Alteration of chemical behavior of L-ascorbic acid in combination with nickel sulfate at different pH solutions in vitro

Objective:To evaluate the alteration of chemical behavior of L-ascorbic acid(vitamin C) with metal ion(nickel) at different pH solutions in vitro.Methods:Spectra of pure aqueous solution of L-ascorbic acid(E mark) compound and NiSO_4(H_2O)(sigma USA) were evaluated by UV visible spectrophotometer.Spectral analysis of L-ascorbic acid and nickel at various pH(2.0, 7.0,7.4 and 8.6) at room temperature of 29℃ was recorded.In this special analysis,combined solution of L-ascorbic acid and nickel sulfate at different pH was also recorded.Results:The result revealed that λ_(max)(peak wavelength of spectra) of L-ascorbic acid at pH 2.0 was 289.0 run whereas at neutral pH 7.0,λ_(max) was 29S.4 run.In alkaline pH 8.6,λ_(max) was 295.4 nm and at pH 7.4 the λ_(max) of L-ascorbic acid remained the same as 295.4 nm.Nickel solution at acidic pH 2.0 was 394.5 nm,whereas at neutral pH 7.0 and pH 7.4 were the same as 394.5 nm.But at alkaline pH 8.6,λ_(max) value of nickel sulfate became 392.0 nm.The combined solution of L-ascorbic acid and nickel sulfate(6 mg/mL each) at pH 2.0 showed 292.5 nm and 392.5 nm,respectively whereas at pH 7.0,L-ascorbic acid showed 296.5 nm and nickel sulfate showed 391.5 nm.At pH 7.4,L-ascorbic acid showed 297.0 nm and nickel sulfate showed 394.0 nm in the combined solution whereas at pH 8.6(alkaline) L-ascorbic acid and nickel sulfate were showing 297.0 and 393.5 nm,respectively. Conclusions:Results clearly indicate an altered chemical behavior of L-ascorbic acid either alone or in combination with nickel sulfate in vitro at different pH.Perhaps oxidation of L-ascorbic acid to L-dehydro ascorbic acid via the free radical(HSc*) generation from the reaction of H,ASc + Ni(Ⅱ) is the cause of such alteration of λ_(max),value of L-ascorbic acid in the presence of metal nickel.

Supplementation of L-ascorbic acid improves the in vitro development of buffalo(Bubalus bubalis)embryos and alters the expression of apoptosis-related genes

Objective:To study the effect of L-ascorbic acid supplementation on the in vitro development of buffalo embryos and evaluate the relative mRNA abundance of some pro-apoptotic,anti-apoptotic,and embryonic development-related genes.Methods:In experiment 1,we evaluated the effect of the addition of 0(control),50,and 100μM L-ascorbic acid to the in vitro maturation medium on the developmental competence in terms of blastocyst rate and relative mRNA abundance of some pro-apoptotic(BAX,BID),anti-apoptotic(BCL-XL,MCL1),and embryonic development(GDF9,BMP15)related genes.Based on the results,we chose 50μM as the suitable dose of L-ascorbic acid for the subsequent experiments.We further evaluated the blastocyst rates following the addition of 50μM L-ascorbic acid to the in vitro culture medium(experiment 2),and in vitro maturation and in vitro culture media(experiment 3).In all three experiments,the maturation and culture media devoid of L-ascorbic acid served as the control group.Results:The blastocyst rate after adding 50μM L-ascorbic acid to the in vitro maturation medium was significantly higher than the control group(P<0.05),whereas 100μM L-ascorbic acid exhibited a negative effect on the blastocyst rate.The blastocyst rates for embryos cultured in 50μM L-ascorbic acid in the in vitro culture medium alone and both in vitro maturation and in vitro culture media were significantly higher than their corresponding control groups(P<0.05).The relative mRNA abundance of BAX significantly decreased in blastocysts produced after the addition of 50μM L-ascorbic acid as compared with the control group(P<0.05),whereas,for MCL1,it significantly decreased in blastocysts produced after the addition of 100μM L-ascorbic acid(P<0.05).Conclusions:The supplementation of 50μM L-ascorbic acid to in vitro maturation and in vitro culture media supports in vitro embryonic development in buffaloes by improving developmental competence and altering the expression of apoptosis-related genes.

Synthesis, Crystal Structure and Antioxidant Activity of 5,6-O-(4-bromophenyl)-L-ascorbic Acid

The title compound 5,6-O-（4-bromophenyl）-L-ascorbic acid （C13H11BrO6, Mr = 343.13） has been synthesized and its structure was characterized by IR, 1H NMR and single-crystal X-ray diffraction. The product is a mixture of two diastereomer compounds （a （7S） and b （7R））. The crystal of a （7S） belongs to orthorhombic system, space group P212121 with a = 6.5362（10）, b = 7.8226（11）, c = 25.294（4） ？, V = 1293.3（3） ？3, Z = 4, Dc = 1.762 g/cm3, μ（MoKα） = 3.202 mm-1, F（000） = 688, R = 0.0235 and wR （I 〉 2σ（I）） = 0.0566. The hydrogen bonding interactions link the molecules to form a three-dimensional system. In addition, 5,6-O-（4-bromophenyl）-L-ascorbic acid （BPAA） exhibits strong free-radical scavenging activities in vitro against 2,2-diphenyl-1-picrylhy- drazyl and superoxide anion. BPAA should be investigated further as a worthy antioxidant.

Synthesis of L-Ascorbic Acid Lactone Derivatives

A small focused library which comprised of L-AA lactone derivatives was built with a facile method.This reported method was optimized by modifying the acidity of the solvent.As a result,12 L-AA lactones were synthesized.Among these lactones,lactones 8–12 were new compounds.The cytotoxicity of these synthetic compounds were investigated.

Conductive Polyacrylonitrile Fiber Prepared by Copper Plating with L-Ascorbic Acid as Reducing Agent

Conductive polyacrylonitrile fibers were prepared by electroless copper plating under weak alkaline conditions,with L-ascorbic acid as reducing agent.The influences of CuSO_(4)·5H_(2)O,L-ascorbic acid,2,2′-bipyridine and K_(4)Fe(CN)_(6) concentration on the conductivity and mass gain percentage of the fibers were studied.The morphological structure of the fibers was characterized by scanning electron microscopy(SEM),and the mechanical properties of the fibers were analyzed through the mechanical property test.The results showed that the optimal reaction conditions were as follows:26 g/L CuSO_(4)·5H_(2)O,26 g/L L-ascorbic acid,12 mg/L 2,2′-bipyridine,7 mg/L K 4Fe(CN)6,and 38℃.The volume resistivity of the conductive PAN fibers prepared by the process was only 3.84×10^(-3)Ω·cm.

Microencapsulation of L-Ascorbic Acid by Spray Drying Using Sodium Alginate as Wall Material

L-ascorbic acid is a water soluble vitamin (vitamin C) widely used as an additive in foods and cosmetics. It has high instability against certain environmental factors;the main cause of its deterioration is oxidation. Microencapsulation is an effective protection technique of L-ascorbic acid from its degradation reactions. This work is focused on the encapsulation of L-ascorbic acid by spray drying technique using sodium alginate as wall material. The microcapsules morphology was observed by scanning electron microscopy (SEM) and the encapsulation efficiency was determined by spectrophotometric analysis. Results showed that encapsulation efficiency was of 93.48% and after 30 days was of 92.55%;differences were not significant, so that the stability of L-ascorbic acid was not affected. Encapsulation yields obtained were low, at around 30%, but the microcapsules morphology obtained is spherical.

Positive feedback between retinoic acid and 2-phospho-L-ascorbic acid trisodium salt during somatic cell reprogramming

Retinoic acid(RA)and 2-phospho-L-ascorbic acid trisodium salt(AscPNa)promote the reprogramming of mouse embryonic fibroblasts to induced pluripotent stem cells.In the current studies,the lower abilities of RA and AscPNa to promote reprogramming in the presence of each other suggested that they may share downstream pathways at least partially.The hypothesis was further supported by the RNA-seq analysis which demonstrated a high-level overlap between RA-activated and AscPNa activated genes during reprogramming.In addition,RA upregulated Glut1/3,facilitated the membrane transportation of dehydroascorbic acid,the oxidized form of L-ascorbic acid,and subsequently maintained intracellular L-ascorbic acid at higher level and for longer time.On the other hand,AscPNa facilitated the mesenchymal-epithelial transition during reprogramming,downregulated key mesenchymal transcriptional factors like Zeb1 and Twist1,subsequently suppressed the expression of Cyp26a1/b1 which mediates the metabolism of RA,and sustained the intracellular level of RA.Furthermore,the different abilities of RA and AscPNa to induce mesenchymal-epithelial transition,pluripotency,and neuronal differentiation explain their complex contribution to reprogramming when used individually or in combination.Therefore,the current studies identified a positive feedback between RA and AscPNa,or possibility between vitamin A and C,and further explored their contributions to reprogramming.

Near-UV light assisted green reduction of graphene oxide films through l-ascorbic acid

Recent studies have highlighted the effects of various stimuli on the chemical reduction of graphene oxide(GO)through green reductant L-ascorbic acid(L-AA);however,the combination of near ultraviolet(NUV)light to increase the reduction rate has yet to be thoroughly explored.In this study,drop-casted GO films were subjected to chemical reduction through L-AA with various levels of exposure under 405 nm NUV radiation.The structure and uniformity of GO stackings that form the film were characterized through scanning electron microscopy(SEM)and wide-angle x-ray scattering(WAXS).Additionally,WAXS was used to track the removal of oxygen-containing functional groups along with Fourier-transform infrared(FT-IR)spectroscopy and x-ray photoelectron spectroscopy(XPS)as a function of L-AA and NUV light exposure times.XPS results demonstrated that the interaction between L-AA and NUV exposure has a significant effect on the reduction of films.Furthermore,the results that yielded the highest reduction(C-C bond concentration of 60.7%)were the longest L-AA and NUV light exposure times(48 hours and 3 hours,respectively).This report provides a study on the effects of NUV on the green reduction of GO films through L-AA with potential application in solar energy and chemical sensing applications.

Comparative genomic analysis of Lactobacillus crispatus strains Lc31 and Lc83 with anti-cervical cancer potential by complete genome sequencing

Lactobacillus crispatus is a commonly found species in the urogenital tract(UGT)of healthy females and can also colonize other niches,such as the gastrointestinal tract(GIT).Although its potential protective role in cervical cancer has been reported,the anticancer mechanisms involved are still unclear.In this study,we sequenced and characterized the complete genomes of two L.crispatus strains(Lc31 and Lc83)isolated from the UGT of healthy women of reproductive age.Phylogenetic and phylogenomic analyses of these two strains and 15 other L.crispatus strains with complete genome sequences revealed that strains from the UGT and GIT clustered separately.UGT strains had a larger genome size,higher GC contents,and more protein-coding sequences and insertion sequence(Is)elements,indicating the likelihood of active horizontal gene transfer in this niche.We found a universal presence of genes encoding bacteriocins and the absence of virulence factors and antibiotic resistance genes in UGT strains,suggesting the potential of L.crispatus as a urogenital probiotic.Comparative genomic analysis identified an ula gene cluster responsible for L-ascorbate catabolism exclusively in UGT strains,and carbohydrate fermentation experiments confirmed that this substrate supported the growth of L.crispatus Lc31 and Lc83.Our findings improve the understanding of how the genome determines niche adaptation by L.crispatus,providing a foundation for investigating the mechanisms by which urogenital-derived L.crispatus promotes female health.

Molecular cloning and functional characterization of a soybean GmG MP1 gene reveals its involvement in ascorbic acid biosynthesis and multiple abiotic stress tolerance in transgenic plants

L-Ascorbic acid （AsA） plays an important role in plants and animals. In plants, GDP-D-mannose pyrophosphorylase （GMP） is essential in the AsA biosynthetic pathway. However, little is known about the genes encoding GMP in soybean and here we report genetic and functional analysis of the GmGMP1 （Glycine max GDP-D-mannose pyrophosphorylase 1） gene in this species. GmGMP1 encoded a GDP-mannose pyrophosphorylase and exhibited higher transcript levels in the leaf than in the root, stem, flower, and seed. Transcript of this gene was ubiquitous in the vegetative and reproductive organs, and was induced by abiotic stress and light. Increasing expression of GmGMP1 in Arabidopsis and soybean through an overexpressing approach caused pronounced enhancement of AsA content, and was implicated in lowering the superoxide anion radical content and lipid peroxidation levels in Arabidopsis, and conferring tolerance to osmotic and high salt stresses during seed germination. The present study represents the first systematic determination of soybean genes encoding GDP-mannose pyrophosphorylase and provides useful evidence for the functional involvement of GmGMP1 in control of AsA content and conferring tolerance to osmotic and salt stress.

Effect of using ascorbic acid and cysteamine supplementation onin-vitrodevelopment of buffalo embryos

Objective:To improvein vitro embryo production in buffalo by supplementation of L-ascorbic acid during maturation and development (experiment 1) and combination with another antioxidant as cysteamine (experiment 2).Methods:Two experiments were performed, the first one aimed to evaluate the different concentrations (0, 25, 50, 100 μM) of L-ascorbic acid on embryo developmental rate of buffalo oocytes. The L-ascorbic acid was added to the maturation and culture media. In the second experiment, oocytes were cultured in media with two type of antioxidant (ascorbic acid + cysteamine) or ascorbic acid only.Results:There was a significant increase in cleavage rate at 25, 50 μM than 100 μM and control group. But, the blastocyst rate was higher at 50 μM ascorbic acid than other concentrations (0, 25, 100 μM). Supplementation of ascorbic acid and cysteamine to maturation and cultured media improved embryo development than ascorbic acid alone.Conclusions: Using of 50 μM L-ascorbic acid duringin vitro maturation and development improve the developmental competence of buffalo oocytes, this effect was increase with the presence of cysteamine.

碱液中L-抗坏血酸盐离子电氧化过程中Ag电催化剂的多硫化物中毒(英文)

L-Ascorbate anion electro-oxidation on a silver electrode in hydroxide solution in the absence and presence of sodium polysulfide of concentrations from 1 × 10-5 to 4.5 × 10-4 mol/L was studied using cyclic voltammetry and electrochemical impedance spectroscopy.Both hydroxide and polysulfide ions inhibited L-ascorbate ion oxidation,with the poisoning effect of polysulfide ion being more pronounced in the potential range of-0.3 to-0.2 V/SCE.The time constants for L-ascorbate ion oxidation in the absence and presence of polysulfide were,10-3 to 1 × 10-2 s and 1 × 10-4 to 1 × 10-2 s,respectively depending on the potential used for the impedance analysis.Based on the cyclic voltammetry findings,a mechanism for L-ascorbate oxidation in the presence of polysulfide ions was proposed.Impedance calculations based on the kinetic analysis can account for the occurrence of a negative impedance in a potential region around-0.2 V/SCE in the Nyquist polts.

Enhanced Iontophoretic Delivery of Magnesium Ascorbyl 2-Phosphate and Sodium Fluorescein to Hairless and Hairy Mouse Skin

We recently reported that L-ascorbic acid 2-phosphate (AP) stimulates the growth of human dermal papilla (DP) cells, induces secretion of IGF-1 from the DP cells to promote hair shafts elongation in cultured human hair follicles, and triggers early progression from the telogen to anagen phase in mice. Since the magnesium salt of AP (APMg) is a highly hydrophilic ionic molecule, it is not easy to deliver this reagent to the skin or hair follicles by topical application alone. In order to enhance skin penetration of APMg without changing any molecular properties, a non-invasive iontophoretic delivery method was introduced. Iontophoresis of the negatively charged APMg under the electrode bearing same charge (cathode) significantly enhanced the in vitro penetration of APMg into a Franz cell equipped with mouse dorsal skin. In contrast, iontophoretic movement with the anode inhibited APMg penetration achieved with passive diffusion alone. The effect of iontophoresis on enhancing the penetration of APMg was also found to be much higher in the skin of hairy mice (3 - 8 times) compared to hairless mice (1.5 - 2.5 times). These findings indicated that iontophoretic movement induced the transfollicular pathway more strongly and effectively than the transdermal pathway. This phenomena was also demonstrated by the in vivo iontophoretic delivery of sodium fluorescein using hairy and hairless mice. The degree of iontophoretic enhancement during APMg penetration was also dependent on various conditions such as current density and application duration.

One-step post-treatment boosts thermoelectric properties of PEDOT:PSS flexible thin films

Developing high-performance poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)sig-nificantly widens the practical applications of flexible organic thermoelectric devices,while the water-based co-solvent dopants and/or post-treatments are still rarely studied so far.Here,we develop a one-step post-treatment to improve the power factor of PEDOT:PSS films by using a water-based solution,which is composed of co-solvent(polar solvent dimethylacetamide(DMAC)and deionized water)and organic reducing agent L-ascorbic acid(LAA).The 80 vol.%DMAC solution significantly boosts the room-temperature electrical conductivity of the films from 5 to 964 S cm^(−1),while the Seebeck coefficient can be further enhanced from 18.7 to 25μV K−1 by treating with 0.5 mol L−1 LAA,contributing to a sig-nificantly improved power factor of 55.3μW m^(−1)K^(−2).The boosted electrical conductivity is ascribed to the separated PEDOT and PSS phases triggered by the high dielectric constant and polarity of DMAC;while the improved Seebeck coefficient is attributed to the reduced oxidation degree of PEDOT from the reducing agent LAA,both confirmed by the comprehensive structural and morphological characteri-zations.Furthermore,a maximum power factor of 64.4μW m^(−1)K^(−2)can be achieved at 360 K and the observed temperature-dependent electrical transport behavior can be well explained by the Mott variable range hopping model.Besides,a flexible thermoelectric device,assembled by the as-fabricated PEDOT:PSS films,exhibits a maximum output power of∼23 nW at a temperature difference of 25 K,indicating the potential for applying to low-grade wearable electronics.

Deciphering Ascorbic Acid Regulatory Pathways in Ripening Tomato Fruit Using a Weighted Gene Correlation Network Analysis Approach

Genotype is generally determined by the co-expression of diverse genes and multiple regulatory pathways in plants. Gene co-expression analysis combining with physiological trait data provides very important information about the gene function and regulatory mechanism. L-Ascorbic acid （AsA）, which is an essential nutrient component for human health and plant metabolism, plays key roles in diverse biological processes such as cell cycle, cell expansion, stress resistance, hormone synthesis, and signaling. Here, we applied a weighted gene correlation network analysis approach based on gene expression values and AsA content data in ripening tomato （Solanum lycopersicum L.） fruit with different AsA content levels, which leads to identification of AsA relevant modules and vital genes in AsA regulatory pathways. Twenty- four modules were compartmentalized according to gene expression profiling. Among these modules, one negatively related module containing genes involved in redox processes and one positively related module enriched with genes involved in AsA biosynthetic and recycling pathways were further analyzed. The present work herein indicates that redox pathways as well as hormone-signal pathways are closely correlated with AsA accumulation in ripening tomato fruit, and allowed us to prioritize candidate genes for follow-up studies to dissect this interplay at the biochemical and molecular level.

Growth-controlled synthesis of polymer-coated colloidal-gold nanoparticles using electrospray-based chemical reduction

In this study,the controlled nucleation and growth of gold nanoparticles(GNPs)were investigated using a self-repelled mist in a liquid chemical reaction environment.An electrospray-based chemical reduction method was conducted in the aqueous region and at room temperature to synthesize the polymeric-stabilized gold nanoparticles.The electrospray technique was used to atomize a hydrogen tetrachloraurate(III)(HAuCl4)precursor solution into electrostatically charged droplets.The atomized droplets were dispersed in an aqueous reaction bath containing L-ascorbic acid as a reducing agent and polyvinylpyrrolidone(PVP)as a stabilizer.The effect of the electrospray parameters,specifically the flow rate and electrospray droplet size,as well as the reaction conditions such as the concentration of reactants,pH,and stabilizer(PVP),were investigated.The mean diameter of the GNPs increased from around 4 to 9 nm with an increase in the electrospray flow rate,droplet size,and current passing through the electrospray jet.Spherical and monodispersed GNPs were synthesized at a relatively high flow rate of 2 mL/h and a moderate concentration of 2 mM of precursor solution.The smallest-sized GNP with a high monodispersity was obtained in the reaction bath at a high pH of 10.5 and in the presence of PVP.It is expected that continuous and mass production of the engineered GNPs and other noble metal nanoparticles could be established for scaling up nanoparticle production via the proposed electrospray-based chemical reduction method.

Sulfonated Graphene Synthesized via a Green Route and Its Capacitive Properties

An environmentally friendly approach is presented to synthesize sulfonated reduced graphene oxide （S-rGO） by using L-ascorbic acid （L-AA） and aryl diazonium salt of sulfanilic acid. The preparation conditions have been optimized in order to obtain isolated and conductive S-rGO, and the products have been characterized by Ultraviolet-Visible spectroscopy, Fourier transformed infrared spectroscopy, Raman, X-ray photoelectron spectroscopy and X-ray powder diffraction and electrochemical methods. The results show that the S-rGO sheets possess excellent water-solubility and high electrical conductivity, which implies that the oxygen-containing functional groups have been removed and conjugated sp2 network has been restored. What＇s more, the electrochemical measurements reveal that the capacitive performance of the S-rGO has been improved compared with the graphene oxide （GO） and the reduced graphene oxide （rGO, reduced by L-AA）. The optimum S-rGO exhibits a specific capacitance of 205 F·g^-1 and good cycling stability （3.9% decreasing after 10000 cycles）, which are better than those for graphene oxide （109 F·g^-1 and decreasing 6.6% after 10000 cycles） and rGO （139 F·g^-1 and decreasing ll.3% after 10000 cycling）. This approach proves a new route to improve the capacitive properties of rGO.

Enhanced production of L-sorbose by systematic engineering of dehydrogenases in Gluconobacter oxydans

L-Sorbose is an essential intermediate for the industrial production of vitamin C(L-ascorbic acid).However,the formation of fructose and some unknown by-products significantly reduces the conversion ratio of D-sorbitol to L-sorbose.This study aimed to identify the key D-sorbitol dehydrogenases in Gluconobacter oxydans WSH-003 by gene knockout.Then,a total of 38 dehydrogenases were knocked out in G.oxydans WSH-003,and 23 dehydrogenase-deficient strains could increase L-sorbose production.G.oxydans-30,wherein a pyrroloquinoline quinone-dependent glucose dehydrogenase was deleted,showed a significant reduction of a by-product with the extension of fermentation time.In addition,the highest conversion ratio of 99.60%was achieved in G.oxydans MD-16,in which 16 different types of dehydrogenases were inactivated consecutively.Finally,the gene vhb encoding hemoglobin was introduced into the strain.The titer of L-sorbose was 298.61 g/L in a 5-L bioreactor.The results showed that the systematic engineering of dehydrogenase could significantly enhance the production of L-sorbose.

Acquired cystic fibrosis transmembrane conductance regulator dysfunction

Sinonasal respiratory epithelium is a highly regulated barrier that employs mucociliary clearance(MCC)as the airways first line of defense.The biological properties of the airway surface liquid(ASL),combined with coordinated ciliary beating,are critical components of the mucociliary apparatus.The ASL volume and viscosity is modulated,in part,by the cystic fibrosis transmembrane conductance regulator(CFTR).The CFTR is an anion transporter of chloride(Cl-)and bicarbonate(HCO 3-)that is located on the apical surface of respiratory epithelium and exocrine glandular epithelium.Improved understanding of how dysfunction or deficiency of CFTR influences the disease process in both genetically defined cystic fibrosis(CF)and acquired conditions has provided further insight into potential avenues of treatment.This review discusses the latest data regarding acquired CFTR deficiency and use of CFTR specific treatment strategies for CRS and other chronic airway diseases.