxant effects induced by 50 or 200μM SMB were partially inhibited by iberiotoxin, NS-2028 or l-NNA. The vasorelaxation of 1000μM SMB was partially inhibited by nifedipine or glibenclamide. The SMB induced vasorelaxation was partially inhibited by tetraethylammonium. These results led to the conclusions that the vasorelaxation of SMB at low concentrations (<400μM) was endothelium-dependent and mediated by the cGMP pathway and BKCa channel, but at high concentrations (>500μM) was endothelium-independent and mediated by KATP channel and L-type Ca2+ channel. The maximal allowable concentration from China and the acceptable daily intake level from WHO of SMB as a food additive should be revised. [Copyright &y& Elsevier]

Abstract: Certain 2-phenylbenzothiazoles containing substituents on the benzothiazole ring possess important biological properties, yet the majority of synthetic methods to 2-phenylbenzothiazoles described to date focus on their unsubstituted ring counterparts. Here we describe a new concise and efficient synthetic route to biologically relevant 2-phenylbenzothiazoles in high yield from the reaction of substituted 2-aminothiophenol disulfides and benzaldehydes, promoted by the inexpensive and non-toxic inorganic oxidant sodium metabisulfite in DMSO at 120°C. Our new method is tolerant of a range of substituents on both the benzothiazole and phenyl ring, and affords efficient access to substituted 2-phenylbenzothiazoles without the need for column chromatography. [Copyright &y& Elsevier]

Abstract: In the present work, we explored the way in which cromoglycate, a drug used to treat allergies acts on ion movements in sickle cells. Cells were either slowly deoxygenated by overnight exposure to nitrogen or acutely deoxygenated by exposure to metabisulfite, a strong reducing agent which induces sickling of red blood sickle cells. Flushing the cells with nitrogen increased the intracellular concentration of Na+ and decreased the intracellular concentration of K+ and the sum of the concentrations of the two cations. One hundred nM cromoglycate inhibited the decrease of intracellular K+ and the increase of intracellular Na+ induced by deoxygenation (n=17). Metabisulfite (100mM) increased the intracellular concentration of Ca2+ (measured by Fura Red) (n=15) and the shape of the cells (measured by light scattering) (n=9). One μM cromoglycate partially inhibited these two responses. In conclusion, cromoglycate partially inhibits abnormal K+ loss, Ca2+ entry pathways or Ca2+ channels opened by cell deoxygenation and ensuing membrane modifications and prevents cell sickling. [Copyright &y& Elsevier]

Abstract: The addition of reduced sulfur compounds (thiosulfate, cysteine, sodium hydrosulfite, and sodium metabisulfite) increased growth and fermentation of dilute acid hydrolysate of sugarcane bagasse by ethanologenic Escherichia coli (strains LY180, EMFR9, and MM160). With sodium metabisulfite (0.5mM), toxicity was sufficiently reduced that slurries of pretreated biomass (10% dry weight including fiber and solubles) could be fermented by E. coli strain MM160 without solid–liquid separation or cleanup of sugars. A 6-h liquefaction step was added to improve mixing. Sodium metabisulfite also caused spectral changes at wavelengths corresponding to furfural and soluble products from lignin. Glucose and cellobiose were rapidly metabolized. Xylose utilization was improved by sodium metabisulfite but remained incomplete after 144h. The overall ethanol yield for this liquefaction plus simultaneous saccharification and co-fermentation process was 0.20g ethanol/g bagasse dry weight, 250 L/tonne (61gal/US ton). [Copyright &y& Elsevier]

Abstract: Sodium metabisulfite (SMB, Na2S2O5) is widely used in the food and pharmaceutical industries, because of its ability to inhibit proliferation of microorganisms and its antioxidant properties. We have evaluated the genotoxic effects of SMB on different tissues of the mouse, by use of the comet assay (liver and blood cells) and the micronucleus test (blood and bone marrow cells). For all tissues, significant increases in damage index and damage frequency values were observed in the SMB-treated groups (1 and 2g/kg doses) compared to the control animals. The Kruskal–Wallis test showed that the mean micronucleus frequencies in peripheral blood and bone marrow cells of mice treated with the highest dose of SMB (2g/kg) showed significant increases, when compared with controls, and a significant reduction in the ratio of polychromatic to normochromatic erythrocytes was also seen. No difference in results between sexes was observed. Our results show that high oral doses of SMB may pose a genotoxic risk. [Copyright &y& Elsevier]

Abstract: Sodium metabisulfite is used in marine shrimp harvesting to prevent the occurrence of black spots. Shrimps are soaked in a sodium metabisulfite solution in ice, which is disposed of in sewages that run into marine canals, creating an environmental hazard. This study evaluates the toxicity and mutagenicity caused by sodium metabisulfite in sea waters and sediments collected in a shrimp farm in Cajueiro da Praia (Luis Correia), state of Piauí, Brazil, using the Allium cepa assay. Water and sediment samples were collected in the dry and in the rainy seasons, in three sites: upstream the shrimp farm (Site 1), at the point sodium metabisulfite is discharged (Site 2), and 100m downstream the farm (Site 3). Three sample dilutions were used (50%, 25% and 10%) for all samples. A negative control (well water) and a positive control (copper sulfate 0.0006mgmL−1) were used in each experiment. At the end of the 72-h exposure period, onion roots were measured and removed. Mutagenicity analysis included the determination of mitotic index, chromosomal aberrations and the detection of micronuclei; analysis of root size and mitotic index were used as an index of toxicity. The A. cepa assay revealed that the water and sediments samples collected in the Piauí coast contaminated with sodium metabisulfite induce toxicity. The results demonstrate that the assay may be used as a regular tool in the analysis of water parameters in shrimp farms in the coast of Piauí state, and in strategies to preserve the region’s marine ecosystem. [ABSTRACT FROM AUTHOR]

• Leaching solution contained metabisulfite, thiosulfate, Cu ions and ascorbic acid. • The leaching efficiency of silver from sulfide concentrate reached 90.5%. • Extraction of one mole of silver needed two moles of organic extractant. • The power of different solvent extractants was: TMTDS + TBP > Cyanex302 > D2EHPA. • Stripping of Ag by aqueous solution was successful at pHe > 2.5. In this study, a silver-containing zinc sulfide concentrate was characterized and then leached to investigate the solvent extraction behavior and recovery of silver. Chemical and phase analyses were performed using X-ray fluorescence (XRF), atomic absorption (AA), and X-ray diffraction (XRD) methods. The microstructure of concentrate was characterized by using optical (OM) and scanning electron microscopes (SEM). The amount of silver in the concentrate equals 580 ppm as an Ag 2 S compound. About 77% of silver sulfide was free. Leaching of Ag 2 S was performed in the presence of sodium metabisulfite (0.2 M), copper sulfate (0.01 M), sodium thiosulfate (0.01 M), and ascorbic acid (2.8 mM). The dissolution efficiency in this condition reached 90.5%. The obtained solution was used to conduct solvent extraction tests. According to the leaching conditions, Cyanex302, TMTDS (Tetramethylthiuram disulfide) + 5 %TBP (Tributyl phosphate), and D2EHPA (Di-(2-Ethylhexyl)phosphoric acid) were used as organic extractants. The results showed that the maximum extraction was reached in about 15 min at pH above 1.5 and extractant concentration above 0.1 M. The presence of metabisulfite ions in high values can reduce the efficiency. The organic solvent released one H+ ion for each silver ion, and 2 mol of the extractant participated in the extraction reaction. The extraction and recovery of silver ions by all three organic solvents were similar. [ABSTRACT FROM AUTHOR]

Abstract: Hairline cracks, which developed after harvest among SO2-treated table grapes, were characterized by small, fine, longitudinal, cracking lines, almost undetectable with the naked eye. Juice exudation from the cracks resulted in a wet and sticky berry skin. Hairline cracks, which we propose to term ‘hairline’, were distinctively different from splitting observed before harvest. Hairline was only induced when table grapes were treated with gaseous SO2, commonly used to prevent decay of table grapes during cold storage in Chile. In practice, conditions that favored higher concentrations of SO2, such as the use of two SO2 generating pads (one on top and one on the bottom of the packaged table grapes), promoted hairline cracking. Hairline incidence increased linearly when the concentration and time product (CT) of SO2 exceeded 3(mLL−1)h, and no hairline cracking was observed with CT below 0.8(mLL−1)h. Hairline symptoms were greatly induced on Thompson Seedless table grapes that were immersed in acidic solutions (citric acid and disodium phosphate) at pH 2 or 4. To reduce this disorder, it is essential to use a minimal dose of SO2 that allows adequate protection from decay without reducing the berry quality. Postharvest practices of table grapes, packaged with a SO2 generating pad, such as extended delay cooling periods and those practices that involve a raise in temperature, considerably enhance this disorder. Hairline cracking is another expression of phytotoxicity due to overexposure of table grapes to SO2. [Copyright &y& Elsevier]

Abstract: Biofilm-forming staphylococci cause a majority of intravascular catheter-related infections. We evaluated the effect of sodium metabisulfite, a preservative commonly added to intravenously administered pharmaceuticals as an antioxidant and previously used as a catheter lock solution, on planktonic and biofilm staphylococci at clinically encountered concentrations. Sodium metabisulfite exhibited bactericidal activity against planktonic Staphylococcus aureus, Staphylococcus lugdunensis, and Staphylococcus epidermidis at concentrations of 512, 512, and 1024 μg/mL, respectively. A concentration of 720 μg/mL inhibited cell growth by all 3 species in a biofilm formation assay. However, established S. aureus and S. lugdunensis biofilms showed less than 1.5 log10 decreases in viable cell counts when treated with 720 μg/mL of sodium metabisulfite for 24 h. These in vitro results suggest that the use of sodium metabisulfite as a catheter lock may inhibit staphylococcal colonization of catheters, thereby preventing catheter-related infection. [Copyright &y& Elsevier]

Abstract: Vitamin C exerts several functions on skin as collagen synthesis, depigmentant and antioxidant activity. Vitamin C is unstable in the presence of oxygen, luminosity, humidity, high temperatures and heavy metals, which presents a significant challenge to the development of cosmetic formulations. Therefore, the utilization of an effective antioxidant system is required to maintain the vitamin C stability. The purpose of this research work was to develop prototypes of cosmetic formulations, as O/W emulsion and extemporaneous aqueous gel, containing vitamin C and to evaluate the influence of sodium metabisulfite (SMB) and glutathione (GLT), as antioxidants, on the stability of the active substance. A HPLC stability-indicating method was developed and validated for this study and stability assays were performed in 90 and 26 days and storage conditions were 5.0±0.5, 24±2 and 40.0±0.5°C. The HPLC stability-indicating method showed linearity (r 2 >0.99), specificity, R.S.D.<1.22% and accuracy/recovery ranging from 95.46 to 101.54%. Preparations with SMB or GLT and the antioxidant-free presented results statistically distinct, demonstrating the necessity of the antioxidant system addition. O/W emulsions with SMB or GLT retained the vitamin C content >90.38% stored at 5.0±0.5 and 24±2°C. For the aqueous gel with SMB or GLT, the active substance concentration was maintained >94.03%. Considering the vitamin C stability, the SMB and the GLT showed to be statistically adequate, as antioxidants, for the cosmetic formulations. [Copyright &y& Elsevier]

Abstract: The performance of a glassy carbon electrode modified with a porphyrin film formed by the [Co(TPyP){Ru(bipy)2Cl}4](TFMS)5·H2O complex for the analysis of sodium metabisulfite in pharmaceuticals is described. The sensor can be rapidly and easily prepared by drop-casting of a microliter volume of a diluted methanolic solution of the complex onto the electrode surface. The modified electrode with a supramolecular cobalt porphyrin film led to more favorable responses than the bare electrode. This can be ascribed to the much faster electron transfer processes to the analyte mediated by the tetraruthenated porphyrin and to the protection of the electrode against fouling. The association of the amperometric sensor with the batch injection analysis technique led to results that combine good repeatability of the current responses (relative standard deviation of 0.94% for 30 measurements), wide linear dynamic range (2.5×10−7 molL−1 to 5.0×10−4 molL−1), high sensitivity and low limits of detection (8.1×10−8 molL−1) and quantification (2.7×10−7 molL−1). The system was successfully applied to sodium metabisulfite quantification in commercial samples of injection formulations of sodium (or potassium) diclofenac. The results compared well with those obtained by the polarographic method. [Copyright &y& Elsevier]

Abstract: The effect of sodium metabisulfite (SMB) on voltage-gated sodium channel currents (I Na) was examined in freshly isolated rat hippocampal CA1 neurons using whole-cell patch-clamp technique under voltage-clamp conditions. SMB irreversibly enhanced I Na in a concentration-dependent manner, shifted the inactivation curve to more positive potential, without affecting the current activation curve. In addition, SMB increased the time to peak and the inactivation time constant of I Na. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) could all partly inhibit the effect of SMB on the sodium current. These results suggested that SMB have neuronal toxicity by increasing the excitability of neurons and its mechanism might involve the oxidative damage on ion channels. [Copyright &y& Elsevier]

Abstract: The fumigation of apple and pear fruit for 2h with 2ml/l of sulfur dioxide at room temperature enabled adequate detection of fresh and old micro-wounds varying from 0.1 to 5mm in diameter. A bleached spot surrounded by a brown halo formed around the wounds allowing their visualization. Otherwise, the same symptoms were observed when fruit were treated for 2h with 20ml sodium metabisulfite solution at 20g/l. The incidence of wounding among SO2 treated apples varied from 9 to 20% and from 13 to 24% in the 2001–2002 and 2002–2003 harvest periods, respectively. The susceptibility was higher on pear fruit which averaged 17–30% of wounded fruit at harvest for the same periods. Comparatively, the incidence of wounding varied between 5 and 11% when apple or pear fruit were evaluated visually for superficial defects. Additional wounds occurred during the sizing of ‘Cameo’ apples. Thus, the incidence of wounding was around 12 and 23% before and after sizing, respectively. SO2 fumigation revealed an abraded surface two-fold larger on fruit after sizing resulting principally from impacts between adjacent fruit and between fruit and the bin sides. [Copyright &y& Elsevier]

Gluten network formed by oxidation of glutenin sulfhydryl groups is the determinant of dough rheological properties, while chemical reagents including oxidants and reductants are both used as dough rheology improvers under different circumstances. This study compares the impact of sodium metabisulfite (SMBS) and azodicarbonamide (ADA), as the representative reductive and oxidative dough improvers, at series of concentrations that offer or remove the same number of electrons form dough, respectively. The alveographic characterization, protein distribution and glutenin composition analysis, and free sulfhydryl measurement were performed on dough containing redox equivalent SMBS or ADA. Finally, at each optimal concentration, the dough protein network was analyzed with confocal microscopy. Results showed that SMBS increased the free sulfhydryl content, loosened the microstructure of gluten network, and thus enhanced dough extensibility. ADA reduced the free sulfhydryl content, compacted the dough microstructure, thus enhanced the tenacity and baking strength of dough. It is therefore proposed that the reductants reduce disulfide bonds in gluten network and renders the formation of one-dimensional gluten network while oxidants promote the disulfide linkage and formation of three-dimensional gluten network. This study offers a theoretic foundation of differentiating dough rheology improvers for their specified application. • Reductive and oxidative dough rheology improvers are compared. • These two additives are added at equal redox equivalent in dough. • Reductive improver promotes one-dimensional gluten network. • Oxidative improver facilitate three-dimensional gluten network. [ABSTRACT FROM AUTHOR]

• Cytotoxic effects of SMB were investigated on HFFF2 cells. • SMB reduced cell viability and induced apoptosis. • SMB modulated the expression of genes involved in apoptosis pathways. • This food additive increased ROS levels and activated autophagy. Sodium metabisulfite (SMB), an antioxidant agent, is extensively used as a preservative in food industry. The current study was aimed to clarify its potential toxic effects on human fetal foreskin fibroblasts (HFFF2) cells, in vitro. Subsequently, MTT results illustrated that exposure to SMB significantly (p < 0.0001) decreased HFFF2 cell viability in a dose-dependent manner, and the concentration of 25 μM reduced cell survival rates to 50% as the half-maximal inhibitory concentration of SMB. It was further shown that SMB exerted this cytotoxic effect on HFFF2 cells through apoptosis induction. qRT-PCR and western blotting results showed that treatment of HFFF2 cells with this food additive led to significant upregulation of Bax, caspase 8, and caspase 9 pro-apoptotic genes and downregulation of Bcl-2 expression as a pro-survival agent. Furthermore, SMB remarkably increased caspase 3 levels and promoted its activation through cleavage in treated cells. Besides, exposure to SMB increased ROS levels and activated autophagy in treated cells, which are considered as the other indicators for cell damage. Taken together, our findings suggested that SMB could exert remarkable toxic effects on human normal cells through multiple mechanisms, including apoptosis activation, and its widespread usage in food safety should be reconsidered. [ABSTRACT FROM AUTHOR]

• MBS depressed molybdenite flotation in DI water. • The depression in DI water was stronger for smaller particles with more edges. • The depression in DI water stemmed from oxidation of MBS forming sulphate complexes on the edges. • MBS did not depress molybdenite flotation in seawater. • Sulphite ions combined with calcium and magnesium ions rather the edges in seawater. Sodium metabisulfite (MBS) has been widely applied to depress pyrite in copper-molybdenum flotation plants in particular when seawater is used as the main water resource. However, whether MBS depresses molybdenite flotation is unknown. In this study, the flotation of molybdenite at 106 and 53 µm was carried out in the absence and presence of MBS in DI water and seawater to determine the depression role of MBS. Then the products formed on molybdenite faces and edges were detected by cryogenic X-ray photoelectron spectroscopy to understand the reactions involving MBS. This study confirmed the depression of MBS on molybdenite flotation especially for fine particles in DI water. The depression was caused by the adsorption and oxidation of sulphite ions on molybdenite edges, forming sulphate complexes which provided a steric barrier to collector adsorption on molybdenite faces. This study also confirmed little effect of MBS on the flotation of molybdenite at 106 and 53 µm in seawater. This is because sulphite ions preferentially combined with calcium and magnesium ions in water rather adsorbed on molybdenite edges. [ABSTRACT FROM AUTHOR]

Abstract: Young coconuts are often presented after cutting parts of the white fibrous husk away. Such fruit rapidly turn brown and are susceptible to mold infection. Sodium metabisulfite (Sms) is commonly used to minimize these problems. Residues were found to be higher in younger fruit than in older ones. The Sms solution penetrated the nut''s interior via air channels in the husk and through the soft eye. To avoid residues in the edible portion, this study recommends using coconuts that are at least 6 months old (after full bloom), minimally trimmed, and dipped in ≤5% Sms solution for ≤5min. [Copyright &y& Elsevier]

• Tooth whitening by oxidation (using peroxides) needs long application times (hours). • Tooth whitening by reduction (using metabilsulfite) reachs impressive results in 3min. • Nanoencapsulation of metabisulfite in liposomes lead to unexpected enhanced results. • Liposomes protect metabisulfite from degradation in the aqueous medium. • Liposomes attach to the tooth surface enhancing the reductant diffusion into enamel. Tooth whitening materials have not undergone relevant advances in the last years. Current materials base their action on the oxidant activity of peroxides, which present the disadvantage of requiring long application times, along with unpleasant side effects of dental hypersensitivity (e.g. sharp pain). In this work, a novel tooth whitening formulation based on the encapsulation of a reducing agent (sodium metabisulfite) in liposomes is developed. An experimental design was applied to optimize the formulation in terms of whitening action and safety, using bovine teeth as in vitro model. Results were obtained by colorimetry, profilometry and nanoindentation techniques. The comparison with standard whitening treatments showed a similar whitening action of the optimized formulation but in remarkable shorter application times. Moreover, teeth roughness values obtained with the presented formulation conformed with ISO 28399. As mechanism of action, results obtained from fluorescent confocal microscopy showed the liposomal formulation to form a layer surrounding the enamel surface, enhancing the treatment efficacy in terms of diffusion of the protected reductant towards the enamel. The better efficiency of this formulation encourages its use as an alternative to current oxidative treatments. [ABSTRACT FROM AUTHOR]