Prodrugs of Persulfides, Sulfur Dioxide, and Carbon Disulfide: Important Tools for Studying Sulfur Signaling at Various Oxidation States.

Significance: Bioactive sulfur species such as hydrogen sulfide (H2S), persulfide species (R-SnSH, n ≥ 1), hydrogen polysulfide (H2Sn, n ≥ 2), sulfur dioxide (SO2), and carbon disulfide (CS2) participate in various physiological and/or pathological pathways such as vasodilation, apoptosis, inflammation, and energy metabolism regulation. The oxidation state of the individual sulfur species endows them unique biological activities. Recent Advances: There have been great strides made in achieving molecular understanding of the sulfur-signaling processes. Critical Issues: The development of various chemical tools that deliver reactive sulfur species in a controllable manner has played an important role in understanding the different roles of various sulfur species. In this review, we focus on three types of sulfur species, including persulfide, SO2, and CS2. Starting with a brief introduction of their physiological functions, we will then assess the various drug delivery strategies to generate persulfide species, SO2, and CS2 as research tools and potentially as therapeutic agents. Future Directions: Development of donors of various sulfur species that respond to distinct stimulus is critical for this field. Another key to the long-term success of this field is the identification of an area of unmet medical need that can be addressed with these sulfur species.

Carbon disulfide induces embryo loss by perturbing the expression of the mTOR signalling pathway in uterine tissue in mice.

Understanding of the mechanism of embryo loss is critical for successful pregnancy considering an increase in the incidence of infertility. In this study, we focus on the effect of alterations in the expression of the AKT/AMPK/mTOR signalling pathway in mouse uterine tissue after embryo loss induced by harmful environmental exposure to carbon disulfide (CS2). CS2 is a material used in certain production processes, and women are sometimes exposed to it in occupational settings. We created an animal model of gestating mice exposed to CS2 on gestation days 3 (GD3), 4 (GD4), 5 (GD5) and 6 (GD6) with various corresponding endpoints after the exposure. The uterine tissue was collected according to the endpoint time series to detect the expression levels of mTOR, p-mTOR, pAKT, and pAMPK using western blot, RT-PCR, immunohistochemistry staining, and ELISA. Dietary supplementation with N-carbamoyl glutamic acid (NCG) was used to verify the effect of the mTOR signalling pathway on embryo loss caused by CS2. We detected down-regulation of the levels of the mTOR and p-mTOR proteins; the levels of these two proteins were decreased by 49.35% and 51.44% at the GD5 endpoint after GD4 exposure and by 38.55% and 59.51% after GD3 exposure, respectively. The change in the expression level of mTOR mRNA was consistent with the protein expression, and the mRNA level at the GD5 endpoint was decreased by 55.0% after GD4 exposure (P < 0.05). Additionally, protein expression levels of pAKT were decreased by 49.05%, and the levels of pAMPK were increased by 25.51% at the GD5 endpoint after GD4 exposure (P < 0.05). A similar trend was observed for pAKT and pAMPK at the GD4 endpoint after GD3 exposure, at the GD6 endpoint after GD5 exposure, and at the GD7 endpoint after GD6 exposure (P < 0.05). Supplementation with NCG contributed to recovery from the effects of CS2 by increasing the protein expression levels of mTOR and pAKT by 47.54% and 63.79% (P < 0.05), respectively, while the pAMPK protein level was decreased by 37.15% (P < 0.05) at the GD5 endpoint after GD4 exposure. It should be noted that the number of implanted embryos was significantly increased after supplementation with NCG. Our results indicate that down-regulation of mTOR at the time of implantation is regulated by pAKT and pAMPK, that may be an important factor for embryo loss induced by CS2.

Evaluation Selenocysteine Protective Effect in Carbon Disulfide Induced Hepatitis with a Mitochondrial Targeting Ratiometric Near-Infrared Fluorescent Probe.

As important active sites of oxidoreductase in mitochondria, selenocysteine (Sec) takes the responsibility for cytoprotective effect and intracellular redox homeostasis. Carbon disulfide (CS2) is a common solvent in industry, which can inhibit the activities of oxidoreductase and induce oxidative stress. It is necessary to investigate the cytoprotective effect of Sec against CS2 exposure. After integrated, the response moiety 2,4-dinitrobenzenesulfonamide and mitochondrial targeting moiety into the near-infrared heptamethine cyanine fluorophore, we develop a mitochondrial targeting near-infrared ratiometric fluorescent probe Mito- diNO2 for the selective and sensitive analysis of Sec concentration fluctuations in living cells and in mice models under the stimulation of CS2. The probe can effectively accumulate in mitochondria and selectively detect the endogenous Sec concentrations in BRL 3A, RH-35, HL-7702, HepG2, and SMMC-7721 cell lines. The results indicate that CS2 exposure can lead to a decrease of Sec level and result in mitochondrial related acute inflammation. The exogenous supplement of Sec can protect cells from oxidative damage and reduce the symptoms of inflammation. We also establish CS2 induced acute and chronic hepatitis mice models to examine the tissue toxicity of CS2 and cytoprotection of Sec in liver. The organism can increase the concentration of Sec to deal with the damage caused by CS2 in acute hepatitis mice model. Also the exogenous supplement of Sec for the two mice models can effectively defend the CS2 induced liver damage. The real-time imaging of Sec concentrations in liver can be used to assess the degrees of liver injury during CS2 poisoning. The above applications make our probe a potential candidate for the clinical accurate diagnosis and treatment of CS2 poisoning.

Carbon disulfide potentiates the effects of impulse noise on the organ of Corti.

Occupational noise can damage workers' hearing, and the phenomenon is even more dangerous when noise is associated with an ototoxic solvent. Aromatic solvents are known to provoke chemical-induced hearing loss, but little is known about the effects on hearing of carbon disulfide (CS2) when combined with noise. Co-exposure to CS2 and noise may have a harmful effect on hearing, but the mechanisms involved are not well understood. For instance, CS2 is not thought to have a cochleotoxic effect, but rather it is thought to cause retrocochlear hearing impairment. In other words, CS2 could have a distal neuropathic effect on the auditory pathway. However, a possible pharmacological effect of CS2 on the central nervous system (CNS) has never been mentioned in the literature. The aim of this study was to assess, in rats, the effects of a noise (continuous vs. impulse), associated with a low concentration of CS2 [(short-term threshold limit value) x 10 as a safety factor] on the peripheral auditory receptor. The noise, whatever its nature, was an octave band noise centered at 8kHz, and the 250-ppm CS2 exposure lasted 15min per hour, 6h per day, for 5 consecutive days. The impact of the different experimental conditions on hearing loss was assessed using distortion product oto-acoustic emissions and histological analyses. Although the LEX,8h (8-h time-weighted average exposure) for the impulse noise was lower (84dB SPL) than that for the continuous noise (89dB SPL), it appeared more damaging to the organ of Corti, in particular to the outer hair cells. CS2 exposure alone did not have any effect on the organ of Corti, but co-exposure to continuous noise with CS2 was less damaging than exposure to continuous noise alone. In contrast, the cochleo-traumatic effects of impulse noise were significantly enhanced by co-exposure to CS2. Therefore, CS2 can clearly modulate the middle-ear reflex function. In fact, CS2 may have two distinct effects: firstly, it has a pharmacological effect on the CNS, modifying the trigger of the acoustic reflex; and secondly, it can make the organ of Corti more susceptible to impulse noise. The pharmacological effects on the CNS and the effects of CS2 on the organ of Corti are discussed to try to explain the overall effect of the solvent on hearing. Once again, the results reported in this article show that the temporal structure (continuous vs. impulse) of noise should be taken into consideration as a key parameter when establishing hearing conservation regulations.

Disgust-Related Olfactory Processing: The Role of Gender and Trait Disgust.

For the rejection of disgusting and potentially health-threatening food, the sense of smell plays a critical role. We conducted two experiments in order to investigate the role of gender and trait disgust (the temporally stable tendency to experience disgust across different situations) on disgust-related olfactory processing. A total of 40 men and women (Study 1), as well as a group of women divided according to high versus low trait disgust (Study 2, n = 59), were compared with regard to their odor thresholds for carbon disulfide (which smells like spoiled food) and a control stimulus ( n-butanol). The stimuli were rated for experienced arousal, negative valence, and familiarity. In addition, all participants underwent the "Sniffin' Sticks" battery assessing general olfactory performance. We found that women had a lower carbon disulfide threshold and rated this odorant as more unpleasant than men. Trait disgust was neither associated with the detection of the odorant signaling spoilage, nor with general olfactory function. The latter finding questions the role of this personality trait for olfactory-driven food-rejection responses, at least for normosmic individuals.

Carbon disulfide activates p62-Nrf2-keap1 pathway in rat nerve tissues.

Oxidative stress is associated with the pathogenesis of carbon disulfide (CS2) induced polyneuropathy. The nuclear factor erythroid 2-related factor 2 (Nrf2) plays a critical role in protecting cells against oxidative stress. However, whether there exists a Nrf2-mediated antioxidative machinery in CS2-induced neuropathy has not been elucidated. In the present study, male wistar rats were randomly divided into three experimental groups and one control group. The rats in experimental groups were treated with CS2 by gavage at dosages of 200, 400 and 600mg/kg/day respectively, six times per week for 6 weeks. Nrf2-keap1 antioxidative pathway and p62-related kinase signaling in rat nerve tissues was examined by western blotting and real-time PCR. The results demonstrated that CS2 treatment resulted in Nrf2 translocation from the cytosol to the nucleus in rat spinal cords. In the meantime, the expression of antioxidative enzymes such as NAD(P)H quinone oxidoreductase-1, heme oxygenase-1, and glutamate-cysteine ligase was significantly increased. Furthermore, CS2 treatment increased the level of p62 and its phosphorylation status, while decreased the level of keap1. In addition, CS2 also lead to the activation of CAMKK2 and ULK1 kinase signaling in rat spinal cords and sciatic nerves. Taken together, our results indicated that CS2 intoxication was associated with the activation of Nrf2-ARE antioxidative machinery, which might play a protective role against CS2-induced neuronal damage.

Carbon disulfide mediates socially-acquired nicotine self-administration.

The social environment plays a critical role in smoking initiation as well as relapse. We previously reported that rats acquired nicotine self-administration with an olfactogustatory cue only when another rat consuming the same cue was present during self-administration. Because carbon disulfide (CS2) mediates social learning of food preference in rodents, we hypothesized that socially acquired nicotine self-administration is also mediated by CS2. We tested this hypothesis by placing female adolescent Sprague-Dawley rats in operant chambers equipped with two lickometers. Licking on the active spout meeting a fixed-ratio 10 schedule triggered the concurrent delivery of an i.v. infusion (saline, or 30 µg/kg nicotine, free base) and an appetitive olfactogustatory cue containing CS2 (0-500 ppm). Rats that self-administered nicotine with the olfactogustatory cue alone licked less on the active spout than on the inactive spout. Adding CS2 to the olfactogustatory cue reversed the preference for the spouts. The group that received 500 ppm CS2 and the olfactogustatory cue obtained a significantly greater number of nicotine infusions than other groups. After extinction training, the original self-administration context reinstated nicotine-seeking behavior in all nicotine groups. In addition, in rats that received the olfactogustatory cue and 500 ppm CS2 during SA, a social environment where the nicotine-associated olfactory cue is present, induced much stronger drug-seeking behavior compared to a social environment lacking the olfactogustatory cue. These data established that CS2 is a critical signal that mediates social learning of nicotine self-administration with olfactogustatory cues in rodents. Additionally, these data showed that the social context can further enhance the drug-seeking behavior induced by the drug-taking environment.

Carbon disulfide inhibits neurite outgrowth and neuronal migration of dorsal root ganglion in vitro.

Carbon disulfide (CS2) is a neurotoxic industrial solvent and widely used in the vulcanization of rubber, rayon, cellophane, and adhesives. Although the neurotoxicity of CS2 has been recognized for over a century, the precise mechanism of neurotoxic action of CS2 remains unknown. In the present study, a embryonic rat dorsal root ganglia (DRG) explants culture model was established. Using the organotypic DRG cultures, the direct neurotoxic effects of CS2 on outgrowth of neurites and migration of neurons from DRG explants were investigated. The organotypic DRG cultures were exposed to different concentrations of CS2 (0.01 mmol/L, 0.1 mmol/L, 1 mmol/L). The number of nerve fiber bundles extended from DRG explants decreased significantly in the presence of CS2 (0.01 mmol/L, 15.00 ± 2.61, p < .05; 0.1 mmol/L, 11.17 ± 1.47, p < .001; 1 mmol/L, 8.00 ± 1.41, p < .001) as compared with that in the absence of CS2 (17.83 ± 2.48). The number of neurons migrated from DRG explants decreased significantly in the presence of CS2 (0.01 mmol/L, 79.50 ± 9.40, p < .01; 0.1 mmol/L, 62.50 ± 14.15, p < .001; 1 mmol/L, 34.67 ± 7.58, p < .001) as compared with that in the absence of CS2 (99.33 ± 15.16). And also, the decreases in the number of nerve fiber bundles and migrated DRG neurons were in a dose-dependent manner of CS2. These data implicated that CS2 could inhibit neurite outgrowth and neuronal migration from DRG explants in vitro.

An olfactory subsystem that detects carbon disulfide and mediates food-related social learning.

Olfactory signals influence social interactions in a variety of species. In mammals, pheromones and other social cues can promote mating or aggression behaviors; can communicate information about social hierarchies, genetic identity and health status; and can contribute to associative learning. However, the molecular, cellular, and neural mechanisms underlying many olfactory-mediated social interactions remain poorly understood. Here, we report that a specialized olfactory subsystem that includes olfactory sensory neurons (OSNs) expressing the receptor guanylyl cyclase GC-D, the cyclic nucleotide-gated channel subunit CNGA3, and the carbonic anhydrase isoform CAII (GC-D(+) OSNs) is required for the acquisition of socially transmitted food preferences (STFPs) in mice. Using electrophysiological recordings from gene-targeted mice, we show that GC-D(+) OSNs are highly sensitive to the volatile semiochemical carbon disulfide (CS(2)), a component of rodent breath and a known social signal mediating the acquisition of STFPs. Olfactory responses to CS(2) are drastically reduced in mice lacking GC-D, CNGA3, or CAII. Disruption of this sensory transduction cascade also results in a failure to acquire STFPs from either live or surrogate demonstrator mice or to exhibit hippocampal correlates of STFP retrieval. Our findings indicate that GC-D(+) OSNs detect chemosignals that facilitate food-related social interactions.

The effects of carbon disulfide on male sexual function and semen quality.

A cross-sectional study was initiated to clarify whether the current level of exposure to carbon disulphide (CS(2)) is low enough to prevent occurrence of subclinical health impairments. This paper describes the effects of exposure to CS(2) on male sexual function and semen quality in a baseline observation. The effects of CS(2) on male sexual function were evaluated, including number of sexual encounters and length of sexual encounters related to solvents in 80 male workers exposed to CS(2) and 49 reference workers from the filature and cotton pulp departments of a fabric factory in China. And the semen samples were obtained from 43 of the exposed and 35 of the control. Adjustment was made for potential confounding factors such as age or alcohol drinking. Exposure to CS(2) was dichotomized by job type. The rate of sexual dysfunction was higher, number of sexual encounters was lower, and length of sexual encounters was shorter compared with the control (p < 0.001). It was indicated that exposed workers had fewer semen quantity, longer liquefaction time, lower acrosomal membrane integrity rate, vitality and density, and more deformity of semen than the control (p < 0.01). The age and type of work played the most important roles in sexual dysfunction by the multinomial logistic regression analysis (p < 0.01).The duration of exposure had the effect on sexual function and semen quality but no statistical significance (p > 0.05). Clinical effects on the male sexual function and semen quality were found in the workers exposed to CS(2).

Effects of carbon disulfide on the expression and activity of nitric oxide synthase in rat hippocampus.

BACKGROUND: Carbon disulfide (CS(2)) is a commonly used organic solvent. Many epidemiological investigations and animal experiments have indicated that learning and memory ability can be affected to different degrees after long-term exposure to CS(2), but the mechanisms are still unclear. The aim of this study was to explore the possible mechanisms of CS(2)-related impairment of the learning and memory ability of rats, by investigating the effects of CS(2) on nitric oxide synthase (NOS) activity and NOS mRNA expression in rat hippocampus. METHODS: Rat models of toxicity were generated by inhalation of various doses of CS(2). After two months of inhaling intoxication, the activities of constitutive NOS (cNOS) and induced NOS (iNOS) in the hippocampus were measured. The levels of neuronal NOS (nNOS) mRNA and iNOS mRNA were measured by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). RESULTS: cNOS activity was significantly decreased compared with controls, while iNOS activity was changed only slightly. CS(2) treatment significantly decreased nNOS mRNA levels. iNOS mRNA levels were significantly increased only at higher doses of CS(2). CONCLUSION: The effect of CS2 on learning and memory ability in rats is related to the activity of NOS and the expression of nNOS in the hippocampus.

Carbon disulfide-induced changes in cytoskeleton protein content of rat cerebral cortex.

To investigate the mechanism of carbon disulfide-induced neuropathy, male wistar rats were administrated by gavage at dosage of 300 or 500 mg/kg carbon disulfide, five times per week for 12 weeks. By the end of the exposure, the animals produced a slight or moderate level of neurological deficits, respectively. Cerebrums of carbon disulfide-intoxicated rats and their age-matched controls were Triton-extracted and centrifuged at a high speed (100,000 x g) to yield a pellet fraction of NF polymer and a corresponding supernatant fraction, which presumably contained mobile monomer. Then, the contents of six cytoskeletal protein (NF-L, NF-M, NF-H, alpha-tubulin, beta-tubulin, and beta-actin) in both fractions were determined by immunoblotting. Results showed that the contents of the three neurofilament subunits in the pellet and the supernatant fraction decreased significantly regardless of dose levels (P<0.01). As for microtubule proteins, in the pellet fraction of cerebrum, the levels of alpha-tubulin and beta-tubulin demonstrated some inconsistent changes. However, in the supernatant fractions, the content of alpha-tubulin and beta-tubulin increased significantly in both two dose groups (P<0.01). In comparison to neurofilament and tubulin proteins, the content of beta-actin changed less markedly, only the supernatant fraction of the high dose group displayed significant increase (P<0.01), but the others remained unaffected. These findings suggested that the changes of cytoskeleton protein contents in rat cerebrum were associated with the intoxication of carbon disulfide, which might be involved in the development of carbon disulfide neurotoxicity.

[The inhibitory effect of Lu-Duo-Wei on carbon disulfide-induced generation of hydroxyl radicals].

OBJECTIVE: To study the scavenging effects of Lu-Duo-Wei, thiourea, superoxide dismutase, and sodium azide on carbon disulfide-induced generation of hydroxyl radicals. METHODS: Phenanthroline-CuSO(4)-Vit C-H(2)O(2) chemiluminescence system (PHEN system) containing alcohol was established to probe the influence of various concentrations of carbon disulfide on hydroxyl radicals emission intensity and the scavenging effects of Lu-Duo-Wei and other antioxidants on carbon disulfide-induced hydroxyl radicals were observed. RESULTS: The average emission intensity of PHEN system containing alcohol appeared lower luminescence [91.03 x 10(3) (cp6s)] and longer time (75 s) to get the peak than the system without alcohol [96.11 x 10(3) (cp6s), 55 s]. The specific scavenger of hydroxyl radical, thiourea, showed clear inhibitory effect on the system. Carbon disulfide in the range of 40 - 160 mmol/L promoted the generation of hydroxyl radical, however, this effect could be efficiently inhibited by thiourea. 160 mmol/L carbon disulfide in PHEN system without copper seemed as an activator to promote the luminescence, while in PHEN system withdrawing phenanthroline appeared some weak action of luminescence agent at low concentration. Meanwhile, Lu-Duo-Wei may efficiently scavenge hydroxyl radicals induced by carbon disulfide in PHEN system but superoxide dismutase and sodium azide had little effects on the system. CONCLUSION: Carbon disulfide may induce PHEN system to generate hydroxyl radicals and Lu-Duo-Wei may efficiently scavenge these free radicals and play an important role in protection against oxidative injury induced by carbon disulfide.

Vanadium nitride functionalization and denitrogenation by carbon disulfide and dioxide.

A dramatic difference in behavior is observed for the dithiocarbamate and carbamate complexes [Ar(But)N]3V(NCE2)Na(THF)2(E = S or O, respectively), prepared from the corresponding nitride species ([Ar(But)N]3V identical to NNa)2 by way of a nucleophilic addition reaction involving carbon disulfide or dioxide, and is rationalized with the aid of DFT calculations.

Bioassay of three sulphur containing compounds as rat attractant admixed in cereal-based bait against Rattus rattus Linn.

Three sulphur containing compounds, carbon disulphide, dimethyl disulphide and dimethyl sulphide were bioassayed for preference after admixing them in cereal base as ready bait block for use against commensal rat, R. rattus (wild type) in four way choice chamber system. Rat preference for different baits was also studied with automatic recording animal activity meter. Rats exhibited attractancy to the baits at 0.005% concentration of all the three compounds while at 0.01% concentration they have showed repellency. Dimethyl sulphide at 0.005% concentration showed better attractancy towards both sexes of rat.

Increased carbon disulfide-stimulated chemiluminescence in the pyrogallol-luminol system.

We studied the effect of carbon disulphide (CS2) on the generation of superoxide anion (O2-*) and its chemiluminescence (CL) in the pyrogallol-luminol system. Testing was conducted with the pyrogallol-luminol system to observe the CL dynamic curve of CS2 and the inhibition by superoxide dismutase (SOD) on CL induced by CS2. Compared with the ethanol solvent control, CS2 enhanced the emission intensity of CL and delayed the peak time. There was a significant dose-concentration relationship between CS2 concentrations (10, 40, 80 mg/mL) and CL peak (r = 0.975 p = 0.012) and CS2 concentrations and peak time (r = 0.990, p = 0.005). The CL peak at 80 mg/mL CS2 was higher than that in a background without ethanol. The enhanced CL evoked by CS2 could be inhibited by SOD. The results suggest that CS2 can induce the pyrogallol-luminol system to generate an increased amount of O2-* and delay the CL peak time.

Influence of carbon disulphide on hydroxyl radicals in the phenanthroline chemiluminescence system.

We investigated the effects of carbon disulphide (CS2) on hydroxyl radical generation using the phenanthroline chemiluminescence system. The influence of CS2 on the phenanthroline chemiluminescence system without CuSO4 and vitamin C were tested. The results showed that CS2 enhanced the emission intensity of chemiluminescence and advanced the peak time of the chemiluminescence. There was a dose-effect relationship between CS2 concentrations (0-160 mg/ml) and chemiluminescence peak intensity (r = 0.955, R2 = 0.913, p = 0.003), as well as CS2 concentrations and peak time (r = -0.927, R2 = 0.860, p = 0.008). The enhanced chemiluminescence induced by CS2 could be inhibited by thiourea, and the inhibition rate gradually deceased along with increasing CS2 concentration (r = -0.816, R2 = 0.666, p = 0.048). When the system was free of CuSO4 and vitamin C, CS2 also induced the emission of chemiluminescence intensity. We conclude from these results that CS2 can induce the phenanthroline chemiluminescence system to generate hydroxyl radicals and advance the peak time, and that thiourea can inhibit the effect. The mechanism may be explained by a catalytic effect of CS2 directly on H2O2.

[Effect of carbon disulfide on pyrogallol- luminol auto-oxidation chemiluminescence system and superoxide anion].

OBJECTIVE: To study the effect of carbon disulfide (CS(2)) on pyrogallol-luminol auto-oxidation chemiluminescence (PA-L) system and production of superoxide anion. METHODS: Luminescence dynamic curve of CS(2) and inhibition effect of superoxide dismutase (SOD) on intensity of chemiluminescence induced by CS(2) were studied with PA-L chemiluminescence system. RESULTS: Different concentrations of CS(2) (10, 40, 80 mg/ml) could enhance the emission intensity of chemiluminescence of PA-L system and delayed its peak time, with a significant dose-effect relationship, as compared with that of solvent ethanol. Peak of chemiluminescence induced by 80 mg/ml of CS(2) was higher than its background value without solvent ethanol. Chemiluminescence induced by CS(2) could be inhibited by SOD. CONCLUSION: CS(2) can generate superoxide anion in PA-L system and delay the peak time of chemiluminescence emission dynamic curve.

Simultaneous analysis of urinary 2-thiothiazolidine-4-carboxylic acid and thiocarbamide as a biological exposure index for carbon disulfide exposure.

The objectives of this study were to develop optimal analytic methods for detecting urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) and thiocarbamide simultaneously and to evaluate the usefulness of these metabolites to a biological exposure index (BEI) for carbon disulfide (CS2) exposure. For this experiment, synthesized TTCA and thiocarbamide were used. The synthesized TTCA was identified by infrared spectrophotometer, nuclear magnetic resonance spectrometer and thin layer chromatography. The recovery rates of both metabolites were calculated to find the optimum analytical method. The amounts of urinary TTCA and thiocarbamide were measured by using an ultraviolet detector connected to high performance liquid chromatography (HPLC) after the administration of CS2 (350, 700 mg/kg) into Sprague-Dawley rats intraperitoneally. The maximum absorbance wave lengths for TTCA and thiocarbamide were 272 and 236 nm, respectively. Ethyl acetate extraction with NaCl as a salting-out reagent was used as a simultaneous extraction method for these metabolites. HPLC conditions for these metabolites included using a NH2 column, 50 mM KH2PO4: acetonitrile (85:15) and pH 3. Excreted amounts of urinary TTCA and thiocarbamide were increased significantly following CS2 administration. TTCA, which was already adopted as a BEI for CS2 by the American Conference of Governmental Industrial Hygienists (ACGIH), seems to be a more useful BEI for CS2 exposure than thiocarbamide. However further studies are needed to increase analytical efficiency before thiocarbamide can be adopted as a BEI and to apply this analytic method for simultaneous analysis of these metabolites in workers exposed to CS2.

Simultaneous analysis of urinary 2-thiothiazolidine-4-carboxylic acid and thiocarbamide as a biological exposure index for carbon disulfide exposure

The objectives of this study were to develop optimal analytic methods for detecting urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) and thiocarbamide simultaneously and to evaluate the usefulness of these metabolites to a biological exposure index (BEI) for carbon disulfide (CS2) exposure. For this experiment, synthesized TTCA and thiocarbamide were used. The synthesized TTCA was identified by infrared spectrophotometer, nuclear magnetic resonance spectrometer and thin layer chromatography. The recovery rates of both metabolites were calculated to find the optimum analytical method. The amounts of urinary TTCA and thiocarbamide were measured by using an ultraviolet detector connected to high performance liquid chromatography (HPLC) after the administration of CS2 (350, 700 mg/kg) into Sprague-Dawley rats intraperitoneally. The maximum absorbance wave lengths for TTCA and thiocarbamide were 272 and 236 nm, respectively. Ethyl acetate extraction with NaCl as a salting-out reagent was used as a simultaneous extraction method for these metabolites. HPLC conditions for these metabolites included using a NH2 column, 50 mM KH2PO4: acetonitrile (85:15) and pH 3. Excreted amounts of urinary TTCA and thiocarbamide were increased significantly following CS2 administration. TTCA, which was already adopted as a BEI for CS2 by the American Conference of Governmental Industrial Hygienists (ACGIH), seems to be a more useful BEI for CS2 exposure than thiocarbamide. However further studies are needed to increase analytical efficiency before thiocarbamide can be adopted as a BEI and to apply this analytic method for simultaneous analysis of these metabolites in workers exposed to CS2.