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The essential oil obtained from the bark of Cinnamomum zeylanicum Blume (Lauraceae) and three of its main components, eugenol, (E)-cinnamaldehyde, and linalool (representing 82.5% of the total composition), were tested in two in vitro models of peroxynitrite-induced nitration and lipid peroxidation. The essential oil and eugenol showed very powerful activities, decreasing 3-nitrotyrosine formation with IC50 values of 18.4 microg/mL and 46.7 microM, respectively (reference compound, ascorbic acid, 71.3 microg/mL and 405.0 microM) and also inhibiting the peroxynitrite-induced lipid peroxidation showing an IC50 of 2.0 microg/mL and 13.1 microM, respectively, against 59.0 microg/mL (235.5 microM) of the reference compound Trolox. On the contrary, (E)-cinnamaldehyde and linalool were completely inactive.

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

The composition of the essential oils of ten Centaurea species from Turkey, Centaurea aladaghensis, C. antiochia var. prealta, C. antitauri, C. babylonica, C. balsamita, C. cheirolepidoides, C. deflexa, C. iconiensis, C. lanigera, C. ptosimopappoides have been studied. Multivariate statistical analyses (Principal Component Analysis, Multidimensional Scaling, Hierarchical Cluster Analysis) applied to GC-MS data, seem to be very useful to investigate and establish the natural taxonomic delimitation of this very difficult genus. The groupings resulted independent from the ecological similarities (i.e. plants that live in the same habitats or share similar morphological characteristics), so it seems that the environment has no influence on the biosynthesis of the volatiles of these plant