JULIO ZYGADLO

The main strategies against Triatoma infestans (primary vector responsible for the Chagas disease transmission) are the elimination or reduction of its abundance in homes through the application of insecticides or repellents with residual power, and environmental management through the improvement of housing. The use of plant-derived compounds as a source of therapeutic agents (i.e., essential oils from aromatic plants and their components) is a valuable alternative to conventional insecticides and repellents. Essential oil-based insect repellents are environmentally friendly and provide reliable personal protection against the bites of mosquitoes and other blood-sucking insects. This study investigates, for the first time to our knowledge, the potential repellent activity of Zuccagnia punctata essential oil (ZEO) and poly(ε-caprolactone) matrices loaded with ZEO (ZEOP) prepared by solvent casting. The analysis of its essential oil from aerial parts by GC–FID and GC-MS, MS allowed t...

The PHA and ConA mitogens are able to stimulate to CD3+ T cells included (¿/¿ ¿/¿) CD4+ and CD8+ T cells leading to its polyclonal activation. Minthostachys verticillata (Griseb.) Epling commonly known as "peperina" is an aromatic bush that grow in the north-west and central regions of Argentina. Its essential oil has demonstrated anti-allergic and lymphoproliferative properties in vitro. In this work, the in vitro effects of pure compounds isolated of the essential oil of M verticillata: pulegone, menthone and limonene, like polyclonals activators on human lymphocytes, were investigated. The cells, isolated from peripheral blood, were cultured in independent assay and stimulated with PHA, ConA, pulegone, menthone or limonene. In addition co-stimulated cultures with: pulegone/men-thone, pulegone/limonene, menthone/limonene and pulegone/menthone/limonene in per-centtage similar to which is these compounds in the vegetable (63% of pulegone, 16% of menthone and 2% of limonene...

ABSTRACT Essential oils obtained from the inflorescences of ACHYROCLINE SATUREIOIDES (Lam.) DC, ACHYROCLINE ALATA (HBK) DC and ACHYROCLINE TOMENTOSA Rusby, collected from central Argentina, were analyzed by GC and GC/MS. Fifty-two compounds representing 93-98% of the oils were identified. Caryophyllene was the most abundant component in all oils studied (39-48%).

The essential oil from aerial parts of Grindelia discoidea was analyzed by GC and GC/MS. Forty-six components were identified, representing more than 95% of the oil. The main constituents were ( E,E)-farnesol (> 9.0%) and ( Z,E)-farnesol (> 15.7%).

The essential oils of the aerial parts of three Baccharis species ( B. articulata, B. myrtilloides, and B. rufescens) were examined by GC and GC/MS. The major constituents were for B. articulata: beta-caryophyllene (16.8%), trans-nerolidol (15.6%); for B. myrtilloides: germacrene D (9.5%) and for B. rufescens: limonene (14.4%) and trans-nerolidol (14.5%).

Phenolic compounds removal is a very active research field due to occurrence and the toxicity of phenolic pollutants in industrial wastewaters. In order to make an a priori selection of the most efficient removal process for a target structure this contribution reviews and compares some of the mechanistic aspects of the oxidation in the presence of hydrogen peroxide and catalyzed by complexed iron which is the in-common element in Fenton systems, plant peroxidases and biomimetics. Different substrates were considered from the most basic phenol molecule to complex structures such as phenolic dyes and lignins. The reactivity of iron is related to its microenvironment generated by ligands and their electron withdrawing capacity thus conditioning the type of cleavage induced on hydrogen peroxide and the oxidation state change on iron upon reaction. The relative concentrations of organic to inorganic free radicals generated control the main catalytic action; i.e. from degradation up to mineralization in Fenton systems or oligomerization up to polymerization in plant peroxidases systems. Moreover, some reaction conditions as the peroxide concentration, the initial molar ratio of organic compounds to peroxide and the type of reaction solvent are identified as key factors to promote a desired action mechanism by peroxidases (and their biomimetics).

Plant tissues may show chemical changes following damage. This possibility was analyzed for Minthostachys mollis, a Lamiaceae native to Central Argentina with medicinal and aromatic uses in the region. Effects of mechanical damage on its two dominant monoterpenes, pulegone and menthone, were analyzed by perforating M. mollis leaves and then assessing essential oil composition at 24, 48, and 120 hr; emission of volatiles was also measured 24 and 48 hr after wounding. Mechanical damage resulted in an increase of pulegone and menthone concentration in M. mollis essential oil during the first 24 hr. These changes did not occur in the adjacent undamaged leaves, suggesting a lack of systemic response. Postwounding changes in the volatiles released from M. mollis damaged leaves were also detected, most noticeably showing an increase in the emission of pulegone. Inducible chemical changes in aromatic plants might be common and widespread, affecting the specific compounds on which commercial exploitation is based.

Italian oregano (Origanumxmajoricum) was subjected to root system inoculation with three species of plant growth-promoting rhizobacteria (PGPRs) (Pseudomonas fluorescens, Bacillus subtilis, Azospirillum brasilense), and essential oil (EO) content and plant growth were measured. Composition of monoterpenes, a major EO component, was analyzed qualitative and quantitatively by gas chromatography. Total EO yield for plants inoculated with P. fluorescens or A. brasilense was 3.57 and 3.41 microg/mg fresh weight, respectively, approximately 2.5-fold higher than controls, without change of quantitative oil composition. The major EO compounds, cis- and trans-sabinene hydrate, gamma-terpinene, carvacrol, and thymol, showed increased biosynthesis. Carvacrol was the only terpene showing significant increase of R% in plants inoculated with A. brasilense. Plant growth parameters (shoot and root fresh and dry weights, numbers of leaves and nodes) were evaluated. Shoot fresh weight was significantly increased by all three PGPR species, but only P. fluorescens and A. brasilense increased root dry weight. These two species have clear commercial potential for economic cultivation of O.xmajoricum. Knowledge of the factors affecting yield and accumulation of monoterpenes is essential for improving production of these economically important plant compounds.

Plant tissues may show chemical changes following herbivory. In aromatic plants such changes could affect the specific compounds on which commercial exploitation is based. This possibility was analyzed for Mintosthachys mollis, a member of the Lamiaceae native to Central Argentina with medicinal and aromatic uses in the region, and two types of insect herbivores: a leaf miner and a gall insect. Analysis of the essential oils of mined/undamaged leaves, as well as leaves from stems with and without galls, revealed changes in concentrations of the two main monoterpenes. A decrease in pulegone concentration was associated with both types of insect damage, whereas menthone increased significantly only in mined leaves. Inducible chemical changes in aromatic and medicinal plants may be common and widespread; their economic implications deserve investigation.

Plants display a diverse array of inducible changes in secondary metabolites following insect herbivory. Herbivores differ in their feeding behavior, physiology, and mode of attachment to the leaf surface, and such variations might be reflected in the induced responses of damaged plants. Induced changes were analyzed for Minthostachys mollis, a Lamiaceae with medicinal and aromatic uses, and four species of folivore insects with different feeding habits (chewing, scraping, sap-sucking, and puncturing). In M. mollis leaves experimentally exposed to the insects, levels of the two dominant monoterpenes pulegone and menthone were assessed 24 and 48 h after wounding. Menthone content generally decreased in the essential oil of damaged leaves, whereas pulegone concentration increased in all treatments. These changes occurred also in the adjacent undamaged leaves, suggesting a systemic response. The relatively uniform response to different kinds of damage could be attributable to the presence of such a strongly active compound as pulegone in the essential oil of M. mollis. The effects of wounding on essential oil concentration may be significant from a commercial point of view.

The antifungal, antibacterial, and insect-repellent activities of the essential oils (EOs) of Acantholippia seriphioides, Artemisia mendozana, Gymnophyton polycephalum, Satureja parvifolia, Tagetes mendocina, and Lippia integrifolia, collected in the Central Andes area, province of San Juan, Argentina, were investigated. The dermatophytes Microsporum gypseum, Trichophyton mentagrophytes, and T. rubrum were inhibited by the EOs of G. polycephalum, L. integrifolia, and S. parvifolia, with minimum inhibitory concentrations (MICs) between 31.2 and 1000 μg/ml. Moreover, all EOs presented moderate activity against the bacteria tested, and the L. integrifolia and G. polycephalum EOs showed excellent repellent properties against Triatoma infestans, the Chagas disease vector, with repellency values between 60 and 100%. The A. seriphioides, G. polycephalum, and L. integrifolia EOs, obtained by hydrodistillation, were characterized by GC-FID and GC/MS analyses. The highest number of components (40) was identified in L. integrifolia EO, which, along with that of A. seriphioides, contained important amounts of oxygenated monoterpenes (44.35 and 29.72%, resp.). Thymol (27.61%) and carvacrol (13.24%) were the main components of A. seriphioides EO, and borneol, lippifoli-1(6)-en-5-one, and terpinen-4-ol (>8.5%) were the principal compounds of L. integrifolia EO. These results support the idea that oxygenated monoterpenes are the bioactive fractions of the EOs. Finally, the study shows that these Andean species might be used to treat superficial fungal infections and to improve the local Chagas disease situation by vector-control.

Plant defensive mechanisms against herbivores include chemical changes following damage. Effects of feeding punctures produced by Liriomyza huidobrensis (pea leafminers) adult females on the plant's dominant monoterpenes, pulegone and menthone were assessed ...