SEARCH · Search PubMed

Results for “Sulfur Compounds”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources

PubMed1979

Purification of Thiobacillus denitrificans siroheme sulfite reductase and investigation of some molecular and catalytic properties.

A siroheme-containing sulfite reductase was isolated from Thiobacillus denitrificans, purified to an electrophoretically homogenous state, and investigated with regard to some of its molecular and catalytic properties. The enzyme was a tetramer with a molecular weight of 160 000, consisting of two types of subunits arranged to an alpha 2 beta 2-structure. The molecular weight of the alpha-subunit was 38 000, that of the beta-subunit 43 000. As prosthetic groups siroheme and Fe/S groupings could be detected. The absorption spectrum showed maxima at 273 nm, 393 nm, and 594 nm; the molar extinction coefficient at these wavelengths were 280, 181, and 60 . 10(3) cm2 . mmol-1, respectively. With reduced viologen dyes the enzyme reduced sulfite to sulfide, thiosulfate and trithionate. In many properties T. denitrificans sulfite reductase closely resembled desulfoviridin, the dissimilatory sulfite reductase of Dssulfovibrio species. It is proposed that the physiological function of this enzyme is not to reduce but rather to form sulfite from reduced sulfur compounds in the course of dissimilatory sulfur oxidation in T. denitrificans.

Catalysis↗

PubMed2001

Exudation of low molecular weight compounds (thiobismethane, methyl isocyanide, and methyl isothiocyanate) as a possible chemical defense mechanism in the marine sponge Ircinia felix.

The volatile constituents of the marine sponge Ircinia felix were obtained by dynamic headspace extraction and analyzed by HRGC, HRGC-MS and HRGC-Odor at sniffing port. Fifty-nine volatiles were identified for the first time in the odor of this sponge. Hydrocarbons (32.9%), alcohols (17.8%) and carbonyl compounds (16.0%) predominated in the sponge volatile profile, followed by esters (11.6%), halogen compounds (8.6%), ethers (7.7%), nitrogen and/or sulfur compounds (4.6%) and carboxylic acids (0.8%). Among the identified volatiles, thiobismethane (commonly known as dimethylsulfide), methyl isocyanide and methyl isothiocyanate were found to be responsible for the nauseating and toxic smell emitted by the sponge and for the antimicrobial activity detected in the volatile extract. Exudation experiments in aquarium and in situ conditions revealed that thiobismethane, methyl isocyanide and methyl isothiocyanate are continuously released by the sponge. Upon injury, the concentration of these volatiles increased strongly. Hence, these substances form a chemical protective barrier which may help these sponges avoid fouling, compete for space, prevent infection in the short term, and/or signal generalist predators regarding the existence of other toxic substances in the internal tissues.

Journal Article↗

PubMed1998

Sulfur oxidation in rice field soil: activity, enumeration, isolation and characterization of thiosulfate-oxidizing bacteria.

In rice paddy fields the bulk soil is anoxic, but oxygenated zones occur in the surrounding of the rice roots to where oxygen is transported via the aerenchyma system of the rice plants. In the anaerobic soil compartments sulfate is consumed by sulfate-reducing bacteria. In the rhizosphere the reduced sulfur compounds can be reoxidized by sulfur-oxidizing bacteria. Measurements of the potential activity of thiosulfate-oxidizing bacteria in soil slurries derived from planted rice soil microcosms showed turnover rates of 2-6 mumol d-1 g-dw-1. Thiosulfate was oxidized to sulfate with tetrathionate as intermediate. Most probable number (MPN) enumeration with three aerobic media and one anaerobic nitrate-amended medium showed that thiosulfate-oxidizing bacteria were abundant in paddy soil and in rhizosphere soil at numbers of 10(5) to 10(6) per gram dry weight soil. Nine isolates of S-oxidizing bacteria were obtained from enrichment cultures or from the highest dilutions of the MPN series and were affiliated to four different phylogenetic groups. These isolates were characterized by physiological properties and by comparative 16S rDNA sequence analysis. Three isolates (TA1-AE1, TA1-A1 and TA12-21) were shown to be facultatively chemolithoautotrophic strains of Ancylobacter aquaticus. Three further isolates (Tv6-2b, Z2A-6A and Z4A-2A) were also facultatively chemolithoautotrophic and were affiliated with the Xanthobacter sp. group, probably representing new strains of X. flavus or X. tagetidis. Strain SZ-2111 was phylogenetically related to Bosea thiooxidans. However, the genus Bosea is described as obligately heterotrophic, whereas strain 5Z-2111 was able to grow autotrophically. The isolates 5Z-C1 and TBW3 were obligate chemolithoautotrophs and were closely affiliated with Thiobacillus thioparus. Our results showed that S-oxidizing bacteria were abundant and active in rice paddy soil and consisted of physiologically and phylogenetically diverse populations.

Anaerobiosis↗

PubMed2003

Analysis of a model reaction system containing cysteine and (E)-2-methyl-2-butenal, (E)-2-hexenal, or mesityl oxide.

Cysteine conjugates, resulting from the addition of cysteine to alpha,beta-unsaturated carbonyl compounds, are important precursors of odorant sulfur compounds in food flavors. The aim of this work was to better understand this chemistry in the light of the unexpected double addition of cysteine to two unsaturated aldehydes. These reactions were studied as a function of pH. When (E)-2-methyl-2-butenal (tiglic aldehyde, 4) was treated with cysteine in water at pH 8, the major product formed was the new compound (4R)-2-(2-[[(2R)-2-amino-2-carboxyethyl]thio]methylpropyl)-1,3-thiazolidine-4-carboxylic acid (6). Under acidic conditions (pH 1), we also observed a double addition, but the second cysteine was linked by a vinylic sulfide bond to form the previously unreported major product, (2R,2'R,E)-S,S'-(2,3-dimethyl-1-propene-1,3-diyl)bis-cysteine (7). When (E)-2-hexenal (12) was treated with cysteine under acidic conditions, the major product was the novel (4R,2' 'R)-2-[2'-(2' '-amino-2' '-carboxyethylthio)pentyl]-1,3-thiazolidine-4-carboxylic acid (13), and the formation of an vinylic sulfide compound analogous to 7 was not observed. Reduction of the acidic crude reaction mixture with NaBH(4) afforded 13 and the cysteine derivative (R)-S-[1-(2-hydroxyethyl)butyl]cysteine (14) in 14% yield. Treating (E)-2-hexenal with cysteine at pH 8 followed by NaBH(4) reduction yielded the new product (3R)-7-propylhexahydro-1,4-thiazepine-3-carboxylic acid (15). Addition of cysteine to mesityl oxide (16), at pH 8, followed by reduction with NaBH(4) furnished (R)-S-(3-hydroxy-1,1-dimethylbutyl)cysteine (3) and the new compound (3R)-hexahydro-5,7,7-trimethyl-1,4-thiazepine-3-carboxylic acid (18).

Aldehydes↗

PubMed1983

Sulfur Dioxide Flux into Leaves of Geranium carolinianum L. : Evidence for a Nonstomatal or Residual Resistance.

The concurrent exchange of SO(2) and H(2)O vapor between the atmosphere and foliage of Geranium carolinianum was investigated using a whole-plant gas exchange chamber. Total leaf flux of SO(2) was partitioned into leaf surface and internal fractions. The emission rate of SO(2)-induced H(2)S was measured to develop a net leaf budget for atmospherically derived sulfur. Stomatal resistance to SO(2) flux was estimated by two techniques: (a) R(s) (SO(2)') from SO(2) data using analog modeling techniques and (b) R(s) (SO(2) ) from analogy to H(2)O (i.e. 1.89 R(s) (H(2)o)).The emission of H(2)S was positively correlated with the rate of SO(2) flux into the leaf interior. An accounting of the simultaneous, bidirectional flux of gaseous sulfur compounds during pollutant exposure showed that sulfur accumulation in the leaf interior of G. carolinianum was 7 to 15% lower than that estimated solely from mass-balance calculations of SO(2) flux data (i.e. ignoring H(2)S emissions).The esimate of stomatal resistance to pollutant flux from the SO(2) data (R(s) (SO(2)')) was consistently less than the simultaneous estimate derived from analogy to H(2)O vapor (R(s) (SO(2) )). The resultant of R(s) (SO(2)') - R(s) (SO(2) ), which was always negative, is indicative of a residual resistance to SO(2) flux into the leaf interior. On a comparative basis, SO(2) molecules experienced less pathway resistance to diffusion than effluxing H(2)O molecules. It is proposed that the SO(2):H(2)O path length ratio is less than unity, as a consequence of the pollutant's high water solubility and unique chemical reactivity in solution. Thus, the diffusive paths for H(2)O and SO(2) in G. carolinianum are not completely synonymous.

Journal Article↗

PubMedDate not supplied

[The role of oxygen in the regulation of the metabolism of aerotolerant spirochetes, a major component of "Thiodendron" bacterial sulfur mats].

Two spirochete strains isolated earlier from "Thiodendron" bacterial sulfur mats grew better under microaerobic (0.3-0.5 mg O2/l) than under anaerobic conditions. The microaerobic growth of these strains was accompanied by a twofold increase in the cell yield and the efficiency of glucose utilization, despite an amount of ATP (and hence glucose) was spent in this case for the synthesis of exopolysaccharides. Glucose metabolism under microaerobic conditions gave rise to more oxidized products (acetate and carbon dioxide) than under anaerobic conditions (formate, ethanol, pyruvate, and hydrogen). The paper considers two putative mechanisms implemented by aerotolerant spirochetes: adaptive (the use of a more efficient pathway of glucose catabolism) and protective (an enhanced synthesis of exopolysaccharides and the reduction of hydrogen peroxide by the reduced sulfur compounds thiosulfate and sulfide, yielding elemental sulfur). The formation of "Thiodendron" bacterial sulfur mats in saltwater environments is also discussed.

Anaerobiosis↗

PubMed1996

Modulation of rat hepatic cytochrome P-450 activity by garlic organosulfur compounds.

Garlic organosulfur compounds exert chemopreventive effects at several organ sites in rodents after administration of chemical carcinogens, possibly by inhibiting carcinogen activation via cytochrome P-450-mediated oxidative metabolism. It has been suggested that the variability in potency of tumor inhibition by garlic sulfur compounds is due to structural differences, such as the number of allyl and sulfur groups. In this study, diallyl sulfide (DAS), diallyl disulfide (DADS), and allyl methyl sulfide (AMS) were administered to acetone-treated adult male Sprague-Dawley rats by gastric gavage at a dose of 1.75 mmol/kg in cottonseed oil. After 15 hours, hepatic microsomal cytochrome P-450 activity and content were examined. The activity of p-nitrophenol (pNP) hydroxylase (E.C. 1.14.13.29) was significantly decreased by all garlic compounds, whereas benzphetamine N-demethylase and ethoxyresorufin O-deethylase activities were not changed. The activity of pNP hydroxylase was decreased to 31%, 54%, and 65% of control activity, and immunodetectable CYP2E1 protein levels were decreased in a similar manner by DAS, DADS, and AMS, respectively. Additional acetone-treated rats were given 4-methyl pyrazole, a ligand specific for CYP2E1, intraperitoneally five hours after garlic compound administration. Ten hours later, pNP hydroxylase activity was decreased to 73%, 78%, and 67% of control levels by DAS, DADS, and AMS, respectively. Further studies are needed to determine whether the variable potency of inhibition of CYP2E1 enzyme activity is related to chemopreventive efficacy of garlic sulfur compounds.

Allyl Compounds↗

PubMed2003

Formation of aroma compounds and lipoxygenase (EC 1.13.11.12) activity in unblanched leek (Allium ampeloprasum Var. Bulga) slices during long-term frozen storage.

The content of aroma compounds (dynamic headspace) and catalytic activity of lipoxygenase (LOX) (EC. 1.13.11.12) were analyzed in 15 mm unblanched leek slices seven times during 12 months of frozen storage. The aroma profile changed from consisting of almost only sulfur compounds such as dipropyl disulfide [concentration in fresh leek (FL) = 0.197 mg/L, concentration after 12 months of frozen storage (12M) = 0.0409 mg/L] and propyl (E)-propenyl disulfide (FL = 0.0437 mg/L, 12M = 0.00452 mg/L) in the fresh leeks to being dominated by numerous saturated and unsaturated aldehydes, such as hexanal (FL = 1.53 mg/L, 12M = 3.63 mg/L), (E,E)-2,4-nonadienal (FL = 0.000 mg/L, 12M = 0.0647 mg/L), and (E,E)-2,4-decadienal (FL = 0.129 mg/L, 12M = 0.594 mg/L) at the end of the storage period. The catalytic activity of LOX diminished throughout frozen storage, but approximately 25% of the original activity was present after 12 months of storage.

Aldehydes↗

PubMed2005

Origin, occurrence, and biodegradation of long-side-chain alkyl compounds in the environment: a review.

Long-side-chain alkyl compounds, such as those present in oil and oil products, either of natural or of anthropogenic origin or released by industrial activities, are a ubiquitous group of chemicals in the environment. Among them, long-side-chain alkylmonocycloalkanes, alkylbenzenes, and alkyl organic sulfur compounds are largely found in fossil fuels while long-side-chain alkylbenzene sulfonates and alkylphenols are released into the environment primarily due to domestic activities. The present article briefly summarizes the advances that have occurred in this field in terms of the identity, abundance, possible origin and significance of these long-side-chain alkyl compounds found in the environment. In addition, the susceptibility to biodegradation and the fate of these chemicals in the environment are discussed.

Biodegradation, Environmental↗

PubMed2001

Effect of pH and temperature on the formation of volatile compounds in cysteine/reducing sugar/starch mixtures during extrusion cooking.

Mixtures of cysteine, reducing sugar (xylose or glucose), and starch were extrusion cooked using feed pH values of 5.5, 6.5, and 7.5 and target die temperatures of 120, 150, and 180 degrees C. Volatile compounds were isolated by headspace trapping onto Tenax and analyzed by gas chromatography--mass spectrometry. Eighty and 38 compounds, respectively, were identified from extrudates prepared using glucose and xylose. Amounts of most compounds increased with temperature and pH. Aliphatic sulfur compounds, thiophenes, pyrazines, and thiazoles were the most abundant chemical classes for the glucose samples, whereas for xylose extrudates highest levels were obtained for non-sulfur-containing furans, thiophenes, sulfur-containing furans, and pyrazines. 2-Furanmethanethiol and 2-methyl-3-furanthiol were present in extrudates prepared using both sugars, but levels were higher in xylose samples. The profiles of reaction products were different from those obtained from aqueous or reduced-moisture systems based on cysteine and either glucose or ribose.

Cysteine↗

PubMed1999

Heating garlic inhibits its ability to suppress 7, 12-dimethylbenz(a)anthracene-induced DNA adduct formation in rat mammary tissue.

The present studies compared the impact of heating, either by microwave or convection oven, on the ability of garlic to reduce the in vivo bioactivation of 7,12-dimethylbenz(a)anthracene (DMBA) in 55-d-old female Sprague-Dawley rats. In study 1, rats were fed a semipurified casein-based diet and treated by gastric gavage thrice weekly for 2-wk with crushed garlic (0.7 g in 2 mL corn oil) or the carrier prior to DMBA treatment (50 mg/kg body weight). Providing crushed garlic reduced by 64% (P < 0.05) the quantity DMBA-induced DNA adducts present in mammary epithelial cells compared to controls. In study 2, microwave treatment for 60 s, but not 30 s, decreased (P < 0.05) the protection provided by garlic against DMBA-induced adduct formation. In study 3, allowing crushed garlic to stand for 10 min prior to microwave heating for 60 s significantly (P < 0.05) restored its anticarcinogenic activity. Microwave heating of garlic for 30 s resulted in a 90% loss of alliinase activity. Heating in a convection oven (study 4) also completely blocked the ability of uncrushed garlic to retard DMBA bioactivation. Study 5 revealed that providing either 0.105 micromol diallyl disulfide or S-allyl cysteine by gastric gavage thrice weekly for 2 wk was effective in retarding DMBA bioactivation but isomolar alliin was not. These studies provide evidence that alliinase may be important for the formation of allyl sulfur compounds that contribute to a depression in DMBA metabolism and bioactivation.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1999

[Halitosis in 1999].

Bad breath is a major concern to the general population and a source of an important profit industry world wide. Between 50 and 60 per cent of the population suffer from chronic halitosis. This can have consequences for private or professional life. Reasons can imply many specialities: ENT, gastro-enterology, pneumology, hepatology, genetics and psychiatry (a high percentage of the patients who come to the clinic with a primary complaint of halitosis do not have a detectable problem). Nevertheless, 85% are stomatological and are explained by the release of volatile sulfur compounds. These substances have a very offensive odor in very low concentrations. A specialized device called a halimeter is available to measure the volatile sulphur compounds in mouth air but in practice the objective assessment of malodor is still best performed by the organoleptic method. A careful examination can determine the patient's problem in most cases. Initial treatment strategy should focus on the exact cause and on oral hygiene. In addition to the usual recommendations, the daily use of tongue cleaners is very beneficial. Other than etiologic therapy, masking can be achieved by oral care products (mouth rinses, toothpastes, chewing gums) which contain metal ions, especially zinc, that inhibit odor formation because of its affinity to sulphur compounds.

Chelating Agents↗

PubMed2005

Composition, stability, and bioavailability of garlic products used in a clinical trial.

In support of a new clinical trial designed to compare the effects of crushed fresh garlic and two types of garlic supplement tablets (enteric-coated dried fresh garlic and dried aged garlic extract) on serum lipids, the three garlic products have been characterized for (a) composition (14 sulfur and 2 non-sulfur compounds), (b) stability of suspected active compounds, and (c) availability of allyl thiosulfinates (mainly allicin) under both simulated gastrointestinal (tablet dissolution) conditions and in vivo. The allyl thiosulfinates of blended fresh garlic were stable for at least 2 years when stored at -80 degrees C. The dissolution release of thiosulfinates from the enteric-coated garlic tablets was found to be >95%. The bioavailability of allyl thiosulfinates from these tablets, measured as breath allyl methyl sulfide, was found to be complete and equivalent to that of crushed fresh garlic. S-Allylcysteine was stable for 12 months at ambient temperature. The stability of the suspected active compounds under the conditions of the study and the bioavailability of allyl thiosulfinates from the dried garlic supplement have validated the use of these preparations for comparison in a clinical trial.

Allyl Compounds↗

PubMed2004

[In-situ sol-gel preparation of nano silica porous layer capillary columns and their applications in gas chromatography].

A new method is described to prepare nano silica porous layer columns by using in-situ sol-gel synthesis technology. By the interaction of ethyl acetate and water glass solution, the nano silica was synthesized on the inner surface of fused silica capillary. The influence of reaction conditions on the morphology surface area, pore volume and pore size was investigated. The experimental results demonstrate that when the mole ratio of ethyl acetate to silica was 0.82, the particle size of the superfine silica powder was in the range of 25-50 nm, the BET specific surface area was 420 m2/g, and the total pore volume was 0.68 cm3/g. The nano silica porous layer on the inner surface of fused silica capillary was formed by bonding reactions through cross-linked polysiloxane chains, and deactivated by 1 g/L KCl. The column shows sufficient selectivity, stable retention performance, proper resistance to water, good reproducibility, and unique activity. The column is suitable for the analysis of chlorofluorocarbons, halohydrocarbons, sulfur compounds, and light hydrocarbons C1-C4.

Chlorofluorocarbons↗

PubMed2005

Production of volatile compounds in cheese by Pseudomonas fragi strains of dairy origin.

Volatile compounds produced in cheese by five Pseudomonas fragi strains isolated from 1-day-old raw milk cheeses were investigated. Each strain was representative of a different biochemical group of isolates of identical phenotypic characteristics, according to identification with API 20 NE strips. The five strains were ascribed to the species P. fragi after 16S rRNA sequencing because of their high degree of coincidence with P. fragi ATCC 4973. In each of two experiments, carried out on different days, five cheeses were made at laboratory scale from pasteurized milk separately inoculated with approximately 10(5) CFU/ml of each P. fragi strain. After 12 days at 10 degrees C, mean counts of P. fragi strains were close to 10(10) CFU/g in the outer part of cheeses and close to 10(8) CFU/g in the inner part. A total of 131 volatile compounds, 49 of which were further characterized, were identified in cheeses by gas chromatography-mass spectrometry after extraction with a purge and trap apparatus. Abundances of compounds were generally higher in the outer part of cheeses. Production of volatile compounds was clearly strain dependent. Only two strains produced ethyl esters, and three produced nonethyl esters. Ethyl acetate, ethyl butyrate, ethyl caproate, methyl acetate, isopropyl acetate, and propyl tiglate were the major esters, and ethanol, 2-propanol, and 3-methyl butanol were the major alcohols. Undecene was the major hydrocarbon, dimethyl sulfide and methyl thiocyanate the major sulfur compounds, and 2-pentanone the major ketone. Two aromatic compounds, styrene and o-dichlorobenzene, were present in all cheeses.

Aldehydes↗

PubMed2004

Desulfurization of dibenzothiophene by a newly isolated Corynebacterium sp. ZD-1 in aqueous phase.

Sulfur emission through fuel combustion is a global problem because it is a major cause of acid rain. Crud oil contains many heterocyclic organic sulfur compounds, among which dibenzothiophene (DBT) and DBTs bearing alkyl substitutions usually are representative compounds. A strain was isolated from refinery sludge and identified as Corynebacterium ZD-1. The behavior of DBT degradation by ZD-1 in aqueous phase was investigated. Corynebacterium ZD-1 could metabolize DBT to 2-hydroxybiphenyl(2-HBP) as the dead-end metabolite through a sulfur-specific pathway. In shake flask culture, ZD-1 had its maximal desulfurization activity in the late exponential growth phase and the specific production rate of 2-HBP was about 0.14 (mmol x kg dry cell(-1) x min(-1), mmol x KDC(-1) x min(-1)). Active resting cells for desulfurization should be prepared only in this period. 2-HBP inhibited the growth of strain ZD-1, the production of DBT degradation enzymes, and the activity of enzymes. Sulfate inhibited the production of dibenzothiophene (DBT) degradation enzymes but had no effect on the enzymes' activity. The production rates of 2-HBP at lower cell densities were higher and the maximum amount conversion of DBT to 2-HBP (0.067 mmol/L) after 8 h was gained at 9.2 g dry cell/L rather higher cell density. The results indicated that this newly isolated strain could be a promising biocatalyst for DBT desulfurization.

Air Pollution↗

PubMed2006

Investigating the capacity of an activated sludge process to reduce volatile organic compounds and odor emissions.

The effects of hydrogen sulfide (H2S) diffusion into activated sludge (AS) on odor and volatile organic compound (VOC) concentrations in offgas were studied over an 8-week period. Most VOCs detected in the offgas of both aeration tanks were aromatic hydrocarbons. The VOC concentrations generally decreased when H2S was introduced to the AS compared with the control, indicating a negative effect of H2S on VOC removal. Two volatile organic sulfur compounds present in the test AS offgas showed an increase followed by a decrease during H2S peak loads. Six VOCs and odor concentration increased during the introduction of an H2S peak; however no correlation was observed between H2S and odor concentration. The increase in odor concentration resulted from the increase in the concentration of six aromatic VOCs, which had their removal slowed down during a 100-ppmv H2S peak. Activated sludge diffusion provides effective H2S removal with minimal affect on odor emissions.

Gases↗

PubMed1999

Identification of major volatile odor compounds in frankfurters.

More than 100 volatile compounds have been identified in the headspace of frankfurter sausages. Most abundant were the terpene hydrocarbons, monoterpene alcohols, phenyl propanoids, and phenols. Separate analyses of solutions of spices and smoke demonstrated that most of the terpenes were derived from the spices, whereas the phenols originated mostly from the smoke ingredients. Many of the compounds contributing to the overall odor of the frankfurters have been identified. Some odors, characteristic of the smokiness and spiciness of frankfurters, were caused by phenols and terpenes, whereas others were due to compounds derived from the meat fraction; these compounds included aldehydes, ketones, furanthiols, and alicyclic sulfur compounds.

Animals↗