Metabolism Of Volatile Organic Compounds Research Articles

Expose to volatile organic compounds is associated with increased risk of depression: A cross-sectional study

With increasing prevalence rate of depression by years, more attention has been paid to the influence of environmental pollutants on depression, but relationship between exposure to volatile organic compounds (VOCs) and depression is rarely studied. Therefore, this cross-sectional study use the National Center for Health Statistics (NHANES) database (2013–2016 years) to explore association between exposure to multiple VOCs and depression in general population. Multiple linear and logistic regression models were used to analyze the association between urinary VOC metabolism (mVOCs) and depression. To further analyze effect of multiple mVOCs mixed exposure, Bayesian kernel machine regression (BKMR) models were performed. A total of 3240 participants and 16 mVOCs were included in the analysis. Results showed that 10 mVOCs exposure were positively correlated with depression by multiple linear and logistic regression models, especially CYMA and MHBMA3, which also showed significant positive association with depression in BKMR model. Mixed exposure of multiple mVOCs was significantly positively correlated with depression. Gender differences were existed in effects of some VOCs concentrations on depression. AAMA, CYMA and MA had significant positive correlations with depression by women, and DHBMA had significant positive correlations with depression by men. Hence, this study showed that exposing to VOCs might have negative impacts on depression, and impact of CYMA and MHBMA3 on depression may be more evident, which provide new ideas for prevention and control of depression. But further research and exploration are needed to clarify the mechanism and influence factors of this relationship, to demonstrate the reliability of these relationship.

Urinary cancer detection by the target urine volatile organic compounds biosensor platform

Volatile organic compounds (VOCs) have grown due to their crucial role in transitioning from invasive to noninvasive cancer diagnostic methods. This study aimed to assess the feasibility of the metal oxide biosensor platform using urine VOCs for detecting genitourinary cancers. Five different commercially available semiconductor sensors were chosen to detect specific VOCs (methane, iso-butane, hydrogen, ethanol, hydrogen sulfide, ammonia, toluene, butane, propane, trimethylamine, and methyl-mercaptan). Changes in electrical resistance due to temperature variations from the voltage heater were examined to characterize VOC metabolism. Logistic regression and ROC analysis were employed to evaluate potential urine VOCs for genitourinary cancer determination. This study involved 64 participants which were categorized into a cancer and a non-cancer group. The genitourinary cancer (confirmed by tissue pathology) comprised 32 patients, including renal cell carcinoma (3.1%), transitional cell carcinoma (46.9%), and prostate cancer (50%). The non-cancer comprised 32 patients, with 9 healthy subjects and 23 individuals with other genitourinary diseases. Results indicated that VOC sensors for methane, iso-butane, hydrogen, and ethanol, at a voltage heater of 2000 mV, demonstrated a significant predictive capability for genitourinary cancer with P = 0.013. The ROC of these biomarkers also indicated statistical significance in predicting the occurrence of the disease (P < 0.05). This report suggested that methane, iso-butane, hydrogen, and ethanol VOCs exhibited potential for diagnosing genitourinary cancer. Developing gas metal oxide sensors tailored to these compounds, and monitoring changes in electrical resistance, could serve as an innovative tool for identifying this specific type of cancer.

Hypoxia and lactate influence VOC production in A549 lung cancer cells.

Introduction: Cancer cells emit characteristic volatile organic compounds (VOCs), which are potentially generated from ROS-based lipid peroxidation of polyunsaturated fatty acids. The metabolism of such VOCs and their regulation remain to be fully investigated. In fact, the enzymes involved in the synthesis of these VOCs have not been described yet. Methods: In this study, we firstly conducted in vitro enzyme assays and demonstrated that recombinant alcohol dehydrogenase (ADH) converted Trans 2-hexenal into Trans 2-hexenol. The latter has previously been reported as a cancer VOC. To study VOC metabolism, 14 different culture conditions were compared in view of Trans 2-hexenol production. Results and discussion: The data indicate that hypoxia and the addition of lactate positively influenced Trans 2-hexenol production in A549 cancer cells. The RNAseq data suggested certain gene expressions in the VOC pathway and in lactate signaling, parallel to VOC production. This implies that hypoxia and lactate signaling with a VOC production can be characteristic for cancer in vitro.

Exposure to volatile organic compounds is a risk factor for diabetes: A cross-sectional study

Currently, more studies showed that environmental chemicals were associated with the development of diabetes. However, the effect of volatile organic compounds (VOCs) on diabetes remained uncertain and needed to be studied. This cross-sectional study examined whether exposure to low levels of VOCs was associated with diabetes, insulin resistance (TyG index) and glucose-related indicators (FPG,HbA1c, insulin) in the general population by using the NHANES dataset (2013–2014 and 2015–2016). We analyzed the association between urinary VOC metabolism (mVOCs) and these indicators in 1409 adults by multiple linear regression models or logistic regression models, further Bayesian kernel machine regression (BKMR) models were performed for mixture exposure analysis. The results showed positive associations between multiple mVOCs and diabetes, TyG index, FPG, HbA1c and insulin, respectively. Among them, HPMMA concentration in urine was significantly positively correlated with diabetes and related indicators (TyG index, FPG and HbA1c), and the concentration of CEMA was significantly positively correlated with insulin. The positive association of mVOCs with diabetes and its related indicators was more significant in the female group and in the 40–59 years group. Thus, our study suggested that exposure to VOCs affected insulin resistance and glucose homeostasis, further affecting diabetes levels, which had important public health implications.

Integrated metabolome and transcriptome analysis of the regulatory network of volatile ester formation during fruit ripening in pear

'Nanguo' pear (Pyrus ussuriensis Maxim.) is a typical climacteric fruit with an attractive aroma after postharvest ripening. Esters are the key volatile compounds determining the typical aroma formation. However, the mechanism of aroma-related ester formation remains largely unknown. In this study, we performed transcriptome and metabolome analyses to reveal the changes of aroma-related compounds during pear ripening in the optimal taste period (OTP). During the pear ripening process, typical fatty acid-derived volatile organic compounds (VOCs) are transformed from aldehydes, alcohols, and ketones to esters, where ethyl hexanoate, hexyl acetate, and ethyl butanoate are the dominant esters in the OTP. Rich aroma-related esters in the OTP are associated with the accumulation of important precursors of aroma volatiles, including linoleic acid, α-linolenic acid, γ-linolenic acid, and oleic acid. Genes encoding key biosynthetic enzymes are associated with the altered levels of aroma-related esters. The candidate genes associated with the high levels of aroma-related esters in 'Nanguo' pears are PuFAD2, PuLOX2, PuLOX5, and PuAAT. Additionally, transcription factor (TF) genes such as PuWRKY24, PuIAA29, and PuTINY may play crucial roles in aroma formation during fruit ripening. Hence, we summarized the TFs that regulate VOC metabolism in different fruit species. The results provided a foundation for further research on aroma-related esters in 'Nanguo' pears and could help to elucidate the mechanisms regulating fruit quality improvement.

Integration of transcriptomic and metabonomic reveals molecular differences of sweetness and aroma between postharvest and vine ripened tomato fruit

The quality of vine ripened (PR) fruit is better than that of postharvest ripened (VR) fruit, which is reflected in taste and aroma. The results indicated that there was a remarkable increase in soluble sugars (sucrose, fructose, and glucose) and volatile organic compounds (VOCs) contents during the process of maturity. At the full red stage, VR fruit possessed higher soluble sugars and VOCs contents, especially (E)-2-Octenal, 6-methyl-5-Hepten-2-one, 6,10-dimethyl-5,9-Undecadien-2-one trans-β-Ionone, methyl salicylate, compared to PR fruit, which partly explained why VR fruit has better flavor quality. The transcriptome analysis indicated that 4989 and 4847 differentially expressed genes (DEGs) were up- and down-regulated in PR vs. VR, respectively. These DEGs participated in multiple metabolic pathways related to sugar and VOCs metabolism. Moreover, MYB transcription factors were critical in sugar metabolism. And, seven hub genes were found which played key roles in the regulation of fruit flavor. These results laid a foundation for the flavor research of postharvest fruit and enhanced our understanding of the differences in flavor, especially sweetness and aroma between PR and VR fruit.

Volatile organic compounds from second-hand smoke may increase susceptibility of children through oxidative stress damage

Although humans are generally exposed to second-hand smoke (SHS), volatile organic compounds (VOCs) exposure derived from SHS and its health hazard to non-smokers are rarely investigated. Thus, we examined the effects of SHS on VOCs exposure and oxidative stress damage via a passive smoking simulation experiment in 6 children and 7 adults. To further validate the studied urinary VOC metabolites as biomarkers for passive smoking, 259 children were recruited. The levels of 8-hydroxy-2′-deoxyguanosine (8-OHdG), malonaldehyde (MDA), trans-3′-hydroxycotinine (OH-Cot) and 31 VOC metabolites in urine were determined. The results showed that the geomean concentrations of 17 VOC metabolites in urine of children were 26.5%–138% higher than those of adults after passive smoking. The levels of urinary 8-OHdG, MDA and OH-Cot increased by 24.6%, 18.8% and 600% in children, but only 1.25%, 10.3% and 116% in adults, respectively. Therefore, children are more vulnerable to SHS than adults. After exposure to SHS, the levels of 8 urinary VOC metabolites of benzene, acrylonitrile, 1-bromopropane, propylene oxide, toluene, methyl methacrylate and cyanide increased by 60.9%–538% within 23 h. These 8 VOC metabolites were also significantly associated with 8-OHdG or MDA in urine (p < 0.01). Therefore, exposure to VOCs caused by SHS increases body oxidative stress damage. OH-Cot level higher than 2.00 μg/g Cr can be used as a threshold of passive smoking. The levels of urinary s-benzylmercapturic acid (BMA) and s-phenylmercapturic acid (PMA) in children increased by 494% and 728% within 6 h after passive smoking, respectively. Population validation study indicated that BMA and PMA levels were significantly elevated in children exposed to SHS. Therefore, in addition to OH-Cot, urinary BMA and PMA are potentially useful short-term biomarkers of passive smoking. Future studies should focus on the differences in VOC metabolism and detoxification mechanisms between children and adults.

Detection of the effects of triclosan (TCS) on the metabolism of VOCs in HepG2 cells by SPI-TOFMS

Volatile organic compounds (VOCs) emitted by organisms and cell metabolism have demonstrated great physiological and pathological values. At present, there is a great interest in the study of volatile metabolome to determine whether VOCs can serve as potential diagnostic biomarkers. In view of the sensitivity of VOCs to physiological changes, the aim of this study was to investigate alterations in VOC profiles in the in vitro headspace of HepG2 cells after exposure to triclosan (TCS). Since the in vivo biological effects of TCS are clearly defined, several TCS-related VOCs may potentially be traced back to common cellular processes. In this study, HepG2 cells were cultured in TCS-containing medium for 2 h, and the emitted VOCs in the headspace of the culture flask were detected using a single photon ionization time-of-flight mass spectrometry instrument. The control group and the TCS-treated group could be well separated by differential VOC profiles, which were related to the physiological states of the HepG2 cells. Compared to the control group, eleven and ten specific VOCs were identified in the 20 μm and 50 μm TCS-treated groups, respectively. Among them, five specific VOCs (m/z 62, 64, 70, 121 and 146) were commonly observed in these two TCS-treated groups. These results indicate that TCS can cause changes in cellular metabolic VOCs, and different concentrations of TCS lead to different VOCs profiles. Based on the findings of the study, the detection of VOCs in cell metabolism can be used as an auxiliary tool to explore the mechanism of drug action, and also as an exploratory method to determine whether drugs play a role in disease treatment.

Elucidation of Biochemical Pathways Underlying VOCs Production in A549 Cells.

Cellular volatile organic compounds (VOCs) are unique compounds whose metabolic pathways remain enigmatic. To elucidate their metabolism, we investigated the VOCs of lung cancer A549 and 2 non-cancer lung cells (HLB; HBEpC). Neutral sugars and lactate in the medium were measured by colorimetric assay. VOCs were enriched by monotrap and profiled by GC-MS. To investigate the enzymes that change VOC metabolism in cells, we conducted ALDH activity assays and qPCR. ROS (reactive oxygen species) assays were conducted to assess oxidation stress. The colorimetric assay showed that especially A549 and HLB took up sugars from the medium and rapidly secreted lactate into the medium. The VOC profile (GC-MS) revealed a trans-2-hexenol increase, especially in A549 lung cancer cells. This is a novel lipid peroxidation product from animal cells. Based on the absolute quantification data, trans-2-hexenol increased in parallel with number of A549 cancer cells incubated. The qPCR data implies that ADH1c potentially plays an important role in the conversion into trans-2-hexenol.

In vitro profiling of endothelial volatile organic compounds under resting and pro-inflammatory conditions.

The evaluation of volatile organic compounds(VOCs) emitted by human body offers a unique tool to set up new non-invasive devices for early diagnosis and long-lasting monitoring of most human diseases. However, their cellular origin and metabolic fate have not been completely elucidated yet, thus limiting their clinical application. Endothelium acts as an interface between blood and surrounding tissues. As such, it adapts its physiology in response to different environmental modifications thus playing a role in the pathogenesis of many metabolic and inflammatory diseases. Since endothelium specifically reshapes its physiologic functions upon environmental changes the objective of this study was to evaluate if and how pro-inflammatory stimuli affect VOC metabolism in endothelial cell in culture. Gas chromatography with mass spectrometric detection was applied to profile VOCs in the headspace of cultured endothelial cells (EC) in the absence or presence of the pro-inflammatory stimulus lipopolysaccharide (LPS). We observed that, under resting conditions, EC affected the amount of 58 VOCs belonging to aldehyde, alkane and ketone families. Among these, LPS significantly altered the amount of 15 VOCs. ROC curves show a perfect performance (AUC = 1) for 10 metabolites including 1-butanol, 3-methyl-1-butanol and 2-ethyl-1-hexanol. The emission and uptake of the aforementioned VOCs disclose potential unexplored metabolic pathways for EC that deserve to be investigated. Overall, we identified new candidate VOC potentially exploitable, upon experimental confirm in in vivo model of disease, as potential biomarkers of sepsis and pro-inflammatory clinical settings.

Expression of CYP2E1 gene in paint workers occupationally exposed to organic solvents

Benzene (B), toluene (T), ethylbenzene (E) and xylene (X) are used commonly in paint industry, so workers who are a high risk of exposure to organic solvent (VOCs). CYP2E1 gene encodes CYP2E1 which plays an important role in the metabolism and bio-activation of volatile organic compounds. When workers expose to VOCs, their body will have a mechanism to metabolize the toxic. The enhancement of mRNA expression of CYP2E1 is a very sensitive and accurate biological marker, which is the basis for the next study to propose the level of mRNA expression of CYP2E1 gene as a human biological indicator to monitor to workers occupationally exposed to VOCs. In this study, we studied the level of mRNA expression of CYP2E1 gene from 118 participants that including 73 workers of exposed group from the paint factories and 45 workers of non-exposed group from garment factories by using Realtime-PCR with SYBR Green – an asymmetrical cyanine dye used as a nucleic acid stain in molecular biology. The initial results, showed that the exposed group had a higher mRNA expression level of CYP2E1 than the non-exposed group approximately 10.47 times, and this difference was statistically significant (P value &lt; 0.05). And the age and the duration of exposure to organic solvents do not affect the expression level of CYP2E1.&#x0D; Keywords&#x0D; CYP2E1, the metabolisms of volatile organic compounds, mRNA expression of CYP2E1.&#x0D; References&#x0D; [1] A. Mendoza-Cantu, F. Castorena-Torres, M. Bermudez De Leon et al., Occupational toluene exposure induces cytochrome P450 2E1 mRNA expression in peripheral lymphocytes, Environmental Health Perspectives, 114 (2006) 494 - 499. https://doi.org/10.1289/ehp.8192.[2] J.H. Hartman, G. Boysen and G.P. Miller, CYP2E1 metabolism of styrene involves allostery, Drug Metabolism and Disposition, 40 (2012) 1976-1983. https://doi.org/10.1124/dmd. 112.046698. [3] S.M. Zhu, X.F. Ren, J.X. Wan et al., Evaluation in vinyl chloride monomer (VCM) - exposed workers and the relationship between liver lesions and gene polymorphisms of metabolic enzymes, World Journal of Gastroenterology,11 (2005) 5821 -5827. 10.3748/wjg.v11.i37.5821.[4] J. Wan, J. Shi, L. Hui et al., Association of genetic polymorphisms in CYP2E1, MPO, NQO1, GSTM1, and GSTT1 genes with benzene poisoning, Environmental Health Perspectives, 110 (2002), 1213-1218. https://doi.org/10.1289/ ehp.021101213.[5] U. Bernauer, B. Vieth, R. Ellrich et al., CYP2E1 - dependent benzene toxicity: the role of extrahepatic benzene metabolism, Archives of Toxicology, 73 (1999) 189 -196. https://doi.org/ 10.1007/s002040050605. [6] P.L. Sheets, G.S. Yost and G.P. Carlson. Benzene metabolism in human lung cell lines BEAS‐2B and A549 and cells overexpressing CYP2F1, Journal of Biochemical and Molecular Toxicology, 18 (2004) 92-99. https://doi.org/10. 1002/jbt.20010.[7] V. Nedelcheva, I. Gut, P. Souček et al., Metabolism of benzene in human liver microsomes: individual variations in relation to CYP2E1 expression, Archives of Toxicology, 73 (1999) 33-40. https://doi.org/10.1007/s0020400 50583.[8] W. Tassaneeyakul, D.J. Birkett, J.W. Edwards et al., Human cytochrome P450 isoform specificity in the regioselective metabolism of toluene and o-, m-and p-xylene, Journal of Pharmacology and Experimental Therapeutics, 276 (1996) 101 - 108. 10.1163/2211730x96x00063[9] A.-H. Wang, S.-M. Zhu, Y.-L. Qiu et al., CYP2E1 mRNA expression, genetic polymorphisms in peripheral blood lymphocytes and liver abnormalities in Chinese VCM-exposed workers, International Journal of Occupational Medicine and Environmental Health, 21 (2008), 141 - 146. 10.2478/v10001-008-0016-x.[10] J. Zhang, Y. Lihong, G. Liang et al., Detection of CYP2E1, a genetic biomarker of susceptibility to benzene metabolism toxicity in immortal human lymphocytes derived from the Han Chinese population, Biomedical and Environmental Sciences, 24 (2011) 300-309. https://doi.org/10. 3967/0895-3988.2011.03.014[11] American Conference of Industrial Hygienists, Guide to Occupational Exposeure Values, ACGIH, Cincinnati, 2018.[12] Bộ Y Tế, Quyết định của Bộ trưởng Bộ Y tế về việc ban hành 21 tiêu chuẩn vệ sinh lao động, 05 nguyên tắc và 07 thông số vệ sinh lao động, 2002.[13] American Conference of Industrial Hygienists, Threshold Limit Value for Chemical Substances and Physical Agents and Biological Exposure Indices, ACGIH, Cincinnati, 2018.[14] Bộ Y Tế, Thông tư 28/2006/TT- BYT hướng dẫn quản lý bệnh bệnh nghề nghiệp, 2016.[15] M. Al Zallouha, Y. Landkocz, J. Brunet et al., Usefulness of toxicological validation of VOCs catalytic degradation by air-liquid interface exposure system", Environmental Research, 152 (2017) 328-335. https://doi.org/10.1016/j.envres. 2016.10.027&#x0D;

A laboratory high-throughput glass chamber using dynamic headspace TD-GC/MS method for the analysis of whole Brassica napus L. plantlet volatiles under cadmium-related abiotic stress.

IntroductionThe dynamic headspace sampling technique using thermal desorption, gas chromatography‐mass spectrometry (TD‐GC/MS) is a powerful method for analysing plant emissions of volatile organic compounds (VOCs), and experiments performed in sterile and controlled conditions can be useful for VOC metabolism investigations.ObjectiveThe main purpose of this study was to set up a laboratory high‐throughput glass chamber for whole plant volatiles analysis. Brassica napus L. plantlets were tested with the developed system to better understand the relationship between low emission of induced terpene and cadmium (Cd)‐related abiotic stress.MethodologyVOCs emitted by 28‐day‐old Brassica napus L. plantlets cultivated in vitro were trapped with our device using adsorbent cartridges that were desorbed with a thermal desorption unit before cryofocusing with a cooled injection system and programmable temperature vaporising inlet into an HP‐5 ms GC column. Terpene detection and quantitation from chromatogram profiles were acquired using selected ion monitoring (SIM) mode during full scan analysis and mass spectra were obtained with a quadrupole‐type mass spectrometer.ResultsThe new trapping method produced reliable qualitative profiles of oilseed rape VOCs. Typical emissions of monoterpenes (myrcene, limonene) and sesquiterpenes (β‐elemene, (E,E)‐α‐farnesene) were found for the different concentrations tested. One‐way analysis of variance for quantitative results of (E,E)‐α‐farnesene emission rates showed a Cd concentration effect.ConclusionThis inexpensive glass chamber has potential for wide application in laboratory sterile approach and replicated research. Moreover, the non‐invasive dynamic sampling technique could also be used to analyse volatiles under both abiotic and biotic stresses.

A systemic view on the distribution of diet-derived methanol and hepatic acetone in mice

Volatile organic compounds (VOCs) from breath can successfully be used to diagnose disease-specific pathological alterations in metabolism. However, the exact origin and underlying biochemical pathways that could be mapped to VOC signatures are mainly unknown. There is a knowledge gap regarding the contribution of tissues, organs, the gut microbiome, and exogenous factors to the ‘sum signal’ from breath samples. Animal models for human disease such as mutant mice provide the possibility to reproduce genetic predisposition to disease, thereby allowing in-depth analysis of metabolic and biochemical functions. We hypothesized that breath VOCs can be traced back to origins and organ-specific metabolic functions by combining breath concentrations with systemic levels detected in different organs and biological media (breath, blood, feces and urine). For this we fed C57Bl/6N mice a grain-based chow or a purified low-fat diet, thereby modifying the emission of methanol in breath whereas acetone levels were unaffected. We then measured headspace concentrations of both VOCs in ex vivo samples of several biological media. Cecum content especially was identified as a likely source of systemic methanol, whereas the liver showed highest acetone concentrations. Our findings are a first step to the systemic mapping of VOC patterns to metabolic functions in mice because differences between VOCs could be traced to different sources in the body. As a future aim, different levels of so-called omics technologies (genomics, proteomics, metabolomics, and breathomics) could be mapped to metabolic pathways in multiple tissues, deepening our understanding of VOC metabolism and possibly leading to early non-invasive biomarkers for human pathologies.

Oxidative Stress Index (OSI) in Children Chronically Exposed to Volatile Organic Compounds (VOC) and their Relation with Genetic Polimorphysms

INTRODUCTION The Atoyac River located in the Tlaxcala and Puebla states in Mexico, is receiving domestic and industrial discharges, causing a dramatic deterioration of the environment; various diseases have been reported like leukemia and renal failure on the Atoyac zone habitants that could be related to industrial water pollution. The objective of the research is to study the OSI in children chronically exposed to VOC carried by the river (toluene, xylene, ethyl-benzene and styrene). METHODS 91 children were studied in the area near the river Atoyac and 61 children in a control site (age range: 8-13, no diagnosed chronic diseases). OSI was measured in plasma samples using the total antioxidant capacity (TAC) and the total oxidant status (TOS) based on Erel’s method. Health parameters and anthropometric data were also determined. VOC metabolites were measured in urine. Furthermore, genetic polymorphisms of enzymes involved in VOCs metabolism will be determined: cytochrome P450-2E1*5, glutathione transferases (T1 and M1), and NQO1*2. RESULTS Exposed children presented the TAC response significantly lower than the control group, while TOS did not differ between the two groups, and a significantly higher OSI (5.23 ± 0.357) was found in exposed children than in the group control (2.62 ± 0.187), 95% CI. In the case of VOC metabolites the children presented a concentration above the biological exposure index established by the ACGIH. The polymorphisms that were determined show a high frequency in our population. Conclusions Our first results show that the exposed population exhibits significantly higher levels of a health risk biomarker such as the OSI, which is of concern since our subjects are children. These data will be analyzed in a multivariate model together with VOC metabolite levels, genetic polymorphisms and other variables, in order to obtain a better picture of the factors affecting this important biomarker (OSI), also, in comparison with a control population.

Characterization of volatile metabolites taken up by or released from Streptococcus pneumoniae and Haemophilus influenzae by using GC-MS

Volatile organic compounds (VOCs) released from or taken up by Streptococcus pneumoniae and Haemophilus influenzae cultures were analysed by means of GC-MS after adsorption of headspace samples on multi-bed sorption tubes. Sampling was performed at different time points during cultivation of bacteria to follow the dynamics of VOC metabolism. VOCs were identified not only by spectral library match but also based on retention times of native standards. As many as 34 volatile metabolites were released from S. pneumoniae and 28 from H. influenzae, comprising alcohols, aldehydes, esters, hydrocarbons, ketones and sulfur-containing compounds. For both species, acetic acid, acetaldehyde, methyl methacrylate, 2,3-butanedione and methanethiol were found in strongly elevated concentrations and 1-butanol and butanal in moderately elevated concentrations. In addition, characteristic volatile biomarkers were detected for both bacterial species and exclusively for S. pneumoniae, also catabolism of aldehydes (3-methylbutanal and hexanal) was found. The results obtained provide important input into the knowledge about volatile bacterial biomarkers, which may become particularly important for detection of pathogens in upper airways by breath-gas analysis in the future.

The impact of CYP2E1 genetic variability on risk assessment of VOC mixtures

Humans are simultaneously exposed to multiple chemicals in the environment. Many of the chemicals use the same enzymes in their metabolic pathways. Competitive inhibition may occur as one of the possible interactions between the xenobiotics in human body. For example, many volatile organic compounds (VOCs) are metabolized using P450 enzymes, specifically CYP2E1. Inheritable gene alterations may result in changes of function of the enzymes in different human subpopulations. Variations in quantity and/or quality of particular isoenzymes may cause differences in the metabolism of VOCs. These variations may cause higher sensitivity in certain populations. Using examples of three different mixtures, this review paper outlines the variances in CYP2E1 isoenzymes, effect of exposure to such mixtures on sensitive populations, and approaches to mixtures risk assessment.