Prediction study on the distribution of polycyclic aromatic hydrocarbons and their halogenated derivatives in the atmospheric particulate phase.

Polycyclic aromatic hydrocarbons (PAHs) and their halogenated derivatives (X-PAHs), which generally produced from photochemical and thermal reactions of parent PAHs, widely exist in the environment. They are semi-volatile organic chemicals (SVOCs) and the partitioning between gas/particulate phases affects their environmental migration, transformation and fate, which further impacts their toxicity and health risk to human. However, there is a large data missing of the experimental distribution ratio in the atmospheric particulate phase (f), especially for X-PAHs. In this study, we first checked the correlation between experimental f values of 53 PAH derivatives and their octanol-air partitioning coefficients (log KOA), which is frequently used to characterize the distribution of chemicals in organic phase, and yielded R2 = 0.803. Then, quantum chemical descriptors derived from molecular structural optimization by M06-2X/6-311 +G (d,p) method were further employed to develop Quantitative Structure-Property Relationship (QSPR) model. The model contains two descriptors, the average molecular polarizability (α) and the equilibrium parameter of molecular electrostatic potential (τ), and yields better performance with R2 = 0.846 and RMSE = 0.122. The mechanism analysis and validation results by different strategies prove that the model can reveal the molecular properties that dominate the distribution between gas and particulate phases and it can be used to predict f values of other PAHs/X-PAHs, providing basic data for their environmental ecological risk assessment.

Fungal compound 1-octen-3-ol induces mitochondrial morphological alterations and respiration dysfunctions in Drosophila melanogaster.

Fungal volatile organic compounds (VOCs) comprise a group of compounds commonly found in damp or water-damaged indoor places affecting air quality. Indoor fungal pollution is a severe threat to human health, contributing to the onset of allergic diseases. The compound 1-octen-3-ol, known as "mushroom alcohol", is the most abundant VOC and confers the characteristic mold odor. Exposure to 1-octen-3-ol induces inflammatory markers and episodes of allergic rhinitis and conjunctivitis; however, the effects of this compound towards mitochondria are fairly known. The present study aimed to evaluate the effects of 1-octen-3-ol on inflammatory targets and on mitochondrial morphology and bioenergetic rate in D. melanogaster. Drosophilas were exposed by inhalation to 2.5 µL/L and 5 µL/L of 1-octen-3-ol for 24 h. Observation showed a decreasing in the survival and locomotor ability of flies. Superoxide dismutase (SOD) activity was induced whereas Catalase (CAT) activity was inhibited. Analysis of the mitochondria respiration, detected inhibition of complex I and II in the electron transport chain and a decreased bioenergetic rate. Electronic microscopy provided morphological insights of the mitochondrial status in which a disarrangement in mitochondrial cristae profile was observed. 1-Octen-3-ol induced increased activity of caspase 3/7 and ERK phosphorylation. The mRNA relative steady-state levels of p38MAPK and JNK were down-regulated, whereas NF-κB and p53 were up-regulated. In parallel, nitrite levels were induced in relation to the non-exposed group. These findings point to the mitochondria as a crucial target for the toxicity of 1-octen-3-ol in parallel with activation of pro-inflammatory factors and apoptotic signaling pathway cascade.

Reversed phase HPLC with high temperature ethanol/water mobile phases as a green alternative method for the estimation of octanol/water partition coefficients.

High temperature ethanol/water was explored as a green eluent in the reversed-phase liquid chromatographic approximation of pure water retention (log kw) and subsequent estimation of the octanol/water partition coefficient (log P) via the Collander equation and the Leave-One-Out method. As part of this work, linear solvation energy relationships were employed to compare the log kw extrapolated systems based on high temperature ethanol/water, ambient acetonitrile/water, and ambient methanol/water mobile phases. Based on the comparisons of the three organic modifiers, high temperature ethanol/water mobile phases were observed to provide the best estimation of log P. This conclusion is based on a high log P correlation of 0.968 R2 and a near unity cos θ value of 0.997 between LSER coefficient vectors of ethanol/water estimated log P and octanol/water log P systems. The method employed in this work, further, provided high correlation for the hydrogen-bonding basicity term between the two systems.

Exploiting the Synergistic Effect of Kairomones and Light-Emitting Diodes on the Attraction of Phlebotomine Sand Flies to Light Traps in Brazil.

The synergistic effect of light-emitting diodes (LEDs) and kairomones on the attraction of sand flies to light traps was evaluated. Octenol and lactic acid were used as chemical attractants. Green LEDs and the incandescent lamps were used as light attractants. Five CDC-type light traps with the respective combination of attractants (incandescent lamp, incandescent lamp + chemical attractant, green LED, green LED + chemical attractant, and chemical attractant alone [without light]) were set between 18:00 and 06:00 following a Latin square design. A total of 6,536 sand flies and 16 species were collected. The most frequent species collected was Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera, Psychodidae) accounting for 43.21% of all individuals. Order of success (mean, SD) of lactic acid attractant fly capture was as follows: LED + lactic acid (36.83 ± 4.74), LED alone (34.87 ± 4.61), incandescent lamp + lactic acid (22.80 ± 3.19), incandescent lamp alone (12.67 ± 2.03), and lactic acid (0.46 ± 0.13). Order of success of octenol attractant fly capture was as follows: LED + octenol (37.23 ± 5.61), LED alone (35.77 ± 5.69), incandescent lamp + octenol (18.63 ± 3.28), incandescent lamp alone (14.67 ± 2.86), and octenol alone (1.80 ± 0.65). With exception of lactic acid + incandescent light, chemical synergists played no part in significantly increasing light trap capture of phlebotomine sand flies. However, the use of LEDs, with or without such attractants, provided significantly higher capture compared to the incandescent lamp with or without such chemicals, showing that LEDs are suitable and efficient light sources for surveillance and monitoring of phlebotomine sand flies in Brazil.

Dynamic changes in norisoprenoids and phenylalanine-derived volatiles in off-vine Vidal blanc grape during late harvest.

We investigated the dynamic changes in norisoprenoids and phenylalanine derivatives in off-vine Vidal blanc. Glycosidically bound as well as free-form volatile compounds were identified by GC-MS in two vintages. Thus, off-vine grape exhibited the development of four higher alcohols (viz. linalool oxide, 2-octanol, 1-pentanol, and 1-heptanol), C13-norisoprenoids (α-ionone), phenylalanine-derivates (2-phenylethanol), whereas ß-ionone and geranial showed high correlation in on-vine grape. Freeze-thaw cycles and desiccation, two exterior stress affect volatile compound development, resulted in content fluctuations during late harvest. Interestingly, the total content of higher alcohols was higher in on-vine grapes than off-vine grapes in two vintages respectively. Interestingly, the content of higher alcohols was higher in off-vine samples in the 2016 and 2017 vintages. In terms of physicochemical parameters, off-vine Vidal showed results similar to those of on-vine sample. Nevertheless, sensorial impression of the grape juice was influenced by interaction of vintages and vine treatments.

Post-storage changes of volatile compounds in air- and sun-dried raisins with different packaging materials using HS-SPME with GC/MS.

Free- and bound-form volatiles in sun-dried raisins (SDRs) and air-dried raisins (ADRs) of 'Thompson Seedless' were analyzed by gas chromatography-mass spectrometry (GC/MS) for 0, 3, 6, 9 and 12 months of storage. The compounds originating from glycosidically bound (GB) volatiles were significantly more abundant in bound-form than their free-form. A total of 89 and 88 free-form compounds were identified in ADRs and SDRs, respectively. Overall, higher concentration of unsaturated fatty-acid-oxidation (UFAO) and Maillard reaction (MR) compounds were observed in the SDRs. The plastic and woven bags have an insignificant effect on the volatiles in the raisins. The main characteristics of ADR aroma were floral and fruity, while fatty, roasted, and chemical aromas were prominent in SDRs. With the exception of chemical aroma, the aromatic series (fruity, floral, herbaceous and roasted) increased during the storage duration and become more compelling in 12 month. The packaging materials have similar effect on aromatic series, except fruity note, which was higher in woven bag. The main floral and fruity aroma contributors were decanal, ß-ionone, ethyl hexanoate, ß-damascenone, and 1-octen-3-ol. Herein we identified UFAO and MR compounds as the main contributors of raisin aromas.

Construction of a Biohybrid Odorant Sensor Using Biological Olfactory Receptors Embedded into Bilayer Lipid Membrane on a Chip.

This paper describes an odorant sensor based on mosquito olfactory receptors (ORs) that is sensitive to the volatile organic compound octenol. The ORs and OR coreceptors were reconstructed in the lipid bilayer membrane in a chamber device equipped with electrodes. Using this odorant sensor, we obtained ion current changes caused by specific OR responses to octenol. We installed the odorant sensor into a mobile robot and succeeded in the demonstration of coupling octenol gas detection and robot actuation. We believe that this biohybrid odorant sensing system will be a key technology for future artificial olfaction.

Linear and nonlinear partition of nonionic organic compounds into resin ADS-21 from water.

The predominance of natural organic matter (NOM) in nonlinear sorption of nonionic organic compounds (NOCs) is a fundamental behavior that controlling the fate, transfer and bioavailability of NOCs in natural environment. There is a debate, i.e., whether the nonlinear sorption is captured by nonlinear partition mechanism or adsorption mechanism. The debate has been going on for decades because characteristics of nonlinear partition are still unknown due to the lack of an adsorbent that can partition NOCs nonlinearly. We find a resin ADS-21, with specific surface area undetectable (<0.5 m2 g-1) but high sorption capacity for NOCs (up to 1000 mg g-1 for phenol as an example), is an ideal adsorbent for examining characteristics of nonlinear partitioning. This resin has nonlinear isotherms for phenols and anilines but linear isotherms for polycyclic aromatic hydrocarbons and nitrobenzenes. The observed positively linear relationship of sorption capacities of NOCs with NOCs solubility in water or octanol, could be one of the characteristics of nonlinear partition. Moreover, competitive sorption and no desorption hysteresis could be observed for the nonlinear partition. Hydrogen-bonding of phenols and anilines with ADS-21 is responsible for nonlinear partition, competitive sorption and isotherm nonlinearity. These evidences would be supportive for understanding nonlinear partition and the nonlinear sorption of NOCs by NOM.

Behavior and Electrophysiological Response of Gravid and Non-Gravid Lucilia cuprina (Diptera: Calliphoridae) to Carrion-Associated Compounds.

The Australian blow fly, Lucilia cuprina Wiedmann (Diptera: Calliphoridae), is a major cause of myiasis (flystrike) in Merino sheep in Australia and New Zealand and, as a primary colonizer of fresh carrion, also an important species in forensic investigations. Olfaction is considered the most important cue for insects to rapidly locate carrion over long distances, so the first carrion visitors are predicted to be very sensitive to carrion-related volatile compounds. We studied the responses of the Australian blow fly, Lucilia cuprina, to the carrion-associated compounds dimethyl trisulfide (DMTS), butyric acid, 1-octen-3-ol and indole. We also tested 2-mercaptoethanol, a compound commonly used in fly traps in Australia. We investigated whether responses of the flies are affected by their ovarian status by comparing responses of gravid and non-gravid L. cuprina in electroantennography (EAG) and two-choice laboratory bioassays. All four compounds evoked an EAG response, while only DMTS evoked responses in gas chromatography-mass spectrometry electroantennographic detection (GCMS-EAD) analyses and two-choice bioassays. Gravid flies detected lower doses of the test compounds than non-gravid flies. Our results indicate that DMTS is an important semiochemical for L. cuprina to locate carrion resources, and has potential for use in fly traps for flystrike control. Our observations also suggest that the greater sensitivity of gravid L. cuprina allows them to find fresh carrion quickly to maximize reproductive success by avoiding unsuitable degraded carrion.

1-Octen-3-ol Is Formed from Its Glycoside during Processing of Soybean [ Glycine max (L.) Merr.] Seeds.

Soaking and maceration of dry soybean seeds induce the formation of aliphatic volatile compounds that impact the flavor properties of food products prepared from soybean. Most aliphatic volatile compounds are formed through oxygenation of unsaturated fatty acids by lipoxygenases; however, lipoxygenases are not responsible for the formation of 1-octen-3-ol. 1-Octen-3-ol in soybean products is in general an off-flavor compound; thus, a procedure to manage its formation is required. In this study, we show that the formation of 1-octen-3-ol after hydration of soybean seed powder is independent of oxygen, suggesting that 1-octen-3-ol is not formed de novo from unsaturated fatty acids but instead from its derivative. When crude methanol extract of soybean seeds was reacted with ß-glycosidases, 1-octen-3-ol was rather liberated from its glycoside. We purified the parent glycoside from soybean seeds and confirmed it as ( R)-1-octen-3-yl ß-primeveroside [( R)-1-octen-3-yl 6- O-ß-d-xylopyranosyl-ß-d-glucopyranoside]. Green immature soybean fruits (pericarp and seeds) contain a high amount of 1-octen-3-yl ß-primeveroside. Its amount decreases after hydration of dry soybean powder. The results indicate that management of 1-octen-3-ol levels in soybean products requires a different strategy than that applied to off-flavor compounds formed de novo.

Elucidating the fate of a mixed toluene, DHM, methanol, and i-propanol plume during in situ bioremediation.

Organic pollutants such as solvents or petroleum products are widespread contaminants in soil and groundwater systems. In-situ bioremediation is a commonly used remediation technology to clean up the subsurface to eliminate the risks of toxic substances to reach potential receptors in surface waters or drinking water wells. This study discusses the development of a subsurface model to analyse the performance of an actively operating field-scale enhanced bioremediation scheme. The study site was affected by a mixed toluene, dihydromyrcenol (DHM), methanol, and i-propanol plume. A high-resolution, time-series of data was used to constrain the model development and calibration. The analysis shows that the observed failure of the treatment system is linked to an inefficient oxygen injection pattern. Moreover, the model simulations also suggest that additional contaminant spillages have occurred in 2012. Those additional spillages and their associated additional oxygen demand resulted in a significant increase in contaminant fluxes that remained untreated. The study emphasises the important role that reactive transport modelling can play in data analyses and for enhancing remediation efficiency.

Approaches for estimating PUF-air partitions coefficient for semi-volatile organic compounds: A critical comparison.

Partition coefficients between polyurethane foam (PUF) and air (KPUF-Air) are important when using PUF as a passive air sampler for semi-volatile organic compounds (SVOCs) and when considering the fate of SVOCs indoors where PUF is a common material. Here, KPUF-Air for selected SVOCs was estimated using published methods, since measured data are unavailable for most of these compounds. Estimates of KPUF-Air were within one order of magnitude for SVOCs having values of log octanol-air partition coefficient (KOA) of 5, but differed by nearly three orders of magnitude for SVOCs with log KOA of 12. Of all the methods, the correlation developed using experimental measurements gave the lowest estimates for the high KOA compounds, likely because the compounds did not reach equilibrium throughout the PUF sample. The surface area/volume ratio of the PUF sample was shown to influence the observed correlation, a reflection of the equilibration status of the PUF. For quantitative comparison, the poly parameter linear free energy relationship (pp-LFER) model of Kamprad and Goss (2007) was used here as a "surrogate" standard. The correlations developed with vapor pressure and KOA produced estimates that were closest to those obtained using the pp-LFER model. COSMO-RS theory, in which intimate and unimpeded contact is assumed between the compound in air and PUF molecules, gave lower estimates for low KOA compounds, but good average agreement for high KOA compounds. When used in modeling applications, the selection of the method for estimating KPUF-Air should reflect the configuration of the products containing PUF and the model assumptions regarding compound homogeneity within the PUF.

Volatile Compounds Produced by Lactobacillus paracasei During Oat Fermentation.

This study investigated the profiles of volatile compounds produced by Lactobacillus paracasei during oat fermentation using gas chromatography-mass spectrometry coupled with headspace solid-phase microextraction method. A total of 60 compounds, including acids, alcohols, aldehydes, esters, furan derivatives, hydrocarbons, ketones, sulfur-containing compounds, terpenes, and other compounds, were identified in fermented oat. Lipid oxidation products such as 2-pentylfuran, 1-octen-3-ol, hexanal, and nonanal were found to be the main contributors to oat samples fermented by L. paracasei with the level of 2-pentylfuran being the highest. In addition, the contents of ketones, alcohols, acids, and furan derivatives in the oat samples consistently increased with the fermentation time. On the other hand, the contents of degradation products of amino acids, such as 3-methylbutanal, benzaldehyde, acetophenone, dimethyl sulfide, and dimethyl disulfide, decreased in oat samples during fermentation. Principal component analysis (PCA) was applied to discriminate the fermented oat samples according to different fermentation times. The fermented oats were clearly differentiated on PCA plots. The initial fermentation stage was mainly affected by aldehydes, whereas the later samples of fermented oats were strongly associated with acids, alcohols, furan derivatives, and ketones. The application of PCA to data of the volatile profiles revealed that the oat samples fermented by L. paracasei could be distinguished according to fermentation time.

Determining Partition Coefficient (Log P), Distribution Coefficient (Log D) and Ionization Constant (pKa) in Early Drug Discovery.

An early prediction of physicochemical properties is highly desirable during drug discovery to find out a viable lead candidate. Although there are several methods available to determine partition coefficient (log P), distribution coefficient (log D) and ionization constant (pKa), none of them involves simple and fixed, miniaturized protocols for diverse set of compounds. Therefore, it is necessary to establish simple, uniform and medium-throughput protocols requiring small sample quantities for the determination of these physicochemical properties. Log P and log D were determined by shake flask method, wherein, the compound was partitioned between presaturated noctanol and water phase (water/PBS pH 7.4) and the concentration of compound in each phase was determined by HPLC. The pKa determination made use of UV spectrophotometric analysis in a 96-well microtiter plate containing a series of aqueous buffers ranging from pH 1.0 to 13.0. The medium-throughput miniaturized protocols described herein, for determination of log P, log D and pKa, are straightforward to set up and require very small quantities of sample (< 5 mg for all three properties). All established protocols were validated using diverse set of compounds.

Removal of dissolved organic carbon by aquifer material: Correlations between column parameters, sorption isotherms and octanol-water partition coefficient.

The correlation between octanol-water partition coefficient (KOW) and the transport of aqueous samples containing single organic compound is well documented. The concept of the KOW of river water containing the mixture of organics was evolved by Pradhan et al. (2015). The present study aims at determining the KOW and sorption parameters of synthetic aqueous samples and river water to finding out the correlation, if any. The laboratory scale columns packed with aquifer materials were fed with synthetic and river water samples. Under the operating conditions, the compounds in the samples did not separate, and all the samples that contain more than one organic compound yielded a single breakthrough curve. Breakthrough curves simulated from sorption isotherms were compared with those from the column runs. The sorption parameters such as retardation factor (Rf), height of mass transfer zone (HMTZ), rate of mass transfer zone (RMTZ), breakpoint column capacity (qb) and maximum column capacity (qx) estimated from column runs, sorption isotherms and models developed by Yoon-Nelson, Bohart-Adam and Thomas were in agreement. The empirical correlations were found between the KOW and sorption parameters. The transport of the organics measured as dissolved organic carbon (DOC) through the aquifer can be predicted from the KOW of the river water and other water samples. The novelty of the study is to measure KOW and to envisage the fate of the DOC of the river water, particularly during riverbank filtration. Statistical analysis of the results revealed a fair agreement between the observed and computed values.

Synthesis of chiral 2-alkanols from n-alkanes by a P. putida whole-cell biocatalyst.

The cytochrome P450 monooxygenase CYP154A8 from Nocardia farcinica was previously found to catalyze hydroxylation of linear alkanes (C7 -C9 ) with a high regio- and stereoselectivity. The objective of this study was to integrate CYP154A8 along with suitable redox partners into a whole-cell system for the production of chiral 2-alkanols starting from alkanes. Both recombinant Escherichia coli and Pseudomonas putida whole-cell biocatalysts tested for this purpose showed the ability to produce chiral alkanols, but a solvent tolerant P. putida strain demonstrated several advantages in the applied biphasic reaction system. The optimized P. putida whole-cell system produced ∼16 mM (S)-2-octanol with 87% ee from octane, which is more than sevenfold higher than the previously described system with isolated enzymes. The achieved enantiopurity of the product could further be increased up to 99% ee by adding an alcohol dehydrogenase (ADH) to the alkane-oxidizing P. putida whole-cell systems. By using this setup for the individual conversions of heptane, octane or nonane, 2.6 mM (S)-2-heptanol with 91% ee, 5.4 mM (S)-2-octanol with 97% ee, or 5.5 mM (S)-2-nonanol with 97% ee were produced, respectively. The achieved concentrations of chiral 2-alkanols are the highest reported for a P450-based whole-cell system so far. Biotechnol. Bioeng. 2016;113: 1845-1852. © 2016 Wiley Periodicals, Inc.

Comparison of prediction methods for octanol-air partition coefficients of diverse organic compounds.

The octanol-air partition coefficient (KOA) is needed for assessing multimedia transport and bioaccumulability of organic chemicals in the environment. As experimental determination of KOA for various chemicals is costly and laborious, development of KOA estimation methods is necessary. We investigated three methods for KOA prediction, conventional quantitative structure-activity relationship (QSAR) models based on molecular structural descriptors, group contribution models based on atom-centered fragments, and a novel model that predicts KOA via solvation free energy from air to octanol phase (ΔGO(0)), with a collection of 939 experimental KOA values for 379 compounds at different temperatures (263.15-323.15 K) as validation or training sets. The developed models were evaluated with the OECD guidelines on QSAR models validation and applicability domain (AD) description. Results showed that although the ΔGO(0) model is theoretically sound and has a broad AD, the prediction accuracy of the model is the poorest. The QSAR models perform better than the group contribution models, and have similar predictability and accuracy with the conventional method that estimates KOA from the octanol-water partition coefficient and Henry's law constant. One QSAR model, which can predict KOA at different temperatures, was recommended for application as to assess the long-range transport potential of chemicals.

High-throughput determination of octanol/water partition coefficients using a shake-flask method and novel two-phase solvent system.

A high-throughput method for determining the octanol/water partition coefficient (P(o/w)) of a large variety of compounds exhibiting a wide range in hydrophobicity was established. The method combines a simple shake-flask method with a novel two-phase solvent system comprising an acetonitrile-phosphate buffer (0.1 M, pH 7.4)-1-octanol (25:25:4, v/v/v; AN system). The AN system partition coefficients (K(AN)) of 51 standard compounds for which log P(o/w) (at pH 7.4; log D) values had been reported were determined by single two-phase partitioning in test tubes, followed by measurement of the solute concentration in both phases using an automatic flow injection-ultraviolet detection system. The log K(AN) values were closely related to reported log D values, and the relationship could be expressed by the following linear regression equation: log D=2.8630 log K(AN) -0.1497(n=51). The relationship reveals that log D values (+8 to -8) for a large variety of highly hydrophobic and/or hydrophilic compounds can be estimated indirectly from the narrow range of log K(AN) values (+3 to -3) determined using the present method. Furthermore, log K(AN) values for highly polar compounds for which no log D values have been reported, such as amino acids, peptides, proteins, nucleosides, and nucleotides, can be estimated using the present method. The wide-ranging log D values (+5.9 to -7.5) of these molecules were estimated for the first time from their log K(AN) values and the above regression equation.

Evaluation of the Key Odorants in Volatile Oils from Tubers of Apios americana Medikus.

This study was investigated the chemical composition of volatile oils and aroma evaluation from the tubers of Apios americana Medikus. Theses volatile oils were obtained by the hydrodistillation (HD) and the solvent-assisted flavor evaporation (SAFE) methods. These oils were analyzed by Gas chromatography (GC), GC-mass spectrometry (GC-MS), GC-olfactometry (GC-O), aroma extract dilution analysis (AEDA) and odor activity values (OAV) for the first time. The major compounds in the HD oil were palmitic acid (36.5%), linoleic acid (10.5%) and nonadecanol (5.7%). Meanwhile, in the SAFE oil, the major compounds were 4-hydroxy-4-methyl-2-pentanone (34.2%), hexanal (11.0%) and hexanol (7.9%). Through aroma evaluation, 20 (HD) and 14 (SAFE) aroma-active compounds were identified by GC-O. As a result, the most intense aroma-active compounds in both extraction methods were 1-octen-3-ol and hexanal, both of which showed high odor activity values (OAV).