Use of chemical variation and predation as plant defenses byEncelia farinosa against a specialist herbivore

Larvae of the monophagous herbivore,Trirhabda geminata, selectively eat particular plants and plant parts of its natural host,Encelia farinosa. Measurements of leaf damage and larval positions on branches through time support this observation. Time-lapse movie photography revealed that larvae are sufficiently mobile to search most of a plant in a 48-hr period and that aggregations were the result of larval activity and not directly the result of oviposition. Experiments withT. geminata larvae on artificial diets containing a range of natural concentrations of chemical extracts fromE. farinosa leaves showed that the larvae grew significantly slower and had a lower overall survivorship at the high concentration. Combining the results of all choice tests, larvae appeared unable to distinguish between high- and low-concentration agar diets. Considered individually, larval preferences for natural production concentrations changed as the season progressed. Early-season larvae preferred low-concentration leaves, while late-season larvae preferred high-concentrations. Measurements of chemical and nitrogen content of leaves selected by larvae in the field confirmed this pattern. Percent parasitism in field-collected larvae increased with season as the larval population decreased. This combination of slowed growth and increasing parasitism and predation is a putative defense strategy ofEncelia farinosa to prevent adaptation by a specialist herbivore to the total range of compounds elaborated.     

The Plants of the Asteraceae Family as Agents in the Protection of Human Health

The Asteraceae family is one of the largest flowering plant families, with over 1600 genera and 2500 species worldwide. Some of its most well-known taxa are lettuce, chicory, artichoke, daisy and dandelion. The members of the Asteraceae have been used in the diet and for medicine for centuries. Despite their wide diversity, most family members share a similar chemical composition: for example, all species are good sources of inulin, a natural polysaccharide with strong prebiotic properties. They also demonstrate strong antioxidant, anti-inflammatory and antimicrobial activity, as well as diuretic and wound healing properties. Their pharmacological effects can be attributed to their range of phytochemical compounds, including polyphenols, phenolic acids, flavonoids, acetylenes and triterpenes. One such example is arctiin: a ligand with numerous antioxidant, antiproliferative and desmutagenic activities. The family is also a source of sesquiterpene lactones: the secondary metabolites responsible for the bitter taste of many plants. This mini review examines the current state of literature regarding the positive effect of the Asteraceae family on human health.     

Phytochemical Composition and Biological Activities of Scorzonera Species

The genus Scorzonera comprises nearly 200 species, naturally occurring in Europe, Asia, and northern parts of Africa. Plants belonging to the Scorzonera genus have been a significant part of folk medicine in Asia, especially China, Mongolia, and Turkey for centuries. Therefore, they have become the subject of research regarding their phytochemical composition and biological activity. The aim of this review is to present and assess the phytochemical composition, and bioactive potential of species within the genus Scorzonera. Studies have shown the presence of many bioactive compounds like triterpenoids, sesquiterpenoids, flavonoids, or caffeic acid and quinic acid derivatives in extracts obtained from aerial and subaerial parts of the plants. The antioxidant and cytotoxic properties have been evaluated, together with the mechanism of anti-inflammatory, analgesic, and hepatoprotective activity. Scorzonera species have also been investigated for their activity against several bacteria and fungi strains. Despite mild cytotoxicity against cancer cell lines in vitro, the bioactive properties in wound healing therapy and the treatment of microbial infections might, in perspective, be the starting point for the research on Scorzonera species as active agents in medical products designed for miscellaneous skin conditions.     

Formononetin 7-O-glucoside (ononin), an additional growth inhibitor in soils associated with the weed,Pluchea lanceolata (DC) C.B. Clarke (Asteraceae)

Formononetin 7-O-glucoside (ononin), an isoflavonoid, was isolated from the soils of cultivated areas associated with the perennial weed,Pluchea lanceolata. Aqueous solutions of this compound inhibited significantly root and shoot growth of mustard at 1×10^–4 M, 5×10^–4 M, and 1×10^–3M. The level of inhibition was similar to that of hesperidin and taxifolin 3-arabinoside, as reported earlier. The potential allelopathic effect of this compound under field conditions is discussed.     

Antifeedant and toxic effects of sesquiterpenes fromSenecio palmensis to colorado potato beetle

A bioassay-guided fractionation of the aerial parts ofSenecio palmensis resulted in the isolation of two sesquiterpenes, 2,10-bisaboladien-1-one and 11-acetoxy-5-angeloyloxy-silphinen-3-one. The bisabolene and the silphinene represented 0.012% and 0.024% of the plant dry weight, respectively. Both compounds showed antifeedant activity againstLeptinotarsa decemlineata larvae and adults in short-term choice and no-choice bioassays. Both compounds were also tested against different species of phytopathogenic fungi. The beetles were more sensitive to these compounds in choice than in no-choice assays, with a gradient of increasing sensitivity from second instars to adults. Bisabolene was 45 times less active as an antifeedant than juglone, which was tested as a positive control. The silphinen was more active than the bisabolene, with a range of activity similar to juglone. Furthermore, exposure of fourth instars to these compounds over a 24-hr period resulted in reduced feeding and growth rates. To distinguish between antifeedant and toxic effects, growth efficiencies were calculated as the slope of the regression of relative growth rate on relative consumption rate. The comparison of these results with those of antifeedant simulation and contact toxicity bioassays indicates that feeding inhibition is the primary mode of action of the bisabolene, while the silphinene shows both antifeedant and toxic effects.     

Seed germination and growth inhibitory cadinenes fromEupatorium adenophorum spreng

Chloroform extract of the aerial parts ofEupatorium adenophorum Spreng was fractionated and examined for growth inhibition. Bioassay-directed fractions of the plant materials afforded three known cadinenes and -sitosterol. The effects of different fractions as well as isolated cadinenes were determined usingAllium cepa, Raphanus sativus, andCucumis sativus seeds. Three-day exposure to these cadinenes significantly inhibited germination and seedling growth of all three assay seeds. The degree of inhibition was dependent upon seed species and the concentrations of the compounds tested. Cadinene(1) was found to be more inhibitory to the seeds tested and the activity of the cadinene(3) was less than that of(1) and(4).     

Triterpene alcohols and fatty acids in lipids and nonsaponifiable matter of Lapsana communis L. subspecies communis (Asteraceae)

The oil content of samples of aerial parts of Lampsana communis L. subsp. communis, harvested in Indre et Loire (France) at different periods, varies from 1.1 to 2.1%. Nonsaponifiable matter in these samples represents 36.0 to 65.7% of the oil. Yields of triterpene alcohols of nonsaponifiable matter (25.9 to 81.8%) were determined by preparative thin-layer chromatography after saponification. Seven of them were identified by gas chromatography-mass spectrometry (GC-MS). Six of the fatty acids in the aerial parts have also been identified by GC-MS. The seeds of L. communis contain 2.6% oil.     

Chemical analysis of edible aromatic plants growing in Tanzania

The volatiles from the aerial parts of edible plants growing in Tanzania, Leucas glabrata, Plectranthus laxiflorus, Salvia nilotica and Vernonia smithiana, were investigated by GC and GC/MS. Thirty-five compounds were identified from L. glabrata, representing 80.4% of the total oil; forty-three from P. laxiflorus (86.7%); twenty-four from S. nilotica (94.3%); and thirty-nine compounds from V. smithiana (92.9%). Among the identified components, menthone, (p + o)-cymene, trans-caryophyllene and caryophyllene oxide were found as the main ones. Furthermore, the essential oils were investigated for their antimicrobial activity as well as for their antiradical activity, through the DPPH method. Upon antimicrobial assays, the oil of V. smithiana showed very strong antimicrobial activity against Gram-positive bacteria, oral pathogens and pathogenic fungi; the oil of P. laxiflorus also exhibited strong activity, mostly against Gram-positive bacteria and especially oral pathogens, while L. glabrata showed strong activity against all assayed bacteria. The essential oil of S. nilotica appeared to have the most antioxidant activity but was almost inactive against all tested microorganisms.     

Coumarins of Matricaria chamomilla L.: Aglycones and glycosides

The identity and quantity of coumarin-like compounds in leaves and anthodia of Matricaria chamomilla L. were studied by LC-DAD and NMR. So far, two monosubstituted coumarins, herniarin and umbelliferone, and two herniarin precursors were identified therein. In this paper, two other coumarin glycosides and one aglycone were confirmed. Skimmin (umbelliferone-7-O-β-d-glucoside), daphnin (daphnetin-7-O-β-d-glucoside) and daphnetin (7,8-dihydroxycoumarin) were found for the first time in diploid and tetraploid leaves and anthodia of M. chamomilla L. Daphnetin is known as a strong sensitizer, so this compound and its glycosidic derivative can contribute to the allergic potential of chamomile. Commercial chamomile preparations were tested for their presence.