2-hexenal--z-isomer and citral

The aim of this work was to investigate the modifications of cell membrane fatty acid composition and volatile molecule profiles of Listeria monocytogenes, Salmonella enteritidis, Escherichia coli, during growth in the presence of different sub-lethal concentrations of thyme and oregano essential oils as well as carvacrol, thymol, trans-2-hexenal and citral. The results evidenced that the tested molecules induced noticeable modifications of membrane fatty acid profiles and volatile compounds produced during the growth. Although specific differences in relation to the species considered were identified, the tested compounds induced a marked increase of some membrane associated fatty acids, particularly unsaturated fatty acids, trans-isomers, and specific released free fatty acids. These findings can contribute to the comprehension of the stress response mechanisms used by different pathogenic microorganisms often involved in food-borne diseases in relation to the exposure to sub-lethal concentrations of natural antimicrobials.

Topics: Acyclic Monoterpenes; Aldehydes; Anti-Infective Agents; Cell Membrane; Cymenes; Dose-Response Relationship, Drug; Escherichia coli; Fatty Acids; Listeria monocytogenes; Monoterpenes; Oils, Volatile; Origanum; Plant Oils; Principal Component Analysis; Salmonella enteritidis; Thymol; Thymus Plant

Volatiles from flowers at three blooming stages of nine citrus cultivars were analyzed by headspace-solid phase microextraction (HS-SPME)-GC-MS. Up to 110 volatiles were detected, with 42 tentatively identified from citrus flowers for the first time. Highest amounts of volatiles were present in fully opened flowers of most citrus, except for pomelos. All cultivars were characterized by a high percentage of either oxygenated monoterpenes or monoterpene hydrocarbons, and the presence of a high percentage of nitrogen containing compounds was also observed. Flower volatiles varied qualitatively and quantitatively among citrus types during blooming. Limonene was the most abundant flower volatile only in citrons; α-citral and β-citral ranked 2nd and 3rd only for Bergamot, and unopened flowers of Ponkan had a higher amount of linalool and β-pinene while much lower amount of γ-terpinene and p-cymene than Satsuma. Taking the average of all cultivars, linalool and limonene were the top two volatiles for all blooming stages; β-pinene ranked 3rd in unopened flowers, while indole ranked 3rd for half opened and fully opened flower volatiles. As flowers bloomed, methyl anthranilate increased while 2-hexenal and p-cymene decreased. In some cases, a volatile could be high in both unopened and fully opened flowers but low in half opened ones. Through multivariate analysis, the nine citrus cultivars were clustered into three groups, consistent with the three true citrus types. Furthermore, an influence of blooming stages on clustering was observed, especially with hybrids Satsuma and Huyou. Altogether, it was suggested that flower volatiles can be suitable markers for revealing the genetic relationships between citrus cultivars but the same blooming stage needs to be strictly controlled.

Topics: Acyclic Monoterpenes; Aldehydes; Bicyclic Monoterpenes; Bridged Bicyclo Compounds; Citrus; Cyclohexane Monoterpenes; Cyclohexenes; Cymenes; Flowers; Gas Chromatography-Mass Spectrometry; Limonene; Monoterpenes; Terpenes

The glutathione S-transferase (GST) activity towards 1-chloro-2,4-dinitrobenzene in intact human IGR-39 melanoma cells was determined by the quantification by HPLC-analysis of the excreted glutathione (GSH) conjugate (S-(2,4-dinitrophenyl)glutathione; DNPSG). The major GST subunit expressed in these melanoma cells is the pi-class GST subunit P1. Using this system, the effect of exposure for 1 h to a series of alpha, beta-unsaturated carbonyl compounds at non-toxic concentrations was studied. Curcumin was the most potent inhibitor (96% inhibition at 25 microM), while 67 and 61% inhibition at 25 microM was observed for ethacrynic acid and trans-2-hexenal, respectively. Moderate inhibition was observed for cinnamaldehyde and crotonaldehyde, while no inhibition was found for citral. The reactive acrolein did not inhibit the DNPSG-excretion at 2.5 microM, the highest non-toxic concentration. Up to about 50% GSH-depletion was found after treatment with crotonaldehyde, curcumin and ethacrynic acid, however the consequences for GST conjugation are presumably small. Reversible inhibition of GST was the major mechanism of inhibition of DNPSG-excretion in melanoma cells, except in the cases of curcumin and ethacrynic acid, which compounds also inactivated GSTP1-1 by covalent modification. This was clear from the fact that depending on the dose between 30 and 80% inhibition was still observed after lysis of the cells, under which conditions reversible inhibition was is absent. Intracellular levels of DNPSG remained relatively high in the case of ethacrynic acid. It is possible that ethacrynic acid also inhibits the transport of DNPSG by inhibition of the multidrug resistance-associated protein gene encoding glutathione conjugate export pump (MRP/GS-X pump) in some way.

Topics: Acrolein; Acyclic Monoterpenes; Aldehydes; Chromatography, High Pressure Liquid; Curcumin; Enzyme Inhibitors; Ethacrynic Acid; Glutathione; Glutathione Transferase; Humans; Melanoma; Monoterpenes; Skin Neoplasms; Terpenes; Tumor Cells, Cultured