Biological Activity of Hybrid Molecules Based on Major Constituents of Cinnammomun verum and Thymus vulgaris Essential Oils.

Plants have been used by humans since ancient times due their antimicrobial and medicinal properties. Essential oils (EOs) are complex mixtures of secondary plant metabolites, including terpenoids, phenylpropanoids, and other aromatic compounds. Cinnamomun verum and Thyme vulgaris EOs and their organic extracts exert numerous biological activities because of their major compounds, particularly thymol, carvacrol, eugenol, and benzoic and cinnamic acid. The structural motifs presented by these phytochemicals are responsible for their biological activities. Modification or hybridization of these structures could lead to new bio-based compounds with improved efficacy or multiple modes of action. In this work, we aimed to develop reliable methods of obtaining six hybrid molecules from the major constituents of C. verum and T. vulgaris EOs. For the first time, we tested their efficacy in the inhibition of the mycelium growth and spore germination of two of the most important phytopathogenic fungi, Fusarium oxysporum and Colletotrichum gloeosporioides, and one opportunistic human pathogen, Aspergillus niger. The cytotoxic activity of the obtained hybrids was assessed using the brine shrimp lethality assay. In addition, we report for the first time a biocatalytic process for the obtention of these bioactive hybrid molecules. The results of this work enable the possibility of using hybrid molecules based on the major constituents of EOs as active ingredients in strategic industries such as agriculture, aquaculture, and pharmaceuticals.

Biopesticide Activity of Guayule Resin.

The extensive use of synthetic pesticides has created considerable concern for both human health and the environment, which has prompted the search for safer alternatives, such as the resin of guayule (Parthenium argentatum). Thus, in the present study, we aimed to test the biopesticide activity of crude guayule resin and three derived fractions and compare them to reference products that act against four of the most economically significant plant pests: Tetranychus urticae, Bemisia tabaci, Myzus persicae and Frankliniella occidentalis. None of the guayule products caused plant damage. The crude guayule resin and the hexane and ethyl acetate fractions displayed moderate to high contact mortality against T. urticae and B. tabaci, as well as moderate to high antifeedant activity against T. urticae, B. tabaci and M. persicae. No significant activity was observed against F. occidentalis. A correlation analysis of the activity and fraction composition revealed that guayulins C and D, isoargentatins A and B, argentatins A, B and D and an unknown compound C6 were likely responsible for the contact mortality. By contrast, the antifeedant activity appeared to be caused by guayulins A and B against T. urticae and B. tabaci and by guayulins C and D and argentatin B against M. persicae. The feeding reduction in F. occidentalis was associated with an unknown compound C2 and argentatin C. Therefore, guayule appears to be a promising novel biopesticide.

Absolute configuration of the ocimene monoterpenoids from Artemisia absinthium.

The absolute configuration (AC) of the naturally occurring ocimenes (-)-(3S,5Z)-2,6-dimethyl-2,3-epoxyocta-5,7-diene (1) and (-)-(3S,5Z)-2,6-dimethylocta-5,7-dien-2,3-diol (2), isolated from the essential oils of domesticated specimens of Artemisia absinthium, followed by vibrational circular dichroism (VCD) studies of 1, as well as from the acetonide 3 and the monoacetate 4, both derived from 2, since secondary alcohols are not the best functional groups to be present during VCD studies in solution due to intermolecular associations. The AC follows from comparison of experimental and calculated VCD spectra that were obtained by Density Functional Theory computation at the B3LYP/DGDZVP level of theory. Careful nuclear magnetic resonance (NMR) measurements were compared with literature values, providing for the first time systematic 1 H and 13 C chemical shift data. Regarding homonuclear 1 H coupling constants, after performing a few irradiation experiments that showed the presence of several small long-range interactions, the complete set of coupling constants for 3, which is representative of the four studied molecules, was determined by iterations using the PERCH software. This procedure even allowed assigning the pro-R and pro-S methyl group signals of the two gem-dimethyl groups present in 3.

Phytotoxic and Nematicidal Components of Lavandula luisieri.

Several preparations were obtained from the aerial parts of predomesticated Lavandula luisieri, including the essential oil and ethanolic, hexane, and ethyl acetate extractives. Additionally, pilot plant vapor pressure extraction was carried out at a pressure range of 0.5-1.0 bar to give a vapor pressure oil and an aqueous residue. A chemical study of the hexane extract led to the isolation of six necrodane derivatives (1, 2, and 4-7), with four of these (1, 2, 5, and 7) being new, as well as camphor, a cadinane sesquiterpene (9), tormentic acid, and ursolic acid. The EtOAc and EtOH extracts contained a mixture of phenolic compounds with rosmarinic acid being the major component. Workup of the aqueous residue resulted in the isolation of the necrodane 3 and (1R*,2S*,4R*)-p-menth-5-ene-1,2,8-triol (8), both new natural compounds. The structures of the new compounds were established based on their spectroscopic data. The phytotoxic and nematicidal activities of these compounds were evaluated.

Selective nematocidal effects of essential oils from two cultivated Artemisia absinthium populations.

Essential oils (EOs) obtained from two crops and populations of thujone-free cultivated Artemisia absinthium were tested against two nematode models, the mammalian parasite Trichinella spiralis, and the plant parasitic root knot nematode Meloidogyne javanica. The EOs were characterized by the presence of (Z)-epoxyocimene and chrysanthenol as major components and showed time and population dependent quantitative and qualitative variations in composition. The EOs showed a strong ex vivo activity against the L1 larvae of the nematode Trichinella spiralis with a reduction of infectivity between 72 and 100% at a dose range of 0.5-1 mg/ml in absence of cytotoxicity against mammalian cells. Moreover, the in vivo activity of the EO against T. spiralis showed a 66% reduction of intestinal adults. However, these oils were not effective against M. javanica.

Trypanocidal, trichomonacidal and cytotoxic components of cultivatedArtemisia absinthium Linnaeus (Asteraceae) essential oil

Artemisia absinthium is an aromatic and medicinal plant of ethnopharmacological interest and it has been widely studied. The use ofA. absinthiumbased on the collection of wild populations can result in variable compositions of the extracts and essential oils (EOs). The aim of this paper is the identification of the active components of the vapour pressure (VP) EO from a selected and cultivated A. absinthiumSpanish population (T2-11) against two parasitic protozoa with different metabolic pathways: Trypanosoma cruzi andTrichomonas vaginalis. VP showed activity on both parasites at the highest concentrations. The chromatographic fractionation of the VP T2-11 resulted in nine fractions (VLC1-9). The chemical composition of the fractions and the antiparasitic effects of fractions and their main compounds suggest that the activity of the VP is related with the presence oftrans-caryophyllene and dihydrochamazulene (main components of fractions VLC1 and VLC2 respectively). Additionally, the cytotoxicity of VP and fractions has been tested on several tumour and no tumour human cell lines. Fractions VLC1 and VLC2 were not cytotoxic against the nontumoural cell line HS5, suggesting selective antiparasitic activity for these two fractions. The VP and fractions inhibited the growth of human tumour cell lines in a dose-dependent manner.

Trypanocidal, trichomonacidal and cytotoxic components of cultivated Artemisia absinthium Linnaeus (Asteraceae) essential oil.

Artemisia absinthium is an aromatic and medicinal plant of ethnopharmacological interest and it has been widely studied. The use ofA. absinthium based on the collection of wild populations can result in variable compositions of the extracts and essential oils (EOs). The aim of this paper is the identification of the active components of the vapour pressure (VP) EO from a selected and cultivated A. absinthium Spanish population (T2-11) against two parasitic protozoa with different metabolic pathways: Trypanosoma cruzi and Trichomonas vaginalis. VP showed activity on both parasites at the highest concentrations. The chromatographic fractionation of the VP T2-11 resulted in nine fractions (VLC1-9). The chemical composition of the fractions and the antiparasitic effects of fractions and their main compounds suggest that the activity of the VP is related with the presence of trans-caryophyllene and dihydrochamazulene (main components of fractions VLC1 and VLC2 respectively). Additionally, the cytotoxicity of VP and fractions has been tested on several tumour and no tumour human cell lines. Fractions VLC1 and VLC2 were not cytotoxic against the nontumoural cell line HS5, suggesting selective antiparasitic activity for these two fractions. The VP and fractions inhibited the growth of human tumour cell lines in a dose-dependent manner.