Showing papers on "Terpene published in 2014"

The Volatome of Aspergillus fumigatus

Abstract: Early detection of invasive aspergillosis is absolutely required for efficient therapy of this fungal infection. The identification of fungal volatiles in patient breath can be an alternative for the detection of Aspergillus fumigatus that still remains problematic. In this work, we investigated the production of volatile organic compounds (VOCs) by A. fumigatus in vitro, and we show that volatile production depends on the nutritional environment. A. fumigatus produces a multiplicity of VOCs, predominantly terpenes and related compounds. The production of sesquiterpenoid compounds was found to be strongly induced by increased iron concentrations and certain drugs, i.e., pravastatin. Terpenes that were always detectable in large amounts were α-pinene, camphene, and limonene, as well as sesquiterpenes, identified as α-bergamotene and β-trans-bergamotene. Other substance classes that were found to be present in the volatome, such as 1-octen-3-ol, 3-octanone, and pyrazines, were found only under specific growth conditions. Drugs that interfere with the terpene biosynthesis pathway influenced the composition of the fungal volatome, and most notably, a block of sesquiterpene biosynthesis by the bisphosphonate alendronate fundamentally changed the VOC composition. Using deletion mutants, we also show that a terpene cyclase and a putative kaurene synthase are essential for the synthesis of volatile terpenes by A. fumigatus. The present analysis of in vitro volatile production by A. fumigatus suggests that VOCs may be used in the diagnosis of infections caused by this fungus.

Terpene and cannabinoid formulations

Abstract: The present invention provides stable, fast-acting liposome and micelle formulations of terpenes, hemp oil, cannabinoids, or mixtures of a cannabinoid and terpenes or hemp oil and cannabinoids that are suitable for pharmaceutical and nutraceutical applications. Also provided are methods for the manufacture of micelle and liposomal formulations.

Allergy to oxidized limonene and linalool is frequent in the U.K.

Abstract: SummaryBackground The oxidized forms of the fragrance terpenes limonene and linalool are known to cause allergic contact dermatitis. Significant rates of contact allergy to these fragrances have been reported in European studies and in a recent worldwide study. Patch testing to oxidized terpenes is not routinely carried out either in the U.K. or in other centres internationally. Objectives To investigate the prevalence of contact allergy to oxidized limonene and linalool in the U.K. Methods Between 1 August 2011 and 31 December 2012, 4731 consecutive patients in 13 U.K. dermatology departments were tested for hydroperoxides of limonene 0·3% pet., hydroperoxides of linalool 1·0% pet., stabilized limonene 10·0% pet. and stabilized linalool 10·0% pet. Doubtful (?+) and equivocal (±) reactions were grouped together as irritant reactions. Results Two hundred and thirty-seven patients (5·0%) had a positive patch test reaction to hydroperoxides of limonene 0·3% pet. and 281 (5·9%) to hydroperoxides of linalool 1·0% pet. Irritant reactions to one or both oxidized terpenes were found in 242 patients (7·3%). Eleven patients (0·2%) had a positive patch test reaction to the stabilized terpenes alone. Conclusions This large, multicentre U.K. audit shows a significant rate of allergy to the hydroperoxides of limonene and linalool plus a high rate of irritant reactions. Testing to the oxidized forms alone captures the majority (97·0%; 411 of 422) of positive reactions; testing to nonoxidized terpenes appears to be less useful. We recommend that the hydroperoxides of limonene and linalool be added to an extended baseline patch test series.

Capturing of the monoterpene olefin limonene produced in Saccharomyces cerevisiae

Abstract: Monoterpene olefins such as limonene are plant compounds with applications as flavouring and fragrance agents, as solvents and potentially also in polymer and fuel chemistry We engineered baker's yeast Saccharomyces cerevisiae to express a (−)-limonene synthase from Perilla frutescens and a (+)-limonene synthase from Citrus limon Both proteins were expressed either with their native plastid targeting signal or in a truncated form in which the plastidial sorting signal was removed The yeast host strain for expression was AE9 K197G, which expresses a mutant Erg20 enzyme This enzyme catalyses the formation of geranyl diphosphate, which is the precursor for monoterpenes Several methods were tested to capture limonene produced by the yeast Extraction from the culture medium by pentane, or by the addition of CaCl2 followed by solid-phase micro-extraction, did not lead to detectable limonene, indicating that limonene is rapidly lost from the culture medium Volatile terpenes such as limonene may also be trapped in a dodecane phase added to the medium during fermentation This method resulted in recovery of 0028 mg/l (+)-limonene and 0060 mg/l (−)-limonene in strains using the truncated Citrus and Perilla synthases, respectively Trapping the headspace during culture of the limonene synthase-expressing strains resulted in higher titres, at 012 mg/l (+)-limonene and 049 mg/l (−)-limonene These results show that the volatile properties of the olefins produced require specific methods for efficient recovery of these molecules from biotechnological production systems Gene Bank Nos were: KM015220 (Perilla limonene synthase; this study); AF317695 (Perilla limonene synthase; Yuba et al, 1996); AF5142871 (Citrus limonene synthase; Lucker et al, 2002) Copyright © 2014 John Wiley & Sons, Ltd

Dynamic adsorption of α-pinene and linalool on silica nanoparticles for enhanced antifeedant activity against agricultural pests

Abstract: The terpene compounds, α-pinene and linalool were formulated with silica nanoparticles (SNPs) by a simple immersion method and the antifeedant activity of these formulations was evaluated against two major agricultural pests, the tobacco cutworm (Spodoptera litura F.) and the castor semilooper (Achaea janata L.) in laboratory bioassays. The interaction between terpenes and SNPs, shelf-life, suspension stability as well as the bioactivity of the nanoformulations were also studied. Both these terpenes in their pure form are known to deter feeding in several lepidopterous insects. However, formulating these pure terpene compounds with nano silica enhanced their biological activity up to 25 times to S. litura. Fourier transform infrared spectroscopy analysis of these nano botanical formulations indicated the presence of hydrogen bonding between terpenes and the surface of SNPs. Transmission electron microscopy images confirmed the higher aggregation property of the SNPs. Suspension studies validated the improved shelf-life of the nano-biocomposites, while X-ray diffraction (XRD) revealed the amorphous nature of formulations and no crystalline impurities. Adsorption of α-pinene and linalool onto SNPs resulted in an effective formulation that enhanced the antifeedant potential of the individual terpenes against insects while producing longer shelf-life for the terpenes.

Terpene down-regulation triggers defense responses in transgenic orange leading to resistance against fungal pathogens.

Abstract: Terpenoid volatiles are isoprene compounds that are emitted by plants to communicate with the environment. In addition to their function in repelling herbivores and attracting carnivorous predators in green tissues, the presumed primary function of terpenoid volatiles released from mature fruits is the attraction of seed-dispersing animals. Mature oranges (Citrus sinensis) primarily accumulate terpenes in peel oil glands, with d-limonene accounting for approximately 97% of the total volatile terpenes. In a previous report, we showed that down-regulation of a d-limonene synthase gene alters monoterpene levels in orange antisense (AS) fruits, leading to resistance against Penicillium digitatum infection. A global gene expression analysis of AS versus empty vector (EV) transgenic fruits revealed that the down-regulation of d-limonene up-regulated genes involved in the innate immune response. Basal levels of jasmonic acid were substantially higher in the EV compared with AS oranges. Upon fungal challenge, salicylic acid levels were triggered in EV samples, while jasmonic acid metabolism and signaling were drastically increased in AS orange peels. In nature, d-limonene levels increase in orange fruit once the seeds are fully viable. The inverse correlation between the increase in d-limonene content and the decrease in the defense response suggests that d-limonene promotes infection by microorganisms that are likely involved in facilitating access to the pulp for seed-dispersing frugivores.

The evolution of foliar terpene diversity in Myrtaceae

Abstract: Plant terpenes play many roles in natural systems, from altering plant–animal interactions, to altering the local abiotic environment. Additionally, many industries depend on terpenes. For example, commercially used essential oils, including tea tree oil and lavender oil, are a mixture of terpenes. Many species of the family Myrtaceae form a key resource for these industries due to the high concentration of terpenes found predominately in their leaves. The frequency of chemotypic differences within many species and populations can lead to costly errors in industry. Terpene diversity in Myrtaceae is driven by variation in the terpene synthase enzymes, which catalyse the conversion a few common substrates into thousands of terpene structures. We review terpene diversity within and between species of Myrtaceae and relate this to variation in the terpene synthase enzymes to reconstruct the evolution of foliar terpene diversity in Myrtaceae. We found that (1) high inter- and intra-species variation exists in terpene profile and that α-pinene the most likely ancestral foliar terpene, and (2) that high concentration of 1,8-cineole (a compound which is regarded as the signature compound of Myrtaceae) is limited to just four Myrtaceae sub-families. We suggest that the terpene synthase enzymes do not limit terpene diversity in this family and variation in these enzymes suggests a mode of enzymatic evolution that could lead to high 1,8-cineole production. Our analysis highlights the need to standardise methods for collecting and reporting foliar terpene data, and we discuss some methods and issues here. Although there are many gaps in the published data, our large scale analysis using the results of many studies, shows the value of a family wide analysis for understanding both the evolution and industrial potential of terpene-producing plants.

Terpenes increase the lipid dynamics in the Leishmania plasma membrane at concentrations similar to their IC50 values.

Abstract: Although many terpenes have shown antitumor, antibacterial, antifungal, and antiparasitic activity, the mechanism of action is not well established. Electron paramagnetic resonance (EPR) spectroscopy of the spin-labeled 5-doxyl stearic acid revealed remarkable fluidity increases in the plasma membrane of terpene-treated Leishmania amazonensis promastigotes. For an antiproliferative activity assay using 5×106 parasites/mL, the sesquiterpene nerolidol and the monoterpenes (+)-limonene, α-terpineol and 1,8-cineole inhibited the growth of the parasites with IC50 values of 0.008, 0.549, 0.678 and 4.697 mM, respectively. The IC50 values of these terpenes increased as the parasite concentration used in the cytotoxicity assay increased, and this behavior was examined using a theoretical treatment of the experimental data. Cytotoxicity tests with the same parasite concentration as in the EPR experiments revealed a correlation between the IC50 values of the terpenes and the concentrations at which they altered the membrane fluidity. In addition, the terpenes induced small amounts of cell lysis (4–9%) at their respective IC50 values. For assays with high cell concentrations (2×109 parasites/mL), the incorporation of terpene into the cell membrane was very fast, and the IC50 values observed for 24 h and 5 min-incubation periods were not significantly different. Taken together, these results suggest that terpene cytotoxicity is associated with the attack on the plasma membrane of the parasite. The in vitro cytotoxicity of nerolidol was similar to that of miltefosine, and nerolidol has high hydrophobicity; thus, nerolidol might be used in drug delivery systems, such as lipid nanoparticles to treat leishmaniasis.

Terpenes in honey: occurrence, origin and their role as chemical biomarkers

Abstract: The major developments and concepts in the study of terpenes (mainly monoterpenes) as well as C9-, C10-, C13-, C14- and C15- norisoprenoids in honey are summarized. Their occurrence and biosynthetic correlations (terpene transformations, particularly the generation of linalool derivatives as well as carotenoid degradation and the corresponding variety of norisoprenoids) are discussed considering the plant/nectar/bee-stomach composition and hive conditions (e.g. warm and acidic conditions that can lead to oxidative degradation of compounds). Terpenes up to C15 have been found as major compounds of the essential oils, but honeys from the same plant sources exhibit only partial similarity to the oil composition (e.g. lavender, sage or citrus essential oils/honeys). The formation of heat-derived or prolonged storage artefacts in honey (mainly the products of Maillard reactions and Strecker degradation reactions) influence the honey composition, and hotrienol is particularly labile among the chemical groups discussed. Stimulated by the challenges of fingerprinting methods and structure identification, exploratory studies (including our published results) on terpenes and norisoprenoids are summarized with emphasis on identifying specific or nonspecific chemical markers of the botanical origin of honey. In general, nonspecific biomarkers dominate in different honey types (e.g. monoterpenes: linalool, linalool oxide isomers or lilac alcohol/aldehyde isomers; norisoprenoids: isophorone and vomifoliol derivatives) while only a few specific biomarkers are found (e.g. anhydrolinalool oxide isomers, 3,4-dihydro-3-oxoedulan isomers, 3-oxo-retro-α-ionol isomers, kamahine A-C or meliracemoic acid).

A High-Throughput Colorimetric Screening Assay for Terpene Synthase Activity Based on Substrate Consumption

Abstract: Terpene synthases catalyze the formation of a variety of terpene chemical structures Systematic mutagenesis studies have been effective in providing insights into the characteristic and complex mechanisms of C-C bond formations and in exploring the enzymatic potential for inventing new chemical structures In addition, there is growing demand to increase terpene synthase activity in heterologous hosts, given the maturation of metabolic engineering and host breeding for terpenoid synthesis We have developed a simple screening method for the cellular activities of terpene synthases by scoring their substrate consumption based on the color loss of the cell harboring carotenoid pathways We demonstrate that this method can be used to detect activities of various terpene synthase or prenyltransferase genes in a high-throughput manner, irrespective of the product type, enabling the mutation analysis and directed evolution of terpene synthases We also report the possibility for substrate-specific screening system of terpene synthases by taking advantage of the substrate-size specificity of C30 and C40 carotenoid pathways

Overexpression of an Isoprenyl Diphosphate Synthase in Spruce Leads to Unexpected Terpene Diversion Products That Function in Plant Defense

Abstract: Spruce (Picea spp.) and other conifers employ terpenoid-based oleoresin as part of their defense against herbivores and pathogens. The short-chain isoprenyl diphosphate synthases (IDS) are situated at critical branch points in terpene biosynthesis, producing the precursors of the different terpenoid classes. To determine the role of IDS and to create altered terpene phenotypes for assessing the defensive role of terpenoids, we overexpressed a bifunctional spruce IDS, a geranyl diphosphate and geranylgeranyl diphosphate synthase in white spruce (Picea glauca) saplings. While transcript level (350-fold), enzyme activity level (7-fold), and in planta geranyl diphosphate and geranylgeranyl diphosphate levels (4- to 8-fold) were significantly increased in the needles of transgenic plants, there was no increase in the major monoterpenes and diterpene acids of the resin and no change in primary isoprenoids, such as sterols, chlorophylls, and carotenoids. Instead, large amounts of geranylgeranyl fatty acid esters, known from various gymnosperm and angiosperm plant species, accumulated in needles and were shown to act defensively in reducing the performance of larvae of the nun moth (Lymantria monacha), a conifer pest in Eurasia. These results show the impact of overexpression of an IDS and the defensive role of an unexpected accumulation product of terpenoid biosynthesis with the potential for a broader function in plant protection.

Air-oxidized linalool elicits eczema in allergic patients - a repeated open application test study.

Abstract: Summary Background Linalool is a commonly used fragrance terpene that forms potent sensitizers upon oxidation. In a recent multicentre study, we found that 7% of 2900 patients showed positive patch test reactions to oxidized linalool at 6.0%. No elicitation studies have been performed. Objective To identify threshold concentrations for elicitation of allergic contact dermatitis caused by oxidized linalool in allergic individuals with repeated exposures. Methods Repeated open application tests were performed in 6 participants previously diagnosed with contact allergy to oxidized linalool. Creams containing 3.0%, 1.0% and 0.30% oxidized linalool (corresponding to 0.56%, 0.19% and 0.056% linalool hydroperoxides, respectively) and ‘fine fragrance’ containing 1.0%, 0.30% and 0.10% oxidized linalool (corresponding to 0.19%, 0.056% and 0.019% linalool hydroperoxides, respectively) were used twice daily for up to 3 weeks. Patch testing with a dilution series of oxidized linalool was performed. Results Five of 6 participants reacted to the cream containing 3% oxidized linalool. With 1% oxidized linalool, a reaction was seen in 3 (cream) and 4 (fine fragrance) participants, respectively. With 0.3% oxidized linalool, 2 (cream) and 1 (fine fragrance) participants reacted. Conclusion Repeated exposure to low concentrations of oxidized linalool can elicit allergic contact dermatitis in previously sensitized individuals.

Reactions of Terpenes Catalyzed by Heteropoly Compounds: Valorization of Biorenewables

Abstract: Heteropoly compounds (HPCs) have already proved their high potential for the clean synthesis of commercially valuable chemicals. However, the use of HPCs for the transformations of terpenic substrates became a research topic only about 20 years ago. Terpenes, natural products available from essential oils, are an important biomass-based feedstock for the pharmaceutical, flavor, and fragrance industries.

In Vitro Screening of α-Amylase Inhibition by Selected Terpenes from Essential Oils

Abstract: Purpose: To assess some terpenes from herbal products for possible inhibitory effects on serum αamylase in order to ascertain their potential usefulness in the prevention and/or treatment of diabetes Type 2. Methods: Solutions of terpenes (citral, eukalyptol, β-pinene, myrcene, eugenol and terpineol) in deonized water were prepared by ultrasonic and manual mixing in four different concentrations ranging from 0.39 ‐ 5.50 µmol cm -3 . Commercial sera (with normal-N and high-H enzyme activity) were used as a source of α-amylase. α-Amylase activity was determined by standard methods using an automated analyzer. Results: All the selected terpenes at their maximal concentrations inhibited α-amylase in N-sera in the range 9.68 ‐ 38.70 and 10.71 - 25.00 % for ultrasonic and manual mixing, respectively, while in H-sera, inhibition was in the range 17.10 - 21.05 and 13.58 ‐ 25.92 % for ultrasonic and manual mixing, respectively. Regardless of the concentration of the inhibitor or the method of mixing, citral was the strongest inhibitor of α-amylase. Conclusion: The selected terpenes, in their appropriate concentrations, influence α-amylase activity to varying degrees. Principal component and agglomerative hierarchical analysis reveal that the most significant factor in α-amylase inhibition is the mode of mixing the samples, rather than their concentrations.

Anti-inflammatory terpenes from flowers of Inula japonica.

Abstract: Five new terpenes (1-5) and ten known compounds (6-15) were isolated from Inula japonica, and their structures were identified by spectroscopic analysis. Compounds 3 and 14 showed positive inhibitory effects on nitric oxide production. Furthermore, compound 14 suppressed both leukotriene C4 synthesis and degranulation in c-kit ligand-induced bone marrow-derived mast cells.

Study on cinnamomum oils: compositional pattern of seven species grown in Vietnam

Abstract: The leaf essential oils of seven Vietnamese species of the genus Cinnamomum were analyzed by gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC/MS). The results showed that the species fall into three groups in which one group contains aromatic components, while the second group contains both terpenes and aromatic constituents and the third group contains only terpene constituents. The first group had only Cinnamomum curvifolium as its member and produced oil rich in benzyl cinnamate and benzyl benzoate. The second group producing mixture of phenylpropanoids and oxygenated monoterpene components includes leaves of Cinnamomum kunstleri (methyl eugenol, terpinen-4-ol and 1,8-cineole) and Cinnamomum mairei (eugenol, 1, 8-cineole, neryl acetate and eugenol acetate). The third group rich in terpene constituents could also be divided into two classes. The first class produced oils rich in monoterpene components and includes Cinnamomum damhaensis (linalool, α-pinene, β-pinene and 1,8-cineole), Cinnamomum cambodianum (linalool and terpinen-4-ol) and Cinnamomum caryophyllus (1,8-cineole, α-pinene and camphene). The second class contains oil with abundance of sesquiterpene compounds and peculiar to Cinnamomum rigidifolium (α-selinene, β-caryophyllene and α-copaene). This paper discusses further the chemotaxonomic importance of these results and previous data on essential oils of Cinnamomum species analysed from Vietnam. Language: en

Selecting microbial strains from pine tree resin: biotechnological applications from a terpene world.

Abstract: Resin is a chemical and physical defensive barrier secreted by many plants, especially coniferous trees, with insecticidal and antimicrobial properties. The degradation of terpenes, the main components accounting for the toxicity of resin, is highly relevant for a vast range of biotechnological processes, including bioremediation. In the present work, we used a resin-based selective medium in order to study the resin-tolerant microbial communities associated with the galls formed by the moth Retinia resinella; as well as resin from Pinus sylvestris forests, one of the largest ecosystems on Earth and a yet-unexplored source of terpene-degrading microorganisms. The taxonomic and functional diversity of the cultivated, resin-tolerant fraction of the whole microbiota were unveiled by high-throughput sequencing, which resulted in the detection of more than 40 bacterial genera among the terpene-degrading microorganisms, and a range of genes involved in the degradation of different terpene families. We further characterized through culture-based approaches and transcriptome sequencing selected microbial strains, including Pseudomonas sp., the most abundant species in both environmental resin and R. resinella resin-rich galls, and three fungal species, and experimentally confirmed their ability to degrade resin and also other terpene-based compounds and, thus, their potential use in biotechnological applications involving terpene catabolism.

In vitro activity of terpenes against Candida albicans and ultrastructural alterations.

Abstract: Objective The purpose of this study was to investigate the in vitro activity of terpene blends combined with tissue conditioner against Candida albicans and the effect on its morphology and sub-micro structure. Study Design The minimal inhibitory concentration (MIC) of terpenes, obtained from a by-product of kraft pulping, was determined using broth microdilution against C. albicans strains, and the activity of terpenes combined with Coe-Comfort tissue conditioner was assessed. Cell morphologic alterations were evaluated using scanning electronic microscopy and transmission electronic microscopy. Data was analyzed using Student’s t test P Results The MIC of terpene blends fluctuated between 0.097% and 0.39% (v/v). Coe-Comfort tissue conditioner mixed with terpenes exhibited a total inhibition of C. albicans (P Conclusions Terpenes had pronounced effects against C. albicans alone and in combination with Coe-Comfort tissue conditioner, which mainly resulted in cell wall damage.

Sulfated Triterpenes from Lemon Balm

Abstract: The hydroalcoholic (EtOH/H2O) extract of matured leaf margins of lemon balm (Melissa officinalis L.) afforded a new 3,23-disulfate of 2α,3β-23,29-tetrahydroxyolean-12-en-28-oic acid 28-O-β-D-glucopyranoside (1) and a new 23-monosulfate of 2α,23-dihydroxyurs-12-en-28-oic acid 3-O-β-D-glucopyranoside (2), along with six known compounds, i.e., 23-monosulfate of 2α,3β,19α,23-tetrahydroxyurs-12-ene-28-oic acid 28-O-β-D-glucopyranoside (3), 3,5,6-trihydroxydehydro-α-ionol 9-O-β-D-glucopyranoside (4), quadranoside III (5), rosmarinic acid (6), caffeic acid (7), and luteolin (8). All the isolated compounds were evaluated for their antioxidant, antimicrobial, antimalarial, and cytotoxic activities. Only rosmarinic acid exhibited substantial antioxidant and antimicrobial activities, whereas sulfated terpenes showed considerably lower or no antimicrobial activity.

Bioproducts, Biofuels, and Perfumes: Conifer Terpene Synthases and their Potential for Metabolic Engineering

Abstract: Conifer trees, including the economically and ecologically important pine (Pinus), spruce (Picea), and fir (Abies) species, produce large amounts of oleoresin terpenoids as a defense against herbivores and pathogens Due to the structural diversity of oleoresin terpenoids and their various chemical and physical properties, which range from solid and viscous resins to liquids and volatiles, many of these compounds are useful to humans for the production of therapeutics, fragrances and flavors, biofuels, and fine chemicals In this chapter, we feature three examples of conifer terpenoids, the diterpene resin acids (DRA), the sesquiterpene E-α-bisabolene, and the diterpenol cis-abienol, to highlight the versatile utility of conifer terpenoids as renewable bioproducts We focus on recent research progress on conifer terpene synthases (TPS) which produce a wealth of terpene scaffolds in nature Our recent advances in conifer transcriptome and genome sequencing as well as metabolite analyses have accelerated discovery and definitive functional annotation of terpenoid pathway genes New insights into the evolutionary diversification of conifer TPS, their modular organization, and dynamic expression will be fundamental to advance metabolic engineering and synthetic biology platforms for high-value terpenoids

Comparative analysis of alpha- and beta-thujone in the essential oil and supercritical CO2 extract of sage (Salvia officinalis L.)

Abstract: Salvia officinalis L. (Sage) is an important industrial plant used both for food and pharmaceutical purposes. The terpene fraction of this plant, which contains thujones and other mono and sesquiterpenoids, is responsible for many of its therapeutic and culinary properties. We used two extraction methods [hydrodistillation (HD) to obtain the essential oil (EO), and supercritical CO2 extraction (SFE)] to analyze by gas chromatography–mass spectrometry (GC–MS) the terpene fraction extracted from sage dried leaves. α-Thujone, β-thujone and other oxygenated monoterpenes (1,8-cineole, linalool, camphor, borneol and bornyl acetate) as well as hydrocarbon (β-caryophyllene and α-humulene) and oxygenated sesquiterpenes (caryophyllene oxide, viridiflorol, humulene epoxide II and III) were found. The EO contained a significantly (p < 0.05) higher percentage of 1,8-cineole (10.4%), α-thujone (17.3%) and camphor (29.2%), whereas supercritical fluid (SF) extracts contained a significantly higher percentage of borneol (...

Modeling with the logistic regression of the growth/no growth interface of Saccharomyces cerevisiae in relation to 2 antimicrobial terpenes (citral and linalool), pH, and a(w).

Abstract: UNLABELLED The antimicrobial effects of 2 terpenes (citral and linalool) on a Saccharomyces cerevisiae strain isolated from spoiled soft drink have been evaluated, alone or in combination, in relation to pH and aw using in vitro assays The obtained data were fitted with the logit model to find the growth/no growth boundary regions of the 2 terpenes, focusing the attention on the type of interaction exerted by citral and linalool In particular, the results showed an increase of citral antimicrobial effect in growth media characterized by low aw value, as well as a higher linalool antimicrobial effect in media at low pH Moreover, the interactive effects of the 2 terpenes were exploited The results obtained with the model were validated in an independent experiment The knowledge of the interactions of essential oil molecules with enhanced antimicrobial activity, in relation to some of the most important chemicophysical variables, can have important industrial applications, since these substances are able to assure the desired antimicrobial effect without negatively modifying the product flavor profile PRACTICAL APPLICATION The effects of the main chemicophysical parameters (such as aw and pH) on the antimicrobial activity of bioactive terpenes are necessary for the definition of an industrially applicable preservation strategy based on the use of essential oils as natural antimicrobials aimed to prolong shelf life of food products