Carotenoid-Related Volatile Compounds of Tobacco (Nicotiana tabacum L.) Essential Oils

Tobacco (Nicotiana tabacum L.) aroma is an important attribute of tobacco quality and is influenced by a variety of minor chemical components, including carotenoid degradation products. The objectives of this work were to determine the content of the most important fragrance-shaping carotenoid degradation products in the essential oils (EOs) of the three types of Bulgarian tobacco-Oriental (OR), flue-cured Virginia (FCV), and Burley (BU)-and to compare them with other aromatic products from tobacco. The content of total carotenoids and β-carotene was highest in BU tobacco (22.23 and 20.34 mg/100 g DW, respectively), followed by OR (13.60 and 12.09 mg/100 g DW in variety "Plovdiv 7" (Pd7); 6.27 and 5.45 mg/100 g DW in "Krumovgrad" (Kr), and FCV (5.93 and 3.73 mg/100 g DW). EOs were obtained by hydrodistillation in an acidified medium, and the main aroma-impact compounds from carotenoid degradation (identified by GC-MS) were as follows: FCV-α-ionone (0.61 mg/100 g DW), dihydro-β-ionone (0.96 mg/100 g DW), β-damascenone (1.26 mg/100 g DW); BU-α-ionone (0.73 mg/100 g DW), dihydro-β-ionone (1.19 mg/100 g DW), β-damascenone (1.35 mg/100 g DW); OR(Kr)-α-ionone (0.20 mg/100 g DW), β-ionone (1.08 mg/100 g DW), dihydro-β-ionone (1.34 mg/100 g DW), β-damascenone (0.36 mg/100 g DW); OR(Pd7)-α-ionone (1.43 mg/100 g DW), dihydro-β-ionone (1.73 mg/100 g DW), β-damascenone (1.23 mg/100 g DW). Ionone and its derivatives were not identified in the aroma extraction products concrete, resinoid, or absolute. The results suggest that temperature, pH of the medium, process duration, and possibly other unknown factors affect carotenoid transformation. The study provides insight into the composition of tobacco EOs and may be of interest to the fragrance industry.

Phytochemical Investigations of Laurel Fruits (Laurus nobilis)

Bay laurel ( Laurus nobilis L.) is an evergreen tree. The objective of this study was to determine the chemical composition (polyphenols, essential oil [EO], lipid fraction, cellulose, and protein content) of laurel fruits collected from Greece (Mount Athos) and Georgia (the village of Meria), and to evaluate the antimicrobial activity of laurel fruit EOs. The major phenolic acids in the fruits from Greece were p-coumaric acid (free 261.6 µg/g) and vanillic acid (free 253.1 µg/g and conjugated 925.8 µg/g). The major phenolic acids in fruits from Georgia were vanillic acid (free 105.6 µg/g and caffeic acid [conjugated 439.2 µg/g], and syringic acid [conjugated 390.7 µg/g]). The laurel fruit EOs from Greece (1.4% content) and Georgia (1.6%) had distinct composition. Monoterpene hydrocarbons were the dominant group of compounds in the EOs, with 49.7% in the EO from Greece and 68.7% in the EO from Georgia. The major constituents of the fruit EO from Greece were 1,8-cineole (18.2%), α-phellandrene (15.0 %), β-pinene (9.4%), and α -pinene (9.1%), whereas the ones from Georgia were trans-β-ocimene (59.4%) and 1,8-cineole (7.6%). Laurel fruit EO from Greece and Georgia demonstrated low to moderate antimicrobial activity against pathogenic and spoilage microorganisms and the dimorphic yeast Candida albicans. The main fatty acids (FAs) in the lipid fractions were oleic, palmitic, and linoleic; there were differences in FA composition between the shells and the seeds of the fruits from the two countries. γ-Тocopherol predominated in the tocopherol fraction of the lipids from fruits shells and seeds from Greece (65.3% and 54.4%, respectively), whereas β-tocopherol predominated in fruits shells and seeds from Georgia (93.7% and 45.6%, respectively). Currently underutilized, the laurel fruits from both Greece and Georgia contain various valuable compounds that may potentially be used for perfumery, cosmetic, and pharmaceutical applications.

Electronic structure, reactivity, and Hirshfeld surface analysis of carvone

The density functional theory (at the B3LYP level using 6-311++G(2d,2p) basis set) was used for the investigation of the geometry and electronic properties of the carvone. The electronic properties and chemical activity of the titled compound were investigated by means of several theoretical approaches, molecular electrostatic potential surface, natural bond orbital, and frontier molecular orbital analyses. It was established that the oxygen atom in the structure characterized the electrophilic reactivity; the positive regions are localized on the hydrogen atoms, which can be considered as possible sites for nucleophilic attack. A detailed analysis of the intermolecular interactions via Hirshfeld surface analysis and fingerprint plots revealed that the carvone structure is stabilized mainly by the formation of O. . .H/H. . .O hydrogen bonds. However, close contacts were established between C. . .H/H. . .C and H. . .H contacts.

Chemical Composition, Olfactory Evaluation and Antimicrobial Activities of Jasminum grandiflorum L. Absolute from India

The chemical composition of a sample of Jasminum grandiflorum L. absolute from India was analyzed by GC and GC/MS. The major compounds identified were benzyl acetate (23.7%), benzyl benzoate (20.7%), phytol (10.9%), linalool (8.2%), isophytol (5.5%), geranyl linalool (3.0%), methyl linoleate (2.8%) and eugenol (2.5%). The odor of this absolute sample was olfactorically evaluated as intense and heavy floral-flowery, with penetrant-animalic and fruity side-notes. Some main and minor compounds were found to be responsible for the aroma impression of this sample.

The antimicrobial activities of the J. grandiflorum sample and of some of its main and minor compounds were tested against Gram-positive and Gram-negative bacteria, as well as against the yeast Candida albicans, using agar dilution and agar diffusion methods. The jasmine absolute showed medium to high activity (reference compounds: eugenol and three synthetic antibiotics) against the Gram-positive bacterium Enterococcus faecalis, against the Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Salmonella sp., as well as against the yeast Candida albicans. A comparison of these biological data with those of some constituents of the jasmine absolute is also given.

Chemical Composition, Olfactory Evaluation and Antioxidant Effects of the Leaf Essential Oil of Corymbia citriodora (Hook) from China

The chemical composition of a sample of lemon eucalyptus essential oil ( Corymbia citriodora) from China was determined by GC/FID and GC/MS. Citronellal (76.3%), citronellol (5.7%) and neo-isopulegol (5.5%) were the major components. The odor of the sample was evaluated as fresh, citrus-like and mildly fruity, with a pleasant woody background note.

Lemon eucalyptus oil was found to exhibit antiradical activity with respect to DPPH and hydroxyl (OH•) radicals. The effect exercised on OH• radicals significantly exceeded that observed for the DPPH radical – the respective concentrations for 50% inhibition of the radicals were 0.38 μg/mL for OH• and 344.0 μg/mL for DPPH. Furthermore, the essential oil revealed antioxidant activities in a model system comprised of a linoleic acid emulsion. At a concentration of 0.1%, inhibition of conjugated dienes-formation by 59.8% was observed and the formation of secondary oxidized products of linoleic acid by 84.7%.

Chemical Composition and Antimicrobial Activity of Laurus nobilis L. Essential Oils from Bulgaria

Laurel, Laurus nobilis L. is an evergreen plant belonging to the Lauraceae family, native to Southern Europe and the Mediterranean area. This is the first report on the composition and bioactivity of laurel essential oil (EO) from Bulgaria. The oil yield was 0.78%, 0.80%, and 3.25% in the fruits, twigs, and leaves, respectively. The main constituents in the fruit EO were 1,8-cineole (33.3%), α-terpinyl acetate (10.3%), α-pinene (11.0%), β-elemene (7.5%), sabinene (6.3%), β-phellandrene (5.2%), bornyl acetate (4.4%), and camphene (4.3%); those in the twig EO were 1,8-cineole (48.5%), α-terpinyl acetate (13.1%), methyl eugenol (6.6%), β-linalool (3.8%), β-pinene (3.4%), sabinene (3.3%) and terpinene-4-ol (3.3%); and the ones in the leaf EO were 1,8-cineole (41.0%), α-terpinyl acetate (14.4%), sabinene (8.8%), methyl eugenole (6.0%), β-linalool (4.9%), and α-terpineol (3.1%). The antibacterial and antifungal properties of laurel EOs were examined according to the agar well diffusion method. The leaf EO showed antibacterial and antifungal activities against almost all strains of the microorganisms tested, whereas the twig EO was only able to inhibit Staphylococcus aureus. Pseudomonas aeruginosa ATCC 9027 and Escherichia coli ATCC 8739 were the bacterial strains that showed the highest resistance to the laurel EO. The results can benefit the EO industry and biopesticide development.

Chemical composition and biological effects of Artemisia maritima and Artemisia nilagirica essential oils from wild plants of western Himalaya

Artemisia species possess pharmacological properties that are used for medical purposes worldwide. In this paper, the essential oils from the aerial parts of Artemisia nilagirica and Artemisia maritima from the western Indian Himalaya region are described. The main compounds analyzed by simultaneous GC/MS and GC/FID were camphor and 1,8-cineole from A. maritima, and camphor and artemisia ketone from A. nilagirica. Additionally, the oils were evaluated for their antibacterial, antifungal, mosquito biting deterrent, and larvicidal activities. A. nilagirica essential oil demonstrated nonselective antifungal activity against plant pathogens Colletotrichum acutatum, Colletotrichum fragariae, and Colletotrichum gloeosporioides, whereas A. maritima did not show antifungal activity. Both Artemisia spp. exhibited considerable mosquito biting deterrence, whereas only A. nilagirica showed larvicidal activity against Aedes aegypti. Antibacterial effects assessed by an agar dilution assay demonstrated greater activity of A. maritima essential oil against Staphylococcus aureus and Pseudomonas aeruginosa compared to A. nilagirica.

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 Gramnegative 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.

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.

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.

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.

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.