José S. Dambolena

In vitro activity of natural phenolic compounds against fluconazole-resistant Candida species: a quantitative structure–activity relationship analysis

To evaluate the antifungal activity and to analyse the structure–activity relationship of eleven natural phenolic compounds against four Candida species which are resistant to fluconazole.

Aromatic plants of northwest Argentina. Constituents of the essential oils of aerial parts of seven Verbenaceae: Lantana and Aloysia.

Abstract The chemical composition of essential oil samples of the aerial parts of Lantana canescens, Lantana tilcarensis, Lantana trifolia, Aloysia citriodora, Aloysia gratissima, Aloysia castellanosii and Aloysia catamarcensis from northwest Argentina, phytogeographic areas of Yungas, Puna, Parque Chaqueño and Monte, have been analyzed by GC and GC/MS. The main oil component group present in the oils of the aerial parts of Lantana species were sesquiterpene hydrocarbons (> 24.8%). In contrast, the main compound group found in the oils of Aloysia species were oxygenated monoterpenes (> 19.6%). The comparison with previous studies performed by other authors points to a significant variation in the chemical composition of essential oil depending on the origin of the plants.

Terpenes: Natural Products for Controlling Insects of Importance to Human Health—A Structure-Activity Relationship Study

Many insects affect food production and human health, and in an attempt to control these insects the use of synthetic insecticides has become widespread. However, this has resulted in the development of resistance in these organisms, human diseases, contamination of food, and pollution of the environment. Plants natural products and essential oil components such as terpenes and phenylpropenes have been shown to have a significant potential for insect control. However, the molecular properties related to their insecticidal activity are not well understood. The purpose of this review is to provide an overview of the toxicity of terpene compounds against three insects of importance to human health: lice, cockroaches, and Triatominae bugs and to evaluate which molecular descriptors are important in the bioactivity of terpenes. For the insects studied, quantitative structure-activity relationship (QSAR) studies were performed in order to predict the insecticidal activity of terpene compounds. The obtained QSAR models indicated that the activity of these compounds depends on their ability to reach the targets and to interact with them. The QSAR analysis can be used to predict the bioactivities of other structurally related molecules. Our findings may provide an important contribution in the search for new compounds with insecticidal activity.

Effects of thymol and isoeugenol feed supplementation on quail adult performance, egg characteristics and hatching success

1. A study was conducted to evaluate whether feed supplementation with thymol or isoeugenol can alter Japanese quail growth rate and final body weight, the female onset of puberty, hen-day egg production and the physical and chemical characteristics of the egg, as well as its potential to alter hatchability. 2. From 4 to 16 weeks of age, birds from each cage (1 male: 3 females) were assigned to 1 of 3 treatments that differed in the supplement added to the feed: control, thymol or isoeugenol (400 mg/kg). The average ages (d) at first egg lay (FIRST), at 25% egg production (A25% EP), at 50% egg production (A50% EP) and weekly and cumulative hen-day egg production (HDEP) were calculated. In addition, physical and chemical characteristics of the eggs, their fertility and hatchability were also evaluated for each group. 3. Feed supplementation did not significantly affect growth rate, final body weight, egg production parameters, fertility and physical characteristics of egg or most of the fatty acid components of the yolk. 4. The group treated with isoeugenol showed an increase in the percentage of palmitoleic fatty acid compared to the control, with thymol group showing intermediates values. 5. Both thymol and isoeugenol supplemented groups showed increased hatchabilities, by 18·8% and 11·8%, respectively, compared to their control counterparts. 6. The improvement in the hatching success of the eggs from the thymol and isoeugenol supplemented groups without a negative impact on their performance may have important economic implications for future breeding programmes, particularly if these effects generalise from quail to other more commercially important poultry species, such as chickens or turkeys.

Essential Oils of Plants Used in Home Medicine in North of Argentina

Abstract Essential oils of the medicinal plants Satureja parvifolia, Satureja boliviana, Hyptis mutabilis, Leonorus sibiricus, Lippia turnerifolia, Xeroaloysia ovatifolia and Acantholippia salsoloides of north Argentina were analyzed by GC and GC/MS. Seventy-five compounds, representing more than 90% of the oils, were identified. The oils of both populations of S. parvifolia studied were characterized by a high content of piperitone (41.9% and 46%) and piperitenone oxide (50.1% and 49.3%). The most abundant constituents identified in S. boliviana oil were isomenthone (33%) and pulegone (25.3%). Hyptis mutabilis oil was characterized by β-phellandrene (27.1%) and β-caryophyllene (59.4%). The main constituents of L. sibiricus oil were the sesquiterpene hydrocarbons β-caryophyllene (35.2%), α-humulene (22.1%) and α-cubebene (18.4%). The oils of L. turnerifolia and X. ovatifolia also had a high content of sesquiterpenes. These were α-humulene (40.1%) and β-bisabolene (22.9%) in the oil of L. turnerifolia and β-caryophyllene (14.4%), (E)-nerolidol (10.5%), spathulenol (21.6%) and epi-α-cadinol (21.9%) in the oil of X. ovatifolia. Acantholippia salsoloides oil from Jujuy accumulated high contents of p-cymene (52.8%) and thymol (46.8%), while the oil from the population of Catamarca accumulated α-thujone (98.8%) as the major compound.

Thymol as natural antioxidant additive for poultry feed: oxidative stability improvement

ABSTRACT Antioxidant are regularly included in poultry feed as protection from deterioration during storage. Recently the interest for the use of natural phytochemicals in animal diets has been increased. Thymol (THY) has been proven to be an effective antioxidant for extending broiler meat quality during storage with similar action to the widely used butylated hydroxytoluene (BHT). This study evaluates whether THY can also have a protective effect on the feed mash by assessing its antioxidant potential and related changes in fatty acid (FA) balance. Feed mash was assigned to 1 of 4 treatments, control (CON, no additive), vehicle (VEH, ethanol 96%), BHT (400 mg BHT /kg feed) and THY (400 mg THY /kg feed). Three replicates of each treatment were taken after 0, 30, and 60 d of storage at room temperature (23 ± 3°C) and relative humidity (40 ± 5%). Peroxide value (PV), titratable acidity (TA) and FA relative composition were determined. As expected, there were no treatment effects on those variables at 0 d of storage. However, higher PV values were detected in the CON and VEH groups after 30 and 60 d of storage in comparison to the THY and BHT treated samples (CON = VEH > THY = BHT). While a slight increase was also observed in TA through storage time, no particular treatment effects were detected. Relative FA composition changed with storage time only in the CON and VEH group which had a decrease in polyunsaturated fatty acids and an increase in saturated FA. No changes were detected in the Thy and BHT treated feeds. The results suggest a similar THY and BHT protective effect on feed mash lipid oxidation. Thus, THY could be considered as a useful natural alternative to help sustain quality of poultry feed.

Biotransformation of 1,8-cineole by solid-state fermentation of Eucalyptus waste from the essential oil industry using Pleurotus ostreatus and Favolus tenuiculus.

Biotechnological conversion of low-cost agro-industrial by-products, such as industrial waste or terpenes from the distillation of essential oils from plants into more valuable oxygenated derivatives, can be achieved by using microbial cells or enzymes. In Argentina, the essential oil industry produces several tons of waste each year that could be used as raw materials in the production of industrially relevant and value-added compounds. In this study, 1,8-cineole, one of the components remaining in the spent leaves of the Eucalyptus cinerea waste, was transformed by solid-state fermentation (SSF) using the two edible mushrooms Pleurotus ostreatus and Favolus tenuiculus. As a result, two new oxygenated derivatives of 1,8-cineole were identified: 1,3,3-trimethyl-2-oxabicyclo [2.2.2]octan-6-ol and 1,3,3-trimethyl-2-oxabicyclo [2.2.2]octan-6-one. Additionally, changes in the relative percentages of other aroma compounds present in the substrate were observed during SSF. Both fungal strains have the ability to produce aroma compounds with potential applications in the food and pharmaceutical industries.

Essential Oil Composition of Three Species of Senecio from Argentina

Abstract The essential oils from the aerial parts of three species of Senecio (Senecio subulatus var. salsus, S. subulatus var. erectus, Senecio viridis and Senecio argophylloides.) were collected in different phytogeographic areas of Northern Argentina. The oils were obtained by hydrodistillation and characterized by GC and GC-MS analyses. Monoterpene hydrocarbons dominated the chemical profile of the oils with ß-pinene (17–31 %), p-cymene (18–33 %) and J-terpinene (16–54 %) as the main constituents of S. subulatus and Ot-thujene (13–32 %), camphene (53–9 %), sabinene (12–7 %) and ß-phellandrene (11–16 %) for S. argophylloides and S. viridis, respectively.