Neutral rhenium(I) tricarbonyl complexes with sulfur-donor ligands: anti-proliferative activity and cellular localization

Rhenium(I) tricarbonyl complexes are widely studied for their cell imaging properties and anti-cancer and anti-microbial activities, but the complexes with S-donor ligands remain relatively unexplored. A series of six fac-[Re(NN)(CO)3(SR)] complexes, where (NN) is 2,2'-bipyridyl (bipy) or 1,10-phenanthroline (phen), and RSH is a series of thiocarboxylic acid methyl esters, have been synthesized and characterized. Cellular uptake and anti-proliferative activities of these complexes in human breast cancer cell lines (MDA-MB-231 and MCF-7) were generally lower than those of the previously described fac-[Re(NN)(CO)3(OH2)]+ complexes; however, one of the complexes, fac-[Re(CO)3(phen)(SC(Ph)CH2C(O)OMe)] (3b), was active (IC50 ∼ 10 μM at 72 h treatment) in thiol-depleted MDA-MB-231 cells. Moreover, unlike fac-[Re(CO)3(phen)(OH2)]+, this complex did not lose activity in the presence of extracellular glutathione. Taken together these properties show promise for further development of 3b and its analogues as potential anti-cancer drugs for co-treatment with thiol-depleting agents. Conversely, the stable and non-toxic complex, fac-[Re(bipy)(CO)3(SC(Me)C(O)OMe)] (1a), predominantly localized in the lysosomes of MDA-MB-231 cells, as shown by live cell confocal microscopy (λex = 405 nm, λem = 470-570 nm). It is strongly localized in a subset of lysosomes (25 μM Re, 4 h treatment), as shown by co-localization with a Lysotracker dye. Longer treatment times with 1a (25 μM Re for 48 h) resulted in partial migration of the probe into the mitochondria, as shown by co-localization with a Mitotracker dye. These properties make complex 1a an attractive target for further development as an organelle probe for multimodal imaging, including phosphorescence, carbonyl tag for vibrational spectroscopy, and Re tag for X-ray fluorescence microscopy.

Enhancement of bio-promoters on hexavalent chromium inhibited sulfur-driven denitrification: repairing damage, accelerating electron transfer, and reshaping microbial collaboration

Proposing recovery strategies to recover heavy-metal-inhibited sulfur-driven denitrification, as well as disclosing recovery mechanisms, can provide technical support for the stable operation of bio-systems. This study proposed an effective bio-promoter (mediator-promoter composed of L-cysteine, biotin, cytokinin, and anthraquinone-2,6-disulfonate) to recover Cr(VI) inhibited sulfur-driven denitrification, which effectively reduced the recovery time of NO3--N reduction (18-21 cycles) and NO2--N reduction (27-42 cycles) compared with self-recovery. The mediator-promoter repaired microbial damage by promoting intracellular chromium efflux. Moreover, the mediator-promoter reduced the accumulated reactive oxygen species by stimulating the secretion of antioxidant enzymes, reaching equilibrium in the oxidative-antioxidant system. To improve electron transmission, the mediator-promoter restored S2O32- oxidation to provide adequate electron donors and increased electron transfer rate by increasing cytochrome c levels. Mediator-promoter boosted the abundance of Thiobacillus (sulfur-oxidizing bacterium) and Simplicispira (denitrifying bacterium), which were positively correlated, facilitating the rapid denitrification recovery and the long-term stable operation of recovered systems.

Sulfur (SⅥ)-containing heterocyclic hybrids as antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA) and its SAR

The discovery of new small molecule-based inhibitors is an attractive field in medicinal chemistry. Structurally diversified heterocyclic derivatives have been investigated to combat multi-drug resistant bacterial infections and they offers several mechanism of action. Methicillin-resistant Staphylococcus aureus (MRSA) is becoming more and more deadly to humans because of its simple method of transmission, quick development of antibiotic resistance, and ability to cause hard-to-treat skin and filmy diseases. The sulfur (SVI) particularly sulfonyl and sulfonamide based heterocyclic moieties, have found to be good anti-MRSA agents. The development of new nontoxic, economical and highly active sulfur (SVI) containing derivatives has become hot research topics in drug discovery research. Presently, more than 150 FDA approved Sulfur (SVI)-based drugs are available in the market, and they are widely used to treat various types of diseases with different therapeutic potential. The present collective data provides the latest advancements in Sulfur (SVI)-hybrid compounds as antibacterial agents against MRSA. It also examines the outcomes of in-vitro and in-vivo investigations, exploring potential mechanisms of action and offering alternative perspectives on the structure-activity relationship (SAR). Sulfur (SVI)-hybrids exhibits synergistic effects with existing drugs to provide antibacterial action against MRSA.

The Roles of Diet and Habitat Use in Pesticide Bioaccumulation by Juvenile Chinook Salmon: Insights from Stable Isotopes and Fatty Acid Biomarkers

Stable isotopes (SI) and fatty acid (FA) biomarkers can provide insights regarding trophic pathways and habitats associated with contaminant bioaccumulation. We assessed relationships between SI and FA biomarkers and published data on concentrations of two pesticides [dichlorodiphenyltrichloroethane and degradation products (DDX) and bifenthrin] in juvenile Chinook Salmon (Oncorhynchus tshawytscha) from the Sacramento River and Yolo Bypass floodplain in Northern California near Sacramento. We also conducted SI and FA analyses of zooplankton and macroinvertebrates to determine whether particular trophic pathways and habitats were associated with elevated pesticide concentrations in fish. Relationships between DDX and both sulfur (δ34S) and carbon (δ13C) SI ratios in salmon indicated that diet is a major exposure route for DDX, particularly for individuals with a benthic detrital energy base. Greater use of a benthic detrital energy base likely accounted for the higher frequency of salmon with DDX concentrations > 60 ng/g dw in the Yolo Bypass compared to the Sacramento River. Chironomid larvae and zooplankton were implicated as prey items likely responsible for trophic transfer of DDX to salmon. Sulfur SI ratios enabled identification of hatchery-origin fish that had likely spent insufficient time in the wild to substantially bioaccumulate DDX. Bifenthrin concentration was unrelated to SI or FA biomarkers in salmon, potentially due to aqueous uptake, biotransformation and elimination of the pesticide, or indistinct biomarker compositions among invertebrates with low and high bifenthrin concentrations. One FA [docosahexaenoic acid (DHA)] and DDX were negatively correlated in salmon, potentially due to a greater uptake of DDX from invertebrates with low DHA or effects of DDX on FA metabolism. Trophic biomarkers may be useful indicators of DDX accumulation and effects in juvenile Chinook Salmon in the Sacramento River Delta.

Effects of Setaria viridis on heavy metal enrichment tolerance and bacterial community establishment in high-sulfur coal gangue

Plant enrichment and tolerance to heavy metals are crucial for the phytoremediation of coal gangue mountain. However, understanding of how plants mobilize and tolerate heavy metals in coal gangue is limited. This study conducted potted experiments using Setaria viridis as a pioneer remediation plant to evaluate its tolerance to coal gangue, its mobilization and enrichment of metals, and its impact on the soil environment. Results showed that the addition of 40% gangue enhanced plant metal and oxidative stress resistance, thereby promoting plant growth. However, over 80% of the gangue inhibited the chlorophyll content, photoelectron conduction rate, and biomass of S. viridis, leading to cellular peroxidative stress. An analysis of metal resistance showed that endogenous S in coal gangue promoted the accumulation of glutathione, plant metal chelators, and non-protein thiols, thereby enhancing its resistance to metal stress. Setaria viridis cultivation affected soil properties by decreasing nitrogen, phosphorus, conductivity, and urease and increasing sucrase and acid phosphatase in the rhizosphere soil. In addition, S. viridis planting increased V, Cr, Ni, As, and Zn in the exchangeable and carbonate-bound states within the gangue, effectively enriching Cd, Cr, Fe, S, U, Cu, and V. The increased mobility of Cd and Pb was correlated with a higher abundance of Proteobacteria and Acidobacteria. Heavy metals, such as As, Fe, V, Mn, Ni, and Cu, along with environmental factors, including total nitrogen, total phosphorus, urease, and acid phosphatase, were the primary regulatory factors for Sphingomonas, Gemmatimonas, and Bryobacter. In summary, S. viridis adapted to gangue stress by modulating antioxidant and elemental enrichment systems and regulating the release and uptake of heavy metals through enhanced bacterial abundance and the recruitment of gangue-tolerant bacteria. These findings highlight the potential of S. viridis for plant enrichment in coal gangue areas and will aid the restoration and remediation of these environments.

Supersulfides support bone growth by promoting chondrocyte proliferation in the growth plates

OBJECTIVES

While chondrocytes have mitochondria, they receive little O2 from the bloodstream. Sulfur respiration, an essential energy production system in mitochondria, uses supersulfides instead of O2. Supersulfides are inorganic and organic sulfides with catenated sulfur atoms and are primarily produced by cysteinyl tRNA synthetase-2 (CARS2). Here, we investigated the role of supersulfides in chondrocyte proliferation and bone growth driven by growth plate chondrocyte proliferation.

METHODS

We examined the effects of NaHS, an HS-/H2S donor, and cystine, the cellular source of cysteine, on the proliferation of mouse primary chondrocytes and growth of embryonic mouse tibia in vitro. We also examined the effect of RNA interference acting on the Cars2 gene on chondrocyte proliferation in the presence of cystine.

RESULTS

NaHS (30 μmol/L) enhanced tibia longitudinal growth in vitro with expansion of the proliferating zone of their growth plates. While NaHS (30 μmol/L) also promoted chondrocyte proliferation only under normoxic conditions (20 % O2), cystine (0.5 mmol/L) promoted it under both normoxic and hypoxic (2 % O2) conditions. Cars2 gene knockdown abrogated the ability of cystine (0.5 mmol/L) to promote chondrocyte proliferation under normoxic conditions, indicating that supersulfides produced by CARS2 were responsible for the cystine-dependent promotion of bone growth.

CONCLUSIONS

The presented results indicate that supersulfides play a vital role in bone growth achieved by chondrocyte proliferation in the growth plates driven by sulfur respiration.

The effect of sulphur supplementation on cadmium phytotoxicity in wheat and lettuce: changes in physiochemical properties of roots and accumulation of phytochelatins

Intensive sulphur fertilisation has been reported to improve the nutrient balance and growth of Cd-exposed plants, but the reasons of this phenomenon and the role of sulphur compounds in the resistance to cadmium are unclear. We investigated sulphur supplementation-induced changes in the surface properties of roots and the level of thiol peptides (PCs) in Cd-stressed Triticum aestivum L. (monocots clade) and Lactuca sativa L. (dicots clade) grown in nutrient solution. The combination of three sulphur (2 mM S-basic level, 6 or 9 mM S-elevated levels) and four cadmium (0, 0.0002, 0.02 or 0.04 mM Cd) concentrations was used. The physicochemical parameters of the roots were determined based on the apparent surface area (Sr), total variable surface charge (Q), cation exchange capacity (CEC) and surface charge density (SCD). In Cd-exposed plants supplied with sulphur, a different character and trend in the physicochemical changes (adsorption and ion exchange) of roots were noted. At the increased sulphur levels, as a rule, the Sr, CEC, Q and SCD values clearly increased in the lettuce but decreased in the wheat in the entire range of the Cd concentrations, except the enhanced Sr of wheat supplied with 6 mM S together with elevated (0.0002 mM) and unchanged (0.02, 0.04 mM Cd) value of this parameter at 9 mM S. This indicates a clade-specific and/or species-specific plant reaction. The 6 mM S appears to be more effective than 9 mM S in alleviation of the cadmium's toxic effects on roots. It was found that at 0.02 and 0.04 mM Cd, the use of 6 mM S limits the Cd accumulation in the roots of both species in comparison with the basic S fertilisation. Moreover, PC accumulation was much more efficient in wheat than in lettuce, and intensive sulphur nutrition generally induced biosynthesis of these chelating compounds. Physicochemical parameters together with quantitative and qualitative assessment of thiol peptides can be important indicators of the efficiency of root system functioning under cadmium stress. The differences between the species and the multidirectional character of the changes are a result of the involvement of a number of multi-level mechanisms engaged in the defence against metal toxicity.

Effects of bathing in different hot spring types on Japanese gut microbiota

Hot springs have been used for a variety of purposes, including the treatment and amelioration of illness and recreation. Japan has ten different types of therapeutic springs (described here as spa types), which are traditionally believed to have different efficacy. However, more research must be conducted to determine how they affect healthy people. Therefore, this study focused on the gut microbiota and aimed to investigate changes in the gut microbiota in healthy people after bathing in different spa types. Using Beppu's hot springs (simple, chloride, bicarbonate, sulfur, and sulfate types), 136 healthy Japanese adults living in the Kyushu area participated in the study and bathed in the same hot spring for seven days. Fecal samples were collected before and after the 7-day bathing period, and the relative abundance of the gut microbiota was determined by 16S rRNA sequencing. The results showed that the relative abundance of Bifidobacterium bifidum increased significantly after seven consecutive days of bathing in the bicarbonate spring. Significant increases in other gut microbiota were also observed after bathing in simple, bicarbonate, and sulfur springs. These results suggest that bathing in different hot springs may affect the gut microbiota in healthy individuals differently.

Combined application of biochar and sulfur alleviates cadmium toxicity in rice by affecting root gene expression and iron plaque accumulation

Biochar and sulfur are considered useful amendments for soil cadmium (Cd) contamination remediation. However, there is still a gap in the understanding of how combined biochar and sulfur application affects Cd resistance in rice, and the role of the accumulation of iron plaque and the expression of Cd efflux transporter-related genes are still unclear in this type of treatment. In this study, we screened an effective combination of biochar and sulfur (0.75 % biochar, 60 mg/kg sulfur) that significantly reduced the Cd content of rice roots (32.9 %) and shoots (12.3 %); significantly reduced the accumulation of amino acids and their derivatives, organic acids and their derivatives and flavonoids in rice roots; and altered secondary metabolite production and release. This combined biochar and sulfur application alleviated the toxicity of Cd to rice, in which the enhancement of iron plaque (24.8 %) formation and upregulated expression of heavy metal effector genes (NRAMP3, MTP3, ZIP1) were important factors. These findings show that iron plaque and heavy metal transport genes are involved in the detoxification of rice under the combined application of biochar and sulfur, which provides useful information for the combined treatment of soil Cd pollution.

The key roles of reactive oxygen species in microglial inflammatory activation: Regulation by endogenous antioxidant system and exogenous sulfur-containing compounds

Aberrant innate immunity in the brain has been implicated in the pathogenesis of several central nervous system (CNS) disorders, including Alzheimer's disease, Huntington's disease, Parkinson's disease, stroke, amyotrophic lateral sclerosis, and depression. Except for extraparenchymal CNS-associated macrophages, which predominantly afford protection against peripheral invading pathogens, it has been reported that microglia, a population of macrophage-like cells governing CNS immune defense in nearly all neurological diseases, are the main CNS resident immune cells. Although microglia have been recognized as the most important source of reactive oxygen species (ROS) in the CNS, ROS also may underlie microglial functions, especially M1 polarization, by modulating redox-sensitive signaling pathways. Recently, endogenous antioxidant systems, including glutathione, hydrogen sulfide, superoxide dismutase, and methionine sulfoxide reductase A, were found to be involved in regulating microglia-mediated neuroinflammation. A series of natural sulfur-containing compounds, including S-adenosyl methionine, S-methyl-L-cysteine, sulforaphane, DMS, and S-alk(enyl)-l-cysteine sulfoxide, modulating endogenous antioxidant systems have been discovered. We have summarized the current knowledge on the involvement of endogenous antioxidant systems in regulating microglial inflammatory activation and the effects of sulfur-containing compounds on endogenous antioxidant systems. Finally, we discuss the possibilities associated with compounds targeting the endogenous antioxidant system to treat neuroinflammation-associated diseases.

Effect of sulfonation time on physicochemical, osteogenic, antibacterial properties and biocompatibility of carbon fiber reinforced polyether ether ketone

The carbon fiber reinforced polyetheretherketone (CFR-PEEK) has been increasingly used in orthopedics dentistry due to its excellent biocompatibility and mechanical properties. However, the biological inertness and poor antibacterial activity limit its clinical applications. This paper focused on the performances of CFR-PEEK with porous morphology that were exposed to different sulfonation periods (1, 3, 5, and 10 min, corresponding to CP-S1, CP-S3, CP-S5, and CP-S10, respectively). Residual sulfuric acid was removed by acetone rinsing, NaOH immersion, and hydrothermal treatment before in vitro and in vivo studies. The results showed some significant difference in the physicochemical properties, including energy dispersive X-ray spectroscopy (EDS) map of sulfur atoms, X-ray photoelectron spectroscopy (XPS) of valences of sulfur ions, Fourier transformation infrared spectroscopy (FTIR), hydrophilicity, hardness, and elastic modulus among CP-S3, CP-S5, and CP-S10. However, CP-S5 and CP-S10 were more effective in promoting the proliferation, adhesion, and osteogenic differentiation of seeded bone mesenchymal stem cells (BMSCs) and growth inhibition of S. aureus and P. gingivalis compared with other groups. Furthermore, the CP-S5 and CP-S10 samples achieved better cranial bone repair than the non-sulfonation group in a rat model. Therefore, it can be inferred that both 5 and 10 min are viable sulfonation durations for 30% CFR-PEEK. These findings provide a theoretical basis for developing CFR-PEEK for clinical applications.

Light stress induced DMS(P) production in Skeletonema costatum: An experimental approach and field observation

Dimethylsulphide is a dominant biogenic sulphur anti-greenhouse gas produced by marine phytoplankton. A non-axenic culture of Skeletonema costatum was studied to comprehend the effects of different growth stages and light stress on DMSP/DMS production. The intracellular DMSP concentration increased during late exponential to mid-stationary phase and attained a maximum (0.59 pg S cell^-1) during the stationary phase, indicating more contribution from actively dividing smaller cells. Likewise, exposure to first light after a 12-hour dark phase caused stress, invariably leading to elevated levels of DMS (~9 fold). These observations were upheld by additional laboratory and field experiments, and a field time-series observation, which recorded higher DMS concentrations during exposure to first light after a dark cycle and during early mornings, respectively. While our study depicts the variable DMSP and DMS concentrations during different growth stages of S. costatum, it gives new information on the effect of light stress on DMS production.

Effect of farmyard manure, elemental sulphur and EDTA on growth and phytoextraction of cadmium by spider plants (Chlorophytum comosum L.) under Cd stress

Cadmium (Cd) contamination is considered as a widespread concern at global scale which is serious threats to human health. Phytoremediation is an eco-friendly approach which can remove or immobilize Cd from the soil. Different organic and inorganic amendments can potentially enhance Cd phytoremediation efficiency but the comparison of farmyard manure (FM), elemental sulphur (S) and ethylenediaminetetraacetic acid (EDTA) for Cd phytoremediation through spider plants (Chlorophytum comosum L.) remained unanswered. The present study evaluated the efficiency of S (0.1 and 0.2%), EDTA (0.1 and 0.2%, represented as EDTA-0.1 and EDTA-0.2) and FM (0.5 and 1%, represented as FM-0.5 and FM-1) for remediation of Cd contaminated soils (50 and 100 mg kg-1, represented as Cd-50 and Cd-100) through spider plants. Results depicted that the highest shoots and roots dry biomass was found in FM treated plants followed by S, EDTA and control except in EDTA-0.2 treatment in which the lowest values of these parameters were observed. Application of FM-1 significantly increased the shoot dry weight (120%), root dry weight (99%), as well as photosynthetic attributes in Cd-50 as compared to control. Application of EDTA-0.2 increased the bioavailable fraction of Cd than control and the maximum increase was observed in Cd-100. The highest Cd concentrations in shoot and roots were found in EDTA treated plants followed by S, control and FM irrespective of Cd and amendment levels. Maximum Cd in roots (109%) and shoots (156%) was recorded in plants grown in Cd-100 with EDTA-0.2 than control. The maximum bioaccumulation factor, translocation index, harvest index and root to shoot translocation were observed with EDTA than control and other treatments. EDTA along with spider plants may enhance the uptake of Cd but lower biomass production in the highest dose of EDTA may questioned the efficiency of EDTA.

Enhancement in the visible light induced photocatalytic and antibacterial properties of titanium dioxide codoped with cobalt and sulfur

In this study, the sol-gel technique was used to develop Cobalt Sulfur codoped Titanium Dioxide (Co-S codoped TiO₂) photocatalysts. For structural analysis of the prepared resultant TiO₂ samples, XRD, FTIR, UV-Vis DRS, SEM, HR-TEM and EDX measurements were used to describe the produced photocatalysts. The characterization findings indicate that the synthesized nanoparticles possessed great crystallinity, high purity, and superior optical characteristics. For the methylene blue (MB) degradation process, Co-S codoped TiO₂ nanoparticles were tested for their photocatalytic degradation performance. The Co-S codoped TiO₂ nanoparticles had improved catalytic activity when compared with pure, Co-doped, S-doped TiO₂ and decomposed 93% of MB in 120 min. When compared to pure and doped TiO₂, the catalysts of Co-S codoped TiO₂ showed a synergistic effect and improved the performance of the catalysts. Furthermore, the antibacterial applications of synthesized Co-S codoped TiO₂ nanoparticles was studied against E. coli (Gram negative) and S. aureus (Gram positive) bacteria and exhibited strong antibacterial activity against the selected strains.

Bioreduction mechanisms of high-concentration hexavalent chromium using sulfur salts by photosynthetic bacteria

Eliminating "sulfur starvation" caused by competition for sulfate transporters between chromate and sulfate is crucial to enhance the content of sulfur-containing compounds and improve the tolerance and reduction capability of Cr(VI) in bacteria. In this study, the effects of sulfur salts on the Cr(VI) bioremediation and the possible mechanism were investigated in Rhodobacter sphaeroides SC01 by cell imaging, spectroscopy, and biochemical measurements. The results showed that, when the concentration of metabisulfite was 2.0 g L^-1, and the initial OD₆₀₀ was 0.33, the reduction rate of R. sphaeroides SC01 reached up to 91.3% for 500 mg L^-1 Cr(VI) exposure at 96 h. Moreover, thiosulfate and sulfite also markedly increased the concentration of reduced Cr(VI) in R. sphaeroides SC01. Furthermore, the characterization results revealed that -OH, -CONH, -COOH, -SO₃, -PO₃, and -S-S- played a major role in the adsorption of Cr, and Cr(III) reduced by bacteria was bioprecipitated in the production of Cr₂P₃S₉ and CrPS₄. In addition, R. sphaeroids SC01 combined with metabisulfite significantly increased the activity of glutathione peroxidase and the content of glutathione (GSH) and total sulfhydryl while decreasing reactive oxygen species (ROS) accumulation and cell death induced by Cr(VI) toxic. Overall, the results of this research revealed a highly efficient and reliable strategy for Cr(VI) removal by photosynthetic bacteria combined with sulfur salts in high-concentration Cr(VI)-contaminated wastewater.

Brominated and Sulfur-Containing Angucyclines Derived from a Single Pathway: Identification of Nocardiopsistins D-F

One novel brominated nocardiopsistin D (1) and two new sulfur-containing nocardiopsistins E-F (2-3) were identified from Nocardiopsis sp. HB-J378. The biosynthetic gene cluster ncd featuring a brominase was identified. Compounds 1-3 exhibited significant anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) activities with minimum inhibitory concentrations (MICs) of 0.098, 3.125, and 0.195 μg/mL, respectively. The single bromination in 1 drastically enhanced the anti-MRSA activity by 128-fold without altering cell toxicity and acquired new activities against the bacterial pathogens vancomycin-resistant S. aureus (VRSA), Enterococcus faecium, and Bacillus cereus.

Proteomic Investigation of the Antibacterial Mechanism of Cefiderocol against Escherichia coli

This study aimed to investigate the antibacterial mechanism of cefiderocol (CFDC) using data-independent acquisition quantitative proteomics combined with cellular and molecular biological assays. Numerous differentially expressed proteins related to the production of NADH, reduced cofactor flavin adenine dinucleotide (FADH2), NADPH and reactive oxygen species (ROS), iron-sulfur cluster binding, and iron ion homeostasis were found to be upregulated by CFDC. Furthermore, parallel reaction monitoring analysis validated these results. Meanwhile, we confirmed that the levels of NADH, ROS, H2O2, and iron ions were induced by CFDC, and the sensitivity of Escherichia coli to CFDC was inhibited by the antioxidant vitamin C, N-acetyl-l-cysteine, and deferoxamine. Moreover, deferoxamine also suppressed the H2O2 stress induced by CFDC. In addition, knockout of the NADH-quinone oxidoreductase genes (nuoA, nuoC, nuoE, nuoF, nuoG, nuoJ, nuoL, nuoM) in the respiratory chain attenuated the sensitivity of E. coli to CFDC far beyond the effects of cefepime and ceftazidime; in particular, the E. coli BW25113 ΔnuoJ strain produced 60-fold increases in MIC to CFDC compared to that of the wild-type E. coli BW25113 strain. The present study revealed that CFDC exerts its antibacterial effects by inducing ROS stress by elevating the levels of NADH and iron ions in E. coli. IMPORTANCE CFDC was the first FDA-approved siderophore cephalosporin antibiotic in 2019 and is known for its Trojan horse tactics and broad antimicrobial activity against Gram-negative bacteria. However, its antibacterial mechanism is not fully understood, and whether it has an impact on in vivo iron ion homeostasis remains unknown. To comprehensively reveal the antibacterial mechanisms of CFDC, data-independent acquisition quantitative proteomics combined with cellular and molecular biological assays were performed in this study. The findings will further facilitate our understanding of the antibacterial mechanism of CFDC and may provide a theoretical foundation for controlling CFDC resistance in the future.

CDGSH iron sulfur domain 2 mitigates apoptosis, oxidative stress and inflammatory response caused by oxygen-glucose deprivation/reoxygenation in HT22 hippocampal neurons by Akt-Nrf2-activated pathway

CDGSH iron sulfur domain 2 (Cisd2) is known as a key determinant factor in maintaining cellular homeostasis. However, whether Cisd2 contributes to the mediation of neuronal injury during ischemic stroke has not been well stressed. This work focuses on investigating the role of Cisd2 in regulating neuronal injury caused by oxygen-glucose deprivation/reoxygenation (OGD/R). The dramatic down-regulation of Cisd2 was observed in hippocampal neurons suffering from OGD/R injury. In Cisd2-overexpressed neurons, OGD/R-induced neuronal apoptosis, oxidative stress and inflammation were prominently mitigated. Further investigation uncovered that the forced expression of Cisd2 reinforced the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in OGD/R-exposed neurons. Moreover, the overexpression of Cisd2 enhanced Akt activation, and the restraint of Akt abolished Cisd2-induced Nrf2 activation. Importantly, restraint of Nrf2 reversed Cisd2-conferred neuroprotective effects in OGD/R-exposed neurons. Taken together, our findings indicate that Cisd2 is able to protect neurons from OGD/R-induced injuries by strengthening Nrf2 activation via Akt. Our work identifies Cisd2 as a potential determinant factor for neuronal injury during cerebral ischemia/reperfusion injury.

Characterization of a new Bacillus velezensis as a powerful biocontrol agent against tomato gray mold

Biocontrol microbes are environment-friendly and safe for humans and animals. To seek biocontrol microbes effective in suppressing tomato gray mold is important for tomato production. Therefore, serial experiments were conducted to characterize the antagonism of Bacillus velezensis HY19, a novel self-isolated biocontrol bacterium, against Botrytis cinerea in vitro and the control on tomato gray mold in greenhouse. This bacterium produced extracellular phosphatase, protease, cellulose and siderophores, and considerably inhibited the growth of B. cinerea. A liquid chromatography-mass spectrometry (LC-MS) detected salicylic acid and numerous antifungal substances present in B. velezensis HY19 fermentation liquid (BVFL). When B. cinerea was grown on potato glucose agar, BVFL crude extract remarkably suppressed the fungal growth and reduced protein content and the activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD). Transcriptome studies showed that BVFL crude extract significantly induced different expression of numerous genes in B. cinerea, most of which were down-regulated. Theses differently expressed genes were involved in the biological process, cell compartment, molecular functions, and metabolisms of glycine, serine, threonine, and sulfur in pathogen hyphae. Thus, this biocontrol bacterium antagonized B. cinerea in multiple ways due to the production of numerous antifungal substances that acted on multiple targets in the cells. BVFL significantly increased antioxidant enzyme activities in tomato leaves and decreased the incidence of tomato gray mold, with the control efficacies of 73.12-76.51%. Taken together, B. velezensis HY19 showed a promising use potential as a powerful bioagent against tomato gray mold.

Antiproliferative and Antiprostate Cancer Activities of Heterocyclic Compounds Derived from Cyclohexane-1,4-dione

2-Amino-6-oxo-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbonitrile (3) was prepared from the reaction of cyclohexane-1,4-dione with elemental sulfur and malononitrile in 1,4-dioxane and triethylamine as catalyst. The latter compound reacted with triethyl orthoformate and either malononitrile or ethyl cyanoacetate in 1,4-dioxane in the presence of triethylamine to produce 4H-thieno[2,3-f]chromene derivatives 10a,b. In addition, fused pyran and pyridine derivatives were synthesized starting from compound 3. The cytotoxicity of the synthesized compounds was studied on six cancer cell lines together with c-Met kinase and PC-3 cell line. The most active compounds were tested against five tyrosine kinases and Pim-1 kinase, most of which showed strong inhibition, encouraging further work.

A two-phase protocol for ambient hydrogen production using Chlamydomonas reinhardtii

H₂ production from green-microalgae, for energy purposes, is the ultimate goal of large-scale production. Here, we present a two-phase protocol for hydrogen production assay under ambient conditions using Chlamydomonas reinhardtii, which eliminates steps used previously, including centrifugation and resuspension with sulfur-deprived media. We detail steps for Chlamydomonas reinhardtii culture, acetate supply replenishment, anaerobic induction, and H₂ quantification. This protocol enables large-scale experiments in an easy and cost-effective method while maintaining cells vital, crucial factors for transition to industrial scales.

For complete details on the use and execution of this protocol, please refer to Elman et al. (2022).

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2-step protocol for ambient hydrogen production in green algae

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Detailed culture steps of Chlamydomonas reinhardtii

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Acetate supply via addition of glacial acetic acid as a carbon source

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H₂ production assay without centrifugation or sulfur-deprivation requirements

Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.

[Hydrogen Sulfide Ameliorates Myocardial Injury Caused by Sepsis Through Suppressing ROS-Mediated Endoplasmic Reticulum Stress]

Objective

To investigate the effect of hydrogen sulfide (H 2S) on reactive oxygen species (ROS)-mediated endoplasmic reticulum stress in myocardial injury caused by sepsis.

Methods

A sepsis model was induced in Sprague-Dawley (SD) rats by cecal ligation and puncture (CLP). The rats were randomly divided into sham operation (sham) group, sepsis (CLP) group, and sepsis+sodium hydrosulfide (NaHS) (CLP+NaHS) group. The left ventricular function of the rats was observed with echocardiography and their plasma H 2S levels were measured. Lactate dehydrogenase (LDH), malondialdehyde (MDA), glutathione (GSH) levels were measured and HE staining was done to evaluate the level of myocardial oxidative stress in rats. HE staining was done to observe the morphological changes of rat myocardium, and transmission electron microscope was used to observe the ultrastructure of myocardial mitochondria. Western blot was done to examine changes in the expression of two endogenous hydrogen sulfide synthases, cystathionine γ-lyase (CSE) and 3-mercaptopyruvate sulfur transferase (3-MST), and changes in the expression of endoplasmic reticulum stress (ERS) marker proteins, including phosphorylated (p) protein kinase R-like endoplasmic reticulum kinase (p-PERK), p-eukaryotic translation initiation factor 2α (p-eIF2α), p-inositol requires enzyme 1α (IRE1α), recombinant activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP). TUNEL staining was performed to observe the changes of cardiomyocyte apoptosis in rats.

Results

Left ventricular ejection fraction (LVEF), left ventricular shortening fraction (LVFS) and plasma H 2S decreased in septic rats ( P<0.05). Plasma H 2S exhibited linear correlation with LVEF and LVFS ( r 2=0.62 and r 2=0.64, all P<0.05). The ROS levels were significantly elevated in rats of the CLP group. In addition, these rats showed increased level of LDH ( P<0.05), increased expression of MDA ( P<0.05), and decreased expression of GSH ( P<0.05). Inflammatory cell infiltration and cardiomyocyte edema were observed in HE staining. Transmission electron microscopic observation revealed significant mitochondrial damage, observable mitochondrial edema, and cristae structure dissolution. The Western blot results showed that the expression levels of CSE and 3-MST decreased ( P<0.05), while the ERS marker proteins, including p-PERK, p-eIF2, IRE1α, ATF4, and CHOP, were expressed at increased levels ( P<0.05). TUNEL staining showed significant increase of apoptosis in cardiomyocytes ( P<0.05). After NaHS treatment, LVEF and LVFS increased ( P<0.05) and plasma H 2S increased in septic rats ( P<0.05). Myocardial oxidative stress levels decreased. HE staining and transmission electron microscopy showed improved myocardial morphology. Mitochondrial damage was reduced and CSE and 3-MST levels were significantly increased ( P<0.05). The expression of p-PERK, p-eIF2α, p-IRE1α, and CHOP proteins decreased ( P<0.05). A decrease in cardiomyocyte apoptosis levels was observed by TUNEL staining ( P<0.05).

Conclusion

H 2S reduces septic cardiomyocyte apoptosis by inhibiting ROS-mediated ERS, thereby improving myocardial dysfunction in sepsis.

Exogenous supplementation of Sulfur (S) and Reduced Glutathione (GSH) Alleviates Arsenic Toxicity in Shoots of Isatis cappadocica Desv and Erysimum allionii L

The current study was conducted to investigate the role of sulfur (S) and reduced glutathione (GSH) in mitigating arsenic (As) toxicity in Isatis cappadocica and Erysimum allionii. These plants were exposed for 3 weeks to different concentrations (0, 400 and 800 μM) of As to measure fresh weight, total chlorophyll, proline and hydrogen peroxide (H₂O₂) content, As and S accumulation, and guaiacol peroxidase (POD) and glutathione S-transferase (GST) along with the supplementation of 20 mg L^-1 of S and 500 μM of GSH. Results revealed the significant reduction of fresh weight (especially in E. allionii), activities of POD and GST enzymes and proline content as compare to control. However, the application of S and GSH enhanced the fresh weight. Inhibition in H₂O₂ accumulation and improvement in antioxidant responses were measured with the application of S and GSH. Hence, the supplementation of S and GSH enhanced fresh weight and total chlorophyll in both I. cappadocica and E. allionii by alleviating the adverse effects of As stress via decreased H₂O₂ content and restricted As uptake.

Hydrogen sulfide manages hexavalent chromium toxicity in wheat and rice seedlings: The role of sulfur assimilation and ascorbate-glutathione cycle

The role of hydrogen sulfide (H₂S) is well known in the regulation of abiotic stress such as toxic heavy metal. However, mechanism(s) lying behind this amelioration are still poorly known. Consequently, the present study was focused on the regulation/mitigation of hexavalent chromium (Cr(VI) toxicity by the application of H₂S in wheat and rice seedlings. Cr(VI) induced accumulation of reactive oxygen species and caused protein oxidation which negatively affect the plant growth in both the cereal crops. We noticed that Cr(VI) toxicity reduced length of wheat and rice seedlings by 21% and 19%, respectively. These reductions in length of both the cereal crops were positively related with the down-regulation in the ascorbate-glutathione cycle, and were recovered by the application NaHS (a donor of H₂S). Though exposure of Cr(VI) slightly stimulated sulfur assimilation but addition of H₂S further caused enhancement in sulfur assimilation, suggesting its role in the H₂S-mediated Cr(VI) stress tolerance in studied cereal crops. Overall, the results revealed that H₂S renders Cr(VI) stress tolerance in wheat and rice seedlings by stimulating sulfur assimilation and ascorbate-glutathione which collectively reduce protein oxidation and thus, improved growth was observed.

Therapeutic Delivery of Nanoscale Sulfur to Suppress Disease in Tomatoes: In Vitro Imaging and Orthogonal Mechanistic Investigation

Nanoscale sulfur can be a multifunctional agricultural amendment to enhance crop nutrition and suppress disease. Pristine (nS) and stearic acid coated (cS) sulfur nanoparticles were added to soil planted with tomatoes (Solanum lycopersicum) at 200 mg/L soil and infested with Fusarium oxysporum. Bulk sulfur, ionic sulfate, and healthy controls were included. Orthogonal end points were measured in two greenhouse experiments, including agronomic and photosynthetic parameters, disease severity/suppression, mechanistic biochemical and molecular end points including the time-dependent expression of 13 genes related to two S bioassimilation and pathogenesis-response, and metabolomic profiles. Disease reduced the plant biomass by up to 87%, but nS and cS amendment significantly reduced disease as determined by area-under-the-disease-progress curve by 54 and 56%, respectively. An increase in planta S accumulation was evident, with size-specific translocation ratios suggesting different uptake mechanisms. In vivo two-photon microscopy and time-dependent gene expression revealed a nanoscale-specific elemental S bioassimilation pathway within the plant that is separate from traditional sulfate accumulation. These findings correlate well with time-dependent metabolomic profiling, which exhibited increased disease resistance and plant immunity related metabolites only with nanoscale treatment. The linked gene expression and metabolomics data demonstrate a time-sensitive physiological window where nanoscale stimulation of plant immunity will be effective. These findings provide mechanistic understandings of nonmetal nanomaterial-based suppression of plant disease and significantly advance sustainable nanoenabled agricultural strategies to increase food production.

Management of Grape Powdery Mildew with an Intelligent Sprayer and Sulfur

Wine grapes are an important agricultural commodity in the Pacific Northwest, where grape powdery mildew (GPM) is one of the main disease problems. The efficacy of various sulfur concentrations and output volumes from an air blast sprayer retrofitted with the Intelligent Spray System (ISS) were evaluated for the management of GPM. The ISS consists of a LiDAR sensor, Doppler speed sensor, embedded computer, flow controller, and individual pulse-width-modulation solenoid valves at each nozzle. GPM cluster severity ranged from 55 to 75% across all trials in the study when the ISS was used at its default spray rate of 62.5 ml/m³ with micronized sulfur at 6 g/liter, which was significantly higher than all other fungicide treatments but lower than nontreated controls. Similarly, leaf incidence values were highest on nontreated vines, followed by micronized sulfur at 6 g/liter applied at 62.5 ml/m³, with all other fungicide treatments being significantly lower in all trials. Using the ISS at the 62.5 ml/m³ rate and a rotation of locally systemic fungicides resulted in the lowest observed GPM leaf incidence and average cluster severity of 11% in both 2019 and 2020, the lowest cluster severity of all fungicide treatments tested. GPM control with the ISS and micronized sulfur was equivalent to a constant-rate air blast treatment at 6 g/liter when the spray rate of the ISS was increased to 125 ml/m³ or the concentration of sulfur was increased to 24 g/liter. In those cases, the amount of sulfur applied to vines was at or above the minimum label rate from bloom until the end of the season, or the entire season, respectively. This study has shown that sufficient disease control cannot always be expected when pesticides are mixed at the same rate as would be used for a constant-rate sprayer in a variable rate sprayer, especially when contact fungicides such as sulfur are used. With appropriate adjustments, the variable-rate ISS can be a useful tool to reduce pesticide quantities, water needed for mixing, and as a result labor, because fewer trips to refill for a given spray event are needed.

Microbial Corrosion in Orthodontics

Even with the exponential popularity of the contemporary clear aligners, the main stream of orthodontic practice still remains to be metal braces especially in adolescent age-group.¹ Along with the advantages of metal braces such as lower cost, reduced friction, etc., there goes the disadvantages such as corrosion possibility, reduced esthetics, etc. Corrosion of orthodontic appliances is a widely researched topic.^2-5 It is surprising to learn that microbially induced corrosion (MIC) has not been addressed in orthodontic literature till date. Microbial corrosion is an interesting arena which requires knowledge of both corrosion science and microbiology. The microorganisms capable of corrosion include various bacteria, fungi, and algae. The most common among them which has been widely indicated in MIC are the bacteria belonging to the sulfur cycle especially the sulfate-reducing bacteria (SRB). The connecting knot with orthodontics is the reported prevalence of these SRB in the oral cavity. SRB is prevalent in healthy individuals,^6,7 patients associated with periodontitis^6-11 and patients with gastrointestinal issues.^12-14 The prevalence of SRB in the oral cavity has a greater clinical implication since the SRB have been proven to cause corrosion of stainless steel.^15-24 There is literature attributing SRB as a potential cause in periodontal diseases^7-11 as well as gastrointestinal diseases such as ulcerative colitis, inflammatory bowel diseases, and Crohn's disease.¹² With its presence in the healthy oral environment already reported in the previous studies,^6,7,25,26 it further emphasizes the absolute need to be researching on its corrosion possibility in the intra oral environment. The genus generally found intraorally was Desulfovibrio and Desulfobacter¹⁰ which is commonly regarded as the most "opportunistic" and ubiquitous group of sulfate reducers.^6,7 There is an interesting literature on the inhibition of Desulfovibrio spp. by human saliva, the reason being quoted as salivary nitrate and nitrite.¹⁴ The mechanism behind the antimicrobial action of nitrate and nitrite is that they increase the oxidative stress on the bacteria.²⁷ However, concentrations of salivary nitrate vary depending on the food intake, endogenous production, and salivary flow rate.^28,29 Despite there exist natural inhibitors, the prevalence in oral cavity is high, 22% in healthy and 86% in patients associated with periodontitis.⁷ There is a predilection for the bacteria to grow when favorable conditions exist. Biofilms is one such favorable medium for the growth of SRB. Paster et al.²⁶ identified SRB in biofilms of patients associated with refractory periodontitis, periodontitis, acute necrotizing ulcerative gingivitis (ANUG), and also in healthy subjects. Biofilm is a surface film composed of organic and inorganic saliva components that are colonized with microorganisms in extracellular polymeric substances adsorbed on all surfaces in the oral cavity.³⁰ The oral biofilm formation is a complex process involving interspecies aggregation, which is surrounded by a cohesive matrix, forms a complex structure which in turn facilitates anaerobic growth. It is the intrinsic nature of oral biofilms which make the survival of facultative anaerobes such as SRB in the oral cavity possible. Literatures^31-35 report that there are increased biofilm formations in orthodontic patients due to increased retentive areas caused by the brackets, ligatures, wires, mini implants, force components, and archwires. Bacteria in dental plaque function as a metabolically, functionally, and physically integrated community.³⁶ The study by Mystkowska et al.³⁷ mentioned that biofilm per se play a critical role in corrosion process by forming corrosive microcells. With time-dependent association, the microbes in the biofilm, along with saliva acting as an electrolyte and components from food, causes a decreased pH in the areas immediately under the biofilms. The decreased pH along with a change of oxygenation releases metal oxides and hydroxides from the metal surface ultimately leading to the corrosion of metallic structures.^37-41 The initial roughness also acts in a vicious form promoting more biofilm adherence and the process repeats causing more corrosion. With the biofilm itself serving to initiate and propagate corrosion, the increased prevalence of SRB in patients associated with orthodontics treatment all the more increases the possibility of MIC of orthodontic materials.

Enhancement of drought tolerance in Arabidopsis plants induced by sulfur dioxide

Sulfur dioxide (SO₂) is a common air pollutant that has multiple effects on plants. In the present study, the improvement of drought tolerance in Arabidopsis plants by SO₂ fumigation was investigated. The results showed that pre-exposure to 30 mg/m³ SO₂ for 72 h could reduce water loss, stomatal conductance (Gs) and the transpiration rate (Tr) but increased the net photosynthetic rate (Pn), water use efficiency (iWUE) and photosynthetic pigment contents under drought conditions. The activities of superoxide dismutase (SOD) and peroxidase (POD) were significantly increased, while the contents of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) were decreased in SO₂-pretreated Arabidopsis plants under drought stress. Additionally, the activity of o-acetylserine(thio)lyase (OASTL) and the content of cysteine (Cys), the rate-limiting enzyme and the first organic product of sulfur assimilation, were significantly increased in drought-stressed plants after SO₂ pretreatment, along with increases in other thiol-containing compounds, such as glutathione (GSH) and nonprotein thiol (NPT). Meanwhile, SO₂ pre-exposure induced a higher level of proline accumulation, with increased activity of proline synthase P5CS and decreased activity of proline dehydrogenase ProDH. Consistent with the changes in enzyme activity, their corresponding gene expression patterns were different after SO₂ treatment. Overall, the enhanced drought tolerance afforded by SO₂ might be related to the improvement of plant photosynthesis, antioxidant defense, sulfur assimilation and osmotic adjustment. These findings provide new insights into the role of SO₂ in plant adaptation to environmental stress.

Role of hydrogen sulfide in sulfur dioxide production and vascular regulation

Both hydrogen sulfide (H₂S) and sulfur dioxide (SO₂) are produced endogenously from the mammalian metabolic pathway of sulfur-containing amino acids and play important roles in several vascular diseases. However, their interaction during the control of vascular function has not been fully clear. Here, we investigated the potential role of H₂S in SO₂ production and vascular regulation in vivo and in vitro. Wistar rats were divided into the vehicle, SO₂, DL-propargylglycine (PPG) + SO₂, β-cyano-L-alanine (BCA) + SO₂ and sodium hydrosulfide (NaHS) + SO₂ groups. SO₂ donor was administered with or without pre-administration of PPG, BCA or NaHS for 30 min after blood pressure was stabilized for 1 h, and then, the change in blood pressure was detected by catheterization via the common carotid artery. Rat plasma SO₂ and H₂S concentrations were measured by high performance liquid chromatography and sensitive sulfur electrode, respectively. The isolated aortic rings were prepared for the measurement of changes in vasorelaxation stimulated by SO₂ after PPG, BCA or NaHS pre-incubation. Results showed that the intravenous injection of SO₂ donors caused transient hypotension in rats compared with vehicle group. After PPG or BCA pretreatment, the plasma H₂S content decreased but the SO₂ content increased markedly, and the hypotensive effect of SO₂ was significantly enhanced. Conversely, NaHS pretreatment upregulated the plasma H₂S content but reduced SO₂ content, and attenuated the hypotensive effect of SO₂. After PPG or BCA pre-incubation, the vasorelaxation response to SO₂ was enhanced significantly. While NaHS pre-administration weakened the SO₂-induced relaxation in aortic rings. In conclusion, our in vivo and in vitro data indicate that H₂S negatively controls the plasma content of SO₂ and the vasorelaxant effect under physiological conditions.

Multifunctional MnO2/Ag3SbS3 Nanotheranostic Agent for Single-Laser-Triggered Tumor Synergistic Therapy in the NIR-II Biowindow

Regulating the level of reactive oxygen species (ROS) in a tumor is an efficient and innovative anticancer strategy. However, the therapeutic efficacy of ROS-based therapies, such as chemodynamic therapy (CDT) and photodynamic therapy (PDT), offers finite outcomes due to the oxygen dependence and limited concentration of hydrogen peroxide (H₂O₂) and overexpression of glutathione (GSH) within the tumor microenvironment (TME), so a single therapeutic strategy is insufficient to completely eliminate tumors. Therefore, we demonstrated an omnipotent nanoplatform MnO₂/Ag₃SbS₃ (abbreviated as MA) with strong optical absorbance in the NIR-II biowindow and oxygen self-sufficient ROS-mediated ability, which not only relieves tumor hypoxia significantly but also enhances the photothermal therapy (PTT)/PDT/CDT efficacy. By 1064 nm laser irradiation, MnO₂/Ag₃SbS₃ nanoparticles (NPs) reveal a favorable photothermal conversion efficiency of 23.15% and achieve a single-laser-triggered NIR-II PTT/PDT effect, resulting in effective tumor elimination. Once internalized into the tumor, MnO₂/Ag₃SbS₃ NPs will be degraded to Mn²⁺ and Ag₃SbS₃. The released Ag₃SbS₃ NPs as a NIR-II phototherapy agent could be utilized for photoacoustic imaging-guided NIR-II PDT/PTT. Mn²⁺ could be used as a Fenton-like catalyst to continuously catalyze endogenous H₂O₂ for generating highly virulent hydroxyl radicals (^•OH) for CDT and O₂ for PDT, enhancing the efficiency of PDT and CDT, respectively. Meanwhile, Mn²⁺ realizes magnetic resonance imaging-guided accurate tumor therapy. Moreover, the MnO₂/Ag₃SbS₃ NPs could deplete intracellular GSH in TME to promote oxidative stress of the tumor, further strengthening ROS-mediated antitumor treatment efficacy. Overall, this work presents a distinctive paradigm of TME-responsive PDT/CDT/PTT in the second near-infrared biowindow by depleting GSH and decomposing H₂O₂ for efficient and precise cancer treatment.

Effect of S-Se Bioisosteric Exchange on Affinity and Intrinsic Efficacy of Novel N-acylhydrazone Derivatives at the Adenosine A2A Receptor

In this work, we evaluated the conformational effect promoted by the isosteric exchange of sulfur by selenium in the heteroaromatic ring of new N-acylhydrazone (NAH) derivatives (3-8, 13, 14), analogues of the cardioactive compounds LASSBio-294 (1) and LASSBio-785 (2). NMR spectra analysis demonstrated a chemical shift variation of the iminic Csp2 of NAH S/Se-isosters, suggesting a stronger intramolecular chalcogen interaction for Se-derivatives. To investigate the pharmacological profile of these compounds at the adenosine A2A receptor (A2AR), we performed a previously validated functional binding assay. As expected for bioisosteres, the isosteric-S/Se replacement affected neither the affinity nor the intrinsic efficacy of our NAH derivatives (1-8). However, the N-methylated compounds (2, 6-8) presented a weak partial agonist profile at A2AR, contrary to the non-methylated counterparts (1, 3-5), which appeared as weak inverse agonists. Additionally, retroisosterism between aromatic rings of NAH on S/Se-isosters mimicked the effect of the N-methylation on intrinsic efficacy at A2AR, while meta-substitution in the phenyl ring of the acyl moiety did not. This study showed that the conformational effect of NAH-N-methylation and aromatic rings retroisosterism changed the intrinsic efficacy on A2AR, indicating the S/Se-chalcogen effect to drive the conformational behavior of this series of NAH.

Comparison of the antioxidant activities of nonfumigated and sulphur-fumigated Chrysanthemum morifolium cv. Hang-ju induced by oxidative stress

CONTEXT

The traditional drying method, sun drying, for Chrysanthemum morifolium Ramat. cv. Hang-ju (Compositae) (HJ) is widely replaced by sulphur fumigation (SF), which has an unknown effect on its efficacy.

OBJECTIVE

To investigate protective effects of nonfumigated HJ (NHJ) and sulphur-fumigated HJ (SHJ) water extracts against oxidative stress and lipid peroxidation.

MATERIALS AND METHODS

Sprague-Dawley rats were administered high-fat diet to induce hyperlipidaemia and randomly divided into eight groups (n = 6): control, fenofibrate, NHJ and SHJ extracts (1, 2 or 4 g crude drugs/kg/d; intragastric administration for 8 weeks). Serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), superoxide dismutase (SOD) and malondialdehyde (MDA) levels were detected. Human umbilical vein endothelial cells (HUVECs) were treated with NHJ and SHJ extracts (50, 100 or 200 μg/mL) for 24 h, followed by oxidized low-density lipoprotein (ox-LDL, 20 μg/mL) for 2 h in vitro. Cellular reactive oxygen species (ROS), SOD and MDA levels and apoptosis were evaluated.

RESULTS

NHJ was more effective than SHJ in decreasing serum TG, TC, LDL-C, LDL/HDL and MDA while increasing serum HDL-C and SOD levels at high doses. SHJ (IC₅₀=19.9 mg/mL) suppressed HUVEC growth stronger than NHJ (IC₅₀=186.7 mg/mL). At 200 μg/mL, NHJ was more effective than SHJ in downregulating ROS and MDA levels, reducing HUVECs apoptosis rate and elevating SOD activity in ox-LDL-treated HUVECs.

CONCLUSIONS

SF causes oxidative damage and attenuates antioxidative activity in ox-LDL-treated HUVECs, which promotes lipid peroxidation. SF is not recommended for processing HJ.

Sulfur-Induced Resistance against Pseudomonas syringae pv. actinidiae via Triggering Salicylic Acid Signaling Pathway in Kiwifruit

Sulfur has been previously reported to modulate plant growth and exhibit significant anti-microbial activities. However, the mechanism underlying its diverse effects on plant pathogens has not been elucidated completely. The present study conducted the two-year field experiment of sulfur application to control kiwifruit canker from 2017 to 2018. For the first time, our study uncovered activation of plant disease resistance by salicylic acid after sulfur application in kiwifruit. The results indicated that when the sulfur concentration was 1.5–2.0 kg m⁻³, the induced effect of kiwifruit canker reached more than 70%. Meanwhile, a salicylic acid high lever was accompanied by the decline of jasmonic acid. Further analysis revealed the high expression of the defense gene, especially AcPR-1, which is a marker of the salicylic acid signaling pathway. Additionally, AcICS1, another critical gene of salicylic acid synthesis, was also highly expressed. All contributed to the synthesis of increasing salicylic acid content in kiwifruit leaves. Moreover, the first key lignin biosynthetic AcPAL gene was marked up-regulated. Thereafter, accumulation of lignin content in the kiwifruit stem and the higher deposition of lignin were visible in histochemical analysis. Moreover, the activity of the endochitinase activity of kiwifruit leaves increased significantly. We suggest that the sulfur-induced resistance against Pseudomonas syringae pv. actinidiae via salicylic activates systemic acquired resistance to enhance plant immune response in kiwifruit.

Expression of potential reference genes in response to macronutrient stress in rice and soybean

Given the complexity of nutrient stress responses and the availability of a few validated reference genes, we aimed to identify robust and stable reference genes for macronutrient stress in rice and soybean. Ten potential reference genes were evaluated using geNorm, NormFinder, BestKeeper, Comparative ΔCt method, and RefFinder algorithms under low and completely starved conditions of nitrogen (N), phosphorus (P), potassium (K), and sulphur (S). Results revealed distinct sets of reference gene pairs, showing stable expression under different experimental conditions. The gene pairs TIP41/UBC(9/10/18) and F-box/UBC10 were most stable in rice and soybean, respectively under N stress. Under P stress, UBC9/UBC10 in rice and F-Box/UBC10 in soybean were most stable. Similarly, TIP41/UBC10 in rice and RING FINGER/UBC9 in soybean were the best gene pairs under K stress while F-Box/TIP41 in rice and UBC9/UBC10 in soybean were the most stable gene pairs under S stress. These reference gene pairs were validated by quantifying the expression levels of high-affinity transporters like NRT2.1/NRT2.5, PT1, AKT1, and SULTR1 for N, P, K, and S stress, respectively. This study reiterates the importance of choosing reference genes based on crop species and the experimental conditions, in order to obtain concrete answers to missing links of gene regulation in response to macronutrient deficiencies.

Effects of sulphur-containing mineral water intake on oxidative status and markers for inflammation in healthy subjects

CONTEXT

Sulphurous mineral waters (SMW) have a wide range of applications. Sulphur content of mineral waters is considered as possible determinant for their anti-inflammatory or pro-inflammatory effects.

OBJECTIVE

To explore the healing properties of Varna basin mineral water by analysing possible antioxidative and anti-inflammatory effects.

MATERIALS AND METHODS

An intervention with Varna SMW intake was performed with healthy volunteers. Total thiols, total glutathione and its fractions, reactive oxygen metabolites, malondialdehyde, intracellular adhesion molecule (ICAM-1) and vascular cell adhesion molecule (VCAM-1) were measured. Expression of γ-gluthamyl-cysteinyl ligase (GCL) and sICAM-1 genes was also analysed.

RESULTS

A significantly increased total glutathione and total thiols were observed at the end of the intervention. GCL and sICAM-1 gene expressions were increased after the intervention.

CONCLUSION

SMW consumption improved redox status of the body. We suggested that these beneficial effects may be attributed to the established high levels of sulphur-containing compounds in Varna mineral water.

Discovery of a Cell-Active SuTEx Ligand of Prostaglandin Reductase 2

Sulfonyl-triazoles have emerged as a new reactive group for covalent modification of tyrosine sites on proteins through sulfur-triazole exchange (SuTEx) chemistry. The extent to which this sulfur electrophile can be tuned for developing ligands with cellular activity remains largely underexplored. Here, we performed fragment-based ligand discovery in live cells to identify SuTEx compounds capable of liganding tyrosine sites on diverse protein targets. We verified our quantitative chemical proteomic findings by demonstrating concentration-dependent activity of SuTEx ligands, but not inactive counterparts, against recombinant protein targets directly in live cells. Our structure-activity relationship studies identified the SuTEx ligand HHS-0701 as a cell-active inhibitor capable of blocking prostaglandin reductase 2 (PTGR2) biochemical activity.

Decrease lysyl oxidase activity in hearts of copper-deficient bovines

BACKGROUND

Lysyl oxidase (LOX) is a metalloenzyme that requires Cu as a cofactor and it is responsible for the formation of collagen and elastin cross-linking. The objective of this work was to measure the LOX enzyme activity in the heart of bovines with Cu deficiency induced by high molybdenum and sulfur levels in the diet.

METHODS

Eighteen myocardial samples were obtained from Cu-deficient (n = 9) and control (n = 9) Holstein bovines during two similar assays. The samples were frozen in liquid nitrogen and stored at -70 °C to measure enzymatic activity. A commercial kit was used, following producer instructions.

RESULTS

The results showed that LOX activity from the hearts of Cu-deficient bovines is 29 % lower than the ones of control bovines, being this difference statistically significant (p = 0.03).

CONCLUSION

To our knowledge, this is the first report that determined LOX enzymatic activity in bovine heart of Cu-deficient animals. The microscopic alterations found in these animals in our previous work, could be explained by a diminished LOX activity. The results are in agreement with other authors, who found a relationship between LOX activity and dietary Cu intake. The information provided by this work could help to clarify the pathogenesis of cardiac lesions in cattle with dietary Cu deficiency.

Sulfur supply reduces barium toxicity in Tanzania guinea grass (Panicum maximum) by inducing antioxidant enzymes and proline metabolism

Sulfur (S) can play essential roles in protecting plants against abiotic stress, including heavy metal toxicity. However, the effect of this nutrient on plants exposed to barium (Ba) is still unknown. This study was designed to evaluate the S supply on oxidative stress and the antioxidant system of Tanzania guinea grass under exposure to Ba, grown in a nutrient solution under greenhouse conditions. It was studied the influence of S/Ba combinations in nutrient solution on oxidative stress indicators (hydrogen peroxide, malondialdehyde, and proline) and antioxidant enzyme activities (superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase, and glutathione reductase). The treatments consisted in thirteen S/Ba combinations in the nutrient solution (0.1/0.0; 0.1/5.0; 0.1/20.0; 1.0/2.5; 1.0/10.0; 1.9/0.0 - control; 1.9/5.0; 1.9/20.0; 2.8/2.5; 2.8/10.0; 3.7/0.0; 3.7/5.0 and 3.7/20.0 mM of S and Ba, respectively). The plants were grown for two growth periods, which consisted of fourteen days of S supply and the eight days of Ba exposure each one. The severe S deficiency decreased the superoxide dismutase activity, regardless of Ba exposure in recently expanded leaves and culms plus sheaths. However, supplemental S supply (above 1.9 mM S, which corresponds to S supply adequate to plant growth) it improved the superoxide dismutase activity in these tissues under high Ba concentrations. Conversely, the severe S deficiency increased the activities of catalase, ascorbate peroxidase, and glutathione reductase in grass leaves slightly, without Ba exposure influence. It was observed that the supplemental S supply also induced the guaiacol peroxidase activity and proline production in culms plus sheaths under high Ba rates, showing values until 2.5 and 3.1 folds higher than the control treatment, respectively. In plants under exposure to 20.0 mM Ba, the supplemental S supply decreased the malondialdehyde content in culms plus sheaths in 17% compared to 1.9 mM S. These results indicate that supplemental S supply can mitigate Ba toxicity in Tanzania guinea grass, mainly by improving superoxide dismutase and guaiacol peroxidase activities, and proline metabolism.

Sulfur Contents in Sulfonated Hyaluronic Acid Direct the Cardiovascular Cells Fate

Hyaluronic acid (HA) is recognized as a functional carbohydrate polymer applied for the surface modification of cardiovascular implanted materials due to its molecular weight (MW) dependent cellular regulation. However, due to the enzyme digestion of hyaluronidase on HA in vivo, the stability of HA MW needs to be further improved. It has been reported that the stability of HA MW can be improved by sulfonation. In this study, sulfonated hyaluronic acids (S-HA) with sulfur content of 2.06, 3.69, 7.10, 8.98, and 9.71 were prepared through different sulfuric acid treatment procedures. Cell tests showed that S-HA with higher sulfur content played a significant role in promoting the proliferation and migration of endothelial cells and regulating smooth muscle cells to the physiological phenotype. In addition, it was also proved to inhibit the inflammatory macrophages adhesion/activation. Our data indicates that S-HA may be a better carbohydrate polymer for potential application of cardiovascular biomaterials.

Mitigation of chromium (VI) toxicity by additional sulfur in some vegetable crops involves glutathione and hydrogen sulfide

Toxic metals cause substantial reduction in crop yields every year. Therefore, worldwide scientific efforts are being made to reduce such losses in crop productivity by using certain chemical protectants such as nutrients like sulfur (S), hydrogen sulfide (H₂S), glutathione (GSH), etc. Therefore in this study, we have tested potential of additional S, along with probable involvement of H₂S and GSH in mitigating hexavalent chromium (CrVI) toxicity in tomato, pea and brinjal seedlings. Chromium (VI) decreased shoot and root length, endogenous H₂S, and cell viability due to greater Cr accumulation that led to cell death in roots. Chromium (VI) enhanced oxidative stress markers i.e. superoxide radical, hydrogen peroxide, lipid peroxidation and protein oxidation due to down-regulation in ascorbate-glutathione cycle. However, additional S reversed toxic effect of Cr(VI). Chromium (VI) slightly stimulated enzymes of glutathione biosynthesis. Besides this, the results also showed that addition of buthionine sulphoximine (BSO, synthetic inhibitor of glutathione biosynthesis) interestingly further enhanced Cr(VI) toxicity even in the presence of additional S. But this effect of BSO was reversed by the addition of GSH. Interestingly, hydroxylamine (HA, synthetic inhibitor of cysteine desulfhydrase) had also further increased Cr(VI) toxicity even in the presence of additional S but sodium hydrosulfide (NaHS, an H₂S donor) reversed this effect. Furthermore, ameliorative behaviour of NaHS against Cr(VI) toxicity was reversed by the hypotaurine (HT, a H₂S scavenger). All together results suggested that additional S involved GSH and H₂S in mitigating Cr(VI) toxicity in studied vegetables, in which GSH acted downstream of H₂S signal.

Metabolic control of acclimation to nutrient deprivation dependent on polyphosphate synthesis

Polyphosphate, an energy-rich polymer conserved in all kingdoms of life, is integral to many cellular stress responses, including nutrient deprivation, and yet, the mechanisms that underlie its biological roles are not well understood. In this work, we elucidate the physiological function of this polymer in the acclimation of the model alga Chlamydomonas reinhardtii to nutrient deprivation. Our data reveal that polyphosphate synthesis is vital to control cellular adenosine 5'-triphosphate homeostasis and maintain both respiratory and photosynthetic electron transport upon sulfur deprivation. Using both genetic and pharmacological approaches, we show that electron flow in the energy-generating organelles is essential to induce and sustain acclimation to sulfur deprivation at the transcriptional level. These previously unidentified links among polyphosphate synthesis, photosynthetic and respiratory electron flow, and the acclimation of cells to nutrient deprivation could unveil the mechanism by which polyphosphate helps organisms cope with a myriad of stress conditions in a fluctuating environment.

Targeted bioimaging and sensing of folate receptor-positive cancer cells using folic acid-conjugated sulfur-doped graphene quantum dots

For the first time is reported a facile in situ synthesis of folic acid-conjugated sulfur-doped graphene quantum dots (FA-SGQDs) through simple pyrolysis of citric acid (CA), 3-mercaptopropionic acid (MPA), and FA. The as-prepared FA-SGQDs were extensively characterized to confirm the synthesis and incidence of FA molecule on the surface of SGQDs through advanced characterization techniques. Upon excitation at 370-nm wavelength, FA-SGQDs exhibited blue fluorescence with an emission band at 455 nm. While exhibiting relatively high quantum yield (~ 78%), favorable biocompatibility, excellent photostability, and desirable optical properties, the FA-SGQDs showed suitability as a fluorescent nanoprobe to distinguish the folate receptor (FR)-positive and FR-negative cancer cells. The experimental studies revealed that FA-SGQDs aptly entered into FR-positive cancer cells via a non-immunogenic FR-mediated endocytosis process. Additionally, the FA-SGQDs exhibited excellent free radical scavenging activity. Hence, these FA-SGQDs hold high promise to serve as efficient fluorescent nanoprobes for the pre-diagnosis of cancer through targeted bioimaging and other pertinent biological studies. Graphical abstract.

Sulfur and nitrogen-containing compounds from the whole bodies of Blaps japanensis

Pipajiains H-J (1-3), three new phenolic derivatives with an unusual sulfone group, pipajiamides A-C (4-6), three new amide derivatives, pipajiaine A (7), one new imidazole analogue, and pipajiaine B (8), a pair of new pyrrolidine derivatives, along with three known compounds were isolated from the insect Blaps japanensis. Their structures were identified by spectroscopic and computational methods. Chiral HPLC was used to separate the (-)- and (+)-antipodes of 4 and 8. Biological activities of all the new compounds against extracellular matrix in rat renal proximal tubular cells, human cancer cells (A549, Huh-7, and K562), COX-2, ROCK1, and JAK3 were evaluated. The results show that compounds 2, (+)-4, and (-)-4 are active against kidney fibrosis, whereas, compound 9 is active toward human cancer cells, inflammation, and JAK3 kinase.

Effect of sulfur-fumigation process on ginseng: Metabolism and absorption evidences

ETHNOPHARMACOLOGICAL RELEVANCE

Sulfur-fumigation has been developed to prevent insects and molds during post-harvest handling of Panax ginseng C.A. Mey (ginseng) in the near decades. Our previous study indicated sulfur-fumigation could transform ginsenosides, the active components of ginseng, into sulfur-containing derivatives (SFCDs), the artifacts with unknown toxicity. However, whether the biotransformation could be occurred and absorption characteristics between ginsenosides and SFCDs are still needed to further investigate.

AIM OF THE STUDY

To evaluate the effect of sulfur-fumigation process on ginseng through comparing the metabolic profile and absorption characteristics between ginsenoside Rg1, Re and their SFCDs.

MATERIALS AND METHODS

Intestinal microflora and liver S9 fraction were utilized to compare the metabolic profile, and single-pass intestinal perfusion and Caco-2 cell models were applied to compare the absorption characteristics, between Rg1, Re and their SFCDs.

RESULTS

Rg1 and Re were metabolized to 7 none sulfur-containing metabolites, while their SFCDs were metabolized to 18 sulfur-containing metabolites. The intestinal absorption and transport of Rg1 and Re were much greater than their SFCDs. Besides, the uptakes of Rg1 and Re were transport-dependent, but their SFCDs were non-transport-dependent.

CONCLUSION

Ginsenosides and their SFCDs could not be bio-transformed with each other and their absorption characteristics were quite different, which suggested that sulfur-fumigation is not a feasible post-harvest process of ginseng.

Sulphur doped carbon dots enhance photodynamic therapy via PI3K/Akt signalling pathway

OBJECTIVES

Photodynamic therapy (PDT) is a promising approach for cancer treatment, and the underlying signalling pathway changes has been carried out for studying the PDT mechanisms, but is majorly limited to organic photosensitizers (PSs). For the emerging nano-PSs typically possessing higher 1 O2 quantum yield, few mechanistic studies were carried out, which limited their further applications in clinical therapeutics. PI3K/Akt signalling pathway, a most frequently activated signalling network in cancers, could promote cancer cell survival, but was seldom reported in previous PDT studies mediated by nano-PSs.

MATERIALS AND METHODS

Sulphur doped carbon dots (S-CDs) was prepared via a hydrothermal synthetic route and was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and so on. CCK-8 assay and Annexin V/PI staining were performed to demonstrate the death of cancer cells, Western blot, RT-PCR and immunofluorescence were employed to explore the underlying mechanism, and variation of PI3K/Akt and other signalling pathways was detected by Western blot.

RESULTS

S-CDs was successfully synthesized, and it was much more efficient compared with classic organic PSs. S-CDs could induce cancer cell death through mitochondria mediated cell apoptosis with the imbalance of Bcl-2 family proteins and caspase cascade via several signalling pathways. Low concentration of S-CDs could effectively inhibit PI3K/Akt pathway and promote p38/JNK pathway, on one way inhibiting cancer cell survival and on the other way promoting cell apoptosis.

CONCLUSIONS

Herein, we found that S-CDs acted as an inhibitor of the PI3K/Akt pathway for efficient cancer cell killing, thus yielding in a higher PDT performance over the existing photosensitizers.

Effects of sulfur on the toxicity of cadmium to Folsomia candida in red earth and paddy soil in southern Fujian

Sulfur has been shown to mitigate the toxic effects of metals on soil organisms. Here we report the effects of sulfur on cadmium toxicity to the collembolan Folsomia candida in soil, including its effects on glutathione (GSH) level, catalase (CAT) activity and metallothionein (MT) content. Following sulfur treatment, catalase, glutathione and metallothionein activities were all significantly increased in cadmium-contaminated soil, and as the cadmium concentration increased, the activities decreased. In addition, because of the reducing effects of pH and organic matter on cadmium bioavailability, the bioavailable cadmium varied among soils of different pH values and organic matter contents, causing the catalase activity, glutathione content and metallothionein levels of F. candida to vary among soils. Our study suggests that sulfur can affect the toxicity of certain concentrations of cadmium and that soil properties are very important to consider. This study provides insight into the effects of sulfur application on soil animals.

Sulphur-doped carbon dots as a highly efficient nano-photodynamic agent against oral squamous cell carcinoma

OBJECTIVES

Photodynamic therapy (PDT) is a novel non-invasive therapeutic method, which has been widely applied for the treatment of human oral cancers. However, the problems of undesirable singlet oxygen (1 O2 ) quantum yields and long-term phototoxicity were inevitable during the application of traditional photosensitizers. Therefore, it is necessary to explore novel photosensitizers for the improvement of therapeutic effects. In our study, the sulphur-doped carbon dots (S-CDs) of high yield of singlet oxygen (1 O2 ) were synthesized as a nano-photosensitizer for OSCC to improve the PDT efficacy in clinical practice.

MATERIALS AND METHODS

After synthesis of the novel S-CDs, the size, morphologic characteristics, surface potential and yield of singlet oxygen (1 O2 ) were determined. In vitro study was performed to compare the therapeutic effect as well as the biocompatibility of the novel S-CDs to those of 5-ALA. Besides, possible mechanism of action was illustrated.

RESULTS

After synthesis of the novel S-CDs, the size, morphologic characteristics, surface potential and yield of singlet oxygen (1 O2 ) were determined. In vitro study was performed to compare the therapeutic effect as well as the biocompatibility of the novel S-CDs to those of 5-ALA. Besides, possible mechanism of action was illustrated.

CONCLUSIONS

These data from the in vitro study demonstrated the promising safety profile of the low dose (nmol/L) S-CDs, which indicated the novel S-CDs could be used as a promising photodynamic agent for oral cancer therapy.

Green synthesis of sulfur nanoparticles using Ocimum basilicum leaves and its prospective effect on manganese-stressed Helianthus annuus (L.) seedlings

A novel green approach was utilized to fabricate sulfur nanoparticles (SNPs) with the aid of Ocimum basilicum leaves extract. The effective formation of the synthesized SNPs was examined and approved using UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy. The average particle size was 23 nm with spherical shape and crystalline in nature. In the pot experiment, the synthesized SNPs were applied with different concentrations (12.5, 25, 50, 100 and 200 μM) as pre-soaking to Helianthus annuus seeds and irrigated with 100 mM MnSO₄. As a result of manganese (Mn) exposure, the harvested 14-day sunflower seedlings showed a significant decline in the growth parameters (shoot length, leaf area and the relative water content of both shoot and root), photosynthetic pigments, mineral content (N, P, K, Ca, and Mg), and protein content compared to the control. The root length, electrolyte leakage, Na and Mn levels, metabolites content (amino acids, protein, glycine betaine, proline, and cysteine) were greatly raised as affected by Mn stress. Mn toxicity reduction using SNPs was demonstrated, as the medium doses enhanced seedlings growth, photosynthetic pigments, and mineral nutrients. Application of SNPs decreased Mn uptake and enhanced S metabolism through increasing cysteine level. Likewise, SNPs elevated seedlings water content and eliminated physiological drought via increasing osmolytes such as amino acids and proline. It can be concluded that green-synthesized SNPs had the potential to limit the deleterious effects of Mn stress.

Increasing soil moisture faciliates the outcomes of exogenous sulfate rather than element sulfur in reducing cadmium accumulation in rice (Oryza sativa L.)

Cadmium (Cd) contamination in paddy soils and the related pollution risk of rice grain have received increasing attention. Agronomic measures, such as the application of sulfur and changes in water regimes, were reported to mitigate the accumulation of Cd in rice. However, there is limited information on the combined effects of sulfur application and water regimes. Therefore, a pot experiment was conducted to investigate the effects of two sulfur forms, three water regimes and multiple sulfur application rates on Cd accumulation in rice. The sulfur was applied as SO₄^2- (S^VI, replacing the traditional fertilizers by SO₄^2--containing fertilizers), and element S (S⁰) was applied at 0, 10, 20, 30 and 40 mg S kg^-1 soil. The water regimes were continuous flooding (F), flooding-moist alternation (FM), and moist irrigation (M), for a total of 30 treatments. The results indicated that application of S^VI exceeding 30 mg S kg^-1 significantly reduced the Cd concentrations in brown rice by 31.1-56.3%, and the Cd concentrations decreased with increasing amount of irrigation water. Similar reductions in Cd concentrations in rice shoots and rice straw collected at tillering and maturity stages were observed after application of S^VI. However, the effect of S⁰ application on Cd accumulation in grain was not significant under different water regimes. Furthermore, this study found that application of both S^VI and S⁰ inhibited the transfer of Cd from rice roots to shoots in most cases. These findings indicate that replacing traditional fertilizers with SO₄^2--containing fertilizers, especially combined with increased irrigation, could be a potential approach to mitigate Cd accumulation in rice growing in Cd-contaminated acidic paddy soils.

Rapid Photo-Sonotherapy for Clinical Treatment of Bacterial Infected Bone Implants by Creating Oxygen Deficiency Using Sulfur Doping

Periprosthetic infection is considered the main cause of implant failure, which is expected to be solved by fabricating an antibacterial coating on the surface of the implant. Nevertheless, systemic antibiotic treatment still represents the mainstream method for preventing infection, and few antibacterial coatings are applied clinically. This is because the externally introduced traditional antibacterial coatings suffer from the risk of invalidation and tissue toxicity induced by the consumption of antibacterial agents, degradation, and shedding. In this work, we proposed a rapid photo-sonotherapy by creating an oxygen deficiency on a titanium (Ti) implant through sulfur (S)-doping (Ti-S-TiO_2-x), which endowed the implants with great sonodynamic and photothermal ability. Without introducing an external antibacterial coating, it reached a high antibacterial efficiency of 99.995% against Staphylococcus aureus under 15 min near-infrared light and ultrasound treatments. Furthermore, bone infection was successfully treated after combination treatments, and improved osseointegration was observed. Importantly, the S-doped Ti implant immersed in water for 6 months showed an unchanged structure and properties, suggesting that the Ti implant with intrinsic modification showed stable antibacterial performance under exogenous stimuli with a high antibacterial performance in vivo. This photo-sonotherapy based on sulfur doping is also promising for cancer therapy with biosafety.