2-Octanone

Fungal-bacterial interaction selects for quorum sensing mutants with increased production of natural antifungal compounds.[Pubmed:33184402]

Commun Biol. 2020 Nov 12;3(1):670.

Soil microorganisms coexist and interact showing antagonistic or mutualistic behaviors. Here, we show that an environmental strain of Bacillus subtilis undergoes heritable phenotypic variation upon interaction with the soil fungal pathogen Setophoma terrestris (ST). Metabolomics analysis revealed differential profiles in B. subtilis before (pre-ST) and after (post-ST) interacting with the fungus, which paradoxically involved the absence of lipopeptides surfactin and plipastatin and yet acquisition of antifungal activity in post-ST variants. The profile of volatile compounds showed that 2-heptanone and 2-Octanone were the most discriminating metabolites present at higher concentrations in post-ST during the interaction process. Both ketones showed strong antifungal activity, which was lost with the addition of exogenous surfactin. Whole-genome analyses indicate that mutations in ComQPXA quorum-sensing system, constituted the genetic bases of post-ST conversion, which rewired B. subtilis metabolism towards the depletion of surfactins and the production of antifungal compounds during its antagonistic interaction with S. terrestris.

Cryogen-free comprehensive heartcut multidimensional gas chromatography using a Deans switch for improved analysis of petrochemical products derived from palmitic acid oxidation.[Pubmed:33136100]

Anal Methods. 2020 Nov 21;12(43):5160-5167.

Comprehensive heartcut multidimensional gas chromatography was applied with example application for analysis of a sample obtained from palmitic acid oxidation in a Rancimat instrument. The system utilized a single Deans switch (DS) located between first dimensional semi-standard nonpolar (30 m) and second dimensional polar (60 m) columns. A cyclic multiple heartcut strategy consisting of 150 heartcuts with a 0.2 min window was applied offering comprehensive analysis and injection of a narrow band of compounds onto the second column without use of cryogenic trapping devices. Untargeted compound analysis of the sample prepared by solid phase micro-extraction was performed based on match between the experimental MS spectra and first dimensional retention indices with that from the NIST library. The sample contained the major compounds of 2-Octanone, 1-methylcyclohexanol, 2,3,6-trimethylphenol, 3-phenylpropanol and 2-nonanone. This approach was then evaluated based on peak capacity and the number of identified compounds. Compared with one dimensional gas chromatography providing a total peak capacity of 172 and 43 identified compounds, the analysis performance was much more improved with a capacity of 5840 and 235 identified compounds by using comprehensive heartcut multidimensional gas chromatography with the total analysis time of 15.3 h. By comparison within the same set of identified compounds, the one dimensional and multidimensional approaches provided the MS match scores of 769 +/- 81 and 836 +/- 88, respectively. In addition, the nonlinear relationship between the analysis time and number of identifiable peaks was calculated according to the set of 235 compounds. This revealed that the analysis time could be shortened with the compensation of lower separation performance, where application of a 2.5 min heartcut window with the total analysis time of 1.2 h could result in the total peak capacity of 390 with 150 identifiable compounds.

Microbiological assessment of aerobically stored horse fillets through predictive microbiology and metabolomic approach.[Pubmed:33032069]

Meat Sci. 2021 Feb;172:108323.

The aim of this work was to investigate the microbial association of horse fillets during aerobic storage at isothermal conditions (0-15 degrees C). Samples were analyzed microbiologically, and in parallel the metabolic profile of the samples was quantified by HS-SPME/GC-MS and HPLC-PDA-RI. Considering HPLC results, the concentration of propionic, formic, lactic and succinic acids decreased during aerobic storage of horse fillets, contrary to acetic, citric, butyric and isobutyric acids, which increased. As far as the volatilome formation during aerobic storage is concerned, pentanal, hexanal, octanal, nonanal, decanal, were correlated with fresh samples, while diacetyl, acetoin, 2-heptanone, 2-Octanone, hexanoic acid, 3-methyl-butanol, 2-methy-butanol and 3-methyl-butanal detected in spoiled ones. Herein, a support vector machine regression model using data from 0, 5 and 15 degrees C predicted the responses of the dataset at 10 degrees C with a correlation coefficient 0.915 and 0.910 for training and testing, respectively.

Stepwise optimization of a Flexible Microtube Plasma (FmicroTP) as an ionization source for Ion Mobility Spectrometry.[Pubmed:32800141]

Anal Chim Acta. 2020 Aug 29;1127:89-97.

The ionization source is the central system of analytical devices such as mass spectrometers or ion mobility spectrometers. In this study, a recently developed flexible microtube plasma (FmuTP) is applied as an ionization source for a custom-made drift tube ion mobility spectrometer (IMS) for the first time. The FmicroTP is based on a highly miniaturized, robust and a small-footprint dielectric barrier discharge design with an outstanding ionization efficiency. In this study, the experimental setup of the FmicroTP was further improved upon to achieve optimal coupling conditions in terms of the ion mobility spectrometry sensitivity and the plasma gas consumption. One major focus of this study was the adjustment of the electrical operation parameters, in particular, the high voltage amplitude, frequency and duty cycle, in order to minimize the electric field disturbances and yield higher signals. Additionally, the consumption of helium plasma gas was reduced by refining the FmicroTP. It was found that the ionization efficiency could be significantly enhanced by increasing the plasma high voltage and through application of a duty cycle up to 90:10. Plasma gas flows could be reduced down to 3 mL min(-1) by increasing the plasma high voltage amplitude. Furthermore, a smaller wire electrode design enables the operation of the FmicroTP with nitrogen and clean air. Moreover, detection limits of a homologous series of ketones in the range of 330 pptv (N2-FmicroTP, 2-decanone) down to 20 pptv (He-FmicroTP, 2-Octanone) could be reached in the optimized setup. To sum up, this feasibility study demonstrates the potential of the optimized FmicroTP as a powerful ionization source for ion mobility spectrometry especially with regard to ionization efficiency.

Inelastic scattering dynamics of naphthalene and 2-octanone on highly oriented pyrolytic graphite.[Pubmed:32610992]

J Chem Phys. 2020 Jun 28;152(24):244709.

The inelastic scattering dynamics of the isobaric molecules, naphthalene (C10H8) and 2-Octanone (C8H16O), on highly oriented pyrolytic graphite (HOPG) have been investigated as part of a broader effort to inform the inlet design of a mass spectrometer for the analysis of atmospheric gases during a flyby mission through the atmosphere of a planet or moon. Molecular beam-surface scattering experiments were conducted, and the scattered products were detected with the use of a rotatable mass spectrometer detector. Continuous, supersonic beams were prepared, with average incident translational energies, Ei, of 247.3 kJ mol(-1) and 538.2 kJ mol(-1) for naphthalene and 268.6 kJ mol(-1) and 433.8 kJ mol(-1) for 2-Octanone. These beams were directed toward an HOPG surface, held at 530 K, at incident angles, thetai, of 30 degrees , 45 degrees , and 70 degrees , and scattered products were detected as functions of their translational energies and scattering angles. The scattering dynamics of both molecules are very similar and mimic the scattering of atoms and small molecules on rough surfaces, where parallel momentum is not conserved, suggesting that the dynamics are dominated by a corrugated interaction potential between the incident molecule and the surface. The effective corrugation of the molecule-surface interaction is apparently caused by the structure of the incident molecule and the consequent myriad available energy transfer pathways between the molecule and the surface during a complex collision event. In addition, the HOPG surface contributes to the corrugation of the interaction potential because it can absorb significant energy from collisions with incident molecules that have high mass and incident energy. Small differences in the scattering dynamics of the two molecules are inferred to arise from the details of the molecule-surface interaction potential, with 2-Octanone exhibiting dynamics that suggest a slightly stronger interaction with the surface than naphthalene. These results add to a growing body of work on the scattering dynamics of organic molecules on HOPG, from which insight into the hypervelocity sampling and analysis of such molecules may be obtained.

Supported Cobalt Catalysts for Acceptorless Alcohol Dehydrogenation.[Pubmed:32567812]

Chempluschem. 2020 Jun;85(6):1315-1324.

The acceptor-less dehydrogenation of 2-octanol was tested over cobalt supported on Al2 O3 , C, ZnO, ZrO2 and various TiO2 substrates. The catalysts were characterized by ICP, XRD and TGA-H2 . For Co/TiO2 P25, the effects of passivation, aging (storage at room temperature), and in situ activation under H2 were investigated. The catalysts must be tested shortly after synthesis in order to prevent deactivation. Cobalt supported on TiO2 P25 was the most active and 69 % yield of 2-Octanone was obtained, using decane as a solvent. Selectivities for 2-Octanone were observed in the range of 90 % to 99.9 %. Small amounts of C16 compounds were also formed due to aldol condensation/dehydration reactions. The catalysts exhibited higher conversion in the dehydrogenation of secondary alcohols (65-69 %), in comparison to primary alcohols (2-10 %). The dehydrogenation of 1,2-octanediol led to 1-hydroxy-2-Octanone, with a selectivity of 90 % and 69 % for Co/TiO2 P25 and Co/TiO2 P90, respectively.

Effect of oxidation on the gel properties of porcine myofibrillar proteins and their binding abilities with selected flavour compounds.[Pubmed:32505986]

Food Chem. 2020 Nov 1;329:127032.

In this work, the effect of oxidation induced by hydroxyl radicals on the binding abilities of myofibrillar protein (MP) gels to aldehydes and ketones and their relationship with MP gel properties were investigated. Mild oxidation (0-0.2 mM H2O2) could induce partial unfolding of MP, thus slightly increasing the salt solubility of MP and enhancing the hardness of MP gels. MP suffering a higher oxidative attack could undergo a reduction in water-holding capacity, with increased mobility of water in MP gels. Oxidation could make MP gel more disordered. The ability of oxidised MP gels to bind to flavours decreased as the carbon chain length of the flavour compound increased. MP oxidation only significantly affected the binding of MP gels to hexanal, heptanal, and 2-Octanone, while other flavour compounds were not affected.

Hydrosilylation of Ketones Catalyzed by Iron Iminobipyridine Complexes and Accelerated by Lewis Bases.[Pubmed:31943952]

Chempluschem. 2019 Aug;84(8):1094-1102.

Fe-iminobipyridine complexes (((R) BPI(Ar,R') )FeBr2 , (R) BPI(Ar,R') =iminobipyridine derivatives) were found to exhibit good catalytic activity for hydrosilylation of ketones. The highest TOF (turnover frequency) was obtained for the hydrosilylation of 2-Octanone with phenylsilane (4190 min(-1) ). The reactions of various 4-substituted acetophenone derivatives revealed that the introduction of an electron-withdrawing group at the 4-position retarded the reaction. The TOF of the hydrosilylation of 4-chloroacetophenone with diphenylsilane was quite low (30 min(-1) ), however the addition of a catalytic amount of Lewis base, especially pyridine, dramatically accelerated this hydrosilylation (980 min(-1) ). Comparison of this additive effect for several N-donor ligands revealed that the coordination ability of the N-donor ligand was responsible for the acceleration. The rate determining step in the hydrosilylation of ketones appeared to be the reductive elimination of alkoxy and silyl groups from the iron center, which was facilitated by the coordination of N-donor ligand to the iron. This coordination ability of the N-donor ligand, however, inhibited olefin hydrosilylation. Addition of KO(t) Bu instead of N-donor also showed the same acceleration and inhibition effects on ketone and olefin hydrosilylations, respectively.

Determination of Volatile Compounds in Nut-Based Milk Alternative Beverages by HS-SPME Prior to GC-MS Analysis.[Pubmed:31454898]

Molecules. 2019 Aug 26;24(17). pii: molecules24173091.

A reliable Headspace-Solid Phase Microextraction (HS-SPME) method was developed for the determination of polar volatile components of commercial nut-based milk alternative drinks prior to Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Under the optimum extraction conditions, a divinylbenzene (DVB)/Carboxen CAR)/polydimethylsiloxane (PDMS) fiber was used and 2 mL of sample was heated at 60 degrees C for 40 min under stirring, without salt addition. Ten compounds from different chemical classes (heptane, a-pinene, toluene, 2-methylpyrazine, 3-heptanone, heptanal, 2-Octanone, 1-heptanol, benzaldehyde and 1-octanol) were chosen as model analytes for quantification. Limits of detection and limits of quantification were found to be 0.33-1.67 ng g(-1) and 1-5 ng g(-1), accordingly. Good linearity, precision and accuracy were obtained as well as a wide linear range. The proposed method was successfully applied to various beverages including almond milk, walnut milk, peanut milk and almond chocolate milk. More than 70 volatile compounds were detected in the different samples. Most of the detected volatiles were aldehydes, ketones and alcohols. This technique can be used for the determination of volatile compounds in nut-based beverages, to detect compositional changes during storage and technological treatment used for their production.

Interactions of selected ketone flavours with porcine myofibrillar proteins: The role of molecular structure of flavour compounds.[Pubmed:31261004]

Food Chem. 2019 Nov 15;298:125060.

Typical ketone flavours (with variations in chain length, position and number of keto group, branched chain) were selected to investigate the effect of molecule structure of ketones on their interactions with myofibrillar proteins (MPs). Results showed that 2,3-pentanedione quenched the fluorescence of MPs more effectively than 2-pentanone and 3-pentanone due to the number of keto group. There was no significant difference between 5-methyl-2-hexanone and 2-heptanone, which was attributed to their similar molecular size and polarity. The quenching effect of homologous ketone flavours increased with carbon chain growth due to the higher hydrophobic interaction. Dynamic quenching played a major role in the fluorescence quenching process of MPs by 2-pentanone, 3-pentanone, 5-methyl-2-hexanone, 2-heptanone and 2-Octanone. The alpha-helix content decreased gradually with the increase of ketones concentration. Results of GC/MS were in accordance with the fluorescence quenching analysis generally, whereas 2,3-pentanedione and 2-nonanone exhibited some differences due to their higher steric hindrance effects.

Control of Filth Flies, Cochliomyia macellaria (Diptera: Calliphoridae), Musca domestica (Diptera: Muscidae), and Sarcophaga bullata (Diptera: Sarcophagidae), Using Novel Plant-Derived Methyl Ketones.[Pubmed:31237324]

J Med Entomol. 2019 Oct 28;56(6):1704-1714.

Filth flies live in close proximity to humans and livestock and transmit pathogens. Current control relies on chemical insecticides, and flies can develop resistance to these insecticides. The public is also interested in natural and safer insecticides. Therefore, alternative pesticides compatible with the synanthropic nature of flies are needed. Four plant aliphatic methyl ketones were evaluated for control of adult house flies, Musca domestica L., blow flies, Cochliomyia macellaria (F.), and gray flesh flies, Sarcophaga bullata (Parker). In sealed petri dish assays, 2-heptanone, 2-Octanone, 2-nonanone, and 2-undecanone exhibited fumigant activity against house flies with 24-h LC50s of 6.9, 7.5, 8.0, and 9.2 microg/cm3, respectively. Further research focused on undecanone (a U.S. EPA-registered biopesticide). When tested in larger enclosures at 1.7, 2.3, and 2.8 microg/cm3, undecanone provided 60.4, 82.2, and 94.4% house fly mortality; 56.9, 75.6, and 92.5% flesh fly mortality; and 62.1, 84.5, and 97.9% blow fly mortality, respectively, after a 2-h exposure. In a two-choice behavioral assay with 194.6 microg/cm2 of the test compound on the treatment versus an untreated surface of the same area, the overall mean repellencies for blow flies were 84.7% for undecanone versus 87.6% for N,N-diethyl-meta-toluamide (DEET). For house flies, mean repellencies were 80.7% for undecanone and 84.9% for DEET. The house fly topical LD50 for undecanone was 58.1 microg per fly. Undecanone was far less expensive for filth fly control than the gold standard for insect fumigation, methyl bromide.

Characterization of key aroma compounds in Chinese rice wine using gas chromatography-mass spectrometry and gas chromatography-olfactometry.[Pubmed:31151652]

Food Chem. 2019 Sep 30;293:8-14.

To determine the key aroma compounds in Chinese rice wine (CRW), four types of CRW (YH, JF, SN, and XX) were analyzed by gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), and sensory evaluation. The contributions of the key aroma compounds to the flavor characteristics were determined by partial least squares regression. Sixty-one aroma compounds were detected. Twenty-five components were identified as odor-active compounds. On the basis of their odor active values, 18 odor-active compounds were determined as key aroma compounds. Ethyl isovalerate, ethyl butyrate, ethyl acetate, ethyl hexanoate, and phenylethyl alcohol were key aroma compounds in all four types of wine. The unique key aroma compounds of JF wine were isovaleraldehyde and isoamyl acetate; those of XX wine were 1-butanol, benzaldehyde, ethyl benzoate, ethyl phenylacetate, 2-Octanone, and furfural; that of YH wine was ethyl 2-methylbutyrate; and those of SN wine were 1-butanol, 1-hexanol, 2-butenoic acid ethyl ester, and 3-methyl-1-butanol.

Identification of dihydro-beta-ionone as a key aroma compound in addition to C8 ketones and alcohols in Volvariella volvacea mushroom.[Pubmed:31151620]

Food Chem. 2019 Sep 30;293:333-339.

The volatile compounds of Volvariella volvacea mushroom were investigated by solvent assisted flavor evaporation (SAFE)/gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), odor activity value (OAV), combined with aroma reconstitution and omission. The results showed that a total of 63 compounds were detected after SAFE extraction. A total of 26 compounds were determined after GC-O and 17 compounds whose OAV greater than 1 were subjected to reconstitution and omission experiments. The results showed that dihydro-beta-ionone, 1-octen-3-one, 1-octen-3-ol, gamma-undecalactone, 3-octanol, 2-Octanone, hexanal, 2-methylbutanal, camphene, carvone, 2-nonanone, and phenylacetaldehyde have been successfully identified as the key aroma compounds. More significantly, dihydro-beta-ionone as a key aroma compound was first found in Volvariella volvacea mushroom.