Screening the essential oil composition of wild Sicilian oregano

The qualitative and quantitative composition of the essential oils obtained from wild Sicilian oregano plants has been investigated. Samples were collected from three areas of Sicily namely Val Mazara (M), Val di Noto (N) and Val Demona (D). These areas are based on historical territorial subdivision. The essential oils were obtained by hydrodistillation and analyzed by GC-FID-MS. Seventy eight compounds were identified representing more than 98% of the compounds in the oils. All samples are thymol-chemotype with variable percentage of γ-terpinene, p-cymene, trans-sabinene hydrate, terpinen-4-ol and carvacrol. Statistical analyses were performed in order to evaluate the variability of the essential oils. Six groups were formed reflecting the compositional differences of the essential oil profiles of the wild Sicilian oregano samples.     

Screening of the essential oil composition of wild Sicilian thyme

Thirty samples of wild thyme collected from as many Sicilian locations have been analysed for their qualitative and quantitative essential oil profiles. The oils, obtained by hydrodistillation, have been analysed by a combination of GC-FID-MS; in all, 46 components, representing more than 98% of the oils, were fully characterized. Monoterpenes, both hydrocarbons and oxygenated, were the most highly represented components: the former with a range of 8–61% and the latter with a range of 31–86%. Carvacrol was the main compound in 29 samples, ranging between 49 and 83%, suggesting that Thymus capitatus Hoff. et Link. [syn. Coridothymus capitatus (L.) Rchb.f., Satureja capitata L., Thymbra capitata (L.) Cav.] is the most widespread wild species in the Sicilian area. Only one sample, identified as Thymus longicaulis C. Presl., collected from the North-East of Sicily showed a different composition, p-cymene and thymol being the main compounds with 40 and 16%, respectively. Statistical analyses allowed establishing a single broad group, confirming the substantial compositional uniformity of the essential oil profiles of the wild Sicilian thyme.     

Screening the essential oil composition of wild Sicilian fennel

Fifty-six samples of wild fennel (Foeniculum vulgare Mill.) have been collected in different localities of Sicily and analysed for their content in seed essential oils. The GC-FID-MS analyses allowed identifying 78 compounds, representing more than 98% of the oils. Phenylpropanoids are the most highly represented components – 55 samples show estragole as the main compound ranging between 34 and 89%, while (E)-anethole is the other phenylpropanoid ranging between 0.1 and 36%, although it only reaches appreciable values in a few samples, largely being present below 1%. The oxygenated monoterpene, fenchone, a typical fennel oil component, has been found in all samples, in the 2–27% range; α-pinene (1–21%), limonene (1–17%) and γ-terpinene (<1–4%) were the monoterpene hydrocarbons found in all samples. Only one sample showed piperitenone oxide and limonene as main components, with 42 and 34%, respectively, and with the lack of any phenylpropanoid. Sesquiterpenes and others compounds class had only negligible values or were not detected in all samples. Statistical analyses allowed to single out five groups, reflecting the compositional differences of the essential oil profiles of the wild Sicilian fennel.     

Chemotaxonomy of Hypericum genus from Portugal: Geographical distribution and essential oils composition of Hypericum perfoliatum, Hypericum humifusum, Hypericum linarifolium and Hypericum pulchrum

The geographical distribution and analysis of the essential oils of species from three sections of Hypericum L. (Guttiferae/Clusiaceae/Hypericaceae) from Portugal are presented. Hypericum perfoliatum (section Drosocarpium) grows wild in the centre and south of Portugal; Hypericum humifusum and Hypericum linarifolium are both from section Oligostema, the former occurring throughout the country, while the second is distributed mainly in the north and centre; Hypericum pulchrum (section Taeniocarpium) is confined to the littoral north of Portugal. The essential oils were obtained by distillation–extraction, hydrodistillation and distillation in a modified Marcusson apparatus from the dried aerial parts of the different populations and were analysed by GC and GC–MS. Monoterpene hydrocarbons constituted the main fraction in all oils (43–69%, 53–85%, 28–45% and 48–65% for H. perfoliatum, H. humifusum, H. linarifolium and H. pulchrum, respectively). Sesquiterpene hydrocarbons (2–13%, 6–18%, 21–27% and 16–18%, respectively) and a third fraction of non-terpenic compounds (20–29%, 3–16%, 2–14% and 5–11%, respectively) from the four species attained relatively high amounts in all oils. Within each species, no major differences were detected in the essential oil composition, despite the fact that different locations, phenological phases and extraction methodologies were used. Notwithstanding the dominance of α-pinene in all four species' oils, cluster and principal components analysis on the identified components showed that the range of α-pinene, β-pinene and n-nonane supported a separation of the four species. The essential oil composition of the four species showed some qualitative resemblances, which correlate well with the taxonomical classification based on morphological characters.     

Essential oil composition of Achyrocline flaccida (Weinm.) DC. (Asteraceae) from different locations of Argentina

The qualitative and quantitative composition of the essential oils obtained from the inflorescences of Achyrocline flaccida (Asteraceae) has been investigated for the first time. Plant material was collected from eleven locations in Argentina. The essential oils were obtained by hydrodistillation (0.1–0.8% v/w, dried material) and analyzed by GC–FID–MS. Eighty-three compounds were identified representing more than the 90% of the oils. The major components were α-pinene and β-caryophyllene. Statistical analysis was performed in order to evaluate the variability of the essential oils analyzed. Two groups were formed reflecting only quantitative differences in the content of major compounds. The chemical pattern of essential oils observed for A. flaccida is similar to other Achyrocline species studied, except Achyrocline hyperchlora.     

Essential oil of Ayapana triplinervis from Reunion Island: A good natural source of thymohydroquinone dimethyl ether

Three specimens of Ayapana triplinervis (Vahl) R.M. King & H. Rob from Reunion Island (Indian Ocean) collected at two distant locations (North of the island; samples 1 and 2, South of the island; sample 3), in different growth phases (flowering; samples 1 and 3, vegetative; sample 2) were investigated for their leaf essential oil composition. This study reports the chemical character of this species on the island and investigates the relationship between essential oil composition, developmental stage and geographic location. Analysis by GC–FID and GC–MS enabled us to identify and quantify a total of 39 constituents accounting for 97.1–98.0% of the oils. The three essential oil samples, all obtained by hydrodistillation, showed a high percentage of the aromatic compound thymohydroquinone dimethyl ether (89.9–92.8%). All other minor components remained more or less unchanged both qualitatively and quantitatively with respect to the stage of growth. On the contrary, variations were observed with geographic distribution. The geographical variation of the chemical composition of the volatile oil of A. triplinervis from several sites in the world is also briefly discussed.     

Chemotypes of Achillea millefolium transferred from 14 different locations in Lithuania to the controlled environment

The composition of essential oils hydrodistilled from 19 samples of inflorescences and leaves of Achillea millefolium L. plants, which were transferred from 14 natural habitats in Lithuania to the field collection, is reported. Total content of oil was 0.15–0.55% in inflorescences and 0.06–0.19% (v/w) in leaves. In total 117 compounds were identified positively or tentatively. Data obtained clearly indicate the presence of a remarkable chemical polymorphism within the population of A. millefolium in Lithuania. The content of the major constituents in the oils from inflorescences varied in the following ranges: β-pinene, 0.33–62.29%; β-myrcene, 0.05–69.76%; α-phelandrene, 0.13–29.96%; 1,8-cineole, 2.30–21.57%; and chamazulene, 0.08–30.70%. According to the major components the essential oils' six chemotypes of A. millefolium were defined.     

Volatile composition and antimicrobial activity of twenty commercial frankincense essential oil samples

Trees from the genus Boswellia (Burseraceae) are traditionally used as a medicine, a fumigant, in various cosmetic formulations and in aromatherapy in several countries around the world. This plant produces a commercial oil known as frankincense which has a woody, spicy and haunting smell. Frankincense oil has several pharmacological properties, of which many elude to the anti-infective potential. Variation in the chemical composition of this oil has been reported in literature. These factors prompted an investigation to study the commercial frankincense oils from various international suppliers. Twenty essential oils were analyzed by gas chromatography coupled to mass spectrometry. Considering the major constituents, the oils were found to be qualitatively similar. However, there was immense quantitative variation for certain oil constituents. The components identified and their range in the oils include α-pinene (2.0–64.7%); α-thujene (0.3–52.4%); β-pinene (0.3–13.1%); myrcene (1.1–22.4%); sabinene (0.5–7.0%); limonene (1.3–20.4%); p-cymene (2.7–16.9%) and β-caryophyllene (0.1–10.5%). The antimicrobial activity (minimum inhibition concentration assay) of the oils was investigated against five reference test organisms and the activity ranged from 4–16 mg/ml (Staphylococcus aureus); 1.5–8.3 mg/ml (Bacillus cereus); 4.0–12.0 mg/ml (Escherichia coli); 2.0–12.8 mg/ml (Proteus vulgaris) and 5.3–12.0 mg/ml (Candida albicans).     

Wild Sicilian Rosemary: Phytochemical and Morphological Screening and Antioxidant Activity Evaluation of Extracts and Essential Oils

To identify the best biotypes, an extensive survey of Sicilian wild rosemary was carried out by collecting 57 samples from various sites, followed by taxonomic characterization from an agronomic perspective. All the biotypes collected were classified as Rosmarinus officinalis L. A cluster analysis based on the morphological characteristics of the plants allowed the division of the biotypes into seven main groups, although the characteristics examined were found to be highly similar and not area‐dependent. Moreover, all samples were analyzed for their phytochemical content, applying an extraction protocol to obtain the nonvolatile components and hydrodistillation to collect the essential oils for the volatile components. The extracts were characterized by LC‐UV‐DAD/ESI‐MS, and the essential oils by GC‐FID and GC/MS analyses. In the nonvolatile fractions, 18 components were identified, namely, 13 flavones, two organic acids, and three diterpenes. In the volatile fractions, a total of 82 components were found, with as predominant components α‐pinene and camphene among the monoterpene hydrocarbons and 1,8‐cineole, camphor, borneol, and verbenone among the oxygenated monoterpenes. Cluster analyses were carried out on both phytochemical profiles, allowing the separation of the rosemary samples into different chemical groups. Finally, the total phenol content and the antioxidant activity of the essential oils and extracts were determined with the Folin–Ciocalteu (FC) colorimetric assay, the UV radiation‐induced peroxidation in liposomal membranes (UV‐IP test), and the scavenging activity of the superoxide radical (O$\rm{{_{2}^{{^\cdot} -}}}$ ). The present study confirmed that the essential oils and organic extracts of the Sicilian rosemary samples analyzed showed a considerable antioxidant/free radical‐scavenging activity.     

Larvicidal and adulticidal activity of essential oils from plants of the Lamiaceae family against the West Nile virus vector,Culex pipiens (Diptera: Culicidae)

Culex pipiens mosquitoes are the most widely distributed primary vector of the West Nile virus worldwide. Many attempts for investigation of botanical pesticides to avoid the development of pesticide resistance to conventional synthetic pesticides that are recognized as a threat to the diversity of ecosystems. The study aimed to determine the components of three essential oils of Lamiaceae family, lavender (Lavandula angustifolia), peppermint (Mentha piperita L.), and rosemary (Rosmarinus officinalis L.) by gas chromatography-mass spectrometry (GC–MS) analysis. Furthermore, aimed to validate the insecticidal activities of these oils as larvicidal agents against the third instar larvae of Culex pipiens using five different concentrations (62.5, 125, 250, 500, and 1000 ppm) for each oil in five replicates and as an adulticidal agent against approximately three-day-old female adults of Cx. Pipiens using 0.5, 1, 2, 4, and 5% concentrations in three replicates. The results generally showed a dose-related response. At 1000 ppm, rosemary oil showed the highest larvicidal (100%) (LC₅₀, 214.97 ppm), followed by peppermint oil (92.00% mortality and LC₅₀ (269.35 ppm). Lavender oil showed the lowest efficacy with 87.20% mortality and LC₅₀ (301.11 ppm). At 5% oil concentration, the highest knockdown rate at 1 h was recorded for lavender oil (95.55%), followed by peppermint oil (88.89%) and lastly rosemary oil (84.44%). After 24 h, rosemary oil showed the lowest adult mortality rate (88.89%; LC₅₀, 1.44%), while lavender and peppermint oils both showed a 100% mortality rate, with (LC₅₀, 0.81% and 0.91%, respectively). The chemical constituents of the oils consisted of monoterpenes and sesquiterpenes that determined their insecticidal activities against the target insect stage. The study proposed that rosemary essential oil may be useful for the control of Cx. pipiens larvae as part of an integrated water treatment strategy, and lavender and peppermint oils may be used in an integrated plan for adult’s control.     

Chemical composition and larvicidal activity of essential oils from Piper species

The larvicidal activity of essential oils of four species of Piper from the Amazon Forest was tested using third-instar larvae of Aedes aegypti. The oils were extracted by steam distillation and analyzed by GC and GC–MS. The main components isolated from each Piper species were as follows: viridiflorol (27.50%), aromadendrene (15.55%) and β-selinene (10.50%) from Piper gaudichaudianum; β-selinene (15.77%) and caryophyllene oxide (16.63%) from Piper humaytanum; dillapiol (54.70%) and myristicin (25.61%) from Piper permucronatum; and asaricin (27.37%) and myristicin (20.26%) from Piper hostmanianum. Amongst all essential oils tested, the most active against larvae of A. aegypti was the oil extracted from P. permucronatum, with a LC₅₀ = 36 μg/ml (LC₉₀ = 47 μg/ml), followed by the essential oil of P. hostmanianum, with a LC₅₀ = 54 μg/ml (LC₉₀ = 72 μg/ml). The oils with higher content of arylpropanoids were more active against larvae of A. aegypti.     

In vitro and in vivo screening of essential oils for the control of wet bubble disease of Agaricus bisporus

Proliferation of fungal pathogens, such as Mycogone perniciosa, can severely affect the yields of cultivated mushrooms, including that of the button mushroom, Agaricus bisporus. A reduction in the number of fungicidal products approved for commercial application is currently providing new challenges to the mushroom industry. Forty essential oils, seven pure terpenoids and one phenylpropanoid were screened in vitro to determine the abilities of these substances to inhibit the growth of M. perniciosa. The fungal growth medium of both A. bisporus and M. perniciosa was supplemented with each test substance at a concentration of 50 μL/L. Ten essential oils were further investigated at lower concentrations ranging from 5 to 40 μL/L. The main components of these oils were determined by GC–FID and GC–MS. Lemon verbena (Lippia citriodora), lemongrass (Cymbopogon citratus) and thyme (Thymus vulgaris) oils were found to substantially inhibit the growth of the pathogen, while demonstrating lower toxicity towards A. bisporus than any of the other oils tested. A preliminary in vivo trial using M. perniciosa-inoculated casings revealed that the preventative use of lemon verbena or thyme oils was able to control the development of the disease. A commercial trial using these oils, as well as two of their main components (nerol and thymol), at a concentration of 40 μL/L, revealed that none of these treatments were detrimental to the growth of the A. bisporus and an overall yield similar to that following application of a commercial fungicide (Chronos 450 SC) was obtained. These results suggest that essential oils or mixtures of selected pure components of essential oils may in future find application in button mushroom production, either as a substitute for synthetic fungicides or as an additional protective measure.     

Essential Oils,Silver Nanoparticles and Propolis as Alternative Agents Against Fluconazole Resistant Candida albicans,Candida glabrata and Candida krusei Clinical Isolates

Development of effective and safe therapeutic treatment of fungal infections remains one of the major challenge for modern medicine. The aim of presented investigation was to analyze the in vitro antifungal activity of selected essential oils, ethanolic extracts of propolis and silver nanoparticles dropped on TiO₂ against azole-resistant C. albicans (n = 20), C. glabrata (n = 14) and C. krusei (n = 10) clinical isolates. Among tested essential oils, the highest activity has definitely been found in the case of the oil isolated from the bark of Cinnamomum cassia, with MIC and MFC values for all tested strains in the range of 0.0006–0.0097 % (v/v) and 0.0012–0.019 % (v/v), respectively. High activity was also observed for the Lemon, Basil, Thyme, Geranium and Clove (from buds) essential oils. Significant differences in fungicidal activity have been observed in the case of four tested propolis samples. Only one of them revealed high activity, with MFC values in the range from 0.156 to 1.25 % (v/v). Satisfactory fungicidal activity, against C. albicans and C. glabrata isolates, was also observed in the case of silver nanoparticles, however C. krusei isolates were mostly resistant. We also revealed that constituents of most of essential oils and propolis as well as silver nanoparticles are not substrates for drug transporters, which belong to the most important factors affecting resistance of Candida spp. clinical isolates to many of conventional antimycotics. To conclude, the results of our investigation revealed that essential oils, propolis and silver nanoparticles represent high potential for controlling and prevention candidiasis.     

Insecticidal activity and chemical composition of the essential oil of Artemisia vestita from China against Sitophilus zeamais

In our screening program for new agrochemicals from local wild plants, essential oil of Artemisia vestita Wall (Asteraceae) was found to possess strong insecticidal activity against maize weevil, Sitophilus zeamais Motsch. Essential oil of aerial parts of A. vestita was obtained from hydrodistillation and was investigated by GC and GC–MS. The main components of essential oil were grandisol (40.29%), 1,8-cineol (14.88%) and camphor (11.37%). The essential oil of A. vestita possessed strong fumigant toxicity against S. zeamais adults with a LC₅₀ value of 13.42 mg/L air. The essential oil of A. vestita also showed contact toxicity against S. zeamais adults with a LD₅₀ value of 50.62 mg/adult.     

Distribution and essential oils of Salvia pomifera subsp. pomifera (Labiatae) on the island of Crete (S Greece)

The distribution of Salvia pomifera subsp. pomifera (Cretan sage) on the island of Crete is presented. The essential oils of six populations scattered on the island are studied. The essential oil content varies from 2.1–4.2%, whereas the main oil components were in all cases α- and/or β-thujone (27.4–72.3% and 7.1–40.8%, respectively). The comparison of our results to literature data, suggest that S. pomifera can be distinguished from S. fruticosa (Greek sage), on the basis of its essential oil composition.     

Laurus novocanariensis essential oil: Seasonal variation and valorization

We investigated the qualitative and quantitative seasonal variation of the leaf and fruit oils of the Macaronesian endemism Laurus novocanariensis and their plant defensive potential. The monoterpene fraction dominated the leaf (74%) and berry essential oils (73–44%, ripe–unripe). The insect antifeedant effects of these oils were species- and season-dependent against the aphids (Myzus persicae and Rhopalosiphum padi). Overall, the biological effects of these oils correlated with the oxygenated terpene fraction. Among the pure components tested, β-caryophyllene and its oxide were strong antifeedants to Leptinotarsa decemlineata and Spodoptera littoralis. The aphids responded to β-ocimene, β-pinene, 1,8-cineole, linalool (antifeedants) and linalool oxide (attractive to M. persicae). The antifungal effects of the leaf oils on Fusarium spp. were season-dependent. β-Caryophyllene oxide proved to be a strong antifungal. L. novocanariensis oils inhibited Lactuca sativa germination and radicle elongation, the leaves being more effective. Linalool also inhibited seed germination.     

Comparative analysis of volatiles from Drimys brasiliensis Miers and D. angustifolia Miers (Winteraceae) from Southern Brazil

The essential oils obtained from Southern Brazilian native Drimys brasiliensis Miers and Drimys angustifolia Miers were analyzed by GC and GC/MS. The oils from leaves of both species showed predominance of monoterpenoids, while the oils from stem barks were characterized by sesquiterpenoids. Bicyclogermacrene (20.0% in leaves and 25.4% in stem bark) and drimenol (1.4% in leaves and 26.2% in stem bark) were the most abundant in D. angustifolia, and cyclocolorenone (from 16.0% to 32.3% in fresh and dried leaves and almost 50% in stem bark) in D. brasiliensis. The oil from fruits of D. brasiliensis was also analyzed and presented 31.0% of cyclocolorenone. The predominance of this unusual aromadendrane-type sesquiterpene in D. brasiliensis essential oils could be used as a chemosystematic marker.     

Antimicrobial Activities of the Essential Oils of Various Plants against Tomato Late Blight Disease Agent Phytophthora infestans

The aim of this study was to find an alternative to synthetic fungicides currently used in the control of devastating oomycete pathogen Phytophthora infestans, causal agent of late blight disease of tomato. Antifungal activities of essential oils obtained from aerial parts of aromatic plants such as oregano (Origanum syriacum var. bevanii), thyme (Thymbra spicata subsp. spicata), lavender (Lavandula stoechas subsp. stoechas), rosemary (Rosmarinus officinalis), fennel (Foeniculum vulgare), and laurel (Laurus nobilis), were investigated against P. infestans. Both contact and volatile phase effects of different concentrations of the essential oils used were determined by using two in vitro methods. Chemical compositions of the essential oils were also determined by GC-MS analysis. Major compounds found in essential oils of thyme, oregano, rosemary, lavender, fennel and laurel were carvacrol (37.9%), carvacrol (79.8), borneol (20.4%), camphor (20.2%), anethole (82.8%) and 1,8-cineole (35.5%), respectively. All essential oils were found to inhibit the growth of P. infestans in a dose-dependent manner. Volatile phase effect of oregano and thyme oils at 0.3 μg/ml air was found to completely inhibit the growth of P. infestans. Complete growth inhibition of pathogen by essential oil of fennel, rosemary, lavender and laurel was, however, observed at 0.4–2.0 μg/ml air concentrations. For the determination of the contact phase effects of the tested essential oils, oregano, thyme and fennel oils at 6.4 μg/ml were found to inhibit the growth of P. infestans completely. Essential oils of rosemary, lavender and laurel were inhibitory at relatively higher concentrations (12.8, 25.6, 51.2 μg/ml respectively). Volatile phase effects of essential oils were consistently found to be more effective on fungal growth than contact phase effect. Sporangial production was also inhibited by the essential oil tested. Light and scanning electron microscopic (SEM) observation on pathogen hyphae, exposed to both volatile and contact phase of oil, revealed considerable morphological alterations in hyphae such as cytoplasmic coagulation, vacuolations, hyphal shrivelling and protoplast leakage.     

Antimicrobial activity of certain natural-based plant oils against the antibiotic-resistant acne bacteria

The unceasing emerging of multidrug-resistant bacteria imposes a global foremost human health threat and discovery of new alternative remedies are necessity. The use of plant essential oil in the treatment of many pathogenic bacteria is promising. Acne vulgaris is the most common skin complaint that fears many people about their aesthetic appearance. In this work we investigated the antibacterial activity of some plant oils against acne-inducing bacteria. Three bacterial isolates were identified from Egypt, biochemically and by means of 16s rRNA gene typing, and were designated as Staphylococcus aureus EG-AE1, Staphylococcus epidermidis EG-AE2 and Cutibacterium acnes EG-AE1. Antibiotic susceptibility test showed resistance of the isolates to at least six antibiotics, yet they are still susceptible to the last resort Vancomycin. In vitro investigations of eleven Egyptian plant oils, identified tea tree and rosemary oils to exhibit antibacterial activity against the antibiotic-resistant acne isolates. Inhibition zones of 15 ± 0.5, 21.02 ± 0.73 and 20.85 ± 0.76 mm was detected when tea tree oil applied against the above-mentioned bacteria respectively, while inhibition zones of 12.5 ± 1.5, 15.18 ± 0.38 and 14.77 ± 0.35 mm were detected by rosemary oils. Tea tree and rosemary oils exhibited bacteriostatic and bactericidal activity against all the strains with MICs/MBCs ranging between 39-78 mg/L for tea tree oil and 39–156 mg/L for rosemary oil. All the isolates were killed after 4 and 6 h upon growing with 200 mg/L of tea tree and rosemary oils, respectively. Additionally, gas chromatography mass spectrometry (GC/MS) profiling identified and detected a variable number of antimicrobial compounds in both oils.     

Chemical and biological profiles of Lavandula luisieri essential oils from western Iberia Peninsula populations

The chemical composition and biological activity of wild Lavandula luisieri (Rozeira) Rivas-Martínez populations from the south Beira interior region in central eastern Portugal are described. The essential oils of these four populations have been analyzed by GC–MS, and their antifeedant effects evaluated against Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi. Relative concentration data (% values) was subjected to principal component and cluster analysis. Relative concentration data and antifeedant effects were subjected to a stepwise multiple regression analysis. Additionally, one of these populations has been adapted to experimental field cultivation.