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The known antimicrobially active oxygenated terpenes, carvone, terpinen-4-ol, α-terpineol, carveol and myrtenol were found to cause significant K+ leakage from E. coli cells. In contrast, the relatively inactive oxygenated terpenes, 1,8-cineole and p-menth-6-ene-2,8-diol, did not cause significant K+ leakage. Slight structural differences between active terpenes were found to affect the rate of K+ leakage from E. coli cells. The membrane permeabilizing effect of the active terpenes is considered a significant factor in their antimicrobial activity.

The commercially available 75 μm Carboxen-Polydimethylsiloxane (PDMS) fibre for solid phase microextraction (SPME) has been shown to rearrange some monoterpenoids to p-cymene during headspace (HS)-SPME analysis. Ten commonly encountered monoterpenoids varying in structural and/or functional group were used as test compounds. The p-menthane hydrocarbons α- and γ-terpinene, α-phellandrene, and terpinolene were the only analytes rearranged by the Carboxen-PDMS coating with p-cymene/analyte ratios determined to be higher than those obtained by the 100 μm PDMS-coated fibre used for comparison. The much higher (>10 times) level of moisture adsorbed by the Carboxen-PDMS coating when compared to the PDMS coating is considered to be one of the factors responsible for the rearrangement process.

The two dimensional separation of low molecular weight polystyrene oligomers and stereoisomers was achieved using a liquid chromatographic system designed for ‘heart-cutting’ multidimensional chromatography. The first separation process incorporated a C18 column and a methanol mobile phase to separate the oligomers, whilst the second separation process utilised the change in selectivity associated with a carbon clad zirconia stationary phase and an acetonitrile mobile phase for the separation of the isomers. The two dimensional separation that was achieved using this automated system was comparable to the individual separations following manual sample manipulation in each individual separation step. Furthermore, the multidimensional LC system was shown to be highly reproducible in routine continuous operation over an eight hour period.

Four pairs of oxygenated terpenes, with closely related chemical structures but considerably different minimum inhibitory concentration values (1) against P. aeruginosa or E. coli, showed differences in rate of cells killed over 2 h. Addition of polymyxin B nonapeptide (PMBN) as an outer membrane permeabilising agent was found to significantly increase the initial rates and overall numbers of cells killed for all compounds. The hydrocarbon limonene and the ester geranyl acetate, normally inactive, were also investigated. Both compounds had little killing effect when added alone to the cells but did show an enhanced killing capacity upon the addition of PBMN.

Consumption of certain phenolics in the diet is considered beneficial to human health. In this study, individual phenolics were measured by diode-array HPLC at monthly intervals in the peel of Granny Smith, Lady Williams, and Crofton apple cultivars stored in air at 0 degrees C for 9 months. The concentrations of total phenolics significantly differed among the cultivars examined, with Lady Williams peel having significantly more phenolics (over 4000 microg x g(-1) peel fresh weight) than Crofton (2668 microg x g(-1) peel fresh weight) and Granny Smith, which had the lowest concentration of total phenolics (1275 microg x g(-1) peel fresh weight). There were also significant differences in individual phenolics among cultivars and during storage. Quercetin glycosides were the only flavonols identified, with quercetin rhamnoglucoside being the most abundant phenolic in the peel. Chlorogenic acid was the major cinnamic acid derivative, with high concentrations, up to 412 microg x g(-1)) peel fresh weight, in Crofton peel. A pre-storage diphenylamine (DPA) treatment had few significant effects on peel phenolic metabolism. Where differences did occur, fruit treated with DPA retained higher concentrations of total peel phenolics during storage than fruit not treated with DPA. Storage of all cultivars for up to 9 months in air at 0 degrees C induced few significant changes in the peel phenolic concentrations. This indicates that phenolic metabolism in apple peel is relatively stable, and the health benefits of phenolics in apple peel should be maintained during long-term storage.

The technique of supercritical fluid extraction (SFE) was applied to various sample matrices under a range of supercritical carbon dioxide (scCO2) densities and chamber temperatures. The purpose was to develop an effective extraction condition for the removal of eight target monoterpenes from Australian tea tree (Melaleuca alternifolia Cheel) leaves. The optimum conditions for extraction were found to be 0.25 g/mL scCO2 density at a chamber temperature of 110oC. These condition were most effective when applied to whole fresh and rehydrated whole dried leaves, where it yielded maximum recovery of target analytes with minimum change in oil composition for the extractor system employed. This study demonstrates the importance of the type of sample matrix used in SFE work, and that a different extraction protocol would need to be developed for each matrix.

Two germacradienols, 4-β-hydroxygermacra-1(10),5-diene (β-germacrenol) and 6-α-hydroxygermacra-1(10), 4-diene (kunzeaol) were identified in the solvent extracts of members of the family Myrtaceae. Acid solvolysis associated with steam distillation or leaf ageing causes these germacradienols to rearrange to a mixture of (+)-δ-cadinene, α-cadinol, τ-cadinol, α-muurolol, τ-muurolol and associated sesquiterpenoids. Copyright © 2001 John Wiley & Sons, Ltd.

The sesquiterpenoids (+)-δ-cadinene, epicubenol and cubenol in the essential oils of the Myrtaceae are by-products of the acid-solvolysis of the sesquiterpene alcohols cubebol and epicubebol. This solvolysis can occur during leaf ageing or steam distillation. Significant proportions of these compounds can be found in many members of the Myrtaceae, most notably commercial tea tree (Melaleuca alternifolia and M. linariifolia). Copyright © 2000 John Wiley & Sons, Ltd.

The steam distillates of the family Myrtaceae are often found to contain the three isomeric sesquiterpene alcohols, β-, β- and γ-eudesmol. Associated with these alcohols but not steam-distilled with them are two hydrates of eudesmol, cryptomeridiol and 4-epicryptomeridiol, compounds which have not been previously reported in the Myrtaceae. These five alcohols are the major by-products of the hydrolysis of hedycaryol, which can occur during leaf ageing or distillation. The use of H218O during distillation implicated the presence of hedycaryol prior to distillation by trapping the eudesmyl-carbocation formed during the hydrolysis. Copyright © 2000 John Wiley & Sons, Ltd.

The minimum inhibitory concentrations (MIC) of 60 terpenoids against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Candida albicans have been determined. Hierarchical cluster analysis was used to group the compounds into five groups according to their activity patterns against the four microorganisms. K-Means cluster analysis was then used to confirm these groupings and to show the differences in the activity patterns of the groups. Ten molecular properties of the terpenoids, either calculated via molecular modelling or determined by direct measurement, were then used as variables in a forward stepwise discriminant analysis to identify which variables discriminated between groups. Low water solubility of Group IV compounds, mainly hydrocarbons and acetates, was found to be associated with their relative inactivity. The remaining groups, all containing oxygenated terpenoids, showed characteristic but distinct activity patterns towards the four test organisms. Hydrogen bonding parameters were found to be associated with antimicrobial activity in all cases. Activity against Gram-negative E. coli and P. aeruginosa was associated with a combination of a hydrogen bonding and size parameters. This was not found to be the case for the Gram-positive S. aureus or the yeast C. albicans. Copyright © 1999 John Wiley & Sons, Ltd.

The presence of terpinen-4-ol in the steam distillates from Melaleuca argentea, M. dissitiflora and M. linariifolia can be linked to high levels of (+)-sabinene and cis- and trans-sabinene hydrate in the leaf material. Incorporation of 18O into the terpinen-4-ol from steam distillates performed in H2 18O confirms the generation of the terpinen-4-yl carbocation intermediate from (+)-sabinene and cis- and trans-sabinene hydrate. This same mechanism is also operating during leaf aging.

(Z)-β-ocimene has been found to occur in amounts of 85% in foliage of Homoranthus montanus Craven and S. R. Jones and 69–71% in H. flavescens Cunn. ex. Schauer. (E)-β-ocimene also occurred in amounts of 5–9% and 2–5% respectively. The oil yield in both cases was 0.3–0.5% based on fresh leaves.

A hydrodistilled oil obtained from the leaves of Leucas milanjiana Gurke (Lamiaceae) was analysed by capillary GC and GC-MS. The leaf volatile oil contained 30 components, out of which 26 were identified. The predominant components were found to be β-cubebene (38.15%), α-pinene (19.71%), trans-caryophyllene (7.41%) and α-terpinolene (5.34%). The results are qualitatively and quantitatively at variance with data on other Leucas species and may therefore be of some chemotaxonomic significance for the genus. Copyright © 2006 John Wiley & Sons, Ltd.

Changes in the aroma volatiles, free amino acids, sugars, principal acids, and soluble minerals were studied during the development and ripening of the fruit of Cucumis melo L. Reticulatis group cv. Makdimon. Ethyl acetate was the most abundant volatile produced during the final growth stage, but ethanol was the major volatile found in immature fruit. Most of the free amino acids exhibited increases in concentration as the fruit underwent the ripening process. Sucrose, although absent in immature fruit, showed a dramatic increase during ripening to become the major carbohydrate constituent in the ripe fruit. The changes in total soluble solids during ripening showed close correlation with those found for pH, certain amino acids, and the elements sodium and potassium. Sucrose concentration has been shown to be an important fruit quality indicator, so these further correlations suggest that some of these parameters may be significant additional determinants of eating quality. Keywords: Melons; fruit develop...

Steam distillation of young leaves of Melaleuca alternifolia in 18O-labelled water resulted in the 180-labelling of the principal oxygenated p-menthanes, terpinen-4-ol and α-terpineol. The p-methanes; terpinen-4-ol, γ-terpinene, α-terpinene, terpinolene and p-cymene, found in M. alternifolia oil are primarily formed from cis-sabinene hydrate and to a lesser extent from trans-sabinene hydrate and sabinene. The pattern of the p-menthanes and the enantiomeric composition of terpinen-4-ol found in young and old leaves, regardless of the isolation process are similar to those formed during the acid catalyzed transformations of sabinene or sabinene hydrate. The incorporation of 180 into terpinen-4-ol during steam distillation in H2 18O supports the formation of terpinen-4-ol and the other p-menthanes from the terpinen-4-yl cation, generated from the hydration of sabinene and/or sabinene hydrate. This same mechanism appears to operate during leaf aging. Around 60% of the terpinen-4-ol obtained from the ...

Fatty acid compositions and lipid contents of five common table species of marine fish from temperate Australian waters were determined for samples taken during two seasons (four species) and three locations of markedly differing latitude (one species). Variabilities in total lipid extract and phospholipid fatty acid compositions were assessed between samples of each species, as well as between individuals of the same sample. These were then compared with data obtained for the other species analysed. The highest n3 polyunsaturated fatty acid (PUFA) content lipids were found in fish from colder waters (southern locations and spring season catches). The leaner species were found to have much more stable lipid characteristics with changes in the water temperature at sampling.

Gamma-irradiation preservation of two species of Australian marine fish (Black Bream and Redfish) resulted in no significant changes in their fatty-acid compositions, even when performed at up to three times the commonly recommended maximum dose for fish. Vitamin E loss was evident in some fillets but could not be correlated with the treatment dosage. All irradiated fillets were found to have vitamin E contents above the levels believed to be desirable for human consumption, relative to the amounts of accompanying polyunsaturated fatty acids.

The concentrations and enantiomeric purity of the major monoterpene constituents in a number of Melaleuca alternifolia (tea tree) oils have been determined by enantioselective gas chromatography. Consrstent enantiomeric ratios of 65:35 (+:-) for terpinen-4-ol and 76:24 (+:-) for a-terpineol were observed for the range of oils analyzed. Attempts to validate these ratios in the intact oil by 1 H NMR together with chiral lanthanide shift reagents have not yet been successful. 1 H NMR was, however, successful in confirming the enantiomeric purity determined by gas chromatography of standard terpinen4-ol [79:21 (+:-)] and α-terpineol [35:65 (+:-)] samples

A method for the rapid identification of fish species by high performance liquid chromatographic (HPLC) analysis of water-soluble sarcoplasmic protein extracts is described. The method relies on the visual comparison of a star-symbol plot constructed from the sample's HPLC profile with those obtained from the mean profile data of morphologically identified species. A library of plots is presented for 15 common edible marine fish species from eastern Australian waters, but any suitable data can be used for star construction. The data presented are applicable to the identification of samples from any season or location, whether they are raw, gamma-irradiated, or dried with infra-red radiation. The procedure involves a single 10 min extraction followed by a 60 min analysis, without the use of an internal standard.

A simple, rapid method for the extraction of cotton terpenoid aldehydes from green tissues and seed is described. Samples were treated by ultrasonification with acidified acetonitrile/water followed by centrifugation. The resulting extract was injected directly onto a C18 HPLC column and no sample concentration or further cleanup steps were required. The level of gossypol, the most labile of the target analytes, decreased by only 2% after 12 h of storage at room temperature, thus enabling automated analysis of individual terpenoid aldehydes by HPLC. The method gives excellent reproducibility and enables large numbers of samples to be screened quickly and accurately. Keywords: Terpenoid aldehydes; gossypol stability; cotton; Gossypium; HPLC

Octanol-water partition coefficients (Kow) for 57 terpenoids were measured using a RP-HPLC method. Sample detection was achieved with standard UV and refractive index detectors and required no special column treatment. Measured log Kow values for the terpenoids ranged from 1.81 to 4.48 with a standard error of between 0.03 and 0.08 over the entire range. Partition coefficients determined by the RP-HPLC method were compared against shake flask, atom/fragment contribution, fragment and atomistic methods. The HPLC values were found to give the best correlation with shake flask results. Log Kow values calculated by the atom/fragment contribution method gave the best correlation with the HPLC values when compared to fragment and atomistic methods.

Analysis of the volatile constituents of melon by HRGC-MS has led to the identification of a number of compounds not previously reported in other varieties. These compounds include a range of thioether and several diesters derived from butane-2,3-diol and propane-1,2-diol. The properties of the thioethers esters are of considerable sensory importance and hence play a role in determining consumer preference.

This work discusses the influence of the ethylene antagonist 1-methyl-cyclopropene (1-MCP) and the timing of its application on the ripening related parameters in bananas such as ethylene, CO 2 and volatiles production, volatiles composition and skin color. The preclimacteric application of 1-MCP to banana fruit delayed the onset of the common parameters associated with ripening, namely ethylene and aroma volatiles production, respiration and skin color changes. The extent of these delays depended on the developmental stage of the fruit at application and on whether the fruit was subsequently challenged with the ethylene analogue, propylene. The application of 1-MCP to bananas continuously challenged with propylene delayed the onset of ripening and volatiles production by two days. When preclimacteric mature green bananas were allowed to naturally ripen in the absence of propylene, 1-MCP delayed the onset of ripening by nine days. Hence 1-MCP application offers a convenient means of examining the role of ethylene in ripening and offers an excellent opportunity to differentiate and clearly study the biochemical and physiological interactions occurring in ripening fruit.

Thirty-two different compounds were detected in the sternal gland secretion of M. eugenii using GC and GC-MS following thermal desorption with cryofocusing. There were no major qualitative differences between the secretions collected from males and females. Compounds commonly present in the secretion included long-chain alkanes, C6-C10 aldehydes, the monoterpene ether 1,8-cineole (eucalyptol), fatty acids and acetic acid. There were no significant differences in the relative proportions of compounds in males related to time of year, unlike the situation in females where long-chain alkanes were major components of the secretion in the early part of the year while C6-C10 aldehydes dominated in the second half of the year. There was some evidence that the female secretion is affected by reproductive condition, as treatment of females with follicle stimulating hormone (FSH) then luteinising hormone (LH) in June altered the sternal secretion towards that found earlier in the year.

Fatty acid compositions and lipid levels of five common table varieties of marine fish from temperate Australian waters were determined. Nutritionally important values were calculated and compared with those of species from similar waters in the northern hemisphere. P/S and n-3/n-6 ratios, and the levels of arachidonic (AA) and docosahexaenoic (DHA) acids in the lipids were comparable for the two, but the Australian species had lower eicosapentaenoic acid (EPA) levels. Oils from Australian fish were shown to have nutritional properties as beneficial as their northern hemisphere counterparts.

The volatile components from the fruit of the Pistacia lentiscus tree were analyzed by capillary gas chromatography (CGC) and CGC-mass spectrometry. The major components were the monoterpenes α-pinene, β-pinene, myrcene and limonene. Several sesquiterpenes, aliphatic esters, ketones, and phenolic compounds such as thymol and carvacrol were also identified.

Separation, dosage et identification, par chromatographie gazeuse sur colonne capillaire et spectrometrie de masse. Tous les composes identifies sont des mono- ou sesquiterpenes, dont les pinenes, le germacrene D et le bicyclogermacrene. La maturation des fruits n'a pas d'incidence sur leurs teneurs en composes volatils