Cyclic Sulfur Research Articles

Changes in flavor profile of vegetable seasonings by innovative drying technologies: A review.

Seasonings like garlic, ginger, and scallion provide spicy and masking flavor or aroma in vegetables. However, the method or technique used for drying these spices can affect the flavor profile. Therefore, this review focuses on vegetable seasonings like ginger, garlic, and scallion, the characteristic flavor of fresh and dehydrated vegetable seasoning, and how drying methods (freeze-drying [FD], convective hot air drying [HAD], infrared drying, microwave drying [MW]), and other recent dryers (swirling fluidized bed [SFB], pulsed-vacuum dryer, relative humidity-convective dryer, etc.) affect the flavor profile of the common vegetable seasonings. HAD increases α-zingiberene, reduces gingerol, and forms β-citral and citral in fresh ginger. FD increased sesquiterpenes, retained terpenoids, sulfides, and other volatiles in fresh ginger, and did not produce new volatile compounds (VOCs) in garlic. SFB drying better preserves 6-gingerol than FD and HAD. MW increases trisulfides and cyclic sulfur compounds in garlic. In general, drying, especially thermal drying reduces the VOCs in fresh garlic, ginger, and scallion and causes the formation of new VOCs.

Structure-Activity Relationship of Benzophenazine Derivatives for Homogeneous and Heterogenized Photooxygenation Catalysis.

Singlet oxygen is a powerful oxidant used in various applications, such as organic synthesis, medicine, and environmental remediation. Organic and inorganic photosensitizers are commonly used to generate this reactive species through energy transfer with the triplet ground state of oxygen. We describe here a series of novel benzophenazine derivatives as a promising class of photosensitizers for singlet oxygen photosensitization. In this study, we investigated the structure-activity relationship of these benzophenazine derivatives. Akin to a molecular compass, the southern fragment was first functionalized with either aromatic tertiary amines, alkyl tertiary amines, aromatic sulfur groups, alkyl sulfur groups, or cyclic ethers. Enhanced photophysical properties (in terms of triplet excited-state lifetime, absorption wavelength, triplet state energy, and O2 quenching capabilities) were obtained with cyclic ether and sulfur groups. Conversely, the presence of an amine moiety was detrimental to the photocatalysts. The western and northern fragments were also investigated and slightly undesirable to negligible changes in photophysical properties were observed. The most promising candidate was then immobilized on silica nanoparticles and its photoactivity was evaluated in the citronellol photooxidation reaction. A high NMR yield of 97 % in desired product was obtained, with only a slight decrease over several recycling runs (85 % in the fourth run). These results provide insights into the design of efficient photosensitizers for singlet oxygen generation and the development of heterogeneous systems.

Molecular interaction between N-butylpyridinium tetrafluoroborate and cyclic sulfur compounds: A DFT study

Extraction of sulfur compounds from crude oil is one of the problems of industries related to crude oil. The use of ionic liquids (ILs) as a green solvent to extract these sulfur compounds, especially cyclic sulfur compounds, can be considered a potential point in this regard. A functional theory comparison was made to investigate the interaction between N-butylpyridinium tetrafluoroborate as IL and several different cyclic sulfur compounds including Thiophene, benzothiophene, dibenzothiophene, and 4,6-dibenzothiophene. The difference between the solution phase and the gas phase has been investigated. Based on the results, the proper interaction between the components of IL and the cyclic sulfur compounds, the extraction of these compounds is theoretically possible. Natural bond orbital, atoms in molecules, HOMO-LUMO overlap integral, and electron density difference were analyzed. The analysis informs on the use of ionic liquids as solvents for the removal of sulfur compounds from crude oil. The hydrogen and vander Waals bonds formed between the anion and cation of ionic liquid and the sulfur compounds have been determined. The main bonds are formed between the anion of ionic liquid and the sulfur compounds. Between the compound [C4Py][BF4] and C4H4S, the hydrogen bonds are S…H13, F29.... H38, F26…H38, has been established. The hydrogen bonds between the anion of the ionic liquid and the sulfur compound are shorter than the other hydrogen bonds formed. Due to the intermolecular bonds, the transition state with the lowest energy has been obtained. In this way, we will have a proposed mechanism for the extraction of the cyclic compounds from oil with the help of ionic liquids.

Chlorocyclization of Alkenoic Thioester.

This study introduces a novel method for ring-closing chlorosulfenylation of alkenoic thioesters using N-chlorosuccinimide in hexafluoroisopropanol under mild conditions. This reaction efficiently forms five-membered cyclic sulfur compounds with high selectivity, representing a significant advancement in the synthesis of chlorinated S-heterocycles. Computational analysis using density functional theory demonstrates the superiority of thioester nucleophiles over traditional benzyl sulfides in this reaction, highlighting the energetic preference for thioesters.

Micro-mesoporous carbon nanofibers loaded with sulfur as a self-supported cathode for high-performance Li-S batteries

Self-supported carbon fibers with hierarchical porous structures regulated by zinc salt and copper salt were prepared through electrospinning technology, and sulfur loaded carbon fibers were obtained through sulfur vapor deposition method. Small molecular sulfur (S2-S4) and cyclic sulfur (S8) were encapsulated effectively in hierarchical pores by this way, both of them could run stably in carbonate electrolyte. Due to the three-dimensional conductive structure and suitable pore structure of the carbon fibers, the self-supported S/MCNF-ZnCu cathode exhibits high capacity, excellent cycling stability and out-standing rate capacity. The reversible capacity after 100 cycles at 0.2 A g−1 based on the mass of cathode is 520 mAh g−1, corresponding to the capacity retention rate of 98.4 %. The reversible capacity after 1000 cycles at 1.0 A g−1 is 429 mAh g−1, with a capacity loss of approximately 0.01 % per cycle. Even at the sulfur loading of 4 mg cm−2, the cathode shows a stable capacity of nearly 500 mAh g−1 at 0.1 A g−1, provides a novel and efficient strategy for the next generation of high-performance batteries.

A One‐Pot Approach to Multi‐Substituted Fused Aziridines: Formal Intermolecular [2+1] Cycloaddition Reaction between Saccharin‐Derived Cyclic Ketimines and Sulfur Ylides

AbstractHerein a concise and efficient method for the synthesis of aziridines has been developed. The reaction proceeds through a formal intermolecular [2+1] cycloaddition reaction of saccharin‐derived cyclic ketimines with sulfur ylides. This methodology features high atom‐economy, broad substrate scope and an operationally simple procedure, affording the aziridines with excellent yields and diastereoselectivity (>20 : 1 dr). In the presence of base, the aziridine products could be readily converted to benzothiazines by an unusual rearrangement reaction.

Catalytic Photodegradation of Cyclic Sulfur Compounds in a Model Fuel Using a Bench-scale Falling-film Reactor Irradiated by a Visible Light

A homemade N doped-TiO2 nanoparticle were used to degrade dibenzothiophene (DBT) in a model fuel flowing on a bench-scale glass-made falling film reactor irradiated by a xenon lamp that emitted visible light. The photocatalyst was immobilized on the glass sheet. EDS, SEM, and FT-IR techniques were utilized to identify the morphology of the N doped-TiO2 nanoparticles. Different operating parameters (e.g., N loading (0, 4, 5, and 6 wt%), light intensity (20, 40, and 60 W/m2), and pH (4, 7, and 10)) were investigated for their effect on the DBT degradation. The effect of the N loading on the wettability of the nano-TiO2 particles was also investigated. Experimental results revealed that the N loading did not affect the wettability characteristics of the nano TiO2 particles. Moreover, results showed that DBT conversion positively depends on N loading, light intensity (hv), and pH increase. The estimated optimal operating parameters were 5 wt% N loading, pH = 10, and hv = 40 W/m2 to ensure the best photo-oxidation efficiency of 91.4% after 120 min of operation. The outcomes of the present work confirmed the effective efficiency of the N-doped TiO2 nanoparticles irradiated by visible light for DBT degradation. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Potent Anti-Cutibacterium acnes Activity of the Essential Oils Derived from Allium sativum, Gerdenia jasminoides, and Hedychium coronarium Cultivated in Thailand

Plant oils derived from medicinal herbs have furnished bioactive synergistics, as well as antibacterial and antifungal properties. The study was to evaluate the antibacterial activity of essential oils (EOs) against Cutibacterium acnes and to analyze the chemical compositions of the effective oils. The experiment was conducted using a completely randomized design with duplications. Three EOs obtained from Allium sativum (garlic), Gardenia jasminoides (gardenia), and Hedychium coronarium (hydechium) cultivated in Thailand were tested for antibacterial activity using an agar well diffusion assay and the macro-dilution method. The chemical compositions of the selected oil were determined by gas chromatography and mass spectrometry (GC-MS). To compare the data, Duncan’s multiple range test (DMRT) was performed, and significance was determined at the p < 0.05 level. The results showed that garlic oil had the highest potent inhibitory zone on C. acnes, according to the findings. As a bactericidal, garlic oil had MIC and MBC values of 0.39 and 0.78 mg/mL, and even a MIC index (MBC/MIC) of 4. Diallyl thiosulfinate (allicin) (20.53%), 1,3-dithiane (12.53%), cyclic octaatomic sulfur (5.02%), 1,4-dihydro-2,3-benzoxathiin-3-oxide (4.73%), and carvone (3.40%) were the major components of garlic oil. The results suggest that garlic oil might be used to develop topical anti-acne treatments.

Organic compounds in the Tarda C2 ungrouped carbonaceous chondrite: Evaluating the sources of contamination in a desert fall

AbstractStudying organic compounds in meteorites provides important insight into the chemical processes that occurred in the early solar system. Once meteorites reach the Earth’s surface, they are subject to terrestrial organic contamination that may confound the conclusions that we draw from meteorite organic analyses. Within this study, specimens of the Tarda C2 ungrouped carbonaceous chondrite, collected within a few days of its fall on August 25, 2020, from a barren desert in Morocco, were analyzed for their organic compound contents. In addition, a sand sample from the strewn field was analyzed to confirm the sources of a handful of contaminating compounds detected in the Tarda stones. Using dichloromethane (DCM) rinses of the Tarda stone exteriors and DCM and hot water extractions of meteorite specimen powders and sand sample, and analysis of the soluble organics by gas chromatography‐mass spectrometry, we distinguish between extraterrestrial and contaminant sources for each organic compound. In this study, N‐tert‐butyldimethylsilyl‐N‐methyltrifluoroacetamide (MTBSTFA) was used to derivatize the hot water extractions to utilize its single‐step derivatization reaction ability. The compounds determined to be intrinsic to Tarda include propanoic acid, propanedioic acid, butanedioic acid, fumaric acid, methylmaleic acid, threonine, proline, glycine, urea, and cyclic octaatomic sulfur. We detected numerous terrestrial organic compounds, all of which were traced back to the meteorites’ collection area, with several being confirmed in the sand sample. Our results have implications for best practices for the collection of freshly fallen meteorites, especially carbonaceous chondrites, as well as how specimens should be handled and curated after collection.

Comparative analysis of lipid profiles and flavor composition of marinated eggs from different species

This study compared lipid profiles and volatile composition in marinated eggs from different species (chicken, quail, and pigeon) using LC-ESI-MS/MS and GC-MS, respectively. The three marinated eggs showed significant differences in phosphatidylcholine, phosphatidylethanolamine (PE) and neutral lipid profiles of the three marinated eggs. Pigeon-eggs contained the highest content of PE but the lowest content of triglycerides. Seventy-six potential lipid metabolites such as Cer(d18:1/21:0), DG(15:0/18:2), and PE-O(16:1/18:2) were selected for the discrimination of all three groups. Pigeon-eggs contained the highest contents of C18:2 and C22:6, as well as n-3 and n-6 PUFA than quail-eggs and chicken-eggs. Major compounds including 2-Nonanone, 1-Octen-3-ol, cyclic octaatomic sulfur have greatly contributed to the distinction of eggs from different species. The highest levels of aldehydes, acids and ketones were found in chicken-eggs. This study reported that lipidomic and volatile composition analysis are promising approaches for discriminating of marinated eggs from different species

Cs-containing hierarchical zeolites as catalysts for Gewald reaction

Catalytic activity of Cs-ion-exchange form of aluminosilicate zeolites with MOR and BEA topology with the morphology of aggregated nanosheets, nanorods, or close to spherical nanoparticles was evaluated in Gewald reaction using cyclic ketones, malonodinitrile and sulphur. It was shown that morphology and zeolite topology significantly influenced on amount of Cs- incorporated into ion-exchange positions of hierarchical zeolites and consequently its catalytic activity in Gevald reaction including cyclic ketones, especially for BEA zeolites.

Effects of Drying Process on the Volatile and Non-Volatile Flavor Compounds of Lentinula edodes.

In this study, fresh Lentinula edodes was dehydrated using freeze-drying (FD), hot-air drying (HAD), and natural drying (ND), and the volatile and non-volatile flavor compounds were analyzed. The drying process changed the contents of eight-carbon compounds and resulted in a weaker “mushroom flavor” for dried L. edodes. HAD mushrooms had higher levels of cyclic sulfur compounds (56.55 μg/g) and showed a stronger typical shiitake mushroom aroma than those of fresh (7.24 μg/g), ND (0.04 μg/g), and FD mushrooms (3.90 μg/g). The levels of 5′-nucleotide increased, whereas the levels of organic acids and free amino acids decreased after the drying process. The dried L. edodes treated with FD had the lowest levels of total free amino acids (29.13 mg/g). However, it had the highest levels of umami taste amino acids (3.97 mg/g), bitter taste amino acids (6.28 mg/g) and equivalent umami concentration (EUC) value (29.88 g monosodium glutamate (MSG) per 100 g). The results indicated that FD was an effective drying method to produce umami flavor in dried mushrooms. Meanwhile, HAD can be used to produce a typical shiitake mushroom aroma. Our results provide a theoretical basis to manufacture L. edodes products with a desirable flavor for daily cuisine or in a processed form.

Cyclic sulfur compounds targeting macrophage polarization into M2/protumor phenotype and their anti-tumor effects.

Tumor-associated macrophages (TAMs), especially the M2-like phenotype, promote tumor progression, making them candidate targets for anti-tumor therapy. We previously discovered a cyclic sulfur compound, Onionin A (ONA), which suppresses tumor progression by inhibiting the M2-polarization of TAMs. In the present study, we sought to find new candidate compounds possessing a stronger effect compared to ONA by exploring compounds with structures similar to those of ONA among several cyclic sulfur compounds. A total of 81 cyclic sulfur compounds were screened, and their effects on macrophage polarization toward an M2-like phenotype were tested using human monocyte-derived macrophages (HMDMs). The anti-tumor effects of the identified candidate compounds were examined in a tumor-bearing mouse model. Three candidate compounds inhibited both IL-10- and tumor culture supernatant (TCS)-induced M2-polarization of HMDMs. These compounds also suppressed STAT3 activation in HMDMs stimulated by IL-10 and TCS, whereas these compounds had no effect on STAT3 activation in tumor cells. Furthermore, these compounds inhibited tumor cell proliferation under co-culture conditions with HMDMs, indicating that the three candidate compounds suppress tumor proliferation by regulating cell-cell interactions between tumor cells and macrophages. In addition, two of these candidate compounds had inhibitory effects on tumor growth and lung metastasis in the LM8 tumor-bearing mouse model. Our study identified new candidate cyclic sulfur compounds for anti-tumor therapy targeting the M2-polarization of TAMs.

Mo-Doped FeS Mediated H2 Production from H2S via an In Situ Cyclic Sulfur Looping Scheme

Mo-Doped FeS Mediated H₂ Production from H₂S via an In Situ Cyclic Sulfur Looping Scheme

The dynamic changes in product attributes of shiitake mushroom pilei and stipes during dehydration by hot air drying

The dynamic changes in product attributes of shiitake mushroom pilei and stipes during dehydration by hot air drying (HAD) were analyzed. During dehydration, discoloration was greater during the fresh point (FP) to standard point (SP) than that during SP to the constant weight point (CWP). The hardness declined and then rose gradually from SP to CWP. C8 compounds (including 1-octen-3-ol, 3-octanol, 2-octen-1-ol, 1-octanol, octanal, 2-octenal, and 3-octanone) showed significant decline (p < .05) from FP to SP. However, the sulfur compounds (including the thioether compounds and cyclic sulfur compounds), 5′-GMP, and 5′-AMP increased significantly (p < .05) from the SP to CWP. The combined model fitted the quality changes with the highest Adj. R2. Besides, e-nose and e-tongue could distinguish samples in different moisture content. The study illustrated that SP was an important turning point for changes in shiitake mushroom product attributes during dehydration. Practical applications Shiitake mushrooms are the second most cultivated edible mushrooms in the world. However, fresh shiitake mushrooms are easy to undergo postharvest quality deterioration. Sun drying is the most common method to preserve agricultural products, but has disadvantages in industrialized production. Hot air drying (HAD) is another processing method. Texture, color, volatile compounds, and nucleotides are important product attributes and flavor qualities for dried products, which influence consumers’ acceptability and products’ market value. Moreover, pilei and stipes in mushrooms usually show different attributes. However, there have been few studies focusing on the quality changes of shiitake mushrooms following the moisture changes and the different parts of shiitake mushrooms treated by HAD. This study will investigate the dynamic changes in product attributes of shiitake mushroom pilei and stipes following moisture content loss during dehydration induced by HAD, and also provide a good basis for clarifying the effect of dehydration on edible fungi manufacture by HAD.

Ring-opening polymerization

Abstract Ring-opening polymerization is defined by IUPAC (Penczek, S., Moad, G. (2008). Glossary of the terms related to kinetics, thermodynamics, and mechanisms of polymerization. (IUPAC Recommendations 2008), Pure and Applied Chemistry, 80(10), 2163–2193) as (cit.) “Ring-opening polymerization (ROP): Polymerization in which a cyclic monomer yields a monomeric unit that is either acyclic or contains fewer rings than the cyclic monomer”. The large part of the resulting polymerizations is living/controlled; practically all belong to chain polymerizations. After the introduction, providing basic information on chain polymerizations, the paper presents the concise overview of major classes of monomers used in ROP, including cyclic ethers, esters, carbonates, and siloxanes as well as cyclic nitrogen, phosphorus, and sulfur containing monomers. There are discussed also thermodynamics, kinetic polymerizability, and major mechanisms of ROP. Special attention is concentrated on polymers prepared by ROP on industrial scale.

Impact of an unusual disulfide transformation on detection of isothermal amplification products

Detection of infectious pathogens such as HIV-1, HPV, and SARS-CoV-2 from biospecimens is critical to healthcare. Particularly sensitive and specific diagnostic techniques to accomplish this include molecular amplification and detection tests of nucleic acids from pathogens. Such tests are comprised of reagent compositions to facilitate hybridization of primers and probes that are complementary to specifically amplified sequences of the analyte target. One of these reagents from an isothermal molecular assay occasionally changed its physical appearance over time, generating interest into the cause of the transformation and suitability of the reagent in diagnostic testing. A preliminary hypothesis was that the 2,2′-dithiodipyridine component was the pre-chromophoric compound of its distinctly yellow reduced form, 2-thiopyridine. However, under oxidizing conditions, 2-thiopyridine is a minor constituent of hybridization reagents and not a major contributor to the yellow colour. Instead, a new yellow compound was isolated from coloured hybridization reagent, identified as 1-(2′-pyridyl)-2-thiopyridone and determined to be the result of an intramolecular cyclic rearrangement and sulfur extrusion from 2,2′-dithiodipyridine under acidic and oxidizing conditions. Neither the appearance of 1-(2′-pyridyl)-2-thiopyridone, nor the concomitant depletion of 2,2′-dithiodipyridine reduced the sensitivity or specificity of in vitro diagnostic screening assay results for detecting amplified nucleic acids from viral pathogens, ensuring the safety of tested blood transfusion products.

Cyclic Octamer of Hydroxyl-functionalized Cations with Net Charge Q=+8e Kinetically Stabilized by a 'Molecular Island' of Cooperative Hydrogen Bonds.

Cyclic octamers are well‐known structural motifs in chemistry, biology and physics. These include covalently bound cyclic octameric sulphur, cylic octa‐alkanes, cyclo‐octameric peptides as well as hydrogen‐bonded ring clusters of alcohols. In this work, we show that even calculated cyclic octamers of hydroxy‐functionalized pyridinium cations with a net charge Q=+8e are kinetically stable. Eight positively charged cations are kept together by hydrogen bonding despite the strong Coulomb repulsive forces. Sufficiently long hydroxy‐octyl chains prevent “Coulomb explosion” by increasing the distance between the positive charges at the pyridinium rings, reducing the Coulomb repulsion and thus strengthen hydrogen bonds between the OH groups. The eightfold positively charged cyclic octamer shows spectroscopic properties similar to those obtained for hydrogen‐bonded neutral cyclic octamers of methanol. Thus, the area of the hydrogen bonded OH ring represents a ‘molecular island’ within an overall cationic environment. Although not observable, the spectroscopic properties and the correlated NBO parameters of the calculated cationic octamer support the detection of smaller cationic clusters in ionic liquids, which we observed despite the competition with ion pairs wherein attractive Coulomb forces enhance hydrogen bonding between cation and anion.

Identification and toxicological evaluation of cyclic sulfonium ion degradation products of sulphur mustard

In the aftermath of WWII large amount seized German chemical munitions were dumped in the Baltic Sea by Allied forces. In this work, we have compared the chemical content of the solidified blocks of dumped WWII mustard gas collected from the Baltic Sea with solid precipitate from stored mustard gas, known as heel. We have identified the same cyclic sulfonium ions in both samples. In assessing the environmental and toxicological impact of dumped sulphur mustard munitions on the world's oceans the potential risk posed by cyclic sulphur mustard salts have so far not been incorporated.The toxicity of 1-(2-chloroethyl)-1,4-dithiane and its hydrolysis product 1-(2-hydroxyethyl)- 1,4-dithiane was evaluated using three different cell lines. Their effect on released pro-inflammatory cytokines was also measured. The toxicity tests showed low toxicity and low pro-inflammatory response and we therefore conclude that the environmental threat posed by these compounds is low.

LaMnO3-La2CuO4 two-phase synergistic system with broad active window in NOx efficient reduction

The phase composition was tuned to discuss the intergrowth and coexistence effect for LaCu0.5Mn0.5O3 catalysts in NOx reduction. The two-phase system consisting of LaMnO3 and La2CuO4 had been thoroughly studied. Different phases in this two-phase system play the key role in NOx reduction at different temperatures, thereby maintaining excellent catalytic performance with broad active window from 300 to 1000 °C. In addition, this two-phase system was the first catalytic system to perform well in all of the following aspects, with decent practicability, superior long-term catalytic ability, excellent cyclic catalytic ability, reliable water and sulfur resistance, low toxicity, low cost, high reserves, and strong stability in high temperature range. This two-phase system had great value in practical applications. Furthermore, by the results of in situ DRIFTS and quasi-in situ XRD and XPS, the reaction mechanism was tentatively described in NOx reduction.