Structural Features for Furan-Derived Fruity and Meaty Aroma Impressions.

Furan derivatives are part of nearly all food aromas. They are mainly formed by thermal degradation of carbohydrates and ascorbic acid and from sugar-amino acid interactions during food processing. Caramel-like, sweet, fruity, nutty, meaty, and burnt odor impressions are associated with this class of compounds. In the presented work, structure-activity relationship (SAR) investigations are performed on a series of furan derivatives in order to find structural subunits, which are responsible for the particular characteristic flavors. Therefore, artificial neural networks are applied on a set of 35 furans with the aroma categories "meaty" or "fruity" to calculate a classification rule and class boundaries for these two aroma impressions. By training a multilayer perceptron network architecture with a backpropagation algorithm, a correct classification rate of 100% is obtained. The neural network is able to distinguish between the two studied groups by using the following significant descriptors as inputs: number of sulfur atoms, Looping Centric Information Index, Folding Degree Index and Petitjean Shape Indices. Finally, the results clearly demonstrate that artificial neural networks are successful tools to investigate non-linear qualitative structure-odor relationships of aroma compounds.

A Pilot Study on the Physiological Effects of Three Essential Oils in Humans.

In the present study, the physiological effects on 32 humans exposed to experimental stress provoked by inhalation of the essential oils of East Indian sandalwood (Santalum album L.), Western Australian sandalwood (Santalum spicatum R.Br.) and lavender (Lavandula angustifolia MILL.) were investigated. During individual testing sessions, several saliva samples were collected, blood pressure was regularly measured and parameters of the autonomic nervous system (heart rate, skin conductance response) were continuously monitored. Salivary cortisol, as an endocrine stress indicator, was determined by time- resolved fluoroimmunoassay. Statistical analyses evidenced that the tested sandalwood essential oils significantly reduced systolic blood pressure, especially during the recreation phase. This finding corresponds with a distinct reduction of salivary cortisol levels during recreation in the Western Australian sandalwood oil compared with the control. In conclusion, the results demonstrate that essential oils can alleviate the physiological reactions to psychological stress and facilitate recovery after exposition to stress.

An Interesting Tour of New Research Results on Umami and Umami Compounds.

Knowledge about the fifth basic taste, the umami taste, has been investigated by many scientists in the last years and continues to gain importance. Therefore, a lot of scientific studies were conducted to explore several effects influencing the mechanism of umami, which is elicited and enhanced by defined concentrations of MSG (monosodium glutamate) and umami compounds. This paper covers the most relevant scientific literature regarding umami, its use as a flavor enhancer, and the latest umami compounds, which have been released in the last ten years. The main goal of this overview was to summarize the most important results which were related to umami as one of the five basic tastes, the umami taste receptor, the essential role of umami in a great number of physiological mechanisms, and the MSG symptom complex. Furthermore, the function of umami in the interaction of taste, aftertaste and olfactory pathways has been discussed.

Biological Properties of Some Volatile Phenylpropanoids.

Plants and their extracts are the new field of interest for many scientists and also of some pharmaceutical industries. In order to provide more information for their usage in the prevention and treatment of diseases many clinical trials and researches are being carried out. In this review the biological activities and the mechanism of action of volatile phenylpropanoids (PPs) found in essential oils (EOs) are presented. The aim of this overview is to show that volatile PPs found in EOs can exert many of the biological activities which are generally attributed to EOs. Almost all of the PPs possess antimicrobial, anti-inflammatory and anticancer activities. These are related to the different substitution of the phenylpropane molecule. For each isolated group not only one, but more pharmacological activities can be credited.

Essential Oils as "A Cry for Help". A Review.

This work is an update of a recently published review and is consistently referred to this article and recent findings about plants' indirect defense are added on. Herbivore induced plant volatiles (HIPVs) and their effects on the third trophic level that involves predators and parasitoids are discussed. The fact that plants are not passive individuals is confirmed on the basis of several studies. Plants can perceive and respond to cues in their environments with plastic morphological, physiological and behavioral traits. Plasticity allows plants to tailor their defenses to their current and expected risks caused by herbivores. The "cry for help" of plants is also observed from the carnivores' point of view. The volatile mixture contains crucial information for decisions of carnivorous insects. Furthermore, the most important methods to examine the behavioral response of carnivorous insects to HIPVs are presented not only in laboratory set ups but also in the field. Manipulations of plants by silencing genes or over-expressing genes can help to understand mechanisms of indirect defense. Various interesting examples of indirect defense reveal the possibility to use HIPVs in biological control. Therefore, the application of synthetic pesticides, that pollute the environment, may be reduced in the future.

[Essential oils and their influence on the actions of drugs: some examples]. / Ätherische Öle und ihr Einfluss auf Arzneimittelwirkungen. Einige Beispiele.

There is a general belief that herbal products, thus essential oils too, are safe because they are natural. Together with the increased appearance of common and self-initiative usage of herbal preparations there is also an increased need of knowing and understanding possible interactions with concomitantly taken drugs. Since essential oils are mixtures of multiple active volatile compounds it is very likely for essential oils and especially their constituents also to interact with drugs. The presented treatise will reveal some of such interactions. Most of them are pharmacokinetic ones, while pharmacodynamic interactions seem to be less studied. While some of these interactions may have a negligible impact on the effect of drugs--and it was the aim of this paper to demonstrate the impact of volatile oils on the effect of drugs when applied together--other mutual effects may be rather harmful. Under certain circumstances it could be possible to use the effects of these interactions also for the benefit of the patients, but further clinical investigations are needed.

Human body scents: do they influence our behavior?

Pheromonal communication in the animal world has been of great research interest for a long time. While extraordinary discoveries in this field have been made, the importance of the human sense of smell was of far lower interest. Humans are seen as poor smellers and therefore research about human olfaction remains quite sparse compared with other animals. Nevertheless amazing achievements have been made during the past 15 years. This is a collection of available data on this topic and a controversial discussion on the role of putative human pheromones in our modem way of living. While the focus was definitely put on behavioral changes evoked by putative human pheromones this article also includes other important aspects such as the possible existence of a human vomeronasal organ. If pheromones do have an influence on human behavior there has to be a receptor organ. How are human body scents secreted and turned into odorous substances? And how can con-specifics detect those very odors and transmit them to the brain? Apart from that the most likely candidates for human pheromones are taken on account and their impact on human behavior is shown in various detail.

Chemical composition, olfactory analysis and antibacterial activity of Thymus vulgaris chemotypes geraniol, 4-thujanol/terpinen-4-ol, thymol and linalool cultivated in southern France.

The essential oils of four chemotypes of Thymus vulgaris L. (Lamiaceae) were analyzed for their composition and antibacterial activity to assess their different properties. GC-MS and GC-FID analyses revealed that the essentials oils can be classified into the chemotypes thymol (41.0% thymol), geraniol (26.4% geraniol), linalool (72.5% linalool) and 4-thujanol/terpinen-4-ol (42.2% cis- and 7.3% trans-sabinene hydrate, 6.5 % terpinen-4-ol). The olfactory examination confirmed the explicit differences between these chemotypes. Furthermore, antibacterial activity was investigated against several strains of two Gram-positive (Brochothrix thermosphacta and Staphylococcus aureus) and four Gram-negative food-borne bacteria (Escherichia coli, Salmonella abony, Pseudomonas aeruginosa and P. fragi). All essential oil samples were demonstrated to be highly effective against Gram-positive strains, whereas the impact on Gram-negative microorganisms was significantly smaller, but still considerable. The results obtained indicate that, despite their different properties, the essential oils of selected T. vulgaris chemotypes are potent antimicrobials to be employed as useful additives in food products as well as for therapeutic applications.

Structure-activity relationships of sandalwood odorants: synthesis of a new campholene derivative.

Structural modifications of natural (-)-(Z)-beta-santalol have shown that the sandalwood odor impression is highly sensitive, even to small structural changes. Particularly, the substitution of the quaternary carbon is of great influence on the scent. Epi-compounds with side chains in the endo-position possess sandalwood odor in only a few derivatives, whereas modifications at this side chain, as well as modification at the bicyclic ring systems mostly lead to a complete loss of sandalwood fragrance.

Chemical composition, olfactory evaluation and antimicrobial activity of selected essential oils and absolutes from Morocco.

The chemical compositions of selected essential oils from North Africa, especially Morocco, of geranium, wild Moroccan chamomile and rosemary as well as absolutes of rose and geranium were determined using GC/FID and GC/MS. These oils and absolutes were tested concerning their antimicrobial activity against some food spoilage strains obtained from fresh milk and minced meat products, like sausages and pork fillet, in accordance with ISO testing procedures. Gram-positive (Bacillus cereus and Staphylococcus aureus) and Gram-negative (Escherichia coli, Salmonella abony and Pseudomonas aeruginosa) strains were used, as well as the yeast Candida albicans. Using a serial broth dilution method, all samples demonstrated weak antimicrobial activity against the Gram-negative bacteria and the yeast, compared with the activity towards the Gram-positive bacteria.

Chemical composition and antimicrobial activity of cumin oil (Cuminum cyminum, Apiaceae).

Cumin oil samples (Cuminum cyminum L.) from four different geographical origins were analyzed using GC-MS and GC-FID for their qualitative and quantitative composition. The major compounds in all cumin oils were the monoterpenes beta-pinene, p-cymene and gamma-terpinene and the terpenoid aldehydes cuminic aldehyde and the isomeric menthadien carboxaldehydes. All essential oils, and cuminic aldehyde, were tested, using agar diffusion and serial dilution methods, against different Gram-positive and Gram-negative bacteria isolated from different sources of food (pork fillet, minced meat and sausages) and clinical isolates, as well as three different Candida albicans isolates. All cumin oils and cuminic aldehyde exhibited a considerable inhibitory effect against all the organisms tested, except Pseudomonas spp.

Chemical composition and antibacterial activity of selected essential oils and some of their main compounds.

The chemical composition of essential oils of cabreuva (Myrocarpus fastigiatus Allemao, Fabaceae) from Brazil, cedarwood (Juniperus ashei, Cupressaceae) from Texas, Juniper berries (Juniperus communis L., Cupressaceae) and myrrh (Commiphora myrrha (Nees) Engl., Burseraceae) were analyzed using GC/FID and GC/MS. The antimicrobial activity of these essential oils and some of their main compounds were tested against eleven different strains of Gram-positive and Gram-negative bacteria by using agar diffusion and agar serial dilution methods. Animal and plant pathogens, food poisoning and spoilage bacteria were selected. The volatile oils exhibited considerable inhibitory effects against all tested organisms, except Pseudomonas, using both test methods. Higher activity was observed against Gram-positive strains in comparison with Gram-negative bacteria. Cabreuva oil from Brazil showed similar results, but in comparison with the other oils tested, only when higher concentrations of oil were used.

Antimicrobial activities of single aroma compounds.

Commercially available aroma samples were evaluated for their olfactory quality by professional perfumers and tested for their antimicrobial activity. Agar diffusion and agar-dilution were used as test methods and a set of two Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and four Gram-negative bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris G, Klebsiella pneumoniae and Salmonella abony) and a yeast, Candida albicans, were the test microorganisms. All the investigated compounds were active against Gram-positive bacteria, especially beta-caryophyllene against Enterococcus faecalis (MIC 6 ppm), but only few substances showed activity towards Gram-negative bacteria, except for cinnamic acid, which was active against all (MIC 60 ppm) and Candida albicans, against which cinnamic acid and caryophyllene oxide showed high activity (MIC < 60 ppm).

Chemical composition, olfactory evaluation and antioxidant effects of essential oil from Mentha x piperita.

The chemical composition of the essential oil from peppermint (Mentha x piperita L.) was analyzed by GC/FID and GC-MS. The main constituents were menthol (40.7%) and menthone (23.4%). Further components were (+/-)-menthyl acetate, 1,8-cineole, limonene, beta-pinene and beta-caryophyllene. Peppermint oil possessed antiradical activity with respect to DPPH (diphenyl picryl hydrazyl) and hydroxyl (OH*) radicals, exercising stronger antioxidant impact on the OH* radical. The concentrations required for 50% inhibition of the respective radical (IC50) were 860 microg/mL for DPPH and 0.26 microg/mL for OH*. Peppermint essential oil demonstrated antioxidant activity in a model linoleic acid emulsion system in terms of inhibiting conjugated dienes formation by 52.4% and linoleic acid secondary oxidized products generation by 76.9% (at 0.1% concentration).

Chemical composition, olfactory evaluation and antioxidant effects of essential oil from Mentha canadensis.

The chemical composition of the essential oil from cornmint (Mentha canadensis L.) was analyzed by GC/FID and GC-MS. The main constituents were menthol (41.2%) and menthone (20.4%). It was established that cornmint oil had antiradical activity with respect to the DPPH and hydroxyl (OH*) radicals. The concentrations necessary for 50% neutralization of the respective radicals (IC50) were 365.0 microg/mL for DPPH and 0.3 microg/mL for OH*, which was indicative that the antioxidant activity in terms of OH* was higher than that of quercetin. Cornmint oil chelated the Fe3+ ions present in the solution. The oil demonstrated antioxidant activity in a linoleic acid emulsion model system, where at 0.1% concentration it inhibited the formation of conjugated dienes by 57.1% and the generation of secondary oxidized products of linoleic acid by 76.1%.

(13)C-NMR spectra of santalol derivatives: a comparison of DFT-based calculations and database-oriented prediction techniques.

A systematic investigation of a series of santalol and epi-santalol derivatives by means of ab initio and density functional theory (DFT) calculations together with database-oriented prediction methods leads to a configurational reassignment within this compound class. The DFT calculations as well as the HOSE-code and neural network-based predictions allow deriving a general rule set for unambiguous assignment within this compound class. The methyl group in position 2' serves as an indication for the configuration at this stereocenter allowing easy differentiation between santalol derivatives and their diastereomers belonging to the epi-santalol series.

Characterisation of various grape seed oils by volatile compounds, triacylglycerol composition, total phenols and antioxidant capacity.

Grape seed oil (Oleum vitis viniferae) representing a promising plant fat, mainly used for culinary and pharmaceutical purposes as well as for various technical applications, was subject of the present investigation. HS-SPME-GC-MS was applied to study volatile compounds in several seed oil samples from different grape oils. The triacylglycerol (TAG) composition of these oils was analyzed by MALDI-TOF-MS/MS. In addition the total phenol content and the antioxidant capacity (using TEAC) of these oils were determined. The headspace of virgin grape oils from white and red grapes was dominated by ethyl octanoate (up to 27.5% related to the total level of volatiles), ethylacetate (up to 25.0%), ethanol (up to 22.7%), acetic acid (up to 17.2%), ethyl hexanoate (up to 17.4%) and 3-methylbutanol (up to 11.0%). Triacylglycerol composition was found to be dominated by LLL (up to 41.8%), LLP (up to 24.3%), LLO (up to 16.3%) and LOO (up to 11.7%), followed by LOP (up to 9.3%) and LOS/OOO (up to 4.3%). Total phenol content ranged between 59µg/g and 115.5µg/g GAE. Antioxidant capacity (TEAC) was analyzed to range between 0.09µg/g and 1.16µg/g.

Structure-activity relationships of sandalwood odorants: total synthesis and fragrance properties of cyclopropano-beta-santalol.

The synthesis and odor properties of cyclopropano-beta-santalol, a new santalol analogue, are described. The exocyclic double bond of the original molecule, beta-santalol, is replaced by a cyclopropane ring. Despite the analogies in the binding properties between the double bond and cyclopropane this change in the bulky hydrophobic part of the molecule leads to the complete loss of the characteristic sandalwood odor: in an olfactory evaluation the (Z)-product appears spicy and sweet, the (E)-isomer woody, but neither of them exhibits the typical sandalwood character.

Differences in (-)citronellal binding to various odorant receptors.

To test the hypothesis that olfactory receptors (ORs) recognize different molecular features of odor molecules termed "odotypes", we studied receptor-ligand interactions of two human and two mouse ORs, recognizing (-)citronellal. Structurally similar receptors provide identical binding pockets (OLFR43, OR1A1, and OR1A2), and have comparable EC(50) values. Other ORs with lower sequence identity bind (-)citronellal in a different way, leading to different EC(50) values.

Antimicrobial effect of trans-cinnamaldehyde, (-)-perillaldehyde, (-)-citronellal, citral, eugenol and carvacrol on airborne microbes using an airwasher.

Citral, trans-cinnamaldehyde, (-)-perillaldehyde, (-)-citronellal, eugenol and carvacrol were tested for their influence on microbial count in air by vaporizing with an air washer. The highest antibacterial activity was observed when (-)-perillaldehyde was sprayed. The average reduce of germ count was 53%. On the other hand, the antimicrobial activity of eugenol was the lowest of these six compounds. The average reduction of germ count was 13%. When water without volatile compounds was sprayed, the colony forming units increased. These results suggest the utility of selected aroma-compounds for the control of bacteria in the room.