Chemistry Of Essential Oils Research Articles

Exploring the Volatile Composition and Antibacterial Activity of Edible Flower Hydrosols with Insights into Their Spontaneous Emissions and Essential Oil Chemistry.

In the circular economy framework, hydrosols, by-products of the essential oil industry, are gaining attention for their potential in waste reduction and resource reuse. This study analyzed hydrosols from six edible flowers, investigating their chemical composition (VOC-Hyd) and antibacterial properties alongside volatile organic compounds of fresh flowers (VOC-Fs) and essential oils (EOs). Antirrhinum majus exhibited ketones as major VOC-Fs (62.6%) and VOC-Hyd (41.4%), while apocarotenoids dominated its EOs (68.0%). Begonia cucullata showed alkanes (33.7%) and aldehydes (25.7%) as primary VOC-Fs, while alkanes were prevalent in both extracts (65.6% and 91.7% in VOC-Hyd and in EOs, respectively). Calandula officinalis had monoterpenoids in VOC-Fs and VOC-Hyd (89.3% and 49.7%, respectively), while its EOs were rich in sesquiterpenoids (59.7%). Dahlia hortensis displayed monoterpenoid richness in both VOC-Fs and extracts. Monocots species' VOC-Fs (Polianthes tuberosa, Tulbaghia cominsii) were esters-rich, replaced by monoterpenoids in VOC-Hyd. P. tuberosa EO maintained ester richness, while T. cominsii EOs contained a significant percentage of sulfur compounds (38.1%). Antibacterial assays indicated comparable minimum inhibitory concentration profiles across VOC-Hyd: B. calcullata and P. tuberosa against Staphylococcus aureus and Salmonella enterica ser. typhimurium, T. cominsii against Escherichia coli and S. enterica, A. majus and C. officinalis against S. aureus, and D. hortensis against S. enterica.

Essential Oils: Chemistry and Pharmacological Activities.

In this review, we provide an overview of the current understanding of the main mechanisms of pharmacological action of essential oils and their components in various biological systems. A brief introduction on essential oil chemistry is presented to better understand the relationship of chemical aspects with the bioactivity of these products. Next, the antioxidant, anti-inflammatory, antitumor, and antimicrobial activities are discussed. The mechanisms of action against various types of viruses are also addressed. The data show that the multiplicity of pharmacological properties of essential oils occurs due to the chemical diversity in their composition and their ability to interfere with biological processes at cellular and multicellular levels via interaction with various biological targets. Therefore, these natural products can be a promising source for the development of new drugs.

The effect of Lavandula Coronopifolia essential oil on the biophysical properties of desensitization and deactivation gating currents in ionotropic receptors

The rising incidence of cancer and the lack of effective therapeutic interventions for many neurological illnesses like Alzheimer's and epilepsy has prompted us to investigate the composition and effects of the Lavandula coronopifolia oil from Palestine on cancer cells and AMPA receptor subunits in the brain due to the vast range of beneficial properties of Lavandula coronopifolia essential oil (EO). GC/MS was used to analyze L. coronopifolia's EO chemistry. EO's cytotoxicity and biophysical effects on AMPA receptors were investigated using MTS and electrophysiological techniques. The GC–MS results revealed that L. coronopifolia EO has a high content of eucalyptol (77.23%), β-pinene (6.93%), and α-pinene (4.95%). The EO showed more significant antiproliferative selectivity activities against HepG2 cancer cell lines than HEK293T cell lines with IC50 values of 58.51 and 133.22 µg/mL, respectively. The EO of L. coronopifolia affected AMPA receptor kinetics (desensitization and deactivation) and preferred homomeric GluA1 and heteromeric GluA1/A2 receptors. These findings indicate the potential therapeutic use of L. coronopifolia EO in the selective treatment of HepG2 cancer cell lines and neurodegenerative diseases.

Evaluating the Potential of Boswellia rivae to Provide Sustainable Livelihood Benefits in Eastern Ethiopia.

Frankincense is an oleo-gum-resin collected from wild Boswellia spp. trees, and widely used in perfumery, cosmetics, aromatherapy, incense, and other industries. Boswellia rivae, growing in Ethiopia, Somalia, and Kenya, is one source of frankincense, but is little-commercialized compared to species such as B. sacra, B. frereana, and B. papyrifera. In this study, we examine the resin essential oil chemistry and harvesting systems of B. rivae in order to evaluate its potential for increased trade and potential positive livelihood benefits. Boswellia rivae produces an essential oil rich in α-thujene (0.1-12.4%), α-pinene (5.5-56.4%), β-pinene (0.3-13.0%), δ-3-carene (0.1-31.5%), p-cymene (1.4-31.2%), limonene (1.8-37.3%), β-phellandrene (tr-5.6%), trans-pinocarveol (0.1-5.0%), trans-verbenol (0.1-11.2%), and trans-β-elemene (0-5.7%), similar to major commercial species, although it is difficult to detect mixing of B. rivae and Commiphora africana resins from chemistry alone. The B. rivae trees are not actively tapped, so resin collection has a neutral impact on the health of the trees, and resin production is unaffected by drought. Consequently, collecting resins acts as a key income supplementing livestock herding, as well as a safety net protecting pastoral communities from the severe negative effects of climate change-exacerbated drought on livestock. Therefore, Boswellia rivae is well positioned chemically, ecologically, and socially to support expanded trade.

Chemistry of essential oils of the shrub Lippia alba (Verbenaceae) from Mexico and Costa Rica

ABSTRACT: Introduction: Lippia is a Verbenaceous genus of flowering plants, which has about 200 species, distributed throughout the southern USA, Mexico, and Central America to South America. Objective: To study and compare the chemical compositions of the essential oils of L. alba growing in Mexico and Costa Rica. Methods: The essential oils were obtained by hydrodistillation in a Clevenger-type apparatus. The chemical composition of the oils was analyzed by capillary GC-FID and GC-MS using the retention indices on a DB-5 type capillary column in addition to mass spectral fragmentation patterns. Results: A total of 65 compounds were identified in the essential oil samples from both countries, accounting for 96,5-98,1% of the total amount of the oils. The main constituents of the Mexican sample were 1,8-cineole (22,3%), myrcenone (11,2%), myrcene (10,9%), (E)-ocimenone (10,7%), (Z)-ocimenone (7,5%), and sabinene (6,8%), while for essential oil from Costa Rica the major compounds were myrcenone (30,4%), 1,8-cineole (21,4%), myrcene (11,0%), hedycaryol (4,4%), and sabinene (4,3%). Samples from both countries can be classified as belonging to chemotype “tagetenone”. Lippia alba (strong form) from Costa Rica produces essential oil that differs from all other essential oils of L. alba studied to date because it contained the sesquiterpenoids hedycaryol and the isomeric alcohols α-eudesmol, β-eudesmol, and γ-eudesmol. Conclusion: L. alba (strong form) from Costa Rica can be classified as a new subtype of the chemotype “tagetenone” (chemotype II).

Essential Oil Composition and Traditional Uses of Salvia dentata, a Poorly Known Medicinal Plant from Namaqualand, South Africa.

South Africa has a rich history of medicinal plant species and their documented uses as traditional medicines, and is also home to three well-known, blue-flowered sage species of ethnobotanical importance. The Namaqualand bloublomsalie (Salvia dentata) has so far remained unstudied and apparently overlooked. Our study is the first to report on the essential oil chemistry of this medicinally relevant species and provide a comparison with the other two (well-studied) closely related Cape bloublomsalies (Salvia africana and S. chamelaeagnea). The data, generated from three geographically isolated populations comprised of 13 individual plants of S. dentata, revealed diagnostically high levels of camphor (14.37%), α-pinene (11.43%), camphene (10.18%), 1,8-cineole (eucalyptol) (9.42%) and bornyl acetate (8.56%) which provide a distinct chemical profile from the other two species.

Fundamental Chemistry of Essential Oils and Volatile Organic Compounds, Methods of Analysis and Authentication.

The current text provides a comprehensive introduction to essential oils, their biosynthesis, naming, analysis, and chemistry. Importantly, this text quickly brings the reader up to a level of competence in the authentication of essential oils and their components. It gives detailed descriptions of enantiomers and other forms of stereoisomers relevant to the study of natural volatiles and essential oils. The text also describes GC-MS work and provides tips on rapid calculation of arithmetic indices, how to interpret suggested names from the NIST mass spectral library, and what additional efforts are required to validate essential oils and defeat sophisticated adulteration tactics. In brief, essential oils are mixtures of volatile organic compounds that were driven out of the raw plant material in distillation, condensed into an oil that is strongly aroma emitting, and collected in a vessel as the top layer (uncommonly bottom layer) of two phase separated liquids: oil and water. Essential oils commonly include components derived from two biosynthetic groups, being terpenes (monoterpenes, sesquiterpenes and their derivatives) and phenylpropanoids (aromatic ring with a propene tail). The current text provides details of how terpenes and phenylpropanoids are further categorised according to their parent skeleton, then recognised by the character of oxidation, which may be from oxygen, nitrogen, or sulphur, or the presence/absence of a double bond. The essential oil’s science niche is an epicentre of individuals from diverse backgrounds, such as aromatherapy, pharmacy, synthetic and analytical chemistry, or the hobbyist. To make the science more accessible to the curious student or researcher, it was necessary to write this fundamentals-level introduction to the chemistry of essential oils (i.e., organic chemistry in the context of essential oils), which is herein presented as a comprehensive and accessible overview. Lastly, the current review constitutes the only resource that highlights common errors and explains in simplistic detail how to correctly interpret GC-MS data then accurately present the respective chemical information to the wider scientific audience. Therefore, detailed study of the contents herein will equip the individual with prerequisite knowledge necessary to effectively analyse an essential oil and make qualified judgement on its authenticity.

Comparing essential oils from Australia's ‘Victorian Christmas Bush’ (Prostanthera lasianthos Labill., Lamiaceae) to closely allied new species: Phenotypic plasticity and taxonomic variability

Prostanthera lasianthos (Lamiaceae) is commonly referred to as the ‘Victorian Christmas Bush’, a name that derives from the floral display it gives in the Christmas period. However, botanists recognise P. lasianthos as a heterogeneous species aggregate that includes several putative new species that are confined to disjunct locations. Recently one taxon was revised to P. eungella B.J.Conn & K.M.Proft. In the current study the chemistry of essential oils was determined for 25 specimens, representative of 8 taxa (including P. eungella). Chemical relationships were investigated using two types of multivariate analysis and several distinct chemical profiles were identified. One taxon (P. sp. Wollomombi Gorge) was sampled nine times from three different locations during the year to determine the effects of seasonal variation and subjectively-assessed soil moisture content. It was demonstrated that the chemistry of this taxon is strongly influenced by soil moisture independently of growth stage, but possibly influenced by periods of dry or wet weather. Two distinct chemotypes and one intermediate type were identified. These chemotypes differed by mediated expression of linalool and hence linalyl acetate. These metabolites were also present in specimens of P. sp. Bald Mountain, but as minor components. This latter taxon could be reliably distinguished by higher relative abundance of butanoic acid, 1-methylbutyl ester. As judged by a smaller sampling size for the other taxa, evidence that this pattern of mediated expression between terpene species was found. However, the identity of terpenes that demonstrated this mediated expression were different for each taxon; for example, volatiles from P. eungella demonstrated mediation between α-pinene and caryophyllene. Nevertheless, it is possible that chemical expression of all taxa in the heterogeneous species aggregate is strongly mediated by the moisture or nutrient content of soils. Thus, the dataset produced during this study can be used as a reference against other chemical data to investigate taxonomic placement in members of this group.

Volatiles from African species of Croton (Euphorbiaceae), including new diterpenes in essential oil from Croton gratissimus

The chemistry of essential oils from the leaves of three African species of Croton (C. gratissimus, C. pseudopulchellus and C. sylvaticus) is comprehensively characterised. Two new volatile diterpenes were isolated from C. gratissimus and the structures assigned using 1D and 2D NMR. One is a furanyl-halimane methyl ester (1) assigned as 12-β-furanyl-halima-5,9-dien-4-methylcarboxylate (gratissihalimanoic ester); the other is an abietane ketone (2) assigned as ent-abiet-8(14), 13(15)-dien-3-one, which we have named gratissimone. High relative abundance of diterpenes in a hydrodistilled essential oil is rare and may be considered an interesting discovery. Known non-volatile diterpenes were also isolated, which were assigned as crotohalimaneic acid (3) and hardwickiic acid (4). All diterpenes occur in fresh leaves prior to distillation and extract into apolar or moderately polar solvents, which demonstrates that the two volatiles are not generated during the hydrodistillation. At this stage it is not clear how widespread this diterpene essential oil chemotype is within the species distribution or if any therapeutic effects can be attributed to them. No antimicrobial activity was observed at 1 mg/ml against a range of bacterial strains.

Identification of potential anti-quorum sensing compounds in essential oils: a gas chromatography-based metabolomics approach

ABSTRACTQuorum sensing is a form of bacterial cell-to-cell communication, which plays an important role in bacterial pathogenicity. Due to increasing drug resistance, quorum sensing has been identified as a potential target to reduce the risk of developing drug resistance. The current study aims at investigating the antiquorum sensing activity of 40 commercial essential oils of therapeutic relevance. The agar well diffusion method, microdilution assay and spectrophotometric quantification of violacein production, assessed antiquorum sensing in Chromobacterium violaceum. Gas chromatography coupled to mass spectrometry (GC-MS) profiled essential oil constituents. A correlation between antiquorum sensing activity and essential oil chemistry was investigated in SIMCA-P + 14.0. The essential oils that displayed remarkable antiquorum sensing activity (inhibition ≥ 90%) at 0.25 mg/ml were; Cymbopogon sp., Citrus limon, Eucalyptus dives, Eugenia caryphyllus, Mentha sp., Myrtus communis and Pinus ponderosa. Eugenol, geraniol, geranial, menthol and pulegone were identified as putative biomarkers correlated to the active oils.

Essential Oils: Biological Activity Beyond Aromatherapy

The essential oils are fragrant products whose complex compositions are obtained from various parts of plants by dry or steam distillation. Plants with variable biological activities have been explored worldwide. The presence of a large number of phenols, terpenes and other aromatic compounds make essential oils more precise in their mode of action. Because of this, they are known to possess many biological activities like antimicrobial, antioxidant and anti-inflammatory etc. In this article, we will review the published literature summarizing the chemistry of essential oils and their important biological activities.

GC/MS Fingerprinting of Solvent Extracts and Essential Oils Obtained from Liverwort Species

Studies concerning chemical profiling of the volatiles present in the solvent extracts from liverworts help to determine inter- and intraspecific relationships in this plant group. Due to the fact that the liverworts are morphologically very small and it is difficult to collect their sufficient amounts, there are still a few data concerning the chemistry of essential oils. The available data indicate however, that the components present in the essential oils can be used in chemosystematic studies of these spore-forming plants. Compounds occurring in the essential oils constitute a powerful tool for studying chemical differences between or within liverwort species for which the characteristic components are mono- and sesquiterpenoids. Good results were obtained for the liverworts species from the genera Asterella, Conocephalum, Diplophyllum, Jungermannia, Lepidozia, Radula, Reboulia or Scapania.

Essential Oils' Chemical Characterization and Investigation of Some Biological Activities: A Critical Review.

This review covers literature data summarizing, on one hand, the chemistry of essential oils and, on the other hand, their most important activities. Essential oils, which are complex mixtures of volatile compounds particularly abundant in aromatic plants, are mainly composed of terpenes biogenerated by the mevalonate pathway. These volatile molecules include monoterpenes (hydrocarbon and oxygenated monoterpens), and also sesquiterpenes (hydrocarbon and oxygenated sesquiterpens). Furthermore, they contain phenolic compounds, which are derived via the shikimate pathway. Thanks to their chemical composition, essential oils possess numerous biological activities (antioxidant, anti-inflammatory, antimicrobial, etc…) of great interest in food and cosmetic industries, as well as in the human health field.

Essential Oils, Part III: Chemical Composition.

Data on the chemistry of essential oils which have caused contact allergy are provided. The largest group of chemicals found in essential oils consists of terpenes. The number of identified components usually ranges from 100 to 250, but in some oils (lavender, geranium, rosemary) 450 to 500 chemicals have been found. Many chemicals are present in a large number of oils, up to 98% for β-caryophyllene and 97% for limonene. Chemicals that are important constituents of >20 oils are limonene, linalool, and α-pinene. In many essential oils, there are 2 to 5 components which together constitute over 50% to 60% of the oil. In some oils, however, there is one dominant ingredient, making up more than 50% of the oil, including (E)-anethole in aniseed and star anise oil, carvone in spearmint oil, 1,8-cineole (eucalyptol) in Eucalyptus globulus oil, and (E)-cinnamaldehyde in cassia oil. The most important chemicals in 93 individual oils are specified.

In vitro flowering, glandular trichomes ultrastructure, and essential oil accumulation in micropropagated Ocimum basilicum L.

The aromatic and medicinal properties of Ocimum basilicum L. (sweet basil) are related to the unique essential oil chemistry in different cultivars. This study describes efficient micropropagation and in vitro flowering protocols from shoot tips and reveals information on seed germination capability, glandular trichomes ultrastructure, and essential oil content and composition at different plant developmental stages from micropropagated O. basilicum ‘Sweet Thai’, chemotype methyl chavicol. Shoot tips from 2-mo-old aseptic seedlings were induced to proliferate shoots on Murashige and Skoog (MS) medium supplemented with 6-benzyl-aminopurine (BAP) and gibberellic acid (GA3) either alone or in combination with α-naphthaleneacetic acid (NAA). Maximum shoot formation was achieved in MS medium supplemented with 1.0 mg L−1 BAP. The micropropagated plants were successfully acclimatized ex vitro with an 80% survival rate. All of the micropropagated plants flowered in vitro on MS medium supplemented with 1.0 mg L−1 GA3. Relative to the mother plant, in vitro plants flowered at a younger stage of plant development but showed a lack of seed formation, fewer fully filled peltate glandular trichomes, lower essential oil content, and higher methyl chavicol content. Ex vitro plants flowered at an intermediate stage of plant development and formed seed with nearly the same seed germinability, essential oil content, and methyl chavicol content as the mother plant.

Essential oil yields and qualities of different clonal lines of Salvia lavandulifolia monitored in Spain over four years of cultivation

The current knowledge about the medicinal properties and marketing possibilities of the Spanish sage (Salvia lavandulifolia Vahl.) requires additional studies about the management of this valuable species. To this end, essential oil yields and chemistries from eleven different mother plants collected in the wild and cultivated in a single plot were obtained and monitored during four years (2010, 2011, 2013 and 2014) at three different phenological stages ((LF) leaves formation-vegetative, (FB) full bloom and (SM) seed maturation). Significant differences have been found in the yield over the phenology being the maximum essential oil production at the stage of SM. Besides, the yield enhanced by both the shortage periods of rainfalls and the plant age with in turn a maximum average yield recorded of 4.15% v/w in SM in 2014, at the end of the experiment. However, no distinction by clonal lines could be made regarding yield. Essential oil chemistry conversely, showed deeply influenced by the genotype from which the material for hydrodistillation was taken. Thus, the main essential oil compound recorded was the oxygenated terpene 1,8-cineole (36.7% in average value for whole experiment), with other accompanying important components such as α-pinene (7.8 %), β-pinene+myrcene (14.5%), limonene (6.2%) and camphor (7.1%). Besides, unlike the yield, essential oil chemistry was only partially influenced by the year of harvest with no relevant changes according to the phenological stage of the plant. Thus, phytochemical differences found in nature in the first place largely and even wider remain when plant growing under a common environment. Hence, some new and stable chemotypes were described according to their high values of α-pinene (>10%), limonene (>17%), 1,8-cineole (>50%), camphor (>20%) and β-caryophyllene (>7 %). This information is highly relevant for standardizing, assuring crop quality and for the proper management of the Spanish sage cultivation.

In vitro antioxidant potentials and chemistry of essential oils and oleoresins from fresh and sun-dried Mentha longifolia L.

The present study was designed to assess differences in chemical composition and antioxidant potential of essential oils and oleoresins from fresh and sun-dried Mentha longifolia L. Essential oils and oleoresins were obtained by hydrodistillation and solvent extraction (n-hexane and ethanol), respectively. The chemical profile was evaluated by using gas chromatography (GC) and GC coupled to mass spectrometry (GC–MS). Antioxidant effectiveness was examined by five different methods, namely the ferric thiocyanate (FTC) method, the 2,2’-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method, determination of the metal chelating power, and determination of the peroxide and thiobarbituric acid values in mustard oil at 0.02% concentration. The chemical composition was dominated by the presence of piperitenone oxide, an oxygenated monoterpene whose composition varied from 23.2% to 88.5% in both essential oils and oleoresins. Based on the antioxidant potential of essential oils, oleoresins and synthetic antioxidants can be sorted in the following descending order: butylatedhydroxytoluene > dried mint essential oil > fresh mint essential oil > propyl gallate > fresh mint ethanol oleoresin > dried mint ethanol oleoresin > dried mint hexane oleoresin > fresh mint hexane oleoresin. The drying process has a significant influence on the qualitative and quantitative content of the extracted substances.

Invasion essentials: does secondary chemistry plasticity contribute to the invasiveness of Thymus vulgaris L.?

Increasing our understanding of spatial patterns of plant secondary chemistry variation may help us understand the mechanisms that underlie plant invasions involving species which exhibit chemical phenotypic variation. We analysed qualitative and quantitative variation in the essential oil terpenes produced by Thymus vulgaris L. (thyme) plants inside and at the edge of thyme-invaded plant communities on north- and south-facing slopes at ten sites across Central Otago, New Zealand. We tested the hypotheses that (1) there are foliar terpene composition quantitative and qualitative differences between the inside and edge of thyme-invaded communities and that these differences vary between north- and south-facing slopes and (2) that environmental variables affect the quantity and quality of thyme essential oil composition. Terpene concentrations were determined using ethanol extraction and GC FID/MS. Environmental data were collected from inside, at the edge and outside of thyme stands. We used multivariate statistical analysis to test differences in foliar terpene composition and linear modelling to investigate the effects of environmental variables on terpene composition. We found no evidence of a link between aspect- and invasion edge-related patterns of variation of thyme’s essential oil chemistry. Site-related differences for aspect and position in thyme stands indicated that thyme’s terpene production may be modulated by environmental factors such as soil moisture, clay, carbon, silt, sand, colloid, N and NH4+. The role of thyme’s novel chemistry in the processes that underlie the spatial patterns of thyme’s successful invasion is modulated by environmental factors.

Glandular Trichomes and Essential Oil of Thymus quinquecostatus

The distribution and types of glandular trichomes and essential oil chemistry of Thymus quinquecostatus were studied. The glandular trichomes are distributed on the surface of stem, leaf, rachis, calyx and corolla, except petiole, pistil and stamen. Three morphologically distinct types of glandular trichomes are described. Peltate trichomes, consisting of a basal cell, a stalk cell and a 12-celled head, are distributed on the stem, leaf, corolla and outer side of calyx. Capitate trichomes, consisting of a unicellular base, a 1–2-celled stalk and a unicellular head, are distributed more diffusely than peltate ones, existing on stem, leaf, rachis and calyx. Digitiform trichomes are just distributed on the outer side of corolla, consisting of 1 basal cell, 3 stalk cells and 1 head cell. All three types of glandular trichomes can secrete essential oil, and in small capitate trichomes of rachis, all peltate trichomes and digitiform trichomes, essential oil is stored in a large subcuticular space, released by cuticle rupture, whereas, in other capitate trichomes, essential oil crosses the thin cuticle. The essential oil of T. quinquecostatus is yellow, and its content is highest in the growth period. 68 constituents were identified in the essential oils. The main constituent is linalool.

Giovanni Dugo: a career devoted to the chemistry of essential oils

Giovanni Dugo: a career devoted to the chemistry of essential oils