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In recent years, antimicrobial activities of essential oils have been intensively explored, mainly in researching and developing new antimicrobial agents to overcome microbial resistance. The present study investigates the chemical composition and antimicrobial activities of essential oils obtained from two Asteraceae: Asteriscus graveolens (Forssk.) Less. and Pulicaria incisa (Lam.) DC. Chemical analysis was performed using a combination of capillary GC-FID and GC/MS analytical techniques. The major component of Asteriscus graveolens were cis-chrysanthenyl acetate (31.1%), myrtenyl acetate (15.1%), and kessane (11.5%), while for Pulicaria incisa the main components were chrysanthenone (45.3%) and 2,6-dimethylphenol (12.6%). The oils obtained from the aerial parts were tested against sixteen microbial strains by agar well diffusion technique and dilution methods and showed minimum inhibitory concentrations (MIC) in the range of 19 - 1250 μg/ml. A good antibacterial activity against a common nosocomial pathogen, Acinetobacter baumanniiATCC 19606 was observed, especially from Pulicaria incisa essential oil, with a MIC value up to 19 μg/ml. These results give significant information about the pharmacological activity of these essential oils, which suggest their benefits to human health, having the potential to be used for medical purposes., (© 2017 Wiley-VHCA AG, Zurich, Switzerland.)

The aim of this study was to assess the percentage and constituents variations in flowers and leaves essential oil of three Glebionis coronaria (L.) Tzvelev population, growing wildly in three different ecotypes (Utique, M'saken, and Sahara Lektar) in Tunisia. The chemical compositions of these essential oils were analyzed by the GC and GC/MS systems. Qualitative and quantitative differences were recorded between essential oils extracted from plants collected from the three geographical provinces and between organs of the same plant (leaves and flowers). In fact, 161 components representing 87.2 - 96.5% of the whole oils were identified. Myrcene (3.2 - 35.7%), (Z)-β-ocimene (0.6 - 23.0%), camphor (0.6 - 17.2%), cis-chrysanthenol (0 - 6.9%), cis-chrysanthenyl acetate (1.1 - 17.9%), isobornyl acetate (1.6 - 3.5%), (E)-β-farnesene (0 - 6.0%), germacrene D (0 - 8.7%), and (E,E)-α-farnesene (0.7 - 12.4%) were the predominant components in the oils. These major constituents occur in different amounts depending on the organs (leaves or flowers) and the geographical origin of the plant. The chemotaxonomic usefulness of these data was discussed according to results of principal component analysis (PCA). The scores, together with the loadings, revealed a different chemical pattern for each population., (© 2016 Wiley-VHCA AG, Zürich.)

The composition of the essential oil (EO) obtained from dry leaves of Chiliadenus bocconei Brullo (Asteraceae subfam. Inulae), a Maltese endemic aromatic plant, collected in two different seasons, was evaluated in this work. The main EO components identified in the summer foliage were camphor (25.6%), borneol (27.1%) and τ-cadinol (13.9%). In the winter foliage τ-cadinol was the most represented compound (59.5%), followed by camphor (13.1). A comparison is also made between the EO composition of the two samples of C. bocconei and the EO obtained from different aerial parts of C. lopadusanus, an endemic plant of Lampedusa Island, another Mediterranean Island.

The essential oil obtained by hydrodistillation of the flowering capitula of Coleostephus myconis (syn. Chrysanthemum myconis) was constituted almost exclusively of oxygenated sesquiterpenes (85.8%). The main constituent was T-cadinol (66.2%), followed by valeranone (8.2%), germacrene D (6.0%) and alpha-cadinol (4.6%). By mean of the SPME technique, the volatiles emitted in vivo by the whole capitula and by tubular and ligulate florets have been identified. Many differences were evidenced among the different organs and with respect to the essential oil.

The seasonal variation of the essential oil, in terms of both yield and composition, of a population of Santolina etrusca (Asteraceae) is reported in detail for different aerial parts, including sterile branches, fertile branches, and capitula. The yields generally increased from November to June, and then decreased in August and September. The main constituents of the sterile branches were 1,8-cineole and viridiflorol. The oil from fertile branches was characterized by myrcene as principal compound, whereas the essential oil obtained from the capitula contained germacrene D as the main constituent. Several compounds, as identified by GC and GC/MS, were found to prevail during the cold season.

The roots of Centaurea bracteata Scop. (Asteraceae) have been studied for the first time. Twenty-three compounds were isolated and identified, namely a sterol glucoside, two quinic acid derivatives, one sugar, and 19 flavonoids (five sulphates), one of which, centaradixin, resulted in a new natural product. Structural elucidation was performed mainly by means of FABMS, 1D and 2D NMR spectroscopy. NMR data of some sulphate flavonoids are reported for the first time.

The flowering aerial parts of Centaurea bracteata Scop. (Asteraceae) have been studied for the first time. Nineteen compounds were isolated and identified, namely a sterol glucoside, two phenolic acids, three quinic acid derivatives, and 13 flavonoids, two of which, are new natural products. Structural elucidation was performed mainly by mean of FABMS, 1D and 2D NMR spectroscopy.

A new natural compound, horridin (1), was isolated from the aerial parts of Centaurea horrida. Its structure as quercetin 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-rhamnopyranoside was determined by spectroscopic methods, including 2D NMR.

The aim of this study was to test the botanical family of Asteraceae as a source of natural herbicides. Twenty Asteraceae species were collected during flowering time and evaluated in terms of the yield and quality of essential oils (germination inhibition and growth of weeds). Half the species showed a sufficient yield of essential oil (from about 0.1% to 1.43%) when testing these phytochemicals in vitro as germination inhibitors of two typical weeds, Amaranthus retroflexus and Setaria viridis. Despite the higher tolerance of S. viridis, the concentration of 100 μg L−1 of essential oils of the two Artemisia species and Xanthium strumarium could totally inhibit germination. In addition, at 10 μg L −1, the same essential oils showed full inhibition of A. retroflexus seeds. A comparison of their effectiveness at suboptimal doses led to a further selection of the most promising sources of essential oils. After their chemical characterisation, the essential oils were tested as post-emergence herbicides on seedlings of the above-cited weeds. After spraying the weeds at different concentrations (10, 100 and 1000 mg L−1) during two different phenological stages of weed seedlings (cotyledons and the third true leaf), the essential oils of Artemisia annua and X. strumarium showed the best performance. The essential oils of X. strumarium were then tested again on both weeds to monitor the dynamics of plant injury. A reduction in plant fresh weight (about 20%-30% after 10 days) and chlorophyll content (destroyed, after the same amount of time) was found, thus confirming the total and rapid effectiveness of these essential oils. In summary, A. annua and X. strumarium have elicited considerable agronomic interest and appear to be suitable as a source of essential oils to act as natural herbicides. [ABSTRACT FROM AUTHOR]

The essential oils obtained from two endemic Centaurea species (Compositae) from Turkey, C. pseudoscabiosa subsp. pseudoscabiosa Boiss. et Buhse (Sect. Acrocentron) and C. hadimensis Wagenitz, K. Ertugrul et H. Dural (Sect. Psephelloideae), have been studied. Germacrene D was the major component (36.0 and 44.3%, respectively), followed by β-caryophyllene, bicyclogermacrene and β-sesquiphellandrene. [Copyright &y& Elsevier]

The volatile oil obtained by hydrodistillation from the leaf of Eclipta indica L. was analyzed for its constituents by means of GC and GC/MS. 2-Tridecanone (89.7%), a straight chain ketone, was the singly most abundant constituent. Caryophyllene oxide (3.9%) and β-caryophyllene (2.6%) were the other compounds occurring in sizeable proportions. [ABSTRACT FROM AUTHOR]